Search found 12 matches

by Liveinabin
Wed Aug 19, 2020 1:39 pm
Forum: Hardware
Topic: Have I fried the ULA?
Replies: 10
Views: 5412

Re: Have I fried the ULA?

That's very true :) OK, I desoldered (very carefully) the internal RAM mod and spent the morning going over the ZX81. I'm satisfied it's clean (no tiny splashes of solder etc.) and the traces are good (checked continuity on every one). I've resoldered any dry dull bits (there were a couple around th...
by Liveinabin
Mon Aug 17, 2020 10:51 pm
Forum: Hardware
Topic: Have I fried the ULA?
Replies: 10
Views: 5412

Re: Have I fried the ULA?

Smart. Right, I’ll find a more powerful pair of glasses and go over those traces. I’m sure to have done something dreadful :)
by Liveinabin
Mon Aug 17, 2020 9:47 pm
Forum: Hardware
Topic: Have I fried the ULA?
Replies: 10
Views: 5412

Re: Have I fried the ULA?

1024MAK wrote: Mon Aug 17, 2020 9:43 pm I would suggest that you double check the PCB tracks and pads before doing any further work, it may just be a dry joint or cracked track, or maybe a solder whisker.

Mark
Will do.
by Liveinabin
Mon Aug 17, 2020 9:46 pm
Forum: Hardware
Topic: Have I fried the ULA?
Replies: 10
Views: 5412

Re: Have I fried the ULA?

Right, I tried the SAVE”S” and, sadly, there was nothing (also did it on my working 81 to gauge what I should be hearing).
Can I infer anything from this?
by Liveinabin
Mon Aug 17, 2020 8:46 pm
Forum: Hardware
Topic: Have I fried the ULA?
Replies: 10
Views: 5412

Re: Have I fried the ULA?

I’ll try SAVEing. Thanks. As for putting the old RAM back, I’m afraid I had to snip some legs. Couldn’t desolder them cleanly (and I do get the fear desoldering on Sinclair boards - I had a bad experience with a Spectrum!).
I guess I could carefully desolder this RAM board and fit some sockets.
by Liveinabin
Sat Aug 15, 2020 10:54 am
Forum: Hardware
Topic: Have I fried the ULA?
Replies: 10
Views: 5412

Have I fried the ULA?

Hallo all. I thought it would be fun to work on my spare ZX81 - which already has a new power regulator and composite mod - but this time, to install an internal 16K unit that I had lying around. Here's my board with the 16K attached. IMG_1386.jpeg I thought I did an okay job on it but, on firing th...
by Liveinabin
Tue Jan 08, 2019 10:40 pm
Forum: GAMES
Topic: Murgatroyd's Revenge (1982) found and uploaded
Replies: 2
Views: 3052

Murgatroyd's Revenge (1982) found and uploaded

Hallo lovely fellow ZX81 users. I'm an infrequent visitor - I think the last time I posted was 8 years ago when several of you good people helped get my 81 back to life. So, by means of recompense, I bear gifts in the shade of a long lost game (I think) Murgatroyd's Revenge. Bit of backstory if I ma...
by Liveinabin
Tue Jan 05, 2010 6:15 pm
Forum: Hardware
Topic: DeadX81 - power supply?
Replies: 10
Views: 17301

Re: DeadX81 - power supply?

Blimey. That was quick. New ULA arrived in the post today and look..

Image

I can't believe it! Thanks SO much for your help guys. Now to start amassing hardware and tapes for it (why did I ever give away my copy of Murgatroyds Revenge?).
by Liveinabin
Mon Jan 04, 2010 12:57 pm
Forum: Hardware
Topic: DeadX81 - power supply?
Replies: 10
Views: 17301

Re: DeadX81 - power supply?

Thanks. That's excellent. Well, the first good news so far. The 7805 reads 4.89V so I guess the power is fine. So I guess the next step is to buy a new ULA and see what happens. Thanks all. And sorry to be scrounging for help in my first thread. I promise give more useful input when I have a working...
by Liveinabin
Mon Jan 04, 2010 11:17 am
Forum: Hardware
Topic: DeadX81 - power supply?
Replies: 10
Views: 17301

Re: DeadX81 - power supply?

Pardon my idiocy but, say, I'm sitting here with Zx81 opened and powered up - multimeter in hand. Where do I stick the prongs to test for this 5v?