Need Help with this Circuit Please

[SteveNielsen]

Re: Need Help with this Circuit Please

Just out of curiosity can you show pictures of the damage? Traces on audio boards are ofter repairable. They are not multi-layer computer boards with tiny traces.

[Khron]

Re: Need Help with this Circuit Please

Well, despite that, even IF you had to retrofit a separate power amp, are you really sure you wanna take quite SUCH a "cheap" route, amp-wise?

For what it's worth, for about 40$ shipped it seems, you can get a pair of P3A pcb's - http://sound.westhost.com/pcb/pp3a.htm

You could potentially re-use (at least) the good silicon from the stock amp board, perhaps also some of the passives, so even the component cost wouldn't be all that much extra But that's just my pair of pennies...

[SteveNielsen]

Re: Need Help with this Circuit Please

Indeed, there's more than one way to skin a cat.

[stj]

Re: Need Help with this Circuit Please

oldskool design.
http://www.ebay.com/itm/161852896480

[tfs2015]

Re: Need Help with this Circuit Please

stand By for picture

[keeney123]

Re: Need Help with this Circuit Please

Some amps in the 60's just had a board with no circuitry. The board was used just to mount the components and wires were soldered point to point.

[tfs2015]

Re: Need Help with this Circuit Please

Looks like I did damage on top of damage when I removed the burnt transistors. Tell me can this be fixed or am I looking at a total rebuild of the board and or circuit.

Thanks
Tom

[stj]

Re: Need Help with this Circuit Please

tracks look o.k. - just loads of sludgy solder all over them that needs cleaning off.
then clean the flux off with IPA and take fresh foto's

[SteveNielsen]

Re: Need Help with this Circuit Please

Yeah, get rid of the blobs of solder and clean the board. Go easy on the pads with the heat so they don't pull up but I don't see damage to traces either, if there are they can be repaired on this board.

[tfs2015]

Re: Need Help with this Circuit Please

The pads are the parts that I am concerned about because some of them pulled up when I was desoldering the bad power transistors.

[keeney123]

Re: Need Help with this Circuit Please

The pads are the parts that I am concerned about because some of them pulled up when I was desoldering the bad power transistors.

I would use solder wick to clean the solder up. Just do not let iron stay to long on the braid. You would want to put a little flux on the solder joints and make sure the tip on the solder iron is tinned, place the braid on the solder that you want to pull up, then put the iron on the braid. The heat will transfer down through the braid heating up the solder. The solder will suck up into the braid as the braid becomes full you will need to feed unused braid into the solder. This should happen in one quick motion. Just make sure you have enough braid out so when you fed it in you do not burn your fingers. If it seems like it is taking to long then you will have to let the solder cool down again and try again. You do this to prevent burning of the board or pad.

[tfs2015]

Re: Need Help with this Circuit Please

If I am unable to repair this circuit board to get the amp working, is there an amp circuit that I can use to put onto a new circuit board maybe one that is not as complicated as this one?

[tfs2015]

Re: Need Help with this Circuit Please

Some of the pads have broken off of the traces

[stj]

Re: Need Help with this Circuit Please

fine, use jump wires - those transistors are mounted on a heatsink.

if you give up, look at the ebay link i posted in post#24

[tfs2015]

Re: Need Help with this Circuit Please

can't use that eBay item says that it uses AC power and the only power I have available is DC Power. I appreciate the information.

[tfs2015]

Re: Need Help with this Circuit Please

What size wire would I need to use as the jumper Wire? I have 18 ga. solid right now.

[SteveNielsen]

Re: Need Help with this Circuit Please

18 ga is too big. I use clipped off leads from parts like small resistors or caps for that.

[budm]

Re: Need Help with this Circuit Please

can't use that eBay item says that it uses AC power and the only power I have available is DC Power. I appreciate the information.

You just feed the DCV directly to the two main filter caps. Your amp has SMPS power supply or linear power supply?

[stj]

Re: Need Help with this Circuit Please

i think ebay add is wrong, i dont see any rectifier diodes in the foto.
even if it had some you could bypass them.

i think the chinese just meant use a split suppy.

[budm]

Re: Need Help with this Circuit Please

The bridge is attached to the heatsink.