My QL failed

[mselkin]

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

[FrancoisLanciault]

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

François

[mselkin]

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?


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[Maskenlos]

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:

Code: Select all

beep 10000,10000

or

Code: Select all

Paper 7
CLS

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

[XorA]

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)

[Ruptor]

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.

[Silvester]

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

[maigretnz]

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

[mselkin]

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.

[maigretnz]

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.