CST Thor 1

The Thor, Aurora, Q40 and Q60 etc. are discussed here.
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bagpuss22
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Re: CST Thor 1

Postby bagpuss22 » Fri Oct 06, 2017 6:54 pm

ON the board removed today

I added the regulators I took off the board I was installing to the Thor.

I have also noticed on this Issue 5 board I removed, that memory ICs 3, 5, 9 and 10 are getting
very hot, +60 degrees within seconds.

The screen seems to be constantly changing with different patterns, I assume this would be
a valid fault display for faulty RAM?

Would anything else be damaged? If I populate these 4 RAM ICs then hopefully the board will be
useable again...

Russ


Martin_Head
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Re: CST Thor 1

Postby Martin_Head » Sat Oct 07, 2017 10:52 am

bagpuss22 wrote:ON the board removed today

I added the regulators I took off the board I was installing to the Thor.

I have also noticed on this Issue 5 board I removed, that memory ICs 3, 5, 9 and 10 are getting
very hot, +60 degrees within seconds.

The screen seems to be constantly changing with different patterns, I assume this would be
a valid fault display for faulty RAM?

Would anything else be damaged? If I populate these 4 RAM ICs then hopefully the board will be
useable again...

Russ

Four RAM chips all going short at the same time seems very suspicious to me. As if the board had been supplied too much power, or something sparked across somewhere.

I would remove the four overheating RAM chips, and see if anything else is getting warmer than expected.

Have you got a Minerva ROM you could fit, this does a RAM test and displays graphically on the screen any errors. If you try it with the faulty RAM's removed and get a display that shows the removed RAM's are faulty. It will suggest that the rest of the logic on the board is working. If you don't then you have other problems than just the RAM's.

With four RAM chips gone so badly faulty, I would be tempted to replace all 16 of then in one go, fitting IC sockets in their place.

On the subject of the new issue 5 board you just received, Did you try it as a stand alone board before fitting it into the Thor. If it did you would at least know that if something has now gone wrong with it, It was caused by something in the Thor. Either the power supply, or if you connected anything to the edge connector.

Are you absolutely sure that the Thor Power Supply is OK, I would also check that all the power supply wiring goes where it's supposed to. Also make sure the ground (0 volt) rails are all correctly connected, and continuous.


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bagpuss22
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Posts: 82
Joined: Thu Sep 29, 2011 10:57 am
Location: East Sussex, United Kingdom

Re: CST Thor 1

Postby bagpuss22 » Sat Oct 07, 2017 1:54 pm

Martin_Head wrote:
bagpuss22 wrote:ON the board removed today

I added the regulators I took off the board I was installing to the Thor.

I have also noticed on this Issue 5 board I removed, that memory ICs 3, 5, 9 and 10 are getting
very hot, +60 degrees within seconds.

The screen seems to be constantly changing with different patterns, I assume this would be
a valid fault display for faulty RAM?

Would anything else be damaged? If I populate these 4 RAM ICs then hopefully the board will be
useable again...

Russ

Four RAM chips all going short at the same time seems very suspicious to me. As if the board had been supplied too much power, or something sparked across somewhere.

I would remove the four overheating RAM chips, and see if anything else is getting warmer than expected.

Have you got a Minerva ROM you could fit, this does a RAM test and displays graphically on the screen any errors. If you try it with the faulty RAM's removed and get a display that shows the removed RAM's are faulty. It will suggest that the rest of the logic on the board is working. If you don't then you have other problems than just the RAM's.

With four RAM chips gone so badly faulty, I would be tempted to replace all 16 of then in one go, fitting IC sockets in their place.

On the subject of the new issue 5 board you just received, Did you try it as a stand alone board before fitting it into the Thor. If it did you would at least know that if something has now gone wrong with it, It was caused by something in the Thor. Either the power supply, or if you connected anything to the edge connector.

Are you absolutely sure that the Thor Power Supply is OK, I would also check that all the power supply wiring goes where it's supposed to. Also make sure the ground (0 volt) rails are all correctly connected, and continuous.


OK,

Replaced the for hot ICs, and powered up. Not getting hot anymore but still not booting.

Put a Minerva ROM in and it fried it! Hot within seconds!

Not a happy bunny.


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bagpuss22
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Posts: 82
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Location: East Sussex, United Kingdom

Re: CST Thor 1

Postby bagpuss22 » Sun Oct 08, 2017 9:09 pm

It was a shorting link put in by CST, by the main connector!

So far I have had to replace the 4 x DRAM and the 8049, just the ZX8302 to check and then
maybe some power can be applied.


Martin_Head
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Re: CST Thor 1

Postby Martin_Head » Mon Oct 09, 2017 10:18 am

If that was a shorting link between the 9v rail and the 5 volt rail, I would expect mass death and destruction amongst the logic circuitry. Watch out for the 74LS... chips, they really shouldn't like more that 5 volts up them at all.


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bagpuss22
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Posts: 82
Joined: Thu Sep 29, 2011 10:57 am
Location: East Sussex, United Kingdom

Re: CST Thor 1

Postby bagpuss22 » Wed Oct 11, 2017 12:19 am

I am hoping that I may not have to change too much. My worry would be, if the board would be
better scrapped or rebuilt!

:?



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