I have been extensively searching. Most amps are easy to fix, except this Kicker AMP. 2005 RED BOARD
I almost had everything working, but..............
Now I am getting BOTH protection and power LEDS on.
I replaced ALL 8 Blown IRF3205 MOSFETS with HRF3205
Found 1 Blown IRF640 in output stage, replaced 3 of them so they all match.
SURFACE MOUNT WORK:
Replaced TL494 (SMT) surface mount chip (what a PITA)
Replaced both PNP down drivers for TL494 with larger TO92 types
Replaced NPN TL494 Collector-Pin Turn-on Transistor with larger TO92, then TO126 (original transistor had hole blown in it)
Replaced NPN Relay driver transistor with TO92
Before I replaced the Relay driver but replaced everything else, the amplifier was WORKING................except no relay, or output at speaker terminal, but I could put the positive speaker wire after the output inductors and get perfectly good output into a speaker.
Measured Relay coil, and got low 300mv output, remove relay and get ~12V, tested relay, it is good. After changing Relay driver transistor, I now get both red and green Power/Protect LEDS on. No other problems, NO HEAT, no excessive load, just both LEDS on, and no output!
My Meter (no scope) measures ~22khz at gates of 3205 MOSFETS. I was getting 54.8V/rail output before, I need to check again, however, still no relay.
Thanks for helping me try to fix this amp nightmare!
I almost had everything working, but..............
Now I am getting BOTH protection and power LEDS on.
I replaced ALL 8 Blown IRF3205 MOSFETS with HRF3205
Found 1 Blown IRF640 in output stage, replaced 3 of them so they all match.
SURFACE MOUNT WORK:
Replaced TL494 (SMT) surface mount chip (what a PITA)
Replaced both PNP down drivers for TL494 with larger TO92 types
Replaced NPN TL494 Collector-Pin Turn-on Transistor with larger TO92, then TO126 (original transistor had hole blown in it)
Replaced NPN Relay driver transistor with TO92
Before I replaced the Relay driver but replaced everything else, the amplifier was WORKING................except no relay, or output at speaker terminal, but I could put the positive speaker wire after the output inductors and get perfectly good output into a speaker.
Measured Relay coil, and got low 300mv output, remove relay and get ~12V, tested relay, it is good. After changing Relay driver transistor, I now get both red and green Power/Protect LEDS on. No other problems, NO HEAT, no excessive load, just both LEDS on, and no output!
My Meter (no scope) measures ~22khz at gates of 3205 MOSFETS. I was getting 54.8V/rail output before, I need to check again, however, still no relay.
Thanks for helping me try to fix this amp nightmare!
Last edited:
List the locator numbers of transistors you replaced.
Are you still getting output after the output inductors? If not check to see what the voltages measured outside to outside (same as Drain to Gate) on all IRF640's and IRF9640's output mosfets. (~3.5v to 4.0v)
Check to see that the relay turn on circuit is working, with amp on black probe on -spkr terminal and red probe on anode (~.10v) and cathode (~12v).
Also, check the voltage from spkr/signal ground to power ground.
If the amp is working,and the relay is good(based on you comments) I suspect there maybe a problem in the softstart circuit or the protection circuit. I've seen where the voltage from softstart is high enough to turn on the TL494 but not enough to switch on relay.You can check the voltages from power ground to PIN 8 and PIN 11 of the 494, it should be ~13v. What your discribing is unusual but I've seen it before. It may take some back and forth but I'm sure it will be resolved.
Are you still getting output after the output inductors? If not check to see what the voltages measured outside to outside (same as Drain to Gate) on all IRF640's and IRF9640's output mosfets. (~3.5v to 4.0v)
Check to see that the relay turn on circuit is working, with amp on black probe on -spkr terminal and red probe on anode (~.10v) and cathode (~12v).
Also, check the voltage from spkr/signal ground to power ground.
If the amp is working,and the relay is good(based on you comments) I suspect there maybe a problem in the softstart circuit or the protection circuit. I've seen where the voltage from softstart is high enough to turn on the TL494 but not enough to switch on relay.You can check the voltages from power ground to PIN 8 and PIN 11 of the 494, it should be ~13v. What your discribing is unusual but I've seen it before. It may take some back and forth but I'm sure it will be resolved.
Good Job PapaZBill. You called some of what is wrong. I took some measurements last night again. The AMP section still is working, my mistake, I also get +/-56V per rail now, then measured again, and got +/-52V rails before I went to bed last night WTF? Output toroids have slight heat like normal, I get audio output if I bypass the relay contacts.
I am getting too low of voltage in turn-on circuitry. Pins 8/11 on TL494 only get 4.6V! So the MOSFETS must barely have enough gate drive to turn on, but they are working, and are cold, no heat at all. I measure 43.4Khz on CT pin of TL494, (with multimeter) so it is working.
Another concern is how does this thing regulate voltage with nothing connected to COMP pin on TL494?
I will list transistor numbers, and pin voltages to TL494
U01 TL494
Pin 1: 0
Pin 2: 4.98
Pin 3: 61.3mV
Pin 4: 84.4mV
Pin 5: 1.412
Pin 6: 3.72
Pin 7: 0
Pin 8: 4.6
Pin 9: 1.642
Pin 10: 1.644
Pin 11: 4.6
Pin 12: 11.16
Pin 13: 4.98
Pin 14: 4.98
Pin 15: 4.98
Pin 16: 0
Q1/Q005 - PNP Pull-Down transistors (replaced with 2SA1020)
Q32 - Turn-On Transistor (Replaced Now with 2SD667)
Q35 - Relay Driver (Replaced with 2SD667)
Q31 - D/K (Don't Know) But connected to Q32
Q33 - D/K
Q34 - D/K
Q01 - D/K
Q02 - D/K
I am getting too low of voltage in turn-on circuitry. Pins 8/11 on TL494 only get 4.6V! So the MOSFETS must barely have enough gate drive to turn on, but they are working, and are cold, no heat at all. I measure 43.4Khz on CT pin of TL494, (with multimeter) so it is working.
Another concern is how does this thing regulate voltage with nothing connected to COMP pin on TL494?
I will list transistor numbers, and pin voltages to TL494
U01 TL494
Pin 1: 0
Pin 2: 4.98
Pin 3: 61.3mV
Pin 4: 84.4mV
Pin 5: 1.412
Pin 6: 3.72
Pin 7: 0
Pin 8: 4.6
Pin 9: 1.642
Pin 10: 1.644
Pin 11: 4.6
Pin 12: 11.16
Pin 13: 4.98
Pin 14: 4.98
Pin 15: 4.98
Pin 16: 0
Q1/Q005 - PNP Pull-Down transistors (replaced with 2SA1020)
Q32 - Turn-On Transistor (Replaced Now with 2SD667)
Q35 - Relay Driver (Replaced with 2SD667)
Q31 - D/K (Don't Know) But connected to Q32
Q33 - D/K
Q34 - D/K
Q01 - D/K
Q02 - D/K
Last edited:
Lift pins 8 & 11 of the 494 and check the voltage at R67-10 ohm smd. This will isolate the soft start circuit from the 494.
Also, check the DC voltages around D05 and D16-KDS184.
And check the DC voltages around Q31-KTC3876GR,Q32-MMBTA14,Q33-KTA1505GR & Q34-KTC3875GR.Also C45-47mf/16v both terminals.This is the soft start circuit. It appears that something is not allowing the capacitor to charge up to the the B+ line and subsequently the soft start is not switching and latching the voltage for Pin 8 and 11.
Also, check the DC voltages around D05 and D16-KDS184.
And check the DC voltages around Q31-KTC3876GR,Q32-MMBTA14,Q33-KTA1505GR & Q34-KTC3875GR.Also C45-47mf/16v both terminals.This is the soft start circuit. It appears that something is not allowing the capacitor to charge up to the the B+ line and subsequently the soft start is not switching and latching the voltage for Pin 8 and 11.
Last edited:
Thanks, you mention Q32 (MMBTA14) and datasheet says it is a darlington transistor, that could definitely be a problem, so I will change that one out, because the one I used is NOT a darlington.
ALSO Q35, what is that transistor part number for that?
Thanks again, that info is vital!
ALSO Q35, what is that transistor part number for that?
Thanks again, that info is vital!
Good News!
I changed out Q32 for a Darlington, and the capacitor for the soft-start was slightly warm[b/] (not good, discovered when testing at a higher 13.4V) so I changed it out as well.
The amp is Working. Rails are slightly higher now. (11.5V gives me 56.9V rails, 13.4V gives 66V rails) Green power light on, and also comes on brighter and protection light off. Relay clicks on every time. The soft start transition from red to green is slightly longer due to the replaced capacitor.
I still have some concerns though. At only 11.5V input (computer power supply for testing) the Drive for TL494 Pins 8 & 11 only gets 8.72V. 0.4V is dropped across the 10 ohm series resistor, so the output darlington Q32 is producing 9.12V At 13.4V input, those values also increase by 1.9V.
I feel this is LOW IMO for adequate gate drive, considering the drop in the TL494 before the MOSFET gates, but it appears normal for this amp, considering it now allows the relay to trigger, but I would like some input on this before I do some heavy audio testing, and eventually return the amplifier to it's owner.
I changed out Q32 for a Darlington, and the capacitor for the soft-start was slightly warm[b/] (not good, discovered when testing at a higher 13.4V) so I changed it out as well.
The amp is Working. Rails are slightly higher now. (11.5V gives me 56.9V rails, 13.4V gives 66V rails) Green power light on, and also comes on brighter and protection light off. Relay clicks on every time. The soft start transition from red to green is slightly longer due to the replaced capacitor.
I still have some concerns though. At only 11.5V input (computer power supply for testing) the Drive for TL494 Pins 8 & 11 only gets 8.72V. 0.4V is dropped across the 10 ohm series resistor, so the output darlington Q32 is producing 9.12V At 13.4V input, those values also increase by 1.9V.
I feel this is LOW IMO for adequate gate drive, considering the drop in the TL494 before the MOSFET gates, but it appears normal for this amp, considering it now allows the relay to trigger, but I would like some input on this before I do some heavy audio testing, and eventually return the amplifier to it's owner.
I test amps with an astron set to 14.4v. The input voltage will determine the B+ (around 14.3v) for the amp. This will produce about ~13.7v from the softstart circuit. With ~.5v drop across the 10 ohm resistor,Pins 8 & 11 will see ~13v. So, this seems to track what you are seeing.
If you are seeing ~5v on drive pins 8 & 11, you should be good to go.
btw this amp is not regulated,hence the comp pins 1 & 16 on the 494 are grounded.
If you are seeing ~5v on drive pins 8 & 11, you should be good to go.
btw this amp is not regulated,hence the comp pins 1 & 16 on the 494 are grounded.
Thank you very much PapaZBill for your very helpful support, and your knowledge of this particular amplifier as well as your knowledge in general, and being polite and thorough with your responses.
Hopefully this thread will be helpful to others that may fix this amp as well, being this part of the amplifier tends to be a common failure point (according to searches).
Hopefully this thread will be helpful to others that may fix this amp as well, being this part of the amplifier tends to be a common failure point (according to searches).
- Status
- Not open for further replies.