Alpine 3558 wont power up

bmore5077 · 2019-01-12 1:58 am

Been working on a alpine 3558. Used to power up but go into mute. Found leaking small caps and replaced now it wont power up at all. No current draw like its just dead. Any help is appreciated.

Perry Babin · 2019-01-12 1:59 am

Post the DC voltage on all terminals of the driver IC.

bmore5077 · 2019-01-12 2:18 am

Hello, is that the board with the black coating on it

Perry Babin · 2019-01-12 2:23 am

If you can't get to the pins to take readings, it's unrepairable.

bmore5077 · 2019-01-12 2:35 am

It does look like the driver ic is under all that coating. Not sure if I can get to pins. I will try. Thanks

bmore5077 · 2019-01-17 12:35 am

Was able to get to 3 pins on ic

Was able to get to pins 5,6,7 which is vcc 1, vcc 1, and remote. All 3 should have 13v according to service manual and only pin 7 which is remote had voltage. This amp was powering up before replacing the small elna caps. Still trying to find a way to save it.

Perry Babin · 2019-01-17 1:00 am

If it's a double-sided board, is it possible that a via was pulled or damaged?

bmore5077 · 2019-01-17 1:33 am

Good thought. Are you talking about when I replaced the capacitors. They removed pretty easily and it didnt look or feel like I pulled hard enough to do that but I'll check and see. I hope not as I've never had that happen and not sure how to repair. maybe rivers. Thanks again

Perry Babin · 2019-01-17 1:44 am

If the caps were leaking, they could have eaten away at the copper.

You can sometimes use a jumper to reconnect the break. The repair technique will vary.

bmore5077 · 2019-01-18 3:46 am

I pulled all the caps I replaced and checked the vias. The vias tested good. All had a good connection top to bottom of board. Put caps back in still wont power up at all. I'm gonna keep searching for my next step....ha

Perry Babin · 2019-01-18 3:52 am

All you want to do is reestablish the connection to B+ if that's what's missing. Find the closest cap on the B+ and connect to the IC with a jumper wire.

bmore5077 · 2019-01-18 11:59 pm

I checked for continuity from cap to cap top to bottom of the board to check vias and to the ic chip pin. It was good. Seems like there is nothing but the 13.2 v from my power supply on this amp no matter where I check. The center pins of the power fets have 13.2v. Oddly on the 40v rails and the capacitors I have like 220mv. Must be something in power section.

Perry Babin · 2019-01-19 12:55 am

Do you have 12v on both terminals of L805?

bmore5077 · 2019-01-20 12:56 am

Yes sir I do.

bmore5077 · 2019-01-20 1:11 am

Caps have like 220mv

bmore5077 · 2019-01-20 1:35 am

Measurements from driver ic 801 on panel main rear. The board has 2 ic chips. One for each side as its split into 2 pieces.
Pin1. 0mv
Pin 2 0mv
Pin 3 .2mv
Pin 4 6.8mv
Pin 5 254.7mv
Pin 6 254.7mv
Pin 7 13.09v
Pin 8 .2mv
Pin 9 8.1mv
Pin 10 1mv
Pin 11 196.5mv
Pin 12 .2mv
Pin 13 .6
Pin 14 1mv
Pin 15 .3mv
Pin 16 .4mv
Pin 17 196.4mv
Pin 18 .790mv dropping steady
Pin 19 3mv
Pin 20 2.6mv

bmore5077 · 2019-01-20 1:39 am

The above measures is for one ic chip as I can only get to the rear main board side. The same side that L805 was on. The only one that seems good is pin 7 for remote.

Perry Babin · 2019-01-20 2:19 am

The break seems like it has to be in the rectangle in the attached diagram. It could be on either side of the board.

bmore5077 · 2019-01-20 2:30 am

Ok I'll start trying to track it down. I was thinking that because of 12v at the inductor but not the caps or ic. Thanks for your help.

bmore5077 · 2019-01-20 3:05 am

Thanks for taking the time to look at the schematic and help me.

Alpine 3558 wont power up

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