| Risto80 |
Finished Car Amplifier schematic + PCB based on Kenwood KAC-716
This Project is Car amplifier and its basic parts- SMPS, Amplifier, Preamplifier and Protection circuit witch are based on originally schematic from service manual of Kenwood Car amplifier KAC-716.
I have work on this project about five mounts and it WORKS.
From originally schematic of KAC-716, I have made PCBs separately for SMPS, Amplifier, Preamplifier and Protection sow it can be build very easy.
All electronics capacitor from Amplifier, Preamplifier and Protection are 50 volts range. Input capacitors 2x 3300uf/16volts and output capacitors 2x2200uf/50volts and additionally 2x1500uf/50volts should have 105 C temperature ranges.
All documents are in PDF format and JPEG. The PCBs are in original sizes.
The SMPS is not regulated so the output voltage will depend on turns ratio in ferrite core. I used 2 x 4 turns primary wire and for second it depends of why high will be the output voltage.
By choosing a proper resistance for resistor R222/1W connected with pin 6 of UPC1237 we must set up maximum current of 80mA. The valley of R222 depends of internal resistance of relay and supply. For better calculation download the datasheet for UPC1237 form Internet-Read the note for using UPC1237 and you can understand what kind of other protections are given from this ICs and used in this design.
The amplifier has specifications:
Max Power Output (4ohm)
.. 240Wx1 (at 100Hz)
Rated Power Output (4ohm)
....120Wx1 (0.08% THD at 100Hz)
Rated Power Output (4ohm)
... 160Wx1 (0.8% THD at 100Hz)
Signal to Noise Ratio
.. 100dB
Sensitivity (MAX)
.. 0.15V
Sensitivity (MIN)
... 4.0V
Input Impedance
.10Kohm
Low-Pass Filter (12dB/oct.)
. 30-200Hz (Variable)
Operating Voltage
..14,4V (11~16V allowable)
Current Consumption (1 kHz, 10% THD, 4ohm)
..15A
Know I will put schematic and PCB for this project and these days also I will put pictures of this project. |
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| Risto80 |
| KAC-716-SMPS-PCB-THE OTHER ONE IS DAMAGE SOW I POST NEW ONE. |
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| Risto80 |
| KAC-716-SMPS-PCB-REPAIRD |
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| Risto80 |
| KAC-716- Amplifier- Schematic |
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| Risto80 |
| KAC-716- Amplifier- PCB |
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| Risto80 |
| KAC-718- Preamplifier- Schematic |
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| Risto80 |
| KAC-718- Preamplifier- PCB |
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| Risto80 |
| KAC-716- Protection- Schematic |
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| Risto80 |
| KAC-716- Protection- PCB |
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| wolfpack |
how many wires in the primary and how many turns and wires in the secondary do you have used.
what kind of toroidal?
thanks! |
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| kpero |
I study your SMPS PCB layout and I see you add one tranzistor and some P-CON pin. What's that? I didn's saw that on shematic.
And question about amplifier. Is it possible to use with 2 ohm, or can I make two of this module and bridge it. And what's nominal power for this amplifier?
Thanks |
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| kpero |
A find that P-COM on protection board but still don't know what's that?
And also on protection board is some feedback. Where is that connected |
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| Risto80 |
Hello
First about calculating the number of primary and secondary windings, you must refer to valveaudio site and project of making car amplifier from ESP projects site.
Second. The P-CON pin from SMPS is connected to Protection PCB.I forgot to put P-CON pin on SMPS schematic. P-CON pin is supply voltage for IC PWM TL494. When you turn off the amplifier, it sometimes causes a shock-off noise, there for is necessary to break off the relay and then to keep the power amplifier apart from speaker at the moment when car amp will go off. This is basic function of P-CON pin. Also the TH1-2k2 witch you will put on a heatsink, will prevent of over-hitting the amplifier.
The Feedback pin from Protection PCB is connected to Amplifier pin feedback for feedback the signal witch will get through relay.
The amplifier is Kenwood and I have made it exactly as the originally just separately PCBs and it can drive 2 ohm speaker.
Max Power Output (4ohm)
.. 240Wx1 (at 100Hz)
Rated Power Output (4ohm)
....120Wx1 (0.08% THD at 100Hz)
Rated Power Output (2ohm)
... 160Wx1 (0.8% THD at 100Hz) |
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| fachri |
Could you also inform how you get those voltages (15V 40V) from a car battery. Any schematic for the inverter ?
Thanks |
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| kpero |
There is shematic and pcb attachment on first page. kac-716 smps pcb and shematic. One file is .zip and one is .pdf
Risto
Is this amp heat's a lot with one pair of output transistor? How did you make cooling on amp? |
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| fachri |
| Yes I have seen all 3 of the schematic/pcb lay out. But none of them shows how to get +/-15V, +/-40 V from a standard car battery. I have also read a toroidal transformer was mentioned earlier in this post. This transformer I believe could be part of the inverter that produces those voltages. Can anybody give me some more informations on this? of which I thank you very much. |
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| kpero |
You don't cache thing?
Here is shematic of smps:
http://www.diyaudio.com/forums/atta...tamp=1116957078
and here is pcb layout for smps:
http://www.diyaudio.com/forums/atta...tamp=1116957686
Smps -or switch mode power suply is DC-DC converter which convert 12 V car batery voltage to +/ 40V in our case.
+/15 V you get from power amp when you paralel zener diode to input voltage for amp. In this case you can drain max 500 ma from zener.
If you still don't cache thing then you must learn basic of power managment which I can't explain you here |
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| fachri |
Hi KPERO;
Thanks for the pictures/info. |
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| Risto80 |
| Here is a picture of car amp+ preamp. |
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| Risto80 |
| Other picture of car amp+ preamp.These days I will put picture of SMPS and complete car amplifer |
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| kpero |
| There is no picture in a last post. |
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| tady |
where is the part's list? only the resistors and capacitors are labled.
i don't know witch IC is witch and also the transistors? |
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| anil |
hi ,
you have mentioned that your smps,amp,preamp is based on Kenwood KAC-716 . could you please post the original kenwood schematics (as used in kenwood amp) for reference purpose . i would be highly obliged.
anil |
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| mwmkravchenko |
Check out post #1
Mark |
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| cfog88 |
Hi!
I have seen quite a few references to winding a ferrite core, but haven't yet managed to find a good source for ferrite cores. Where did you get yours?
Thanks,
Chjris |
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| leinahtan |
| Thanks for those pdf. and zip. files.........it was a big boost to a hobbysist like me |
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| Risto80 |
Now days I will post pictures of finished car amplifier KAC-716. ALso I am finishing car amplifier based on KAC-529S - 2x70W.
The promotional materilas will be shown here on this site.
Thanks |
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| leinahtan |
| quote: | Originally posted by cfog88
Hi!
I have seen quite a few references to winding a ferrite core, but haven't yet managed to find a good source for ferrite cores. Where did you get yours?
Thanks,
Chjris |
hi, i've been looking for it here in my country...and i found out that those apc ups have it because it has an inverter 12v to 220volts....and probably all ups and inverter are a good source....hope you find one...good luck |
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| mwmkravchenko |
| quote: | | Source of Transformer / Core Post #26 |
As above you will find the needed cors in computer power supplies.
Mark |
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| N-Channel |
| quote: | Originally posted by cfog88
Hi!
I have seen quite a few references to winding a ferrite core, but haven't yet managed to find a good source for ferrite cores. Where did you get yours?
Thanks,
Chjris |
Chris,
Try Amidon Incorporated out of California. For power conversion, they stock ferrite toroid cores in the #77 material that can handle up to 1.5kW at 40kHz! For energy storage (as in the output inductor in an SMPS), they stock powdered-iron toroid cores in the #26 material up to 5.200" (O.D.)!
Their entire catalogue can be downloaded from their website, at:
www.amidoncorp.com
I have made many SMPSs with toroids from Amidon for both the power transformer and the output inductor, with great results.
Steve :cool: |
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| leinahtan |
| Hi, RISTO80....i just want to know the switching frequency of your smps via the schematic diagram of KAC-716 scheme......i am kinda confused about it.. |
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| leinahtan |
| Hello everyone especially to RISTO80.....i have posted here the schematic diagram below......of JBL-50 SMPS and i would like to know if you have a way to design the pcb layout like the one you posted upon the modification of KAC-716 SMPS.....i think its the same but different in mosfet used...Kindly look it up for our references... thank you |
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| arasuk |
Hi, RISTO80,
Have you finished this project, can you give more details on the pre amp and amp, Whats the turns for the ferrite .
Thanks
Arasuk |
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| MosfetBoy |
I'm surprised to see so many amps with no regulation on the switchmode.
If you look at the Elliot Sound Products web page, their switchmode is regulated ( can be seen at http://sound.westhost.com/project89.htm#fig9)
The only drawback with this one is that there is no temperature shutdown on their design, which i think i'd want if it was in a car. |
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| aman |
hi RISTO80
I built the smps of kenwood amp as per ur schematic and layout .I used a toroidal stripped off from an old car amplifier (35-0-35, primary 6+6 and secondary 12+12) though the output voltage is ok but as soon as i connect the load (amplifier) the bridge rectifier diodes 35Amp/400volt start becoming hot. I didnt use the remote transistor c925 and a1534 as i have connected the +12v directly to the ic. I dont have the scope to determine the frequency wave.What could be the problem.
regards |
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| Risto80 |
Hello to everybody
I am glad to see that the interest of this project is very big.
Firs of all now days my project is finish I now days I am testing with 12 sub speaker and it works very good. I will put digital and more clearance picture when I find data cable for Minolta Damage X.
I will answer for some questions:
The switching frequency is determined with RT-resistor 16k and CT-capacitor 1nf witch are connected with pin 6 and pin 5. The approach is done with equation Fclk= 1/(RTxCT). So RT=16k and CT=0.001uf and Fclk=62.5Khz.You can read more from valveaudio site.
I used standard ferrite core with primary turns 2x4 turns and secondary 2x12 turns and I have +/-37 volts.
The schematic of JBL-50 SMPS will not work wit amp of that design. Better is to build the smps of Kenwood because is more powerful and better designed.
About the regulation of SMPS. Most trade marks like Kenwood used non regulation system because is more powerful and the fets is not so hot.
And for aman. The toroid and winding is good. Used the transistors for remote control dont connected direct to +12 volts to pin of TL494.
For bridge rectifier you used regular of fast recovery bridge rectifier. You must used fast bridge rectifier the regular one will always burn.
Also check the wirings from bridge and the PCB because the PCB is not design for bridge rectifier. Check if you connected correctly.
By for know and if you have any questions put them on this site. |
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| aman |
Hi Risto80
I made the smps work.I used the fast diode now MUR22 and correctrly inserted the 1000p in the output of the toroidal which i wrongly connected before. I used it with my existing amplifier and it sounded awesome,smps is really powerful and the mosfets and the toroidal are cool.
However there is something wrong in the pcb tracks for the diodes MUR22 i.e the secondary of the toroidal should go to the center pins of the diodes and the. so i also corrected the tracks on my pcb. I also used another toroidal with more secondary and it gave me 56-0-56 volts.I m thinking of using it for an amp using 2* a1943/c5200 working on 56-0-56 for which i have only made the pcb and not filled it with components yet. What are ur suggestions??
regards
Aman |
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| arasuk |
Hi Aman
Great to hear that your smps works , which amp did you check with, and where could you get the toroids,
whats the primary & secondary turns & whats the wire guage.
Thanks
Arasuk:D :D :D |
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| aman |
Hi Arasuk
I tested the smps with a car amp using tip2955/3055 in the output. I first disconnected its own 35-0-35 from its smps supply ,just disconnected the jumper to the amp section. I got the toroidal core from the lajpat rai market in delhi.The shop has got every king of ferrite core.I bought 3-4 pieces of the cores of 2cm and 3cm inner diameter.There are 6+6 turns in the primary and 12+12 in the secondary.I dont remember the wire guage but i used double wires of 20guage i think for the primary and single wire of 19guage for the secondary. sorry......i am not sure abt the wire guage. But if u wanna really wanna know the guage i will tell u.
regards
Aman
Aman_4g@yahoo.com |
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| kpero |
Hi Aman
I see you used small toroidal core. How much power did you get with that 2 cm core.
best regards, Pero |
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| aman |
hi kpero,
The core is 2cm. i think it is suitable for a 100wrms car amp....
:)regards
Aman |
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| sagarverma |
hi aman
i had used the 4.5cm diameter core for my smps from ESP.the small core that u used,i also used that one but for tests only.the smps is a blast.tested it with power res. and heavy duty power supply at my college.it was supplying 900w of continous power without any sign of strain on the core!!!!the small core became hot(not warm) during small operations(80w or so)..i dunno what is its peak out bec i didnt go further but 900w is more than enough.so i have a very powerful power supply for any amp in the car:D |
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| aman |
hi Sagar,
900watt continuous is great power and that too without any problem. I too have got a 4.5 cm toroid but it has been wounded for 30-0-30 volt which was driving a 4 channel car amp. Someday i will rewind the secondary and add more turns to get 60-0-60 and use it in another smps project(kenwood schematic) of Risto80 which i would use for the 300watt subwoofer amp of esp(which i have already built and tested with a 40-0-40 transformer) for my car. Sagar...I dont have o'scope and just got a cheap DMM. So there are some problems in measurements to do some learning. Anyway which amp are u going to connect that smps with.
best regards from
Aman,Delhi:) |
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| sagarverma |
hi aman
i had never anticipated that the smps would go so high.the car battery will be drained in less than an hour at this power(however smps can go higher than that,i believe!!)
i will use tda7294 for two subs(poineer 12").and pioneer ts(not lajpat rai dupplies) series speakers for with tda1554q.this was original plan but with so much of power at disposal,i think i can think about bridging of tda7294 as well as to get some monsterous power i m looking at tda7293 ic in modular application.
the whole setup is biamped with 12db/octave lr active filter.
i willl finish up soon |
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| sagarverma |
| have u built the preamp given out here?i have tlo72 opamps.are they sufficient?is the preamp good? |
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| aman |
hi sagar
i too used 7294 one or two year back with the 12" pioneer TSW304C made for 1.2cuft sealed enclosure.And also used the tda1514a.The 7294 was good for the bass coz it has got mosfets in the output and the 1514a was good for mid and treble .I used them both in single and in bridged mode with 2nd order active low pass filter with the 7294 amp.It sounded thundering with my homebuild 2way speakers.
I haven't build the preamp using tl072 but i have made many low and high pass filters and bass boost circuits with it.However i built the preamp using bc550/560 from the esp.
regrds |
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| sagarverma |
i have sony discman which has a very low o/p for the amp.
i want a good preamp.please advise. |
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| aman |
hi sagar
The output from the discman is not enough to drive an amp like tda7294 efficiently.I have only built the pre amp project 37 from the esp site which works very good and cant say abt tl072.However u can use the simplest preamp using ne5532 from the same site .
hope this will help u
regrds
Aman_4g@yahoo.com |
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| sagarverma |
is ne5532 available in lr market?shop no.,min qnty,cost etc plz.u built on vero or pcb.do u have pcb layout?
is the o/p of chinese discman higher than sony? |
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| aman |
hi sagar,
ne5532 are available in plenty in LR ,one shop no. is 559 and others are mehta electronics,UMI electronics and kamrit electronics. I dont remember their number exactly but i think they are 3xx and 4xx. They can give u even one piece and it costs abt 10Rs.
regrds
The preamp can very easily be assembled on a veroboard. I dont have any discman.I have got only LG DVD player. |
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| sagarverma |
thanks aman
will post results soon |
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| sagarverma |
hey,
anyone please see the preamplifier posted here in this thread
please tell me about the pots used
sw1 has five leads??????:confused:
the pot to the right of sw1 has six leads??????:confused:
what r these???
if i dont want to use them.then to make direct connections what point on pcb must be connected by jumpers
help req.
thanks in advance. |
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| anil |
hi sagar
i m from bangalore . please tell me how much tda7294 costs . i have so far used lm3886 & lm3875 . could you tell me how tda 7294 compares to lm 3886 in performance
anil |
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| sagarverma |
hi anil
i got them for Rs130 each
very great ic.
noise rejection is superior than lm series.power is also great with solid punch
but lm series has great low freq response so go 4 tda if u need clarity in upper and lows go 4 lm if u need good low freq response(high freq response bit low)
all in all both r good.my vote for tda(i dunno y but i simply love these,both tda7293 and 7294,currently listening to this chip :-)
sagar |
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| ataxerxes2 |
Hi guys. Am building a low cost booster for my car audio and picked on the TDA 1555q in stereo bridge config(22W/channel). Problem is, on powering this device, it draws a crazyishly large current(>20A) even on no signal and no load. I eventually discovered that cutting power to the second amplifier(pin 5) reduces current to a modest 150mA. Fine, i decide to test with just this one channel. And on connecting a signal source powered from same battery, the quiescent current drops to 0mA, and of course no output!. I discovered the signal ground pin causes this whenever you attach it to power ground, i dont know why. The output dc voltage is also 9.5V instead of about 6.9V. As you probably know, the TDA 1555Q requires almost no external components, so i dont know what i could have been doing wrongly. 'Ve also tried to keep my leads reasonably short. Pls Help
N.B.
I've experienced similar probs with the TDA 2005 before |
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| MosfetBoy |
These things sure do churn out some power.
I have made a similar design using SG3525 control IC, 3x10000uF caps on input, 100uH input inductor, 8 x sfp50n06 as switchers, etd/pst39 as a core. the windings are 8x0.5mm strands of insulated wire and i seem to be able to take about 400W of power before the core starts heating up quite radically. voltage out is 35V.
At 300W its ok still so i think the core is saturating. When this happens, the mosfets start heating up a bit too.
Do you have any specs on the 4.5cm core being used? I would really like to get my hands on one.
At 900W, there would be enough reserve power for _ANY_ event :) hehehehe
Regards
John |
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| MosfetBoy |
| quote: | Originally posted by ataxerxes2
Hi guys. Am building a low cost booster for my car audio and picked on the TDA 1555q in stereo bridge config(22W/channel). Problem is, on powering this device, it draws a crazyishly large current(>20A) even on no signal and no load. I eventually discovered that cutting power to the second amplifier(pin 5) reduces current to a modest 150mA. Fine, i decide to test with just this one channel.
N.B.
I've experienced similar probs with the TDA 2005 before |
I have had that too.
1) connect 100nF cap between power supply pins ( i.e. on chip)
2) connect 220uF cap between power supply pins ( i.e. on chip)
3) place 100K resistor between inputs and ground.
It looks to me like your chip is oscillating and hence will be drawing huge amounts of power. the second channel may be blown.
Try the caps and resistors ... if not... try some asprin :) or a new chip
Which circuit diagram are you working off ? |
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| weq_wijaya |
hi risto
when i saw u'r smps schematic,what transistor n MOSFET type u use? |
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| bullit_90 |
Nice amplifier risto :D
do you have a list of the all components used in the project?
thanks Henning |
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| Nordic |
I am looking for some educational links for beginning to work with SMPS supplies... at the moment, that is all greek to me... I'm pretty fluent with typical single and dual rail PSU's but trying to follow Rod's circuit required too much external knowledge not contained in his site...
Plan is to be able to construct a car amp, say 50 to 100W or so...
would it be better to just buy one of those complete inverter units? Although this would severely cut the educational value, not to mention DIY funness.. |
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| Risto80 |
| The valveaudio site is the best for car smps |
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| Risto80 |
I forgot, these days I will post all pictures plus remoduling some parts of amplifier and preamplifer (pcb)
I used this amp with kenwood kfc-w3011 1200W peak power,rated 400W sub speaker and it work great so much power with so little amp |
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| Razorback |
Hola, querνa saber para que sirbe el preset (Vr3 en el esquematico) de 330 Ohms que estα ubicado en el pcb del Amplificador. Saludos desde Argentina.
Hello, it wanted to know so that preset (Vr3 in the schematic) of 330 Ohms that is located in pcb of the Amplifier. Greetings from Argentina. |
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| Risto80 |
| For full text, pictures, pcb and schematic for this article visit my web site: www.elkomak.4t.com |
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| djQUAN |
| quote: | Originally posted by Risto80
For full text, pictures, pcb and schematic for this article visit my web site: www.elkomak.4t.com |
http://www.elkomak.4t.com/catalog.html
I see sections of the ESP P89 article and some parts from the valveaudio website copied and pasted to your article but you don't refer to them in any of your texts. I would like to point that out before the copyright owners do something about it. |
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| MikeHunt79 |
Hey, I've recently got hold of a non working KAC-716. The light comes on, but nothing comes out the speaker output....
Would it be possible to just use the SMPS from it?
The only problem is that +-40v is way too much for me...
I really want +-12v, as I want to power a 41Hz.com AMP9 module in my car, which needs 24v. I was thinking a 1:1 turns ratio would give me +-12v, but I would need 10A (peak) from each rail... which is probably a lot more current than the KAC-716, so would I end up blowing up the MOSFETS?
Also, anyone know of a good source of toroids or enameled wire in the UK?
EDIT: Also, could someone kindly post up the service manual, it would be a great help for me as I will then know which parts of the PCB do what. :) |
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| Perry Babin |
1:1 would give you approximately ±12v with ~13v in.
The lower ratio would reduce the demand on the FETs so they should easily survive.
If you're interested in continuing this thread, have a moderator split this off to a new thread. |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
1:1 would give you approximately ±12v with ~13v in.
The lower ratio would reduce the demand on the FETs so they should easily survive.
If you're interested in continuing this thread, have a moderator split this off to a new thread. |
I've e-mailed a mod asking exactly that...
I've just tested the rails on the amp (with no load)...
It seems one of the rails is a little low at -21v. :( |
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| Perry Babin |
| Check the legs on the rectifiers. One may be broken. |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
Check the legs on the rectifiers. One may be broken. |
When you say rectifiers do you mean D206 and D207? I've checked the outside legs on D206 and D207, and they are both getting a square wave, 32Vrms @ 33khz according to my Fluke 863.
This is measuring from one of the outside legs to ground. Here is a photo of the wave:
EDIT: Could it be one of the 50v 1500uF caps that has gone? |
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| Perry Babin |
| The voltage on the center leg should be the same as the peak voltage of the square wave on both the top (for the positive rectifier) and the bottom (for the negative rectifier). Is this the case for both rectifiers (yes, D206 and D207)? |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
The voltage on the center leg should be the same as the peak voltage of the square wave on both the top (for the positive rectifier) and the bottom (for the negative rectifier). Is this the case for both rectifiers (yes, D206 and D207)? |
Well, the voltage on the center leg of D206 is fine, as it measures as 46v.
But the voltage on the center leg D207 is a little low, at -21V, which seems strange. If the rectifier was broken, shouldn't it read 0v?
This is why I think it could possibly be one of the 1500uF caps...
I've blown up the part with the rectifiers to make things a little clearer (I hope). :) |
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| Perry Babin |
| If you have the same signal on the outer legs of BOTH rectifiers and the DC on the output of the negative rectifier (on the center leg) is clean (no excessive ripple), the negative rectifier has to be defective. |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
If you have the same signal on the outer legs of BOTH rectifiers and the DC on the output of the negative rectifier (on the center leg) is clean (no excessive ripple), the negative rectifier has to be defective. |
Well the caps looks visually fine, no bulges or goo... so a bad rectifier makes more sense.
As far as ripple goes, 46v on the middle leg of D206 is pretty ripple free.
The -21v on the middle leg of D207 has a bit of ripple, around 2-4v above and below the -21v line... I'll see if I can get a good pic somehow.
FWIW, Here's what It says on the rectifiers:
D206 =
FMU22S
-->|---|<--
8531
D207 =
FMU22R
--|<--->|--
8606
Also, I can quite easily cut to wires on the top of the PCB to isolate the output of D207 from the caps... Would this help at all? |
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| Perry Babin |
| Desolder D207 and check it out of the board. |
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| dangus |
How similar is the Kenwood 816 to the 716? Power rating looks similar...
As for info on building SMPS for car amps... there's a pretty good article in Audio Amateur, back around 1988 by Randall K. Vikan. I'm pretty sure it is reprinted in an Audio Amateur book of amplifier projects. |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
Desolder D207 and check it out of the board. |
It won't be until tomorrow until I'll be able to find the soldering iron, as it's 1am here, and I don't want to wake the others in my house...
Anyway, I cut the wires linking the centre leg of D207 to the caps, and I'm still getting the same reading... -22v
I'll desolder it tomorrow, and check it out of the circuit.
Also, the part doesn't seem to be available any more, but I managed to dig up some info on it...
http://www.americanmicrosemi.com/in...c/?ss_pn=FMU22R
I guess if I was going to have to get a replacement, I'd have to match the specs, or would it be better to change both rectifiers at the same time so the specs would match?
I'm going to get some sleep now, thanks very much for the help. My plan is it get it working at +-40v first, then change the transformer for one with a 1:1 ratio.
Another option would be to use a 1:2 ratio toroid, and just use the output from the 1 good rectifier, as my AMP9 module only needs +24v, as opposed to +-24v. Would this be possible? |
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| Perry Babin |
There are lots of substitute rectifiers available.
The positive and negative rectifiers don't have to match. Unless D207 is broken physically, I wouldn't change both. If D207 is broken physically, I'd suggest changing both because they would have received the same stress and D206 may be ready to break. If you don't find that the legs are broken inside the case of the rectifier, I'll be surprised.
If you're going to use this in your vehicle, you'll have to break the ground for the secondary side of the transformer. It appears that the metal buss bar may be the connector for the two grounds. If so, you'd have to cut it or remove it.
I don't know enough about the amp9 to determine if a single supply or a dual supply would work best. The 41hz site indicates that it uses a single-ended supply. You should ask someone in the class D forum which supply would be the best for that amp. |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
If you're going to use this in your vehicle, you'll have to break the ground for the secondary side of the transformer. It appears that the metal buss bar may be the connector for the two grounds. If so, you'd have to cut it or remove it. |
I do plan on using this in the car - I'm not sure what you mean by breaking the ground for the 2nd side of the transformer... I plan to replace the transformer anyway, as 40v is too high for my AMP9.
I've attached a pic of the top of the PCB which may help.... I should be able to get the big metal thing out without a problem tho. :)| quote: | Originally posted by Perry Babin
I don't know enough about the amp9 to determine if a single supply or a dual supply would work best. The 41hz site indicates that it uses a single-ended supply. You should ask someone in the class D forum which supply would be the best for that amp. |
Well I'm using the AMP9 in the house on a single ended supply and it works great. In fact I now think it would be better to go single ended, and the ground for everything would be the same... I may get ground loops from my headunit if I go with +-12v supply...
So for single ended I guess I would still need a centre tapped 1:2 toroid to replace the existing transformer to get +24v, and simply not wire anything up to the -ve rail... Perhaps it would be best to leave D207 out of the PCB one I have de-soldered it...
EDIT: I think I know what you mean about not connecting the secondary ground to the PCB. As I'm replacing the transformer anyway, I can simply not wire it up to the PCB. I can also remove all the 1500uF caps and simply wire them up outside the PCB. :) |
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| Perry Babin |
Is a schematic for amp9 available?
In an automobile, you have a significant differential between the ground at the head unit and the ground in the rear of the vehicle where the amp will be grounded. If you don't isolate the secondary side of the power supply from the primary, you'll have ground loop noise. If you break the ground connection in the amp (buss bar?), the secondary should float so you won't have two grounds for the audio circuit. The RCA shield ground will be the ground for the audio. The chassis ground connection in the rear of the vehicle will be the ground for the primary side of the transformer. |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
Is a schematic for amp9 available?
In an automobile, you have a significant differential between the ground at the head unit and the ground in the rear of the vehicle where the amp will be grounded. If you don't isolate the secondary side of the power supply from the primary, you'll have ground loop noise. If you break the ground connection in the amp (buss bar?), the secondary should float so you won't have two grounds for the audio circuit. The RCA shield ground will be the ground for the audio. The chassis ground connection in the rear of the vehicle will be the ground for the primary side of the transformer. |
Ok, I'll be sure to keep the secondary ground separated and I'll also isolate my RCA plugs so my vehicles ground won't be connected to RCA ground. Now I'd better get toroid hunting.... :) Just a quick question, does the toroid rating have to exceed my amps power? I don't think I'll ever need more than 240W (24v @ 10A), so should I get a 250VA toroid? Or will I get away with less as it's high frequency (33kHz). |
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| luka |
Hi
| quote: | | In an automobile, you have a significant differential between the ground at the head unit and the ground in the rear of the vehicle |
How so? There is just a lot of steel or Al, like having big cable from front to back. How is then there any big diffrence? |
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| Perry Babin |
The difference is not significant for 12v DC devices such as motors or lamps but for audio, the difference is significant.
The difference in potential is amplified by the amplifier and will get into the audio stream. |
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| N-Channel |
| Would you like some alternator whine with that cheese? :D |
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| Risto80 |
Dear All
You can find voarious service manuals for Kenwood Car Audio on this web site, there is no requiremen of registration just download.
http://archive.espec.ws/section391/
Regards,
Risto |
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| MikeHunt79 |
I managed to find another more suitable amp to butcher 12v SPMS to power my amp9 in the end, so I didn't have to butcher this one after all. :)
Anyway, I thought I'd have a go at fixing this amp anyway, as more of a learning experience than anything. :) If I can get it working, it may come in useful as a backup amp...| quote: | Originally posted by Perry Babin
There are lots of substitute rectifiers available.
The positive and negative rectifiers don't have to match. Unless D207 is broken physically, I wouldn't change both. If D207 is broken physically, I'd suggest changing both because they would have received the same stress and D206 may be ready to break. If you don't find that the legs are broken inside the case of the rectifier, I'll be surprised. |
Ok, I managed to get D207 out without too much drama.
I didn't have much to test it with apart from a 12v SLA and a computer fan, but with a few croc clips I managed to find out that it works...
It passes current from the outside two legs to the inside leg. and I tried putting reverse current on it, and it blocks the reverse current ok.
Would it be worth pulling D206 and testing it also?:smash: |
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| Perry Babin |
If the square wave on the outer legs was swinging plus and minus 40v but the center leg had only -21v (using your scope to measure the voltage), the rectifier has to be defective. There should be no more than ~1v difference between the outer legs and the center leg.
I'm assuming that the -21v output was clean (no excessive ripple). |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
If the square wave on the outer legs was swinging plus and minus 40v but the center leg had only -21v (using your scope to measure the voltage), the rectifier has to be defective. There should be no more than ~1v difference between the outer legs and the center leg.
I'm assuming that the -21v output was clean (no excessive ripple). |
I've just re soldered the recifier, and it's doing exactly the same as before... -21v.
Now, I double checked everything as I've got the PCB out of the chassis... I must admit I'm still getting to grips with my scope multimeter... I've only just found on VDC mode you get a more zoomed in view of the square wave going to the outside legs of the recifiers, and I've found that the wave looks offset vertically, the is far more of the wave above the x axis compared to below, around twice as much above compared to below... which explains why i was getting over +40V and only -21v.
I wish I noticed this before. :o I was always using VAC mode where it's more zoomed out vertically for some reason, so I didn't spot the offset before... So it looks like the rectifier isn't causing the problem after all. I can grab a photo of the square wave if that's of any use at all?
I'm guessing it's got to be one of the components in the oscillator part of the circuit, but I'm not really sure what part does what tbh. Where would be the best place to start? |
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| Perry Babin |
I think there may be a bad connection somewhere. The windings that drive the positive rectifier also drive the negative rectifier so the voltage should swing to the same level both above and below ground.
Try resoldering all of the connections on the power transformer and all connections between the transformer and the rectifiers (jumper wires, etc). |
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| MikeHunt79 |
Another screw up by me... :o
I was measuring everything with respect to the battery ground. I totally forgot that the trafo has a different ground on the secondaries...
Anyway, I remeasured the outputs of the rectifiers with the ground on the secondary this time, and I'm getting a +33v and -33v... I assume this is ok, even tho the schematic states +48v and -48v (I think). The secondary ground is 12v away from the battery ground if that makes any sense....
So by the looks of it the SPMS part of the circuit is fine. :) I guess some other part of the circuit must be the problem. I'll see if I can check the output stage somehow... bit I've got a pizza that's about to burn to I'm gonna have some food first then come back to it in a bit.... :smash: |
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| Perry Babin |
The schematic has ±40v as the rail voltage with 14.4v in.
According to the schematic, the secondary is directly connected to the chassis ground. If you don't have continuity (~0 ohms) between the chassis ground and the secondary ground, there is a broken connection. W70 (very near the point where the B+ terminal goes into the board) and the large metal buss bar are part of the circuit that connects the chassis ground and the secondary ground. |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
W70 (very near the point where the B+ terminal goes into the board) and the large metal buss bar are part of the circuit that connects the chassis ground and the secondary ground. |
I checked it with a multimeter, and the resistance readings were all over the place... Certainly more than 1Kohm.
After a little searching, it looks like W70 has a bad solder joint:
I'll fix that, then put it back in the chassis and give it a whirl. :) |
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| MikeHunt79 |
Ok, I've put it all back together, and it's doing the same thing, no output on the speakers...
Now, I can hear the relay (K1) clicking almost instantly after I connect the remote wire, and after seeing it on the schematic, it looks like it's some sort of speaker protection system...
It does this with or without a speaker connected, so I'm guessing something somewhere is making the relay switch when it shouldn't.. |
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| Perry Babin |
Since you have the schematic diagram and a scope, you can trace the signal through the amp.
Before you begin, confirm that you have both + and - 15v (approximately) on the op-amps. {pin 4 of the op-amp is -15. Pin 8 is +15. If those are present, begin tracing the signal.
Begin at the RCA jacks and follow the signal through the op-amps. The signal line is a bold black line. Where does the signal stop? |
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| MikeHunt79 |
All the op-amps are getting + and + 15v.
Also, the signal gets to pin1 on IC3 ok, I'm just about to start tracing it thru the Q parts of the circuit.... :) |
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| MikeHunt79 |
My signal is around 150mV (rms), just a 70Hz sine wave. The signal actually makes it all the way to the speaker terminal, but is now 200mV when the amp is on, and 150mV when the remote wire is disconnected (but still 30V or so in the rail caps). All these readings were taken with my black probe going to signal ground.
I tried measuring the voltage across the + and - speaker terminals, and there is nothing. 0v, not even the 150mV from the signal...
Could the "input muting" part of the amp just be muting all the time? |
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| Perry Babin |
With the black lead on the negative speaker terminal and a speaker connected to the amp...
What is the AC voltage on...
the base of Q101?
the emitter of Q112?
pin 1 of IC3?
the positive speaker terminal? |
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| MikeHunt79 |
| quote: | Originally posted by Perry Babin
With the black lead on the negative speaker terminal and a speaker connected to the amp...
What is the AC voltage on...
the base of Q101? |
7.95mV| quote: | | [i]the emitter of Q112?[/B] |
6.64mV| quote: | | [i]pin 1 of IC3?[/B] |
2.01-2.05mV| quote: | | [i]the positive speaker terminal? [/B] |
around 7 mv.... |
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| Perry Babin |
| Try it again but increase the signal until you get 100mv at pin 1 of IC3. |
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