Investigation and repair of one of the most common types of fault to affect 48K (and 16K) ZX Spectrums. The ZX Spectrum lower RAM (4116) replacement module is available here: zx.zigg.net/LRR/
I'm so glad I found this series of videos. Your videos are not only great for Spectrum repairs, but also perfect for learning about general electronics repair. Very nicely done sir. Thanks a lot.
Good job ! i like that you use a wrist strap and an antistatic mat . Very good! I like also that you work clean. And every defect you analyze in detail at component level. I observe that you know very well how it works every component on that zx spectrum. This mean that you practice this (hobby) for over 10 years. Congratulation! And don't give up! These "old " technology is still beautiful.
Your electronic knowledge is absolutely amazing. Thank you so much for sharing these videos, they are very inspirational. Please keep posting them, they are invaluable.
Ah that brings back memories. Specially the repairs I ran over the years, keyboard membrane would always break on the rubber keyboards after a time. Maybe because Daley Thompson Decathlon demanded such fast keyboard thumbing! . As for the memory blowing up, I know who to blame for the spilt cider on my speccy! That was a job to fix. Great video
oops... well it is a sure way to take out the lower 16k of ram anyways... oh and what about the pencil across the user port... I think they felt the *ka-boom* across the channel didn't they?
Good video, thanks for explaining everything. Note: a much simpler way to check for 16k/48k is to do "CLEAR 55555" [or anything above 32767]. On a 16k Spectrum an error "M Ramtop No Good" will pop up. Much easier to do using just a membrane. 8^)
yeah really this is one of the better ones, and its nice to know if I ever Get a Bad Spectrum that i have most, if not all the replacement parts., thanks Mate.!I I have all the transistors Coils and everything.
Wonderful videos I've been following trying to fix a non working Issue 3B. I've replaced TR4 and TR5 and all the initial checks from the first video pass however the 12v resistance for the lower RAM fails. I'm now removing them one by one any advice on being able to diagnose which one has failed without completely removing them?
Hi! Great videos. Have you repaired ever a spectrum 48k which has no colors on screen? I have a issue two and no colors on screen. Tried to adjust color sync trimmer,but no luck... what would you suggest be? I self believe that IC14 maybe faulty? I have made a av mod with the transistor. Other spectrums that i have works fine with that kind of mod. The spectrum that not giving colors was faulty and i was able to fix it that it othervise works.
Hi I have two ZX Spectrums but only one ULA between them. Both when powered give no display at all. The power supply is good and the 7805 on both are good as they produce 5 volts. Both have the right voltages on the rams. On one of them the ULA is cold when powered up and on the other it warms up. I suspect the ULA is faulty, what do you think ? I also tried a brand new CPU on one of them (which has it socketed) but made no difference.
Excellent video mate. Can you please tell me how you remove old glue from plastic without damaging plastic? I need to install new membrane for my zx these days? Thanx in advance Cheers
If it's just the residue from the original double-sided tape, a long soak in soapy water and lots of scrubbing (take care not to mark any of the plastic that won't be hidden) usually works. I've found that a little Mr Muscle Kitchen Cleaner is good at removing any remaining stickiness. If the adhesive is very stubborn, you might have to resort to a solvent mixture of the sort sold for removing sticky labels. However, test a little somewhere it won't show first to check it won't attack the plastic. Most of these do affect the rubbery keyboard mat, so keep that out of the way. If someone has added some hard-setting adhesive to keep the faceplate in place, I haven't found any alternative to scraping or filing it away.
Thanx for advice mate. I think its original membrane inside. I still didnt remove face plate. I will wait for new membrane/rubber matt/face plate from retro radionics :)
