Hi,
I'm new to this forum as well as to Spectrums in general. I got myself a grey Spectrum +2. It had a bad RAM IC, I replaced that one. I recapped the board (some caps were slightly out of spec but nothing serious), I turned the 3 transistors around that Amstrad fitted backwards and I cleaned the board. The machine now boots fine.
I then tried to load something from tape (I have two tapes, one game and this Horizons tape). Neither of them loaded. I adjusted the head by ear and tried again but to no avail. It finds the program and displays the name, I see the flashing bars and hear the beeping sounds but after loading the header and a little bit of the program, the flashing stops and the tapes run through to the end... it's still beeping, but nothing else happens.
I then tried to load it via the Tape Loader menu entry. That loader sometimes started but most of the time, it didn't and the machine either crashed or reset itself when I selected that menu entry.
I then tried to save a short program from basic onto a new, blank tape. It seemed to write the header and then crashed with a blue image with some black pixels on it.
I investigated the tape driver's PCB and found 4 capacitors that I hadn't swapped (I only did the board). 1 was fine, 2 out of spec and one shorted, so I replaced them. I also checked the transistor that's on this board, it was fine. Replacing the caps fixed the issue with the Tape Loader menu. I can now enter the Tape Loader every time without crashing or resetting.
However, the tape still can't load anything except for the header and trying to save something still crashes the machine. Because I had a modern replacement at hand, I swapped the ULA but that didn't change anything.
I'm a bit stuck now. Something seems to be wrong with loading and saving from/to tape, but I don't think it's the tape drive itself, because I can hear it beeping away happily.
I tried to find some schematics for my board, but the copies that I found are so bad, that you can hardly see anything.
Any ideas on where I should look next? I tried to Google for this issue, but couldn't find any hints either. Maybe one of the 74-logic chips is involved in this loading/saving from tape?
Spectrum +2 (grey) crashes when saving to tape
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Lardo Boffin
- Posts: 2169
- Joined: Sat Nov 26, 2016 2:42 am
Re: Spectrum +2 (grey) crashes when saving to tape
Welcome on board and good luck!
It might be worth getting hold of a DivMMC or similar (https://www.retroleum.co.uk/spectrum-peripherals) to see if the rest of the computer is at fault somehow rather than the tapeloading. If nothing will load via an edge connector based loader then the tape issue might be unrelated.
The Retroleum SmartCard has the double bonus of acting as a diagnostic ROM as well. Very useful.
It might be worth getting hold of a DivMMC or similar (https://www.retroleum.co.uk/spectrum-peripherals) to see if the rest of the computer is at fault somehow rather than the tapeloading. If nothing will load via an edge connector based loader then the tape issue might be unrelated.
The Retroleum SmartCard has the double bonus of acting as a diagnostic ROM as well. Very useful.
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: Spectrum +2 (grey) crashes when saving to tape
A DivIDE is on the way. I'll report back once it arrived.
Re: Spectrum +2 (grey) crashes when saving to tape
The DivIDE arrived today (it's the revised version from Lotharek). At first, it didn't work reliably. Most of the time, it boot looped (it constantly refreshed it's setup screen).
Without it plugged in, the machine booted fine. I figured out that the CF card that I was using pulled down the CPU's reset line to around 1.5V when inserted into the DivIDE. I removed it, the reset line went back to 5V again. I then took another CF card, which pulled it down to 3.8V, which works but isn't correct either. I then tried two other cards, which both left the reset line at 5V, just as it should be. I've no idea what's going on there, but when using one of the working cards, the DivIDE works reliably now.
So the device works, I can enter the menu and select games. However, I tried several of them but most of them won't work. Trying them either crashes the Spectrum or resets it.
I checked CPU and ULA again, they are (still) fine. I socketed the complete lower row of RAMs and swapped them out to known good ones but that didn't change anything either.
I'm a bit stuck now...any pointers would be appreciated.
Without it plugged in, the machine booted fine. I figured out that the CF card that I was using pulled down the CPU's reset line to around 1.5V when inserted into the DivIDE. I removed it, the reset line went back to 5V again. I then took another CF card, which pulled it down to 3.8V, which works but isn't correct either. I then tried two other cards, which both left the reset line at 5V, just as it should be. I've no idea what's going on there, but when using one of the working cards, the DivIDE works reliably now.
So the device works, I can enter the menu and select games. However, I tried several of them but most of them won't work. Trying them either crashes the Spectrum or resets it.
I checked CPU and ULA again, they are (still) fine. I socketed the complete lower row of RAMs and swapped them out to known good ones but that didn't change anything either.
I'm a bit stuck now...any pointers would be appreciated.
Re: Spectrum +2 (grey) crashes when saving to tape
To bring this to a conclusion in case somebody has a similar issue: It was caused by the upper 64K of RAM. A faulty chip in there somehow impacted the lower 64K in a way that the machine somehow worked but crashed when doing anything remotely complex. A RAM test of the lower RAM worked fine though. Swapping the upper RAM was the last idea that I had after checking everything else on the board including the two custom "multiplexer" chips.