Commodore C64C wrong colors

[robbo]

Hello, i have a problem with colors in my C64C, they are different in basic also in games changing colors ,
i use video port with composite cable, but also in rf situations is the same.
Please help me, what is wrong and how i can fix it.

Regards

 

[Bryce]

That's usually a sign of damaged colour RAM (U19 - MN2114)

Bryce.

 

[TheCorfiot]

Or the PLA beginning to fail

 

[robbo]

I cant localize U19, i see U20,U18 but not U19, i make photo of mainboard can you localize U19?

 

[Jameson]

Bryce is correct - your COLOUR RAM chip is faulty. The PLA VERY rarely fails on the C64C (however VERY often fails on the ole' Breadbins - different design).

However, looking at your motherboard, you unfortunately appear to have the last revision of the C64C.... which integrated the colour ram into the PLA..... which means instead of simply replacing a cheap (about $2.00) easy to acquire part (there are dozens of 2114 ram chips on eBay), you need to replace the entire PLA - which not only is a real test of your desoldering skills (the pitch of the IC legs is closer than the standard 2.54mm) but these "all in one" PLAs are difficult to find.

I wish I had better news.

 

[wilykat]

Maybe it'd be better to put that board aside as spare part board and get another C64C? That chip usually don't fail and when it goes, it's not going to be easy to remove it. A replacement C64C should be working fine. And if not, you got plenty of spare chips from your C64C to salvage from.

 

[demolition]

Couldn't it also be caused by a faulty VIC (8565R5)? In any case, it will be easy to test since it is already in a socket (at least it usually is and also looks like it on the picture).

 

[robbo]

Thanks demolition I put a chip from another commodore and the problem disappeared but my chip has symbol 8565R2 not 8565R5 Do I have to buy a chip with the same symbol, and where local I can get it at a reasonable price on eBay because the price is about 15 euros for that price i can buy Commodore computer (main unit). Thanks again.

 

[demolition]

Thanks demolition I put a chip from another commodore and the problem disappeared but my chip has symbol 8565R2 not 8565R5 Do I have to buy a chip with the same symbol

R2 or R5 doesn't matter as they are fully interchangable as long as it says 8565.

As for where to get one, I'd look through Amibay or put up a wanted thread. Surely someone must have one they can part with for a decent price.

 

[Bryce]

I probably have a spare 8565 in my spare parts. I'll check tomorrow and let you know.

Bryce.

 

[Bryce]

Sorry Robbo, big things got in the way and messed up my weekend, I'll check tonight.

Bryce.

 

[roy_bates]

its pla or sram (2114) since its a newer c64 its most likely the sram

 

[Bryce]

its pla or sram (2114) since its a newer c64 its most likely the sram

Eh? He has already established that it's the 8565, a few posts back.

Bryce.

 

[robbo]

Unfortunately i run Commodore today and problem come back thats mean is not 8565, i dont now what i must check next

 

[Bryce]

If that's the case I'm with Roy: the SRAM is dodgy.

Bryce.

 

[robbo]

Im not a expert but in this sitehttp://ist.uwaterloo.ca/~schepers/MJK/c64__.html also is 4066 ColorRam in U21

 

[roy_bates]

Im not a expert but in this sitehttp://ist.uwaterloo.ca/~schepers/MJK/c64__.html also is 4066 ColorRam in U21

the 4066 isnt colour ram,just look for a part marked 2114 and number before and after its the same part on all c64's apart fromthe very last ones that built it into the pla,on a c64c its normally between the pla and vic

if you dont know take a picture of yuor board,i have seen c64c's with older boards fitted


EDIT: i just looked at a picture you uploaded,you have the last c64 board made your sram is built into the pla you wont find it on the board on its own,its seems your out of luck...unless by some miracle its something else

 

[mrr19121970]

@robbo

I might be able to help. I'll PM you.