Some problems with Dragon 64

A place to discuss everything Dragon related that doesn't fall into the other categories.
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JoeMorgan
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Joined: Mon Jan 11, 2016 12:14 pm

Re: Some problems with Dragon 64

Post by 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:

Image
Shows an icy surface, crystallized. :shock:

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

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

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

EDIT: Could you see resistor over L4? WTF?

Thanks!
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JoeMorgan
Posts: 9
Joined: Mon Jan 11, 2016 12:14 pm

Re: Some problems with Dragon 64

Post by 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
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JoeMorgan
Posts: 9
Joined: Mon Jan 11, 2016 12:14 pm

Re: Some problems with Dragon 64

Post by JoeMorgan »

Hi guys!

I changed 5 electrolytic capacitors ... nothing.

The damn thing fails in the same way. :evil:

You have any idea?

Thanks in advance, again!
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robcfg
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Re: Some problems with Dragon 64

Post by 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?
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