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XDanger
May 4th, 2009, 01:16 PM
I hadnt been able to get a picture from it, but after plugging in my amiga (which works fine) I noticed that also had a black screen
I re-tuned the tv and all was fine, gave the c64 another go after another re-tune and managed a boot up screen ,Joy was short lived as the keyboard did nothing so I turned her off and on and it was back to black again.

What fault would allow a seemingly one-off boot up display like this?

I've tried the c64 on my crt also and it was black so its not just an LCD TV related problem.

cosam
May 4th, 2009, 02:29 PM
Could be a bad connection that was momentarily good enough to get things working. I'd try reseating any socketed chips for starters - I recently had a similar problem which was solved just be reseating the kernal ROM.

XDanger
May 4th, 2009, 02:35 PM
http://www.commodore.ca/manuals/Tips/c64_tips.htm

Blank screen on power up----Should I be looking at these

Intermittent blank screen or graphics--- or these possible faults

Out of about 40 attempts ive only had 1 partial succes

Ive tried an alternate PSU (which I dont know if is good either but the power light comes on) but I also have a square black commodore supply, Whats that from, a vic20?

Like in my atari st thread ,I'll' definiltey try pulling the chip ,Thanks


C64 parts seem to be a rarity on ebay, Maybe easier to wait for another cheap (faulty) one and hope for the best.

The innards of newer c64 are the same arent they?
____________________________
If I ever get a working c64 can I wire the c2n plug to a 3.5mm jack for pc/mp3 loading?

I have 3 c2n's going spare atm :(

cosam
May 4th, 2009, 02:58 PM
Out of about 40 attempts ive only had 1 partial succes
That you got to see anything sensible on the screen, even just the once, would suggest that the parts are probably OK. Then again, maybe something just made an extra effort before giving up the ghost completely ;-)


Ive tried an alternate PSU (which I dont know if is good either but the power light comes on) but I also have a square black commodore supply, Whats that from, a vic20?
Power is always a good thing to check if you can (in fact I was going to suggest that if the reseating didn't help). The original C64 PSU isn't known for its reliability and there were numerous after market replacements - maybe you have one of those? Worth checking the right juice is coming out of the right pins before plugging it in though.


C64 parts seem to be a rarity on ebay, Maybe easier to wait for another cheap (faulty) one and hope for the best.
There are so many C64s floating around that it's often easier (and even cheaper) to pick up an entire machine and salvage what you need.


The innards of newer c64 are the same arent they?
Not really - there were quite a few revisions (http://en.wikipedia.org/wiki/Commodore_64#Hardware_revisions).

XDanger
May 4th, 2009, 03:05 PM
Just tried it again and got garble, Random charachters, different colors mostly @'s



Not really - there were quite a few revisions (http://en.wikipedia.org/wiki/Commodore_64#Hardware_revisions).
I could just swap out the whole mobo though couldnt I?

Are the keyboard connection pins the same?

I like the brown.


Does the "International Soccer" cart replace any onboard parts like some carts do (i've read).

carlsson
May 4th, 2009, 10:09 PM
Yes, the keyboard connector is identical in all VIC-20 and C64s. There was a report about the very first breadbox C64s having a different pinout but I think it was a mistake by the poster.

Autostarting game cartridges would not make any calls to Basic ROM, which is why some of them might work. If your Kernel ROM would be completely wasted, I don't think cartridges can start anyway since the 6502 (6510 more precisely) looks for an autostart vector at the end of Kernel ROM, and the routine the vector points to checks for a cartridge.

XDanger
May 5th, 2009, 10:29 AM
Last night I tried the cart and managed about 15 seconds of gameplay :)

Today I re-seated the only chip thats seated, I also gave the mobo a nice clean but still get black :(

Is the fuse wire supposed to be spiraled?

Back in the day my c64's fuse went and I used a paperclip in the meantime I think?

Maybe I'm thinking of the poke reset paperclippery.

carlsson
May 5th, 2009, 02:29 PM
I believe a fuse with a spiraled wire means it is a slow fuse as opposed to the fast ones. The C64 should have a slow one. A paperclip works fine as long as you're sure there is nothing wrong with your computer or power supply, e.g. the fuse blew because you touched some connector from the outside.

Terry Yager
May 5th, 2009, 04:19 PM
1. Insert paperclip in place of the fuse.

2. Turn on machine.

3. Observe board till MajikSmoke(tm) appears.

4. Replace all components which smoked (after turning off machine).

--T

XDanger
May 6th, 2009, 11:09 AM
Is that the smoke they put in there when its built and sometimes escapes?

channelmaniac
May 6th, 2009, 01:10 PM
Black screen... or blank screen and no keyboard response?

Bad CIA chip or bad PLA. My money is on the PLA.

You can swap the 2 CIA (6526) chips to see if it then boots but has other problems.

If the screen was full of @ symbols then it's a bad VIC-II chip...

If the screen has some, but not full of @ then you have bad RAM.

RJ

XDanger
May 6th, 2009, 01:43 PM
Its like @ @ @ @ @ @

@ @ @ @ @ @ @

Not @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@

linuxlove
May 6th, 2009, 01:49 PM
If the screen has some, but not full of @ then you have bad RAM.


What he said

XDanger
May 6th, 2009, 02:06 PM
Ram then ,Ah well, I guess that explains why it only likes cold boots

Pic?
http://img22.imageshack.us/img22/6124/garble.jpg
http://img22.imageshack.us/img22/6124/garble.jpg
I dont suppose theres a magical way of connecting one of those c64 tv joysticks to it to make it work is there ...

linuxlove
May 6th, 2009, 02:11 PM
There is no pic, just an ad for a picture hosting site. But i thinki can guess, it's just a black screen with a few @ on it?

XDanger
May 6th, 2009, 02:16 PM
damn aol selling off its pictures ,useless bunch of @@@@'s

No its pretty blues and colorful @'s and stuff

channelmaniac
May 6th, 2009, 08:38 PM
Ram then ,Ah well, I guess that explains why it only likes cold boots

Pic?
http://img22.imageshack.us/img22/6124/garble.jpg
http://img22.imageshack.us/img22/6124/garble.jpg
I dont suppose theres a magical way of connecting one of those c64 tv joysticks to it to make it work is there ...

You have a case of RAMitis there... ;)

The cure is a handful of 16 pin sockets and a few 4164 DRAM chips to swap out the bad ones.

Luckily those DRAMs are cheap.

XDanger
May 7th, 2009, 09:30 AM
So Id have to de-solder the ram and solder the slots in?


You have a case of RAMitis there... ;)

The cure is a handful of 16 pin sockets and a few 4164 DRAM chips to swap out the bad ones.

Luckily those DRAMs are cheap.

Where would I look for them in the UK?

The sockets I can get from RS but the ram not so much...

channelmaniac
May 7th, 2009, 02:02 PM
Dunno on buying old 4164 DRAM in the UK. I have it on my site but I'm in the US.

XDanger
May 7th, 2009, 02:19 PM
From http://www.robotron-2084.co.uk/ ..."Set of 25x 4164 RAM for Williams games - 20 ( US$38 ) "

This is still over the price of a working c64

XDanger
May 9th, 2009, 03:34 AM
Apart from Williams arcade machines is there anything else that uses the same ram as a breadbin c64?

channelmaniac
May 9th, 2009, 05:15 AM
A lot of old systems used 4164 DRAM...

TRS-80 Color Computers, Apple IIe/IIc, Atari home computers, PC XT, and more.

If you have an Apple II series you are thinking of scrapping RAM out of then run the built-in diagnostics on it first. Press Ctrl-Open Apple-Closed Apple-Reset to do that.

RJ

XDanger
May 9th, 2009, 10:59 AM
I have a joystick for a TRS-80, Thats about as near as I get to that list :(

I just went and bought a wedge off ebay, Maybe I'll swap the board and sell the wedge case.

My soldering iron is staying pristine...