Search found 57 matches

by questarian
Thu Jun 28, 2012 1:44 pm
Forum: Hardware
Topic: Broken ZXpander
Replies: 52
Views: 26118

Re: Broken ZXpander

For completeness' sake have you tried just swapping the PIC and EPROM individually? It's possible that one of these took the hit..? I'll speak with Rich offline about repairing it. TTFN C Sorry, should have mentioned that I also did swap each chip individually between the two boards with the same r...
by questarian
Thu Jun 28, 2012 1:01 am
Forum: Hardware
Topic: Broken ZXpander
Replies: 52
Views: 26118

Re: Broken ZXpander

Ok, I swapped out the GAL's and it didn't help... did a complete chip swap between the two Zxpanders and the new one works even saw the upgrade to 1.7 I tried... So it's got to be the RAM.
by questarian
Tue Jun 19, 2012 2:36 am
Forum: SALES
Topic: ZX81CCP
Replies: 104
Views: 45375

Re: ZX81CCP

Just wanted to say WOW and thanks! I put one your boards in one of my ZX81 and the picture was incredible!
by questarian
Tue Jun 19, 2012 2:23 am
Forum: Hardware
Topic: Broken ZXpander
Replies: 52
Views: 26118

Re: Broken ZXpander

I killed one of my Zeddies by eletrostatic discharge, when I tried to reprogram an EEPROM on ZXPAND, when I touched one of the jumper pins on ZXPAND (going to the Z80 /WR line). Electrostatic discharge can destroy anything :( Siggi I've been lucky. With the one possible exception of a TS-2068, I ha...
by questarian
Tue Jun 19, 2012 2:10 am
Forum: Hardware
Topic: Broken ZXpander
Replies: 52
Views: 26118

Re: Broken ZXpander

Hi John, Sorry to hear about the board. I think that a short across the back of the board is indeed the most likely culprit. Like Rich says, you could try swapping chips from a known working board which would be low risk - with appropriate static handling - and that could mean a repair is as simple...
by questarian
Mon Jun 18, 2012 2:02 pm
Forum: Hardware
Topic: Broken ZXpander
Replies: 52
Views: 26118

Re: Broken ZXpander

Hi, RAM is certainly a possibility. There are no real delicate areas around the original LEDs or breakout connector and like you say, the interface seems to be booting with the green and red LEDs reporting activity. Another possible target is the EPROM or memory decoder GAL. If either of those are ...
by questarian
Sun Jun 17, 2012 10:58 pm
Forum: Hardware
Topic: Broken ZXpander
Replies: 52
Views: 26118

Broken ZXpander

I recently picked up a ZXpander, and was casing in an old Memotech casing, and everything worked perfectly until I hooked up external busy/error status LED's and removed the surface mount ones. The screen comes up blank... (occasionally full of junk, scrolling noise, but that may just a bad/loose co...