RCM - RETRO COMPUTER MUSEUM

GENERAL => HARDWARE/SYSTEMS DISCUSSION => Topic started by: jack_farmer on February 14, 2015, 01:38:30 PM

Title: Bizarre C64 fault
Post by: jack_farmer on February 14, 2015, 01:38:30 PM
Hello,

I've just uncovered a new problem with my Commodore 64 (64E). Plugged into my TV via RF, it starts up just fine first time; but if I come to restart it for whatever reason I get a black screen. The C64 must still be powered on, as the red LED lights up, and my TV does not give a 'no signal' screen.  The black screen occasionally flickers, but I really have no idea what is wrong. It just seems to strange since when it does power up it works perfectly.

To get it powering up and working properly again, I have found that just leaving the C64 turned off for a while does the trick; but this is hardly a long-term solution!  :-\

I have cleaned the C64's board, checked for any 'chip creep' and checked for any broken traces or leaky caps; but this hasn't yielded any results. Where do I go from here?

Thanks in advance,
Jack :)
Title: Re: Bizarre C64 fault
Post by: AndyRCM on February 14, 2015, 05:38:57 PM
I would say the PLA chip is on its way out. :( Expensive to fix - £15+ :(
Title: Re: Bizarre C64 fault
Post by: jack_farmer on February 14, 2015, 06:53:39 PM
Fantastic  :'( - is the PLA one of the easily removable chips? If so, I'll just keep an eye out until a working one shows up cheap on eBay.

Thanks Andy :)
Title: Re: Bizarre C64 fault
Post by: AndyRCM on February 14, 2015, 08:44:18 PM
On some machines the PLA is socketed - on others it isnt. :(

Title: Re: Bizarre C64 fault
Post by: jack_farmer on February 15, 2015, 12:42:08 AM
Thanks Andy, will do some more research tomorrow :)
Title: Re: Bizarre C64 fault
Post by: jack_farmer on February 15, 2015, 01:25:17 PM
Turns out my PLA is soldered in, so it probably wouldn't be worth trying to remove it and soldering in a new one (at least with my poor soldering skills). I think my plan of action is to find another C64 online (perhaps with a warranty or guarantee) to replace mine; and I'll keep the dead one as a parts machine or something.

Thanks, Jack :)
Title: Re: Bizarre C64 fault
Post by: Panther on February 17, 2015, 10:53:37 AM
One cheap here

http://www.ebay.co.uk/itm/Commodore-64-/151587848739?pt=LH_DefaultDomain_3&hash=item234b570223 (http://www.ebay.co.uk/itm/Commodore-64-/151587848739?pt=LH_DefaultDomain_3&hash=item234b570223)

Well cheap at the moment (£!5.00), but will probably go for a lot more  :-\
Title: Re: Bizarre C64 fault
Post by: jack_farmer on February 17, 2015, 01:48:39 PM
Thanks for that! I'd love a bread bin, since I have the slimmer (but far less retro-looking) 64C.

Jack :)
Title: Re: Bizarre C64 fault
Post by: AndyRCM on February 17, 2015, 05:29:59 PM
If you can source a PLA (there are replacements available) . . . we can de-solder your old one and put you in a socket . . . :)

A
Title: Re: Bizarre C64 fault
Post by: jack_farmer on February 18, 2015, 10:41:24 PM
Thanks a lot Andy! I'll keep my eye out for cheap PLA's online. It must only be a matter of time before someone puts one on for a fiver  :)
Title: Re: Bizarre C64 fault
Post by: AndyRCM on February 19, 2015, 08:17:05 AM
These are the ones that we have . . . none left now at RCM or indeed on this website. Hopefully some more will be made. :)

http://www.protovision-online.de/shop/product_info.php?products_id=137&language=en

Title: Re: Bizarre C64 fault
Post by: jack_farmer on February 19, 2015, 11:44:34 PM
Fingers crossed!  :)
Title: Re: Bizarre C64 fault
Post by: porchy on February 20, 2015, 07:29:59 PM
The ones I used to get are also no longer available. You could always give the EPROM method a go
Title: Re: Bizarre C64 fault
Post by: porchy on February 20, 2015, 07:36:09 PM
actually, try here.
http://www.sinchai.de/index.php?main_page=product_info&cPath=3&products_id=139 (http://www.sinchai.de/index.php?main_page=product_info&cPath=3&products_id=139)

Ive ordered quite a few things from here and they are decent, but they arent too cheap
Title: Re: Bizarre C64 fault
Post by: jack_farmer on February 20, 2015, 07:54:58 PM
Thanks guys, I'm just worried that it would end up costing more than another working C64 on eBay  :-\
Title: Re: Bizarre C64 fault
Post by: Panther on February 23, 2015, 10:41:42 AM
£20 on ebay inc postage from the states.

http://www.ebay.co.uk/itm/commodore-C64-PLA-906114-01-tested-good-socket-pull-/301531404652?pt=LH_DefaultDomain_0&hash=item4634ac196c (http://www.ebay.co.uk/itm/commodore-C64-PLA-906114-01-tested-good-socket-pull-/301531404652?pt=LH_DefaultDomain_0&hash=item4634ac196c)