Equivalent Transistors for JL 500/1

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I have been working on the above amp and I have found some of the driver transistors around the main audio channel that are defective. I can't seem to find the A1070 or the C3207 transistors. I searched a few thread and saw where the KSA1220A might work for the A1070, would the KSC2690A be a good replacement for the C3207? It looks like the voltages are lower than the original parts for both transistors. I am assuming the KSC2690A would be a good match since it is the NPN counterpart to the KSA1220A.
 
Thanks Perry, I will order the KSC2690A and the KSC1220A, would you recommend that I replace both sets of the original A1070 and C3207 with these new parts. It looks like the pre-drivers on the right side of the audio transistors are good but since this is a mono amp and all 4 audio transistors are the IRF540, I was thinking that replacing all of the old A1070's and C3207's might be a good idea to keep consistent parts in the pre-driver section even though the ones on the right side of the Audio Transistiors don't seem to be parallel parts with the bad ones on the right side of the Audio Transistors.

Kelvin
 
Okay, I got the parts in and this one is still acting strange. The power supply is not showing a nice square wave and one of the main audio transistors is getting real hot. Powering through my headlamp, it pulses the lamp as it tries to power up. The PNP pre driver transistor on one side of the audio transistors is showing .134 volts in diode mode on its outer legs no mater which way I have the probs posistioned. The one on the other side of the audio transistors s showing .543 volts with probes one way and OL with them swapped. Not sure where to go from here. May take picks of what o-Scope is showing when I go back in. The wife was getting up set with me spending so much time in my workshop, I had to call it for a few hours while I regroup.
 
I will remove the rectifier when I get home, I was thinking it must be in the power supply section since the square wave was looking so bad, not sure if something bad in the audio section could be causing the power supply to react this way but removing the rectifier should help isolate the problem.
 
Well, i was able to get home before and work on the JL Audio amp again. The power supply waveform looked almost perfect with the rectifier out of teh amp. I soldered it back in a took a picture of what the waveform looks like while it is attempting to power the audio section. I also took a pic of 60 Hz sin wave that I was playing through the head unit. The one pic is of the output waveform with no audio and the last pic is of the distorted sin wave. I did a bit more trouble shooting and found some bad resistors near the old 3906's in the pre driver section that I was able to replace with very similar value test parts (using through hole resistors temporary since the original are surface mount componets that I will need to order, but I was wanting to wait until I had a good handle on what other parts this amp may be needing). Does anyone have any idea what may be causing this do you think that using the KSC2690A and KSA1220A to replace the A1070 or the C3207 may be part of the problem. I almost wonder if I got these soldered in wrong (NPN in place of the PNP) I took my time, but it was late at night and I wouldn't put anything past my lack of sleep causing me to rush and make that kind of mistake. Hopefully the waveforms will help diagonose the problem. THanks,
Kelvin
 

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For every scope photo that you post, you must post the vertical amplifier and timebase settings as well as the terminal that you had the probe on. In most instances, it's best to post a single photo with all of the relevant information in each post.

There is nothing wrong with the power supply waveform as far as I can tell.
 
Sorry Perry, they were of bad quality. I have tried again. I could not get a good focus on the screen when trying to capture the knob setting in the photo. The volts are all set at 5 volts per division on each shot and the time division is set to 5 us. one of the transistors on the heatsink gets real hot while it is running, it is all I can do to keep it held tight to the heat sink, the other 3 feel good. The transistor is good, I just replaced that same one that fried the other day. Thanks for any help and I hope the pics are better this time.

Kelvin
 

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Sorry they were rotated wrong again, my wife will be the first to tell you that I am horrible at following instructions, LOL. The one pic is of the power supply at almost idle, then next is the power supply while it is producing that distorted sin wave in the last pic
 

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I agree about the grounding issue with the last pic of the sine wave output. Since this is a mono amp and does not have the non bridged speaker terminals that I typically use for ground when taking measurements in the audio section I was just relying on the ground between the pyramid power supply. I need to find a good grounding point off the high side of the transformer and try again. The first pic of the power supply was locked in nice (this was what the power supply looked like right before I played the sine wave). The middle pic was jittering from left to right as the sine wave played, pretty much at the peaks and valleys of the wave form where it looks fuzzy. The last pic jittered up and down and was not properly grounded to the step up side of the transformer. I tore back into the amp last night and I think I may have found what might have been causing this particular problem. There are 3 resistors on each side of the pre driver section, a 75 ohm a 240 ohm and a 470 ohm. The 75 and 240 resistors where way out I tolerance. I noticed that they appeared to be in series and I had wired an equivalent 320 at what I thought were their end points. As I went through trying to jot out a circuit diagram, I found a trace that was connect to where these two resistors appeared to just be ties together in series which pretty much left one of the pre drivers without a gate resistor. It's ashame we don't have a handy store nearby that sells surface mount parts and has a good supply of transistors. I guess I will go by the mall and pick up some potentiometers to temporary wire in to make sure this takes care of the problem before I order the correct parts online. Also, I notice this amp appears to have a trimmer pot in the audio section, I didn't think class D amps had the bias pots, I assume you set it the same way as the class AB pots?
 
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