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Topics - Witchy

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Hardware / 12V coil (L1 on schematic)
« on: 2017.August.23. 01:00:59 »
Hi folks,

One of my EPs has a dead coil so I've done what I normally do with ZX Spectrum coils and unwound it to remake it with new magnet wire, only to discover these coils use a thinner wire than 0.3mm. Since I don't have any calipers to measure this wire I have to send it off to a wire company so before I do...Questions:

: has anyone successfully remade one and if so what size wire did you use?
: is there a modern equivalent
: can I rewire this one in the same way I do Spectrum ones with the same turn ratio and 0.3mm wire? I'm ashamedly crap at maths to work this out for myself :)

There's one post here from 2014 where Zozo suggests replacing the entire 12V circuit which is easily done I guess but I'd like to rewind this coil if I can.


Maintenance / 64K RAM board troubleshooting
« on: 2017.June.24. 15:30:23 »
Hi folks,

After embarrassingly fixing my failing EXDOS problem earlier I now seem to have a dead 64K card in my hand-upgraded EP128. Zozo's RAM test in EXOS 2.3 detects 128K but fails it instantly which makes me think it's a 5V problem so I'll look at that later, but in the meanwhile is there a known fault with these boards? I've already reseated it.



Interface / bridgeboard to EP contact
« on: 2017.June.23. 23:51:55 »
Hi folks,

I can't believe it's a year since I was last here, pretty much. I've been dipping in and out every so often to check up on the progress of the SDcard adapter, it's looking pretty sweet now!

Anyway, it's exhibition time again so I've dug out my fixed-and-upgraded-last-year EP128 only to remember that its connection to the bridgeboard and therefore EXDOS just doesn't work despite cleaning and trying 3 different bridgeboards.

Has anyone come up with a 'oh wow THIS works!' moment in the last few months? :)



Maintenance / EP64/128 expansion port no longer working
« on: 2016.June.16. 23:54:29 »
Hi folks,

I've dug out all my EP stuff again after FAR too many years and I'm sadly not surprised to see some things have failed given the age of the components. Thanks to this forum (hi Zozo :ds_icon_cheesygrin:  ) I've already fixed a video problem with my main ep64 and the ep128 came back to life by itself so I'm expecting that one to fail again soon, probably dried out capacitors.

Main issue I have at the minute is none of my expansion boards work any more and I'm trying to find the common problem between them all. I have at least 2 EXDOS modules, the original Spectrum Emulator and 3 bridge boards but none of them seem to work any more and I can't remember the mechanism that detects the expansion board.

Voltages are OK and the bridgeboard's 7805 is generating +5V for the expansion boxes. I haven't dared to open the EXDOS modules as they're still 'as new' but if they have died over time I'm going to have to. I'm using the same Spectrum+2 PSU I did last time all this kit was at an exhibition in 2005.

Thinking about it I also have a couple of old prototype HDD cards, I'll dig those out too.

Any clues?


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