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Old 05 November 2019, 13:16   #1
mja65
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Amiga 600 video issues

Yes I've become *that person - the long time lurker who only posts when he needs something.

I will try and get over the self loathing shortly, but would appreciate comments and suggestions. I just bought an Amiga 600 and the monitor connection works perfectly. Unfortunately, just getting back into the amiga scene recently (my original A500 is sitting in a box but the monitor is long since dead) means using a monitor for the time being is not an option. Given, neither the RF out nor the composite works at all. It seems more than coincidence both are failing and suggests to me it's a common cause.

I've opened up the machine, and apart from the exterior being filthy, the inside is actually remarkably clean. Apart from some very small rust on the shielding, the motherboard seems perfect and there is no obvious signs of capacitor bulging. While replacing the capacitors would seem prudent, would it be too easy to assume this will solve all my problems?

Advice and input welcome!
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Old 05 November 2019, 13:52   #2
lord of time
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I have lost composite on a couple of 600's in the past and it was due to capacitor leak damage... the caps on the 600's dont bulge they just slowly seep and destroy the pcb under them. I reccomend Amiga Passion for a recap he has done a couple of mine now.
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Old 05 November 2019, 13:54   #3
solarmon
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If the A600 has not been recapped then the SMT electorlytic caps (the aluminium can ones) will certainly have leaked and caused corrosion, and be out of spec.

If might not be obvious if you are not sure what to look for. Typically, a good (bad?!) sign is if the SMT electorlytic caps legs solder are dull and not bright/shiny.

It will be good if you can post some clear and close up pictures of you motherboard so that others can advise.

In terms of video issues, typically the U12 CXA1145 encoder chip and associated components could become faulty - some of which are the SMT electorlytic caps themselves.

You can use the following online resources to help locate and troubleshoot:

http://www.amigapcb.org
https://www.amigawiki.org/doku.php?i...chematics#a600
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Old 06 November 2019, 11:51   #4
mja65
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Thanks all for the feedback. I've attached a photo here, but not sure it shows much of use? For what it's worth the underside of the board is very clean with no apparent damage, but I think it's obvious based on the comments my engineering skills are not great!

I live in Australia, so will need to consider local options for recapping - I've reached out to someone on the following thread http://eab.abime.net/showthread.php?t=88046 so hopefully they are still around!
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Old 06 November 2019, 11:55   #5
Daedalus
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It doesn't look *too* bad, but there are definitely signs of leakage there, and it's impossible to know the full extent of any damage caused until the affected parts are removed and the board cleaned. Replacing the capacitors alone is very unlikely to solve the issue, it's more likely to be damaged traces in the area, the chip in your photo being damaged, or damage to the delay lines and filters (the square metal cans to the left of the area).
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