QL board damage

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QL board damage

Postby robineattell » Thu Nov 14, 2013 8:59 pm

In removing the QL board from my Thor and plugging in my old QL power supply and connercting it upside down can anyone tell me what I have likely cooked ?

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Re: QL board damage

Postby vanpeebles » Thu Nov 14, 2013 10:03 pm

Moved to hardware section :)

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Re: QL board damage

Postby tofro » Thu Nov 14, 2013 10:37 pm

Thor 20, I assume?

Provided you have not shorted anything or bent or broken the expansion port, I would assume the connection between the QL socket and the 68020 daughter board would be the problem (that is kind of a bit of weight for the socket it lives in.

What's the exact symptoms?


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Re: QL board damage

Postby robineattell » Fri Nov 15, 2013 7:59 pm

Thanks Tobias ,
I forgot to mention I have a Thor 1 , no daughter board .
What I did was to separate to QL board to test the board itself , connect the RGB to a monitor and then , unfortunately , the QL power supply incorrectly .
Not having a QL I couldn't see which way up the power connector should be , I know now after downloading QL tech manual .
Could it be the ZX 8301 ? I assume capacitors and resistors are ok , but ICs can be damaged by reverse polarity .
I do appreciate the humour in my situ !

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Re: QL board damage

Postby Dave » Fri Nov 15, 2013 9:19 pm

The pin-out is 9v DC, GND, 15.6V AC. If it was connected inverted at the rear power socket, the 7805 regulator would not operate correctly, but also would not pass a voltage higher than +5v DC, for some considerable time. It's unlikely this could damage your 5v components after the PSU.

However, in the Thor, if you connected the supply inverted to the 7805's socket directly, the reversed -5v could do quite widespread damage to every IC.

You might be better off buying a replacement QL PCB from RWAP and using it as a replacement.

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