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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: webmany on October 16, 2007, 11:15:48 PM
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I have a GVP 1230 connected to a A1200 1D3 motherboard that is having problems. It starts fine sometimes. The res of the time it gets a gray screen.
Even when it starts it can freeze up when doing simple things like the starting screen for Sim City.
It has a new AT power supply, so power should not be an issue.
Any ideas?
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Power Supply could be the issue!
Some of those AT-PSUs don't have a fine 5V line in the tolerance rating (i.e. aprox. 4.95~5.25V). Check the voltage with a multimeter.
Other clue: 1D3 revisions are buggy, so check the motherboard if you don't have fixed it already.
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I found problems with 1d4, but nothing on 1d3 so far. What should I be looking for?
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Bad caps is a good start. Replace all electrolytic ones. Easy and inexpensive (if you have SMD soldering skills).
I've have post a list of all needed caps here on a.org.
But I'm too lazy to search for the link ;-) .
So here is the "shopping list":
18 caps (all electrolytics)
3 units 10Uf x 16 volts SMD
5 || 22Uf x 35 Volts SMD
2 || 47Uf x 16 Volts SMD
4 || 100Uf x 65 Volts SMD
2 || 470Uf x 16 Volts Regular size
2 || 1000Uf x 10 Volts Regular size
Be happy!
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BTW: two of the 22uF 35V caps are intended for use in the audio out circuit.
It's a bug in the project! Nevertheless they still function as they are, prefer to change those two with unpolarized equivalents (maybe hard to find).
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Don't caps bulge when they go bad?
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webmany wrote:
Don't caps bulge when they go bad?
Not always. Sometimes they simply dry (and lost capacitance in the process).
Bulging caps are common only in high voltages (>60V).
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Is there a way to test them, or just replace them.
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rkauer wrote:
Power Supply could be the issue!
Some of those AT-PSUs don't have a fine 5V line in the tolerance rating (i.e. aprox. 4.95~5.25V). Check the voltage with a multimeter.
I can second this. I had first an ATX PSU with my old A590 HD. The unit kept rebooting all the time. When I got an original A590 PSU, the drive was rock steady.
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Just because C= used SMD caps doesn't mean you have to!
I've repaired two A600s which just sat on the grey screen for aeons by whipping out the bad SMD cap (which had gone furry - it's what SMD ones do when they leak) and soldered in a few common-or-garden electrolytics I got from Maplin. Works fine. Doesn't look so good but who cares? It's all under the hood...
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Did a test of the PSU and on the it went between 4.85 -> 5.20. Could this be enough to cause my problems?
Also, I am tracking down the capacitors.
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webmany wrote:
Did a test of the PSU and on the it went between 4.85 -> 5.20. Could this be enough to cause my problems?
Also, I am tracking down the capacitors.
Anything less than 4.92V aren't good enough. But when the power oscillate among those values you surely get a problem with the PSU.
But there is a chance of you doing the wrong measure approach: you must read the value with the PSU attached to the Amiga.
+5V must be rock steady around just one voltage! Doesn't care if it be 4.95 or 5.08, only must be steady.
Replace your PSU ASAP.
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I was doing it wrong. When I hooked it up to the 1200 and powered it up it was 5.08 - 5.10. Most of the time steady on 5.10.
Will replace the caps and let you know.
Thanks for the help