| Rixsta |
hi im new here and new to electronics but have managed to build two zen v4's
one channel works ok but has a lot of hum when a cd player or input isnt connected. While the other channel the one i bult first worked ok for about a week, but now works for minuite or two and then all the irfp044's blow, and resistor r0 goes up in smoke:hot:
this has happened twice and im wasting me money so just wondering weather you smart people here have got any clue what the problem is..
The sound was amazing compared to my bang and olufsen
http://www.beocentral.com/productin...roductid=BM2400
With the zen v4 the kick drums in most songs seemed to be more pronounced and i tried eq ing my bang & olufsen to try and get the same sound as my zen but it just couldent do it lol.
Cheers Rixsta |
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| kilowattski |
| There are so many possibilities. Firstly check all your wiring because you most assuredly have a grounding problem. Did you build the Zen V4 exactly as described in the PassDIY article? When you first turned the unit on did you perform the adjustments? When you keep replacing the Mosfets are you replacing them with matched pairs? This should get a dialog started so we can help you. |
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| till |
Did you use enough heatsink? what temperature did the FETs reach? Is mounting of FETs with grease and good contact to heatsink?
Is the amp oscillating? My Zen V4 did oscillationsat 166kHz and blew Rs. when i build it, this happened with thin cables between PS and amp and bad contacts (crocos) With good connection and thicker wire between PS and amp it workedwithout problems.
Do a search, you are not the first one. |
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| Rixsta |
Thanks people
first im going to check the for right voltages present, can i do this without the mosfets attached ? probably no
The circuit i built has the feedback circuit there but not connecting to the output, and im using a 15,000 output capacitor with no bypass
the mosfets are irfp044n everything else is the same as nelsons exept theres no resistor going from ground to the chassis.
im not using matched pairs but there probably not that different,
iv'e kept the mosfets the way they were when the amp was working. so i cant see heat being problem
when it works it sounds fine and only a bit of hum present and no oscilations. im using thick wire from the power supply to a prototyping board. |
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| Rixsta |
| actualy iv'e just remembered i unplugged the input whilst the amp was on, maybee the cd player i had it conected to was prventing the problem from happening by grounding the amp properly. |
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| Rixsta |
| heres the prototyping board |
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| kilowattski |
| No hum when you had your cd player attached is a real good indication that you have a grounding problem. What feedback did you add to the circuit? Also make sure you included the bridge rectifier for isolation to the power supply. |
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| Rixsta |
Im still curently checking my amp over but have also found this site http://www.geocities.com/fuherb/sonofzen.htm
and have noticed the zener diodes
my question is can theise be used in the zen 4 for mosfet protection, also giving me the time to test my amp for the corect voltages before the mosfets blow.
if someone could show me how to add the zeners corectly i would be very pleased indeed.. |
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| kilowattski |
| My suggestion is before you go start adding stuff, get the unit working when built exactly to the schematic. Once it is working reliably, then make your modifications. The Zen 4 works very well as advertised with no modifications. It is a tried and true design and many have been built to print and worked well. Since you are a beginner I suggest you get the original design working first and learn from the experience. If you go willy nilly and start modifying before you got the original nailed you may never get it to work no matter who helps you. As a start you know there is a ground problem. If you have made any mods, remove them and lets see if we can get this thing working reliably first. |
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| Rixsta |
cheers for the help kilowattski and till you are most probably right so i shall post here sometime again when iv'e fixed it.
Positive thinking might just work too.:cool: |
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| Super_BQ |
Rixsta,
Sorry to hear about your Zen 4. When it comes to building amplifiers, it is always a good idea to be "ULTRA Paranoid". Especially in high voltage valve amplifiers like my 211. In being paranoid means triple checking everything out before you turn that dial on the variac.
Tips i've heard in the past:
1) No silly pads or mica insulators. Some may forget to isolate the transistors from the heatsink.
2) Test the power supply voltages 1st before hook-up to the main boards.
3) Zener diodes matched? Buy lots of them because you need to get a sizeable sample to arrange all the different zeners so they "add" up to the right regulated voltage. More than 50V on the IRF-044 may be the problem if you regulate too high. *POOF*
4) I don't think matching the mosfets is too much of a concern in the zen 4. For my Zen 4 "Twins" I only matched Q1 & Q2 and both were at least 0.02 volts out.
Zener diode input protection on fets:
Refer to the Bride of SOZ project that shows input protection on the mosfets. Normally, i've never had a mosfet blow on hooking up interconnects. You need like static electricity to blow the fets. For each input, wire a pair of 12v zeners back to back (the squigly lines on each zener facing AWAY from each other). One squigly end to ground and the other squigly end to the gate of the mosfet.
BQ
PS: Does using proto, vero, breadboards count as P2P wiring? |
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| Rixsta |
Exelent help thank ya i wont give up yet.
I cant find the Bride of SOZ schematic..
i will post again soon until then have a good week..
ps i dont know what P2P wiring is |
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| Alain Dupont |
Rixsta,
>> ps i dont know what P2P wiring is
Its point to point wiring, only components, a minimum of wire, but some connectors are usefull...
Alain. :cool: |
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| Rixsta |
Hi all
Iv'e had to halt work on the penultimate zen because i cant risk the trip switch going where i live.
Me old man dont like it. lol
Well before i continue with building the amp i was wondering weather anyone can recomend a good bench power supply.
and of course would it stop the trip switch in my house tripi'n out ?
I thought if it had surge protection it might help.
also any things i should look out for in a bench supply i will probably buy from ebay..
Cant wait to continue building..
cheers for the help everyone |
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| RKH |
A variac will allow you to bring things up slowly.
Building a bench supply won't necessarily solve the problem of tripping the mains if your amp is too great a load (for what ever reason)
Randy Slone has some 'bench supply' designs in his book; they have some current limiting circuitry etc. But any power supply from one of the Pass DIY articles will provide power as long as you scale the components (transformer, caps, bridge) correctly.
Mr Pass recommends (frequently) that bringing up designs with a variac (essentially a variable A/C supply that gets power from the mains) is a good thing.
Ryan |
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| Rixsta |
wow that was a quick reply
the problem of tripping the mains is my main priority
but i will check out a variac too..
even a light bulb blowing trips the mains in my house. lol |
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| BobEllis |
If you don't have / budget won't support a variac you can place a 60-100 W ligth bulb in series with your amp - It will prevent your breaker tripping, since a dead short in your amp would just light up the bulb. It acts as a current limiter.
Of course, a variac is a more elegant, probably safer solution.
Be sure to have a fuse in amp's your mains line. If it is 5 amps or so, it ought to go before knocking out the breaker with Dad's TV on it. Yes it is annoying to replace them until you get teh amp working right, but it is an important safety feature. |
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| Rixsta |
exelent cheers for that i can deffinetly handle the light bulb solution i have a habbit of being too safe when it comes to mains electricity..
Lunch time for me now.. bye
oh yeah it's dads computer that will restart if the breaker goes
not good. lol |
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| Super_BQ |
I like to add that you'll still get the same problem of tripping the main power breaker by using a variac (notably the high amp ones). Just by pluging in the variac, if you hit it on the right cycle, the variac can momentarily act like a dead short (because of the huge current draw) and still trip the circuit breaker.
Small wee hand size variacs don't seem to have this problem. I do know that my 0-260 10A variac means I have to plug it into a dedicated breaker.
BQ |
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| Rixsta |
Hey im learning stuff here cause of you dude's cheers
So it's a variac to vary mains input voltage
The light bulb idea is realy good too
Well iv'e gotta go spend some money....
Any other ideas on stoping a breaker/trip switch tripin would be apreciated ?
Hey id be interested to see anyone elses amps if you wanna post a link here
i cant send a photo of mine cause i have no digital camera
Cheers rixsta |
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| till |
Why donīt you simply buy a handfull of 2 or 3 Ampere fuses and use them in series with your transformators primary winding. Also a Thermistor for current limiting at power on helps.
:cop:
This image was removed. Find it here, Figure #6 at the PassDIY site.
:cop:
If you build the PS like Nelsons example i donīt see why your mains breaker should trip. The thermistor cares for power on current limit - the fuse for max. current. |
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| Rixsta |
ive got a 2 amp on the live and 1.5 on the neautral and the trip still goes but the fuses dont.
the previous person who lived here was a electrician and we think he made the trip too sensitive
maybee he wanted to save hes fuses.
Every single time a light bulb in this house goes the trip goes.
But i understand what your saying about the proper power supply and i intend building it too.
I sopose realy im looking for something which will work with all the projects i build
at the moment i have to go over to a freinds house every time i wanna build my amp (not good).
actualy i dont think a fuse has ever blown in this house.
apart from mine when i get stressed lol sorry.
i sopose i should be greatfull for what this electrician has done cause it could save my life i think. |
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| till |
| Is the breaker a fuse, does it break at a current level, or is it a FI, that breaks in case it senses a current flow from live against earth ground instead to neutral? |
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| Rixsta |
Dont know what a FI is but it's not a fuse..
i could go and check now wont take a mo ill tell you what i see. |
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| Rixsta |
Yep right i should have read this before the circuit breaker says it automaticly switches off the power suply if a earth fault develops.
Well kilowattski said
Firstly check all your wiring because you most assuredly have a grounding problem.
I sopose the circuit breaker confirms kilowattski was right before.
stupid me doh |
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| till |
I dont know the right words in english. You could have a device that switch off the line in case a current (like 16Ampere) is reached for a amount of time (1ms or so) or you can have an additional device (for bathrooms etc) that switches off the line in case it senses there is not the same amount of current going throug live and coming bach throug neutral. In this case some of the current must be lost - and may flow throug a human body to earth ground.
In case its the first kind of device, and you have correctly wired a 1,5A fuse in your PS - the device has nominal less than 1,5A , you have no thermistor/power on current limiter, or the device is broken.
In case it is the second kind of device and your PS has any connection to earth ground, you may have current going the wrong way back because of mistakes in wireing or bad insulation. |
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| Rixsta |
yeah i understand your english fine no problems there
second kind sounds good to me but i shall check my wiring
and ground conections shouldn't take me too long.. |
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| Rixsta |
i have a seperate wire connecting ground from the plug soket to the amp because i wasnt using 3 core wire so i added my own earth wire
but the gard damn ground wire has no connection on my multimetre so tommorow ill fix it and ill go from there.
So does that mean because my amp had no ground the trip switch kept going..? |
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| Rixsta |
Im gettin there with my amp just building the suggested power supply for the zen v4
Can anyone tell me what the coloured rectifier in this circuit does
my gues is some type of isolation
it dosent make sence to my brain lol |
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| Super_BQ |
| Rixsta, that ground rectifier has been covered before in this forum. Do a search. Mr. Pass has convered this issue. |
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| Rixsta |
i genuinely forgot mate being new here will doo
cheers man
Doh |
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| Rixsta |
Can you use a circuit breaker to stop another circuit breaker tripping..
Ive just found theise circuit breakers and there quite cheap
my idea is that if i put a circut breaker onto my amp im hoping it will trip before the main circuit breaker to the house goes.
please let me know if the idea wont work.
If not ill just give up....:smash: lol
Theres two links here is it posible to have a look and tell me weather they would be ok for my amp ?
Aparently they act realy quickly
http://rswww.com/cgi-bin/bv/browse/...&stockNo=409801
http://rswww.com/cgi-bin/bv/browse/...atoid=-84889411
Iv'e searched this site but cant find any info about this idea
im going to use the lightbulb idea that BobEllis said about ill just wire me bedside lamp in series with the mains of the amp right ?
does it matter weather it's in series with the live or neatural ?
oh yeah do i create a new thread because iv'e changed the subject with the last few posts ? i just dont wanna be a pain |
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| Rixsta |
Ok sorry the links dont work
but can someone reply is it a good idea ? |
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| D1GGY |
RIXTA,
the device which is tripping your supply is called an RCD. (residual Current Device) This device will operate (switch off your mains) if it senses an imbalance in the phase and nuetral conductors.
If all is well with the circuit the current will flow out on the phase conductor to the item drawing the current, in this case your amp. The current will then flow back out of the device on the neutral the same amount of current will flow in each conductor, they are balanced. Therefore the RCD will not operate,
If we now consider a fault, (your Amp! ;) sorry) More current will be drawn from the supply (phase cable, the red one as you are in the UK)to "feed" the fault, this increase will not be seen by the RCD on the Neutral cable (the fault current may be going to earth or being released as free super excited electrons which break their covalent bonds Heat, burning etc ;) in a familiar mushroom shaped cloud) so the unit operates, tripping your house supply.
Different options exist for you to overcome this:-
Fix your amp to stop the problem
Or:-
get an RCD which will operate quicker tjan the one installed in your fuse box. This is achieved by getting a lower Leakage one installed on the circuit you are useing to dwevelope your amp with. this is measured in Milliamps, you can get them in B&Q etc for lawn mowers,m if these have a lower leakage (which they should) then this will trip and not the main house one.
they are available as an extension lead arrangement as well
Do not remove the other one from the house supply, it will save your life if you forget that the mains is on when you go to desolder something :eek: ............ |
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| till |
| The only way is to fix the amp. I run a ZEN V4 without any problems in my house, and the net in house has loads of these RCDs. No line without, different parts of the house different kinds of theses devices. If the amps power supply is done right there should be no problem. |
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| Rixsta |
ok thank you
much apriciated
right thats all the questions im gonna ask for now.
yeah i found that part of the case of my amp had cut into the transformer cause a nasty short betwwen live and neatrul
or something like that. |
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| Rixsta |
Hi all this should be titled penultimate zen all mosfets working
thanks to all the help here iv'e finaly just about got my amp working now theres just one question..
if you look at the schematic you will see i have about 1.5 volts where it needs to be .66
also where it says <----- 4V ------> i have just over or maybee 5 volts
i have adjusted the bias but cant get the voltages right
theise voltage readings were taken quickly then i turned it off
I am using a 0.23 ohm 7 watt resistor instead of r1 and r0
my thought is change the resistor r1 and r0
Please anyone tell me what you think but dont be nasty lol
as im only a begginer.
:cop:
Pic was removed. See the The Zen Variations - Part 4 atrtical, Figure #3 at the PassDIY site.
:cop: |
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| till |
| you run 6,5 Ampere through your amp? |
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| Rixsta |
whats that ?
im dumb lol please explain
im only joking im not dumb but please explain it to me |
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| till |
1,5V / 0.23 Ohms = 6,5A
start at Ohms law.
You amp must be very hot, have 20kG heatsinks, or something is wrong.
a) your measurement/values
b) your NPN
is the amp oscillating?
use a little larger resistor, like 1 or 0,5 Ohms
use a new NPN
use a good connection with short and thick wires between amp and power supply / caps. Test for oscillations. |
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| Rixsta |
Hi till cheers
I have no oscillations ut i will change the resistor to make 0,5 ohms
my amp does run very hot but the voltages were measured within 10 seconds after i turned the amp on.
so the mosfets were still cold when i measured .66 volts ect |
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| Rixsta |
Iv'e just replaced r1 r0 to make 0.3 ohms and because its a 3 watt resistor it's going up in smoke
is there too much ampage running through it ?
Dam it urggg
any ideas
i will learn ohms law |
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| jam |
Guys,
I would remove all Mr. Pass's schematics from this thread or at least only post partial schematics according to his wishes, pertaining to copyrights (see relavent thread). It is ok to post links to his web site.
Regards,
Jam |
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| Rixsta |
ok jam thanks for letting us know i will change the pic's soon
till you are right mate
so can anyone figure out why i have 6,5A and how to lower it ?
do i just need to change the bias ?
I have a feling if someone answers this question my amp will be sorted
please people
thanks rixsta |
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| till |
the bias current is set by the value of the resistor choosen for R0/R1. If the current source is wired right and Q2 and Q3 is ok, there should be 0,66 V across this resistor independent on its value. The bias current would be the 0,66V/ Ohms of resistor. For 2A this are 0,33Ohm, whats formed by ~ (0,47*1)/(0,47+1) (R0 and R1) .
The voltage of the Fets gate is adjusted at R4 and should be set for ~ 22V at Drain of Q1.
jam, there are hundreds of Nelsons schematics posted in this board. How on earth we should diskuss the Pass amp related problems without schematics? I doubt Nelson donīt allows to use his schematics at this place and for this purposes.
For everyone who found this place, and donīt knows the site, Penultimate Zen at Passdiy: http://www.passdiy.com/projects/zenv4-1.htm |
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| Rixsta |
ok dude now i get the point
so how do remove the images anyone ? |
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| till |
you canīt, you need to ask a moderator to do for you. Instead of the attached picture, you could link the same picture by paste the link to it http://www.passdiy.com/images/projects/zen-v4-f3.gif in the IMG function : 
all those intellectual property threads tsc did not tell me, which way is allowed and which not... |
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| Rixsta |
till thanks for helping but i have no idea what the equations mean
could you tell me what resistor i have to change to get lower voltage and current through r0 and r1.
becuse you see the other 1/4 watt resistors im using are not that acuurate tolarance and might be quite a bit off in resistance to what they should be
so i fear one of them may be the problem
maybee i should just replace them all so there 1% tolarance
computers is something i can understand lol
cheers for the hint with showing images with a link i get ya mate:)
Im going to college later this year hopefully to do electronics so one day i might know as much as till yey lol |
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| till |
the tolerance is not critical, iīm sure everything will work fine with 10% resistors. Above i did not post equations but i tried to descibe. The NPN in the current source cares forfeeding the FET Q2s gate that way, the FET lets pass the amount of current through R0 for 0,66V across it. The 0,66V is the Vbe of the NPN. This way you set the current by choosing a value for R0. Start with 1 Ohm. You should measure about 0,7V over R0 and have about the same number as current through it. (0,66/1)
If not your current source does not work. First deconnect R12 or C6 for test if something is wrong with this line, the modulation for the current source taken from output.
If still not ~0,66V --> change NPN. Still not working? change Q2.
At last now you need to double check your wireing - better do that first.
edit: i donīt know much about it, iīm only a stupid mechanical engineering undergraduate... |
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| pro |
Try also to test if you not inverted the connections of Q3.
It is easy to make confusion with the three termilals them of the transistors since changing type often it changes also the disposition of terminals them. It assures to you, watching on the date sheet that the logons are right. |
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| Rixsta |
Cheers for all the help
Iv'e decided to buy the penultimate zen pcb's from pass diy
it will make life a lot easier for me
with less wires going all over the place lol
and ill use two transformers for the power supply
seems a good idea to me
now i just gotta get a massive heat sink oh man
hope it dont cost loadsa money.. and ill build a cool wooden shassis, in about 5 months ill put pictures of my amp on this site..
LOL
ill also build a passive graphic eq into the amp because i recon passive is better and of course not adding any colour or unwanted noise to the amp, unless anyones got any ideas on good graphic eq circuits (op amps are a no way for me)
ill probably make it twenty band
well thanks for listening to my ramblings |
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| Rixsta |
Hey people im having problems finding a good place to buy heatsinks in the uk
anyone got an idea
i want to use sinks like this one mounted on the side of the amp
http://www.diyaudio.com/forums/show...6515#post326515
1 heatsink per channel id like them to be able to dissipate 120W or more and be at least .3 deg C. / watt.
like nelson pass mentions in the zen 4 documentation
ps: thanks for all your help on this site i apriciate it a lot
and thanxs in advance if you can answer this Q |
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| till |
take a look at
http://www.fischerelektronik.de/
My Zen V4 runs at below 50°C at the moment with SK438 + 150mm with 2A bias.
You can order directly at Fischer by email. |
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| Rixsta |
exelent they have loads of heatsinks but lol
can you give me a link to the right pdf with the SK438
i cant seem to find it maybee im just braindead...
also how long do they take to ship ect
i mainly shop at rs components but they dont have pics of there heatsinks...........
but thankyou till
do you have any pictures of your amp, can i bee cheeky and have a look ? |
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| Rixsta |
also how much was the heatsink i cant find a price
iv'e looked on the rs website and heatsinks are Ģ37 for a 0·32°C/W
isnt this a bit expensive..
i have no idea
olso do you use one sk 438 or two ?
sorry to ask so many questions
god i am so stupid im gonna have a look at the project gallery at pass diy and see what they used for heatsink.. |
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| till |
http://www.fischerelektronik.de/dow...DF/A_Gruppe.zip
Pictures: sorry, no really good at the moment. Only this bad quality, Zen V4 is at bottom, above to see a BOZ and a CD player. I promise someday to make good pictures of everything and post.
One heatsink for each channel. |
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| Rixsta |
he he lol cool
nice rack to put your hi-fi stuff on
the sinks look about the right size for me
Right im of to enqure as to how much two sinks will be
cheers dude |
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| till |
for the rack: thanks.
all diy. |
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| Rixsta |
oh exelent in that case i might make one too!!
as long as it's not too hard i hope... lol |
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| till |
The rack? is an easy task:
Boards of multiplex, 4 holes drilled in the corners diameter 28mm. A grubscrew for each hole to clamp the board to the leg. Legs are cut from water tube "Mannesmann MaPress" 28mm stainless steel http://www.mapress.de/english/index.htm
Feet are aluminium from Bulthaupt system 20 kitchen furniture.
http://www.bulthaup.de/countries/re...60ersyst20.jpg/$FILE/Neuh_160ersyst20.jpg
for connection of tube and foot an adapter mapress 28 to 3/4" stainless steel |
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| Rixsta |
cool
Seems like you have a good diy mind
It's good also knowing how to use the things you have lying round the house and putting them to good use too.. when your building something...
If you know what i mean |
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| Rixsta |
Yuo know i can be stupid sometimes
those heatsinks wont ship to the uk so for all you american diy,ers
iv'e just found ya something worth lokin at ... |
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