| Posted By
Medienfloh
on 2002-04-25
|  Tecnical Problem
Hello! I hope I may ask a tecnical question in this forum...
Today I started my Plus/4 the first time since many, many years. Unfortunately after power switch on the screen is completely filled out with "P".
After a few minutes this signs are changing their color and some of them starts blinking.
Inputs by the keyboard are without effects. Pushing "Reset" returns the Plus/4 to the screen with the "P"s.
The prozessor is a 8501. TED is standard.
Any hints out there?
hopefully,
Florian "Medienfloh" Schuster
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Posted By
JamesC
on 2002-04-25
| I would suspect TED
I suspect the TED because it's responsible for maintaining (refreshing) RAM. On the Plus/4 and other 264-series systems, color and screen memory are part of the system RAM and not seperate like on the 64 series.
Try to reseat the TED chip (it's the one in the metal cage) and make sure that the white gunk between it and the top of the cage is still pliable. Once the white heat-transfer material dries out, it doesn't remove heat from the chip like it should.
I actually burned out my first TED this way back in '86, being a whole 16 years of age and not knowing what I was doing.  I removed the top of the cage as well as the heat-transfer material, thinking I was keeping the chip cooler. I ended up overheating it instead.
If you need to replace that white gunk, any computer assembler can supply it. It comes with the fan that is used to cool new CPUs. Or you can go to your hobbyist and buy 'heat-sink silicone'; it doesn't have to be white.
James C in USA
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Posted By
MIK
on 2002-04-26
 | yes agree TED is dead..
A common fault with the screen displaying chars and colours.. Good Idea about the gunck James. I might just replace it on my machines because I know it's srinking and drying out.
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