Alpine 3545 squared

[Dr Zeus]

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. Alpine 3545 (alpines best) problems



This is gonna be fun... All transistors are individually screwed down.

[spooney]

Most early Alpines had individual screws per transistor. Makes it a real pain to work on but it is so worth it in the end in my opinion. Love these old Alpines

[Perry Babin]

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:

[SIRDRINKSALLOT]

I'm no expert with these, but the 2 that I have repaired had solder issues with the vertical boards. Check where it connects to the main board on the under side of the amp. This is where I found the problems on mine.

[Dr Zeus]

Thanks Perry:

494:

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.

[Perry Babin]

Remove ZD601. Does the amp power up with that diode out of the circuit?

[Dr Zeus]

I removed D601 and the amp did not appear to want to power up.

[Perry Babin]

Can you be more specific?

Is everything precisely as it was before?

[Dr Zeus]

Yes I was about to edit. The LEDs on the front come on just as before - REM and Overheat LEDs.

[Perry Babin]

Remove Q602. Does the amp power up?