Fixed my old amp today!!

[mikelaubach 10+ year member]

I'm pumped and wanted to share with people who understood. The wife just gives me the "That's nice for you, honey" response.

It's just an old Coustic AMP-360 (65W x 2 at 4O) that I've had in the attic for about 10 years. I did some internet research to learn about the power supply and the audio section since nothing was burned/charred/otherwise. I learned a TON about how these amps work (I have an electronics background so it was far from a noob looking at the same stuff). I was on the couch for a while this afternoon, and the wife looked over a few times at the laptop and commented that "it must be serious, I see graphs." LOL

Anyway, it turned out to be a simple cold solder joint at the diode bridge. I had the +30VDC out of the bridge on the component side, but it did not make it to the audio amplification section. So I started to trace it backwards, but was getting nowhere fast. So I traced forward, and where the diode chip was soldered on the board, there was no +30 on the backside. "WTF??" I don't have one of those lighted magnifying soldering lenses, so I had to get my nose in there with a flashlight.

Broke out the iron and resoldered the joint, and BANG! audio. Sweeeeeeet. It's been YEARS since I've played with the o-scope, so that was nice too. Of course, I had to get re-acquainted with it after all this time. And my probe is out of adjustment - the square wave, well, wasn't so square. But it was quite good enough to get the job done.

Now to figure out how to mount these amps in the Bronco. Once I get nice matching amps, I don't mind them being exposed. But I have this one, a PPI 2240, and an old art-series PPI (2050AM). The sub enclosure is built (DIY with 3/4" MDF and fiberglass) and needs to be mounted too. Gees, it's like I'm just starting. Oh, I am!

Anyway, another antique saved from the junkman!

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[05fronty 5,000+ posts]

That's nice for you, honey

 

[Kangaroux 5,000+ posts]

That's nice for you, honey

how many beers are we at now? lol

 

[05fronty 5,000+ posts]

how many beers are we at now? lol

i stopped counting lutz

 

[Louisiana_CRX 5,000+ posts]

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[mikelaubach 10+ year member]

Have another beer for me, honey. LOL

Here is a guts shot:

And this is the cold solder joint. It looks like it was cooked at the factory (I bought these new and never had to have them repaired). I re-wet the solder and it's working now.

 

[Louisiana_CRX 5,000+ posts]

nice

 

[05fronty 5,000+ posts]

you know i'm messin with ya. good work to get it fixed

 

[mikelaubach 10+ year member]

you know i'm messin with ya. good work to get it fixed

I know, it's all goooood. And thanks.

 

[surreal 10+ year member]

Link to helpful articles?

 

[mikelaubach 10+ year member]

I used Basic Amplifier Repair to fill me in on how the car amplifier world works, but again, I have a background in electronics and the tools to do the job, so it really was a small step.

Look luck.