Sinclair ZX80 / ZX81 / Z88 Forums

Any unregulated PSU gives you more voltage than its rated voltage if the load is lower that the nominal load. Make the story shorty, it is uncommon that the ZX81 PSU gives approx. 10.5V when connected to the ZX81. In idle (no load connected) the PSU output voltage can reach 14.5V easily. Bear in min...

Or TEA2000 is dead (high probability).

Nice and good to hear from you that you made some progress. My unit is in a storage box waiting till I will be back home in a few weeks.

BTW do you have the barebone 32K RAM on your testing PCB?

Have a look and measure a supplying voltage to TEA200 chip. The PAL encoder requires 12V supply (pin 11 on it).

On the output should be +5V +/- 0.25V. Anything above +5.25V means that something is wrong the voltage regulator chip. Take it out and measure a resistance between GND (middle soldering point of this chip) and +5V rail (right soldering point). The reading should be in low kiloohms but definitely mor...

Hi Ogien, Good that you joined us on here. I have attached a picture of the 1st broken RAM pack (48K) There is one IC on there that gets very hot quickly on it which I circled. Not sure if that is the problem but in my limited experience very hot ICs are usually not good. This pointed IC is a voltag...

Well done! I enjoy it and it is addictive.

Some annoying flickering when I unroll the pipe horizontally. I run the game under the ZXSP Emulator.

Hi Bill, TXZduino works with p. files out of the box, if the firmware is in version 1.3 or above. I know this as the fact, because I use it in that way. Maybe the f/w needs an update. See there: http://arduitape.blogspot.co.uk/2017/03/zx81-p-and-o-filetype-added-to-tzxduino.html?m=1 :geek: From whom...

Nice one! Hats off to you guys.

Burn before soldering.

The space inside the Zeddy's case is very limited. Unfortunately you will not be able to fit your adapter there and close the case.