Some problems with Dragon 64

[JoeMorgan]

I have found that the voltage values are correct:

Input: 9V
Output: 5V

(Before and after freezing this shows same results).

checking the surface of the motherboard, I found these weird things:


Shows an icy surface, crystallized.


Also a kind of plastic sheath attached to the pin of the capacitor.


And finally, the "icy surface" is repeated around the power connector.

That's all for now... Any ideas?

EDIT: Could you see resistor over L4? WTF?

Thanks!

[JoeMorgan]

I have already made some progress in the analysis of failure of the Dragon.

A friend left me his Dragon 32 to exchange components and the result is this:

After...
- Change of external transformer
- Change CPU
- Switching Multiplexer
- Changing rectification "daughterboard" (Being Dragon 32, the voltage of the video wasn't present [no video signal generated], but checking operation with cassette relay, writing "cload" and listening to the reaction)

None of these changes makes no hang.

A glance to the motherboard is not seen nothing damaged. Next step: change 5 electrolytic capacitors on motherboard? Replace quartz crystals?

Thanks in advance for your help.

Joe Morgan

[JoeMorgan]

Hi guys!

I changed 5 electrolytic capacitors ... nothing.

The damn thing fails in the same way.

You have any idea?

Thanks in advance, again!

[robcfg]

I know it's a pain to desolder the 6847, but maybe you should desolder it, solder a socket in its place and swap it with a known working 6847.

Maybe the ram?