Sinclair ZX80 / ZX81 / Z88 Forums

An update. I have sent it for repair to ByteDelight. It appears I made a huge mistake :oops: but using some flux when I was soldering in the audio mod onto the AY chip. The flux got under the chip (I used alcohol to clean it after, but it was not enough as I see now) and shortened some of the traces...

Visually, it looks something like this through ZX-HD:

https://youtu.be/xRZkVUMxZV8

So to test it, it is more complicated with AY than just probing the voltages.

Hi. I have finally received the memory modules and sockets. I have socketed the first 8 modules, and tested them with the tester and they were OK. Then I inserted the memory into the sockets, started the Tastrack, and got the same garbage on the screen. On the third or fourth time while I was testin...

Hi. When I was trying to solder an audio mod onto the AY chip, I managed to shorten some pins, and now even though I removed the short, I think this is the AY chip that is damaged and prevents the Toastrack from starting properly. It just shows the garbage on the screen. At some point I while testin...

Hejsan!
Förlåt att jag har inte svarat tidigare. Jag bo i Årsta, men det borde vara linkade på fancy Lidingö

cj7hawk wrote: ↑Tue Nov 09, 2021 4:08 pm Also, the Fruitcake ram test rom is pretty useful. You don't have to plug it in externally - just replace the onboard ROM with it.

I was wondering how different is "Fruitcake ram test" compared to ZX-Diag in terms of functionality?

Hi after a couple of decades, the membrane contacts got stuck and even though I tried to be careful when disconnecting them, they have got damaged. left_contact.jpg right_contact_1a.jpg Should I try using conductive paint to restore them or should I just cut the bottom a bit, so that the contacts wo...

Thanks for the reply! I am learning new things :). I think that from the 10 assorted chips I got from Ali, I have one like this, which should work, I think: 4164B.jpg so, when the sockets arrive and the testing tool, I will test it and then see if it works in the toastrack. I will update about the p...

McKlaud wrote: ↑Wed Nov 10, 2021 6:27 am For Toastracks and the upper RAM of any Spectrum 48K, suitable Samsung brand chips are KM4146B

Do you mean KM4164B ?

Thanks for the reply!

A side question, Is it possible to test 3764 chip on a tester like this that is for 4164?


Thanks!