VOGONS


First post, by Croccy22

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I have recently acquired a non-working Compaq SLT 286 "Laptop".

The external PSU seems to work fine and is outputting 17.8V, but the internal power supply isn't supplying anything but the 17.8V at the output connecter.

I'm not a power supply expert but I've checked all the Caps and they all seem fine, but the middle transformer on the board seems to be broken, there is no connection between the two ends on the secondary coil, but there is on the other two so I think this is where the issue lies.

I can't find a replacement part for this so I am thinking the chances of resurrecting this PSU are slim. But I would still like to see if I can at least bring the device back to life.

Does anyone have the pinouts for the cable going between the internal PSU and the mainboard? Maybe then I could squeeze a different PSU in the unit (Has anyone ever done this?) I know I would lose the battery functionality but not sure if there are any other options.

Has anyone ever had this issue and managed to resurrect the device?

Matt.

Reply 1 of 3, by dominusprog

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LMEsbb9.jpg

How do you select replacement capacitors? (For Compaq Portable 2)

Duke_2600.png
A-Trend ATC-1020 V1.1 ❇ Cyrix 6x86 150+ @ 120MHz ❇ 32MiB EDO RAM (8MiBx4) ❇ A-Trend S3 Trio64V2 2MiB
Aztech Pro16 II-3D PnP ❇ 8.4GiB Quantum Fireball ❇ Win95 OSR2 Plus!

Reply 2 of 3, by pentiumspeed

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SLT 286 and SLT 386s/20 shares same power supply which is not a power supply. Rather it is dc to dc converters and a circuit to charge a battery.

I had SLT 386s/20 with internally broken pin on one of long capacitors. Best to replace these three long capacitors first. The "power supply" should be fine but make sure tantalum capacitor is not shorted by checking with your meter.

Cheers,

Great Northern aka Canada.

Reply 3 of 3, by Croccy22

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I've checked the capacitors already, the one on its own had a broken leg, but the other two were fine and looked like they may have already been replaced as they were blue and not silver like in all the photos i have seen. I desoldered them anyway and tested them in my Capacitor tester and they are both good.

There just isnt any other voltages anywhere else on the board apart from the 18v, and there is no voltage getting to the caps on the right hand side. The middle transformer of the 3 seems to be dead, but without schematics I dont know which voltage it is reponsible for. I was thinking I could swap it out with a pico atx psu but without the pinouts or a working device to measure, its not going to be an easy job.