I tried powering up the amp with the higher current limits, but the idle current never stabilizes. Sometimes is wanders between 3-4 amps, while at other times it pegs the current limit (at both 5A and 9A). This was without twisting the components.
I then tried twisting the inductors and the transformer as suggested when the current was varying between 3-4 amps. I could not find any component that significantly caused this current to rise or fall significantly. Even when the amp was "stable" pulling 3-4 amps the power supply was still squealing also. I checked again for DC on the speaker outputs, but there was none. I was only able to look at the amp for about 20 minutes today, so I will have to wait until the weekend to pull the rectifiers and then try again. My spare parts for the blown transistor should be here tomorrow or Friday also. Should I still keep out the new Q121 transistor or install it before trying again? I have some spares if Q121 blows again.
With Q04, Q121, and the rectifiers out, the amp powers up fine. It draws about 700mA rock solid and the relay still clicks. There is no squealing.
Outside the circuit, both rectifiers still measure out as good.
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Reinstall the rectifiers, clamp everything down and power up the amp. If it's drawing excessive current, measure the resistance across the four 0.02 ohm cylindrical black resistors. They should all read 0.000 volts. If any read higher, post the resistor's circuit board designation and the voltage.
I can only get to one on each side due to the black silicon on the output inductors covering the leads and pads for the others.
Power Supply FET side of board
R168: 0.00V
R167: 0.00V
Output FET side of board
R???: 0.00V
R???: 0.00V
Just for kicks I hooked up a speaker and used a function generator as my audio source (daugher board not installed) and it actually output audio on the the speaker. I still have the horrible whining and wildly swinging current though. The power out to the speaker seems constant though... that does not wildly swing around with the current. The whining seems like its coming from the smaller transformer/inductor near the rectifiers or the blue rectangular capacitors right next to the rectifiers (C28, C29, C23).
Without preamp board, no speaker connected:
Current draw at 12V: 3-5 amps singing like a bird
With preamp board and no signal, no speaker connected:
Current draw at 12V: 4-5 amps singing like a bird
With preamp board and 100Hz 200mV signal, no speaker connected:
Current draw at 12V: 4-5 amps singing like a bird
It seems installing the preamp did not change anything.
Is there any reason to change the old PS gate resistors back to the original 100 Ohm? They are current at 47.5 Ohm. Only thing left that I know I've changed...
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You can leave the 47 ohm resistors.
You can reinstall Q121 and R183. If the amp goes into protect, remove Q183 again. You can also try reinstalling Q04. It shouldn't make a difference now. If it does, you may have to remove it again.
Does it help if you ground the heatsink directly to the chassis ground terminal of the amp (use a short jumper wire and make sure you contact bare aluminum)?
I've seen some kicker class D amps that would malfunction if the sink wasn't grounded (directly or through a capacitor).
If it still squeals with the sink grounded, pull it out of the sink and power it up for just a few seconds at a time. Each time you power it down, touch the transistors (plastic side first, in case they're really hot). Which ones are getting hot?
You can reinstall Q121 and R183. If the amp goes into protect, remove Q183 again. You can also try reinstalling Q04. It shouldn't make a difference now. If it does, you may have to remove it again.
Does it help if you ground the heatsink directly to the chassis ground terminal of the amp (use a short jumper wire and make sure you contact bare aluminum)?
I've seen some kicker class D amps that would malfunction if the sink wasn't grounded (directly or through a capacitor).
If it still squeals with the sink grounded, pull it out of the sink and power it up for just a few seconds at a time. Each time you power it down, touch the transistors (plastic side first, in case they're really hot). Which ones are getting hot?
Perry.... I'm very agitated and very happy at the same time. In between my other post and this one I went ahead and reinstalled all the other parts Q121, R183 (with a 34.5kOhm instead of 33.2kOhm because that's what I have on hand
) and Q04 before you suggested it. All of those are fresh new parts or the equivalents we talked about earlier. Amp powered on, no protect anymore. My guess is Q121 was causing the false protect since it was the only "bad" part we found. What I noticed is that the amp was still drawing random current, but I went and hooked up a function generator to the input anyway (no preamp board). What I had on the speaker output (with no speaker hooked up) surprised me.... a perfectly clean 100Hz (my test frequency) sine wave. So encouraged by this and ignoring the loud squealing, I reinstalled the preamp board and repeated. Again, perfectly clean sine wave on the output. Also, the gain, crossover, and bass boost controls work exactly as intended. So then the ground idea was the last thing I tried. And boom (not literally!) squeal went away, idle current sitting steady around 2A @12V, 2.4A @14V both with clean sine wave outputs. Now I'm agitated we went all through this for a simple grounding issue. I design RF amplifiers (not class D... this is new to me 
) and pretty much the golden rule is there is no such thing as too much ground. I guess on other amps I've seen they have a small wire going to one of the mounting screws to the ground, but there was no such wire on this amp. So I guess my final (hopefully) question to you is what would be the best way to permanently connect the grounds? Should I connect through a capacitor or just directly? Right now I just used a small lock washer around one of the screws because one of the screw holes actually has solder under the screw head. Maybe it was the original intention of this particular hole, but if someone previous tried to repair this amp maybe they left this out. The screw does not contact the PCB without the lock washer because the nylon standoff prevents this. With the lock washer, there is continuity all the way through from the screwhead (chassis) down to the PCB directly.
Now I just need to load test this amp... hopefully no other issues! I thank you a ton for your advice and patience.
We went through quite a bit just to find the leaking Q121. With the amp in front of me, it would have taken just minutes but via a message board, it takes a good bit longer.
Yes, the lockwasher is there as a jumper between the screw and the board.
If the factory ground doesn't solve your problem, I'd recommend a 0.1uf cap in parallel with a 1k, 1/4w resistor. Connect the sink to chassis ground through the RC network.
Yes, the lockwasher is there as a jumper between the screw and the board.
If the factory ground doesn't solve your problem, I'd recommend a 0.1uf cap in parallel with a 1k, 1/4w resistor. Connect the sink to chassis ground through the RC network.
Well that's why you're the master
Just recently got into this amp repair thing in the past couple months. All of the other ones (about 8ish) have been pretty easy to identify and fix. Most have had been blown PS or output transistors, with one having smoked rectifiers. Everything else has checked out on them. This one had me baffled though. I hate it when its one of the small components! Not as bad as having to hunt down a single SMD cap or resistor though... especially without being familiar with the particular amp or having no schematic.I will keep the lock washer there for now. I plan to load test the amp sometime soon here. If more issues arise, I'll add the RC snubber.
It gets easier. If you know this amp well, you know ~10% of the class D amps because there are so many clones (Memphis, JBL, Cadence, Crossfire, Orion...). There are minor differences but the class D sections are very similar.
I'm no 'master'. I'm simply an average tech with a bit of experience. Most everyone who does this type of work knows what I know.
I'm no 'master'. I'm simply an average tech with a bit of experience. Most everyone who does this type of work knows what I know.
Kicker zx750.1 Amp. burnt resistors ID help..
I have a Kicker ZX750.1 Amp. with two burnt resistors :
R01 and R06 next to IC01 (TL494c) also looks like damaged
Anybody can Please tell me the ohm values of R01 and R06
and where to order TL494C (SMD) from ? Thank You.
Teknofix@bellsouth.net
I have a Kicker ZX750.1 Amp. with two burnt resistors :
R01 and R06 next to IC01 (TL494c) also looks like damaged
Anybody can Please tell me the ohm values of R01 and R06
and where to order TL494C (SMD) from ? Thank You.
Teknofix@bellsouth.net
Kicker zx750.1 Amp. burnt resistors ID help..
Thank you for your reply Perry,
Thank you for your help, I appreciated, will let you know when I replace the mentioned parts, see it turns on.. may be I have to replace the Q01
as well ?
Thank you for your reply Perry,
Thank you for your help, I appreciated, will let you know when I replace the mentioned parts, see it turns on.. may be I have to replace the Q01
as well ?
Kicker ZX-750.1 Amp. burnt component ID help..
Thank you for your reply Perry,
Regarding resistors R01 and R06 (they are side by side) Perry stated that they are both 10 Ohms. so the markings will be: (100) on these SMD resistors, just want to make sure that they are not 100 Ohms, as I measured like 500 Ohms.across the burnt one, the other one was placed
cracked in half by manufacturing as I stated earlier. Just want to confirm they are 10 Ohms. I'll try to find and remove them from other Amp. Pcb.
Also,C08 (next to IC 01) is also shorted, markings on it is
Can someone please confirm, and if I can use 1N4148 or 1N4001 instead ?
Thank You. Teknofix@bellsouth.net
C08 is a tantalum capacitor.
Are the markings burned away on the resistors?
The resistor wasn't likely installed cracked. When these (SMD) resistors fail, they can do so violently. I've seen quite a few that the two halves were blown apart. While failing, they heated the solder and the two halves were left standing upright on the solder pads.
Are the markings burned away on the resistors?
The resistor wasn't likely installed cracked. When these (SMD) resistors fail, they can do so violently. I've seen quite a few that the two halves were blown apart. While failing, they heated the solder and the two halves were left standing upright on the solder pads.
Kicker ZX-750.1 Amp. burnt component ID help..
Thank You for your response Perry, there are no markings on cracked and burned resistors, I looked with magnifier no markings just black.
therefore I want to make sure of their values ( R01-R06 ) you said both
are 10 Ohms, I measured 500 Ohms across burnt one by lifting one side off
could 10 Ohm resistor can go to up to 500 Ohms when burned ?
I need verification of original values of these two resistors, before replacing, so any confirmation of the values of R01 and R06 will be appreciated.
if C08 is a tantalum capacitor, what is the value please ? markings on it is:
( C106L ) compare with the others on the board, they check and measure like a diode, rather than a capacitor, which is confusing..
Thank You for your response Perry, there are no markings on cracked and burned resistors, I looked with magnifier no markings just black.
therefore I want to make sure of their values ( R01-R06 ) you said both
are 10 Ohms, I measured 500 Ohms across burnt one by lifting one side off
could 10 Ohm resistor can go to up to 500 Ohms when burned ?
I need verification of original values of these two resistors, before replacing, so any confirmation of the values of R01 and R06 will be appreciated.
if C08 is a tantalum capacitor, what is the value please ? markings on it is:
( C106L ) compare with the others on the board, they check and measure like a diode, rather than a capacitor, which is confusing..
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