This Spectrum was very poorly but we got there in the end DCDC Mod Walkthrough - • Issue 3 ZX Spectrum 48... Patron - / happylittlediodes Join me on Discord! - / discord
According to a few companies I've spoken to, axial capacitors are being phased out, so you get them whilst you can. It's probably why they're so expensive, compared to a few years ago.
I've not tried this but thanks for the tip, I guess the heat dissipation wouldn't be as good as one with fins, but to avoid the rework it could be well worth it
I never had any luck with CMOS Z80's in a Spectrum. Depending on the board, they either not work at all, or appear to be working but cause all kinds of intermittent errors. Rule of the thumb, TTL and CMOS don't play well together.
@@HappyLittleDiodes Hopefully it stays that way. I've had boards that went thru 100+ iteration of diagnostics without problems and decided to crash when playing games. I've decided not to take any chances and keep the CMOS Z80's away from Spectrums. I have never tried them with issue 6 boards, but they even caused problems with the issue 4V board that I built which is more or less an issue 4B.
great stuff .. that broken dc/dc mod is crazy .. ouch that was bad luck with the address line short .. i haven't tried that method for identifying the defective lower ram module but i will be trying it in the future ..✔
Top tip. When you're trying to wiggle the pin so it's not touching the sides, use your multimeter probe (instead of your iron or a screwdriver) because it stops beeping when it's free
Never DC-DC modded an issue 4... done a few Issue 2's though... generally i would DC-DC mod *any* of them that use the old converter circuit BTW if you ever find BA157 hard to get, UF4004's work very well... the important parameter is the reverse recovery time (trr in the datasheet) and anything faster than the original will be fine.
This is an excellent video thank you. Very helpful. However, is there a case for declaring a spectrum like this, with so many issues, BER? You must have spent hours and hours on it. I'm all for saving vintage computers but there is a limit.
Yes there is absolutely a case for that, but the owners can be quite sentimental about the machines and willing to put the money it. For me it's absolutely not a good business to repair them, especially with the cost of axial capacitors going up, but the mission is to keep as many machines going as possible, patreon contributions go towards components and they make good interesting RU-vid content.
