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Old 04 October 2017, 14:33   #1
MikeyG
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A600 - Reboot not working after recap

Hi,

After recapping my Amiga 600 I have found that it works fine all except it now no longer responds to a Ctl+Amiga+Amiga reboot. Tested all the keys and the keyboard is working fine.
I have recently recapped the motherboard so wondering if a slightly different capacitance would cause this issue.
Does anyone know which capacitor could possibly cause this to happen?

As I have a furia 600 card I need to do a Ctrl+A+A for 3 seconds to enable the PCMCIA port.
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Old 04 October 2017, 14:40   #2
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The capacitance shouldn't affect the reset, though there should be at least some capacitance there... Have you checked that the traces are in good shape around the 555 timer? There's a little bit of logic circuitry involved in the keyboard reset that could be buzzed for continuity to see if any damage to those traces in the area might be the issue. Check out the schematics, the Keyboard page in particular. Pin 2 of the 555 should go low when the three keys are pressed to start the reset process.
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Old 04 October 2017, 14:41   #3
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I would agree, definitely should not be because you replaced caps.
You can run Amiga without any caps (only 47uf are needed for power).
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Old 04 October 2017, 15:57   #4
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Being that this is an A600, I would suspect that shitty keyboard membrane first of all. Taking it out and putting back in could be enough stress for that shit to stop working. I mean it, it's terrible!

Have you checked that all your keys work fine? Go to Workbench, there's a program in Sys:Tools/ called KeyShow, and see if Ctrl works. Then on Workbench, try to do right A+E (should bring up execute window), and then open another software that executes itself in its own screen, like Dopus or PPaint, and try left a+M (should switch between WB/Dopus screens).

That should be enough testing to see if those keys work.

I have a similar problem, and it is my left Amiga key having gotten rotten. I think it's the contact pad that has gone boom, because otherwise I'd miss a whole bunch of keys, but I don't.
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Old 04 October 2017, 16:40   #5
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Thank you for the responses. I did repair the pad for C612 which I see is part of the 555 timer so I'll check around it to see if I missed something. There was a bad cap before so maybe its caused a broken trace elsewhere. I did a continuity test when repairing the pad on the components around it but will investigate further.
I will also check using KeyShow as I have tested using text editor and typing on all the character keys so i know its not a complete bank of keys that are out.
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Old 05 October 2017, 10:47   #6
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Quote:
Originally Posted by MikeyG View Post
Thank you for the responses. I did repair the pad for C612 which I see is part of the 555 timer so I'll check around it to see if I missed something. There was a bad cap before so maybe its caused a broken trace elsewhere. I did a continuity test when repairing the pad on the components around it but will investigate further.
I will also check using KeyShow as I have tested using text editor and typing on all the character keys so i know its not a complete bank of keys that are out.
If a whole row of keys is out. Could be membrame as akira said.
You could try the old cut 1mm off cable trick.
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Old 05 October 2017, 14:55   #7
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Quote:
Originally Posted by MikeyG View Post
I will also check using KeyShow as I have tested using text editor and typing on all the character keys so i know its not a complete bank of keys that are out.
Be careful - that can be misleading as the "qualifier" keys (Ctrl, Shift, Amiga, Alt) are all on separate lines from the ordinary keys. This is so the computer can always detect when they're pressed in combination with other keys, but it means a qualifier can be faulty without affecting the rest of the keyboard. A better test method would be, as was suggested, trying to use the keys for something. Load up Workbench and press right Amiga + E, which should open the Execute command requester. Then hold down the left Amiga key and press the arrow keys. The mouse pointer should move. Finally, try typing text in the Shell while holding Ctrl down - you shouldn't get the normal characters if Ctrl is working.
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Old 05 October 2017, 16:12   #8
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Yeah I was not talking at all about a whole bank/row of keys, my test (as Daedalus) is to single out a key not working.

The conductive pads can wear off, it's not just the membrane contacts that go bad, although I can see how my post could be a bit misleading. In any case, using those keys in the system will tell you if they are fine or not!
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Old 05 October 2017, 23:00   #9
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I found the issue. It was a dry solder joint on one of the pins I think 14 or 15 which is one of the Amiga Keys.

But tonight I have found an even bigger problem. Turned on the A600 and was getting massive distortion on the video output. Thought I'd check the PSU see what reading I'm getting and 5v line was fluctuating from +1 to + 8v and 12v was again fluctuating +100v
Even after been off for a while and disconnected from mains I was reading 30v from the 12v line.
Not healthy at all. I'm not prepared to open PSU's so I will looking now for a replacement PSU.
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Old 05 October 2017, 23:12   #10
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Mikey that PSU sounds horrible - Hope that new one comes through all good and proper mate. Look forward to the response and good read so far
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Old 05 October 2017, 23:14   #11
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Yeah, that doesn't sound good at all! Though the Amiga won't run once it drops below ~4.7V or so, so are you sure you were measuring it okay?
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Old 08 October 2017, 13:48   #12
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Measure it again today using different meter. 12v is around 14.6v
The 5v line is fluctuating between 4.8 and 5.3v.
The PSU is also making an audible clicking which doesn't sound encouraging, reluctant to use it.

I've seen on other threads that people have used MeanWell RT-50B and put them in the original PSU housing. So might give that a go?
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Old 09 October 2017, 02:56   #13
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Does it make that clicking sound even while the Amiga is running?
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Old 09 October 2017, 08:33   #14
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It stops after a while when running the Amiga I think.
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Old 09 October 2017, 09:46   #15
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Hmmm... Yeah, I wouldn't trust that PSU myself. A lot of people have used the Meanwell PSUs to replace the innards of their original Amiga units, seems like a good option.
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