The Sinclair QL Forum

Hi everyone,

Today my QL failed, showing this on boot up:


I’m using a Minerva ROM but it is not showing a RAM error.

Any suggestions re trouble shooting would be appreciated.

Mark


Sent from my iPhone using Tapatalk

Is it always the same exact pattern or there is some variation every time you plug it in ?

François

It’s a different pattern.
I can here the speaker click if I press a key so that little processor is working. If I leave the power on, the screen turns black after a few seconds. That could be Minerva entering F2?


Sent from my iPhone using Tapatalk

Hi Mark,

If I leave the power on, the screen turns black after a few seconds. That could be Minerva entering F2?

Does the QL then behave as expected? I mean beside the corrupted display?

Try to enter:
or
If this simple code works as expected my guess is video error. But I am far away from being a QL Expert.

Maybe this is helpful, see paragraph 2.2 ff

http://sinclairql.net/srv/qlsm4.html#s4

Rgs,

Stephan

That looks like minerva is running and has tried to print a ram error. And you are generating a valid video signal, my money would be on a failed address or data line somewhere around the ram (bad chip, multiplexer chip fail etc)

XorA wrote:That looks like minerva is running and has tried to print a ram error. And you are generating a valid video signal, my money would be on a failed address or data line somewhere around the ram (bad chip, multiplexer chip fail etc)

Yes and the little dashes under each line are telling us something but I don't know enough about the memory display. Mine had lines that is longer dashes caused by one dead ram chip. I think the memory error number display area is big so even if one ram chip is dead you can still see the address but best get input from an expert.

IMHO the first thing to do is replace IC19, IC20 and IC21 with HCT equivalents (IIRC Dennis Briggs suggested this back in 1980's).

(on our TV)
I have a similar failure.
Has there been any consensus on the remedy?
(on my old monitor)

Sorry, I don't have the expertise to help fix it.
I tried replacing any chip that was socketed but there was no change in the display output.
I have not had time to try unsoldering RAM chips.

As it may be a RAM issue I used my phones thermal imaging camera to monitor the temps of the chips.

None seemed hot but I note IC7 & IC8 stayed cold.

So not working or is this normal?

Edit: Examining more closely it was just a parallax with the camera and all the RAM chips appear evenly heating.

I note IC 19 & IC 20 are a lot cooler than the others and it was suggested 19,20 & 21 can cause trouble. So perhaps I should look at those.