What does C0C resistor do? Looks toasted.

Turran · 25 June 2012, 16:08

Greetings.

While replacing caps on one of my A1200s, I turned it over and see a burn mark. It has burned through the protective plastics below the motherboard.

No problems with the amiga though. Everything seems to work. So anyone know what C0C does? Should I try to clean it up with a fibre brush, remove the solder and resolder it? If I want to replace it, what kind is it?

The motherboard is a Rev 1A

Thanks in advance!

Turran · 25 June 2012, 16:24

C45 does not look that healthy either...

Turran · 25 June 2012, 16:29

And C18B is not too nice either..

Thats the last of them though.. Advice? =) How can this beast still work?

Turran · 25 June 2012, 17:44

After cleanup, C0C kinda popped loose after just touching it.. Looks a bit better though.

keitha1200 · 25 June 2012, 22:31

I've no idea!! but to be honest? if your computer still works? I wouldn't bother. Maybe a protective PCB spray? but i'm purely speculating.

Turran · 25 June 2012, 22:48

My guess is that someone replaced them with a shitugly soldering job. I dont like that so I'd like to correct it if they are used for anything important. Would like to know if someone who knows how to read schematics could check and tell me what they are so I can buy new ones =)

Thanks.

Turran · 25 June 2012, 23:13

Lets see if I get this right from reading the schematics and searching google..

C0C is used for the unused FPU socket on the motherboards (source http://www.amiga.org/forums/archive/...p/t-30722.html - search for C0C ) So should be OK to just remove?

C18B is found in the DRAM page, listed as optional..

No idea what C45 is for from reading the schematics. Listed at the "Memory Card" page.

Any help appreciated.

FOL · 26 June 2012, 00:26

Well as its toasted that means you have a short. Its drawing current, hence its cooking.

Check across the component and see if it reads short or low in ohms.
Could also be something connected to the component/s in circuit.

Both components are across + and -.

Turran · 26 June 2012, 22:14

I removed C0C and cleaned it up. It seems to do nothing as it goes to the unused FPU slot.

The other two I just re-soldered and they look a lot better now =)

FOL · 27 June 2012, 01:28

Quote:

Originally Posted by Turran

I removed C0C and cleaned it up. It seems to do nothing as it goes to the unused FPU slot.

The other two I just re-soldered and they look a lot better now =)

lol, not the best way to do it. Did you find the cause, was cap short, is there a short on the VCC rail to ground?

altcomputing · 27 June 2012, 01:48

They have shorted and are burnt now. You may replace them with new ones, but really, it should not make a difference for A1200 to run without them. They are to eliminate voltage rippling across PCB sections and numerous IC's.

I would not recomment leaving them as they are. They may short ocasionally again and make some smoke...

Just remove them and everything should be 100% perfect.

Turran · 27 June 2012, 09:52

Quote:

Originally Posted by FOL

lol, not the best way to do it. Did you find the cause, was cap short, is there a short on the VCC rail to ground?

I don't know. Accidentally burned my multimeter on my last high voltage job =)

Thanks for the advice. I'll remove the other two as well.

25 June 2012, 16:08	#1
Turran Moderator Join Date: May 2012 Location: Stockholm / Sweden Age: 49 Posts: 1,575	What does C0C resistor do? Looks toasted. Greetings. While replacing caps on one of my A1200s, I turned it over and see a burn mark. It has burned through the protective plastics below the motherboard. No problems with the amiga though. Everything seems to work. So anyone know what C0C does? Should I try to clean it up with a fibre brush, remove the solder and resolder it? If I want to replace it, what kind is it? The motherboard is a Rev 1A Thanks in advance!

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25 June 2012, 16:24	#2
Turran Moderator Join Date: May 2012 Location: Stockholm / Sweden Age: 49 Posts: 1,575	C45 does not look that healthy either...

25 June 2012, 16:29	#3
Turran Moderator Join Date: May 2012 Location: Stockholm / Sweden Age: 49 Posts: 1,575	And C18B is not too nice either.. Thats the last of them though.. Advice? =) How can this beast still work?

25 June 2012, 17:44	#4
Turran Moderator Join Date: May 2012 Location: Stockholm / Sweden Age: 49 Posts: 1,575	After cleanup, C0C kinda popped loose after just touching it.. Looks a bit better though.

25 June 2012, 22:31	#5
keitha1200 Registered User Join Date: Feb 2012 Location: Tayside Posts: 181	I've no idea!! but to be honest? if your computer still works? I wouldn't bother. Maybe a protective PCB spray? but i'm purely speculating.

25 June 2012, 22:48	#6
Turran Moderator Join Date: May 2012 Location: Stockholm / Sweden Age: 49 Posts: 1,575	My guess is that someone replaced them with a shitugly soldering job. I dont like that so I'd like to correct it if they are used for anything important. Would like to know if someone who knows how to read schematics could check and tell me what they are so I can buy new ones =) Thanks.

25 June 2012, 23:13	#7
Turran Moderator Join Date: May 2012 Location: Stockholm / Sweden Age: 49 Posts: 1,575	Lets see if I get this right from reading the schematics and searching google.. C0C is used for the unused FPU socket on the motherboards (source http://www.amiga.org/forums/archive/...p/t-30722.html - search for C0C ) So should be OK to just remove? C18B is found in the DRAM page, listed as optional.. No idea what C45 is for from reading the schematics. Listed at the "Memory Card" page. Any help appreciated.

26 June 2012, 00:26	#8
FOL PSPUAE DEV Join Date: Nov 2006 Location: Wales / UK Age: 45 Posts: 6,020	Well as its toasted that means you have a short. Its drawing current, hence its cooking. Check across the component and see if it reads short or low in ohms. Could also be something connected to the component/s in circuit. Both components are across + and -.

26 June 2012, 22:14	#9
Turran Moderator Join Date: May 2012 Location: Stockholm / Sweden Age: 49 Posts: 1,575	I removed C0C and cleaned it up. It seems to do nothing as it goes to the unused FPU slot. The other two I just re-soldered and they look a lot better now =)

27 June 2012, 01:48	#11
altcomputing MC68060@85MHz Join Date: Jan 2011 Location: Poland/Wroclaw Age: 38 Posts: 76	They have shorted and are burnt now. You may replace them with new ones, but really, it should not make a difference for A1200 to run without them. They are to eliminate voltage rippling across PCB sections and numerous IC's. I would not recomment leaving them as they are. They may short ocasionally again and make some smoke... Just remove them and everything should be 100% perfect.

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