17 July 2024, 20:03 | #1 |
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Recapped a 1200, no keyboard
Hi,
I recapped my amiga 1200. The machine boots off a compact flash HD, I have video, mouse but no keyboard. (I did not connect the floppy but from previous tests I know it tries to boot off from it) I checked the connector on the mother board with a magnifying len, and it seems ok. I tried two different membranes, but still nothing when I press any key. What do you suggest I do to try to find the fault that is preventing keys from being registered ? I have electronics tools like multimeters, oscilloscope and such. Thanks, Regards |
17 July 2024, 20:05 | #2 |
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Did the keyboard register before you recapped the board?
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17 July 2024, 22:15 | #3 |
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yes
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17 July 2024, 23:48 | #4 |
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It could be a faulty keyboard MPU or more likely a broken trace caused by the recapping.
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18 July 2024, 10:13 | #5 |
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Indeed I broke a pad while recapping, but I repaired it with a piece of wire. Maybe the job was not done correctly. Itas on the C304 negative pad.
According to the amiga PcB explorer the brokn pad is in the -AV circuit pad. |
18 July 2024, 11:47 | #6 |
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That is a de-coupling cap for the +/- 12V for the audio op amp. Unless there was other damage nearby it will only impact the audio not the keyboard.
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18 July 2024, 12:17 | #7 |
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I'd check continuity around the Keyboard MPU, none of the capacitors are really around anything keyboard related apart from the audio one directly behind the connector. Maybe it was just corrosion and the act of moving the board around to solder has severed something?
Perhaps it could be the voltage detector (U49) that is faulty but it's probably a long shot. Last edited by Mick; 18 July 2024 at 12:28. |
18 July 2024, 12:49 | #8 |
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Check Y621 component, which is a ceramic resonator. It generates 3 MHz clock signal driving the keyboard MPU. Presence of the signal may be checked with an oscilloscope.
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18 July 2024, 16:42 | #9 |
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I found the problem. It was a noob mistake.
I put the keyboard connector retainer the wrong way around. I reversed it and now I have a keyboard. |
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