Parts needed for Rockford Fosgate 800a2

[chipper]

Hey guys so today I bought myself a little project off a friend I guess who tried to fix himself eventually gave up. Anyway the power supply is non working and I can't solder in new 3205's to get it working and go from there. I was wondering if anyone has a dead parts amp out there who's willing to sell me the mehsa boards only. I'll post a picture what I'm talking about.

 

[chipper]

Or can I use another method for cooling?

 

[RiLoWa]

If the amp isn't part of a special collection, why not cut the bad portion of MESHA off, use a different insulator and make some clamping bars?

If it is special, I may have a pair of those boards laying around.

 

[chipper]

If the amp isn't part of a special collection, why not cut the bad portion of MESHA off, use a different insulator and make some clamping bars?

If it is special, I may have a pair of those boards laying around.

It is and it isn't.. It's just something that would bother me you know? Like an odd number I guess... can you pm me I'd like to get those MEHSA boards of you.

 

[chipper]

I'm having a trouble getting this amp to work. I'm getting 1.4 volts on the gate pads on all 8. I replaced the driver transistors and nothing still. What else do I check?

 

[Perry Babin]

Are the power supply FETs in the circuit?

 

[chipper]

I only have four test fets in just waiting on some 3205's to come in

 

[Perry Babin]

If your 12v power supply is adjustable, set the voltage at about 11v. That should get the duty cycle to increase and give you the voltage you expect.

 

[chipper]

It's non adjustable. What else can I do?

 

[Perry Babin]

Did you check for rail and regulated voltages in the audio circuit?

Did you check for audio?

 

[chipper]

It produces no audio and no rail voltage. What else do check?

 

[RiLoWa]

Is your 494 operating?

From your picture it looks like it and the 339 have been removed once before.

 

[chipper]

I don't think so I checked voltages on another a good 800a2 I have here and yes I believe they were both replaced at one time on the other 800a2 it has TL494C and this one just has TL494 same with LM339. Where i start next?

 

[Perry Babin]

I forgot that someone else was helping so I'll drop out to avoid confusion. That said, he'll need something to work with. Post the DC voltage on all pins of the 494 and the 339. Copy and past the following.

339
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:


494
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:

 

[chipper]

I found the issue they were the wrong parts installed. I swapped them out for TL494C and LM339D amplifier powered on. It produces rail and has audio but it's got a cracking distorted output with music playing as well as no music playing.

 

[RiLoWa]

You may need to clean the switches and gain pots next. Operating the switches with the amp on may help you identify which one(s) need cleaned.