Different ROMs for Lambda 8300

frankc64
Posts: 8
Joined: Mon Sep 19, 2022 10:18 pm
Location: Denmark

Re: Different ROMs for Lambda 8300

Post by frankc64 »

OK, thanks. So the original 15V supply should be good then. Well, I get something on the screen with the 15V, but not with the 9V, and only briefly something with the 12V.
I heard that some machines actually had a piece of plastic in place of the heatsink. Mine is metal though, so I should be good.
frankc64
Posts: 8
Joined: Mon Sep 19, 2022 10:18 pm
Location: Denmark

Re: Different ROMs for Lambda 8300

Post by frankc64 »

Hmmm. Changing the 74LS05 made no differrence. The levels on the data bus are still low. But there is lots of activity on both busses, so I assume the Z80 is working. But after measuring around, it seems that no video signal is coming from the ULA. So probably the ULA is dead. Too bad. I suppose noone has come up with a replacement solution, so it means I have a spare parts machine.
User avatar
mrtinb
Posts: 1709
Joined: Fri Nov 06, 2015 5:44 pm
Location: Denmark
Contact:

Re: Different ROMs for Lambda 8300

Post by mrtinb »

Have you meassured the video signal on the ULA with a voltmeter, or an oscilloscope?
Martin
https://zx.rtin.be
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
frankc64
Posts: 8
Joined: Mon Sep 19, 2022 10:18 pm
Location: Denmark

Re: Different ROMs for Lambda 8300

Post by frankc64 »

Oscilloscope. Also the busses.
Post Reply