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Hi guys,
I'm looking for somebody who can repair my C64 please?
The images are all garbled up probably due to it being in the loft the past 15 years.
Images here - http://imageshack.us/g/1/9953513/
If you could let me know I would really appreciated and a possible total cost too.
Regards,
rom defect or ram, have cartridge for test?
more cartridge exclude internal rom
I have one cartridge game and that loads, but the image is all scrambled. The scrambled black image is hat cartridge trying to load. Music comes on, but the image is broken.Quote:
Originally Posted by piacc64
Hope that helps. Let me know if anybody can help.
It could be that the PLA or RAM is on it's way out. Is this a 'Breadbin' early C64 or a later C64C?
I have a donor board for the early C64 and could desolder the PLA or RAM from that for you; whereabouts are you in Lancashire?
I have the earlier Amiga looking one Mate. I'm in Oldham if that's any good?Quote:
Originally Posted by Merlin
I'm happy to pay for parts, work, p&p etc etc. I just want this baby working again :)
I think is PLA.
I have used with success an EPROM 27C512 as replacement of original chip. You can Google EPROM PLA :)
That's a short C64C board.
The 'Amiga' looking one is the C64C model and it's the later one. The old C64 was a sort of grey/brown colour and was nicknamed the 'Breadbin' because of it's shape, like the old breadbins.Quote:
Originally Posted by mancity12I have the earlier Amiga looking one Mate. I'm in Oldham if that's any good?Quote:
Originally Posted by Merlin
I'm happy to pay for parts, work, p&p etc etc. I just want this baby working again :)
@ Gennyflick / anyone
My first thought was PLA as well. Do you know if the earlier PLA will fit the later model, as a direct swap-out?
@Mancity12
The PLA (chip U5) in the board I've got is version 901225-01 - what version is the one on your board?
My board still has the RAM chips, if any need to be swapped out.
I have see PCB image now: this is one of the last versions, in this case isn't possible PLA replacement using an EPROM because PLA chip is not present. Try change RAM chip and electrolitic capacitors.
---------- Post added at 23:01 ---------- Previous post was at 22:56 ----------
In this version there isn't PLA chip, however in older versions you can use same PLA.Quote:
Originally Posted by Merlin
@ Genny_flick
Is this the version with the 906114-01 PLA in it?
@Mancity12
If it's the RAM chips, you need to source some 64k x4 DRAM chips. A certain auction site *cough* may be able to assist you.
problem is ram 2114 or 41464
the pla not exist, there are 251715-01 in the c64c
Quote:
Originally Posted by Merlin
Hi mate,
901225-01 is character rom;
906114-01 is PLA (still same in all PCB having 8 x 4164 chips (64K x 1bit)
C64C version have a glue logic chip to reduce more of TTL chip of previous version and PLA. This is an all in one solution ;)
So, basically we need to know which RAM chips are on his board, either 2114 or 41464 DRAMs? Are these interchangeable, as they both appear to be 18-pin devices? I realise it may be an 'either one or the other' situation and that you can't mix them.
@ Genny_flick
The early board I have (250407) dating from 1983 still has all of the 4164 RAM chips on it. I'll remove them over the next few days and keep them to one side for this repair.
No, the 2 types of RAM have a different job in C64:
4164 or 41464, classic RAM for programs and datas;
2114 is the COLOR RAM, used to generate video image.
This version I have is all 4164 RAM chips, 15 nanosecond versions, unless I'm missing something; I am tired though so the grey slush isn't 100%.
The version I have is definitely 250407, Artwork No. 251137 Rev C. It's an older version than the C64C that Mancity12 has.
Quote:
Originally Posted by Merlin
4164 RAM is very easy to find and his cost is very low.
To summarize:
2114 have 1Kb x 4 bit and is COLOR RAM;
4164 have 64Kb x 1 bit, so 8 chips required to make a BYTE;
41464 have 64Kb x 4 bit, so 2 chips required to make a BYTE :)
2114 is a sram
41464 is a dram
not are pin to pin
mn2114n-3l = lc3514a-15
m41464-15 = lh2464-12
OK, I understand all of that, but I don't remember seeing any 2114 SRAM chips on the old C64 board I was looking at last night, unless I missed something.
Would it at all help if I listed all the Chips on my C64 tonight Merlin?Quote:
Originally Posted by Merlin
Also, dont know if it helps, but this is the one I have here http://scacom.bplaced.net/Collection/64/6419.jpg and it was bought in 1990. It has a test date inside of 1990 too.
Hi,
If you could take a couple of hi-res photos of the board and stick them up on Photobucket or similar, we can probably work out what chips are present from those.
There were several revisions of C64C motherboards and it's best if we work on your actual board; Commodore weren't averse to 'mix and match' when it came to chips at times.
Edit: It's chips U10 and U11 we are interested in, as these are the RAM chips. They should be 41464 -150 DRAMs, according to the schematics. These are the ones that are likely to need replacing.
We are also interested in chip U19 (the 2114 video SRAM chip). If replacing the RAM chips makes no difference, this chip is next on the list for a swap-out.
Schematics are here:-
http://www.zimmers.net/anonftp/pub/c...c64/index.html
A good night's sleep and some coffee and I'm back on the case.
Ok I will take a few pics tonight and upload them for you Merlin.
I know it says Rev. B on the board, but you will see for yourself once I get the pics up :).
Thank you.
Links for replacement chips:-
http://www.ebay.co.uk/sch/i.html?_sa..._nkw=2114+SRAM
http://www.ebay.co.uk/itm/KM41464AP-...-/251181473089
These are BIN offers so are within the site rules to post the links.
You need two 41464 chips and one 2114 chip. The best approach is to convert the board to sockets to accept the new chips and I could do that for you. Strips of turned pin socket strip are cheap enough from Maplin.
I doubt the SRAM is bad. I've fixed several C64s with exactly the same symptoms. 99% of the time it's just the Character ROM that needs to be replaced. If the 41464 RAMs die, this will either produce an "Out of Memory in 0" failure or complete rubbish on the screen - a bit like the second picture you posted.
On rare occassions the 2114 SRAM will fail, but this produces strange coloured text, not jumbled as in your pictures. So assume they are still good.
I'd recommend only changing the Character ROM first, the 41464s may still be good. Only change them if the Char ROM replacement doesn't solve all the problems.
Bryce.
OK, thanks for that. I guess that he needs one of these then:-
http://www.sellmyretro.com/offer/det...64_ROM%29-2339
So I just need to buy that chip from the second link then?
If that's correct and I go and order it, would you be willing to fix it Merlin for me for a cost?
You can replace the Char ROM with a standard EPROM too, you'll just need to make an adapter if you use a modern one with a different pinout configuration.
Or buy an original: http://www.ebay.co.uk/itm/Commodore-...item2a27a259fe
Bryce.
I could probably source a NOS 2382 from my stock of CBM chips for much cheaper than that..Quote:
Originally Posted by mancity12
@mancity12: just drop me a PM if you are interested
Thank you,Quote:
Originally Posted by tbtorroI could probably source a NOS 2382 from my stock of CBM chips for much cheaper than that..Quote:
Originally Posted by mancity12
@mancity12: just drop me a PM if you are interested
If I find this is all I need then I will.
TBH, im in over my depth here :(. AND, my soldering skills would destroy any motherboard!
I'm prepared to do the repair, as long as Mancity12 gets the part required.
:thumbsup:
Ok thanks alot il let you know when I get a 2382 chip.
---------- Post added at 13:24 ---------- Previous post was at 13:20 ----------
Tbtorro ive PM'd you mate.
---------- Post added at 13:30 ---------- Previous post was at 13:24 ----------
Just to be clear (sorry), am I wanting a 2364 or a 2382 or are they the same thing?
The 2364 is an EEPROM (a chip that can be erased and reprogrammed with a firmware file, to replace the original part).
The 2382 is the original part and is non-programmable. I'd go for this if I were you.
Thanks Merlin,
Hopefully Tbtorro can sort me with one of these then :D.
Will check tonight after work..Quote:
Originally Posted by mancity12
Update:-
I've found a genuine 2382 character ROM in my scrap pile. It's untested, but I am prepared to convert Mancity12's C64 to have a socket to take the ROM chip.
If the ROM I've got proves to be duff, he can remove it and buy a replacement genuine one from tbtorro.
The rwap (sellmyretro) replacement is sold as blank and needs to be programmed before use. This is so rwap doesn't breach any copyright laws by selling them programmed. I'm mentioning this here in case anyone is thinking of getting one.
If theres any concerns or doubts, i'm quite happy to repair the 64 for our friend, I can even prog a new rom if required.Quote:
Originally Posted by Merlin
TC :)
Thanks alot for the offer :).
I can vouch for TheCorfiot very good chap, serviced my BBC master PSU and floppy and soon to have a go at my Intellivision.
He's currently trying too resurrect my battery damaged Apollo 1260.
Looked around but I don't have the chip unfortunately..
It would be much cheaper. less time wasted, less postage paid this way and that way to buy a second C64 and keep that one for spares. They are dirt cheap ...
Just had a quick check on e-bay and there aren't that many and they dont sell dirt cheap :D.
That's kind of missing the point; this is 'his' machine and he wants it back alive again. I would feel the same in his position.Quote:
Originally Posted by bebek
I second that. I have several C64s here with different faults, but I'm unable to scrap them even though it will probably cost more in time for me to fix them than actually buying another one. There is something about the satisfaction of saving a piece of hw. by fixing it and cleaning it up..Quote:
Originally Posted by MerlinThat's kind of missing the point; this is 'his' machine and he wants it back alive again. I would feel the same in his position.Quote:
Originally Posted by bebek
Yep this is it.Quote:
Originally Posted by MerlinThat's kind of missing the point; this is 'his' machine and he wants it back alive again. I would feel the same in his position.Quote:
Originally Posted by bebek
I was given this exact machine for christmas when I was 3 with Batman the Movie.
I had 2 breadbin C64's a couple of years later (well, my dad did), but this one was what got ime into gaming and is very important to me :).
Never knew what happened to the breadbin 64's though...
Offer still open :lol:
Cheers Corfiot. I have agreed with Merlin I will send it him to have a look.Quote:
Originally Posted by TheCorfiot
I did not say to scrap it but to keep it for organs. Cruel but you will need it at some point anyway. Just a 15min after I posted my replym one C64 went for equivalent of two way insured postage ... .
I fully understand what your saying, but the more retro machines alive the better :). Found 2 copies of my original Commodore 64 usr manual today too and there's plenty of BASIC tutorials etc so im probably going to have a bash at that if it can be fixed.Quote:
Originally Posted by bebek
Unfortunately, in retro world one machine dies so other can live :) , not many NOS components left :).Quote:
Originally Posted by mancity12I fully understand what your saying, but the more retro machines alive the better :). Found 2 copies of my original Commodore 64 usr manual today too and there's plenty of BASIC tutorials etc so im probably going to have a bash at that if it can be fixed.Quote:
Originally Posted by bebek
I am sure you will have it repaired. C64 was my first computer and it is one of my favorite :).
OK, a bit of an update...
I dug the rework station out over the weekend and carefully removed the character ROM. I soldered in two strips of turned pin strip to create a socket and inserted the ROM I had removed from my scrap breadbin board - fortunately, the ROM versions were identical. I had kept the original ROM intact just in case.
I switched on and... no difference :(. It is slightly better, but the text is still corrupted. Whatever the fault is, it's unlikely to be the character ROM.
We can rule out a faulty PSU as I used my PSU. I guess we need to start digging a little deeper. Any ideas, please? I'll start checking voltage rails this evening but I'm open to ideas as to what could be next on the surgery list.
Thanks for the update Merlin :).
Really appreciate your help.
Bob,