Spectrum Computing

I'm aware of various types of trimmable capacitors
My question rather was "what's a reasonable range for use in Spectrums?"

Would suck to go too high on the low end (as they wouldn't allow the correct value) or too high on the high end to make them even more sensitive than they are.

Hi, anyone know what range the trimmer capacitors on issue 2 spectrums have? Sadly on one of my boards one of them was slightly damaged (probably by a soldering iron). While it still works I'd prefer to replace it before it turns into a problem. Checking the Issue3 schematics the value should be som...

Thread can be closed/archived - managed to get a good deal for both computers.

Not gonna join this discussion, but those standalone tape emulators certainly have their purpose.

(Hint: Some Android phones need external amps or need to be rooted to reach the volume needed for various incarnations of the Spectrum - including Sinclair made ones)

Decided to go with this instead: https://www.youtube.com/watch?v=3e1QOAQLEZs Resources used: https://vym.cz/sercp/ & https://cygnus.speccy.cz/popis_zx-spectrum_dg192k_rs232.php Works like a charm (but requires a DivIDE connected for "sercp") :) Also tried the RS232 ROM being mapped via...

No. An unmodified ZX also needs -5 and 12V due to the 16K RAM bank. Those can be replaced with 64K*1 or 256K*1 DRAMs tho (still running at 16K capacity) eliminating the need for a -5V rail. 12V are still needed for the video encoder tho, which can probably be replaced/bypassed as well, but that exce...

I'll let the picture speak for themselves: https://i.imgur.com/ZpipNm8.jpg https://i.imgur.com/SfdNx1h.jpg Supposedly this was done in very small runs also from factory: https://billy48.speccy.cz/hardware/didaktik_m-rgb.html I've used a different pinout to comply with my other clones and directly im...

Bend them down slightly and then do surface mount style soldering with larger blobs.

Hi, I recently build this AY Interface and thought maybe it's possible to add RS232 functionality to a 48K machine using this ROM and this part of the 128 schematic . While the changed ROM introduced it's own issues (i.e. Buzzsaw has the intro screen semi-blacked out, while highly sensible software ...

I'm aware that shipping would be considerably expensive (roughly 48€ / 320 Real) :/ Recently a TK90X was sold on eBay Germany for 149€ ... I actually had the second highest bid and would go as high as that with shipping for a machine in good condition. But I do have a contact in Uruguay who might be...

Check whether the flex connectors are seated properly and aren't broken/snapped? Also worth a try to validate with a multimeter that the rubber spacers aren't flat causing permanent keypresses (was the issue on an Acord Archimedes I worked on a while back - quick & dirty fix: rebuilding the spac...

I know it's a bit of a far shot, but hey ... it's worth a try considering a number of south american users seem to be present here.

In case anyone of you has such a computer for sale I'd be glad to recieve any offers.

Do any of the RAM chips get excessively hot? That's usually a good indicator. Also check the output of your PSU. While the 20V supply can be neglected (it's only used for the video output and can go as low as 9V [albeit the picture being black/white then]) the 5V supply is critical. Otherwise verify...

Check chipkin.ru ... that's where I got my ATM Turbo 2+ 7.11 board (which I still need to solder) - one of the advantages of the 7.11 is that one of the near impossible to obtain/programm russian PLDs got replaced by an ordinary GAL. They're currently out of stock, but he might produce some more boa...