stepleton
Well-known member
Hi all, excited to be a new member.
My friend and I have been debugging a recapped 5126 lately and are looking for some advice. Once again this machine was recapped some time ago
The machine is in OK shape overall with a well-behaved 40MB hard drive. Unfortunately, leakage from the three caps under J13 (left-hand kb/trackpad port) took a toll on the circuit board. We've recently bridged two pins of J13 that were attached to broken traces over to their cousins on the other side of the board. Also, I just now finished wiring the interrupt switch directly to the Misc GLU to work around a rotten via just above RP201.
The board has a flaky SWIM. There is a replacement on standby. However, we suspect the power regulation may also be off, and this may have caused the SWIM to break in the first place. So we'd like to fix the power first before we exchange that chip.
The problem is similar to the behaviour discussed in this thread from 2015. Plugged into the wall and with the battery installed, the system runs well enough, although some screen flicker occurs when the drive spins up. Unplugged, the battery meter shows the power plunging very quickly. It takes about 15 seconds or so before the computer gives up the ghost and shuts down altogether.
The thread just linked suggests to me that bad continuity in the region south of J13 can cause problems like these, and given all of the continuity problems seen so far in that area, I wouldn't be surprised if more continuity issues were at fault, so it seems useful to check for that first. The thread suggested measuring continuity between C26 and pins 14/15 of the op-amp U1M, but those seem to be fine. What else might be worth probing?
For what it's worth, we're using the original charger and a replacement 6v sealed lead-acid battery of the usual kind.
Thanks for any help!
--Tom
My friend and I have been debugging a recapped 5126 lately and are looking for some advice. Once again this machine was recapped some time ago
The machine is in OK shape overall with a well-behaved 40MB hard drive. Unfortunately, leakage from the three caps under J13 (left-hand kb/trackpad port) took a toll on the circuit board. We've recently bridged two pins of J13 that were attached to broken traces over to their cousins on the other side of the board. Also, I just now finished wiring the interrupt switch directly to the Misc GLU to work around a rotten via just above RP201.
The board has a flaky SWIM. There is a replacement on standby. However, we suspect the power regulation may also be off, and this may have caused the SWIM to break in the first place. So we'd like to fix the power first before we exchange that chip.
The problem is similar to the behaviour discussed in this thread from 2015. Plugged into the wall and with the battery installed, the system runs well enough, although some screen flicker occurs when the drive spins up. Unplugged, the battery meter shows the power plunging very quickly. It takes about 15 seconds or so before the computer gives up the ghost and shuts down altogether.
The thread just linked suggests to me that bad continuity in the region south of J13 can cause problems like these, and given all of the continuity problems seen so far in that area, I wouldn't be surprised if more continuity issues were at fault, so it seems useful to check for that first. The thread suggested measuring continuity between C26 and pins 14/15 of the op-amp U1M, but those seem to be fine. What else might be worth probing?
For what it's worth, we're using the original charger and a replacement 6v sealed lead-acid battery of the usual kind.
Thanks for any help!
--Tom
Last edited by a moderator: