Sold ZX Spectrum 48K Rev 4S Board with Comp Mod

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manic23

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This board is in a lovely and working condition, taken from my rubber key only to replace with a rev 6A (see below for why).

I have been using this board for years without any issues, it's working fine with every DivMMC/IDE I have owned. It was comp video modded by myself about 2 years ago. I do not know the history of this board before I owned it so I am not sure if it is re capped, but the Caps look lovely and clean with no viable sings of leaking.

There is just one minor issue with this board in that it does not play nicely with the Spectra Interface board. As you may know the Spectra is a device that enables RGB output for Spectrums without it, it also has a ROM socket on board as well as a few other things, click here for more info. The RGB works fine but when some (not all) games are loaded either via DivMMC or the ROM socket, serious screen corruption is experienced and eventually the game wil crash. Note that this ONLY happens when the Spectra is connected, take the Spectra away and the board works flawlessly. Obviously if you don't have a Spectra or don't intend to use one, then you'll be fine using this board. I don't fully understand why this happens, but I think it's something to do with the 5v rail not working properly on the Rev 4 boards.

Asking £30 £25 with free UK postage, PP only please and buyer bays fees or uses friends and family.

Pictures are here: https://www.dropbox.com/sh/pdpc718wq7b6j39/AAAaYRAEWJQBYMWJRHmZRbiba?dl=0Price
 
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4S revision was produced by Samsung (hence S in the revisions name, actually You can also read it on the housing, mentinoed there Made by Samsung, Korea ) and has dark blue caps by default.
Belive me or not, but i had also a lot of trouble with this board. It worked fine, but i was unable to load any game from cassette. divIDE and Smart Card was working fine. I checked the whole lineIn till ULA..the ULA was the problem, it was partially damaged! I swapped it to another, and HERE several problems started: working unstable, crashes and so on.. It seems, that the ULA clock is very picky on this revision boards, and needs it's own ULA version: 6C001E-7! if 6C001E (without the -7 at end) is installed several issues may accure unless You change some resistors.. i have found a comment in the schematics:

http://www.retroisle.com/sinclair/zxspectrum/Technical/Hardware/ZXSpectrumIssue4ab-Schematics.gif

regards,
-Viktor
 
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You are welcome! Just wanted to let You know about these issues, it can be, that someone has swapped ULA in it, and the crashes are here because of that. It can also be because of the clocks, that Spectra generates and how it interferrates with ULA..Actually i think it's the Spectra, there is very interesting video on Youtube about this interface, and the author of the video claims, this interface doesen't work on issue 2 boards properly..
https://www.youtube.com/watch?v=WgWNiLEXLM8&t=911s
as for me - i wanted to buy this interface too, but have bought a 4Mb programmable rom cartridge first, it is well built, but the edge connector of the cartridge is left too long, the connection is a bit flimsy because of that, i don't like how the cartridge is jiggling in the slot, and i will not buy from him again. That's my opinion..
 
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I don't find it loose seems ok to me, the spectra is working fine with my new rev 6A so I'm happy


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