Alpine 3545 squared

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I got two of these beasts sitting on my bench. I guess they are pretty rare - they say Fabrique Au Japon; AKA Made in Japan. The last time one of these was serviced was in 1996 but these are likely from the late 80s. Class AB from the looks of it (The 3558 was a Class A / Class AB). Their approximate power rating would be about 250w X 2 at 4 Ohms.

Internally these amps are in very good shape. Nothing imidiate catches the DVM off guard. i dont think these are going to be that costly to fix.

From left to right;

The one on the left has a plate number #1105. Powers up but sounds like there is an internal speaker under the PCB - making a white-noise sound.

The one on the right's plate is numbered #0471 and proclaims itself to be 'overheated' when power and rem is applied.

There seems to only be one other thread on DIY about these amps and not a whole lot else.


This is gonna be fun... All transistors are individually screwed down.
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You don't remove the individual screws unless you're removing the transistors. The transistors are screwed to a riser plate. You unscrew that plate.

Let's start with the one in thermal protection. Start a new thread for the other one when we finish this one.

Post the DC voltage on all pins of the 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:


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Thanks Perry:


Pin 1: 0.021
Pin 2: 0.899
Pin 3: 0.837
Pin 4: 5.06
Pin 5: 1.697
Pin 6: 3.741
Pin 7: 0
Pin 8: 13.63
Pin 9: 0.789
Pin 10: 0.799
Pin 11: 13.68
Pin 12: 13.68
Pin 13: 5.07
Pin 14: 5.07
Pin 15: 5.07
Pin 16: 0.001

Theres no more than 13.7vDC anywhere

Also, (on both of these amps) the power curcuitry is using D1065 transistors. Measuring from legs 1-3 I get only 3 ohms like they are shorted; but 1-2 and 2-3 I get 5M Ohms.
With Q602 off the board, the amp powers up with only Remote-On lit. Over-heat is off. There doesnt seem to be any voltage greater than 13.7v anywhere in the amp though.

I wonder if I have to have everything bolted down in the heatsync for this amp to fully come on. Right now I'm just powering it up on the bench w/o the sync and parts laying all over.
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110vAC at the rail. This thing must not have been been powered on in ~10 years. It smells like a RAT PISSED on it. And it almost crys as my (fixed) power supply barely powers it up out of protection mode.

I cant test audio on it though; speaker terminals have 18vDC on them.
Come to think of it, I dont think theres any voltage at the rails. I was measuring the incoming voltage from the transformer, before the rectifiers. The center leg of the rectifiers are not putting out any more than +- 1vDC or AC, but legs 1&3 both have 110vDC on them. The output transistors have hardly any DC on them either.
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