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Dead Compaq Portable III

eddieb76

New Member
Joined
Jun 15, 2020
Messages
5
Picked up a Compaq Portable III at a yard sale last week. Other than the typical keyboard cable cracking, the rest of the PC is in really good shape. Of course it doesn't power up. Turning it on, results in a quiet click, which I assume is the relay in the power supply shutting it down. The fan makes no attempt to turn at all. I disconnected a few devices and get the same results. Pulled the power supply out and looked it over. Nothing visually wrong, no swelled or leaky caps. Didn't want to necessarily just blindly replace all of the electrolytic caps in it without going any further into it. On a side note, noticed that the X any Y caps are in a separate sealed section along with a filter and the switch. Interesting. used to having to replace RIFA caps on earlier computers. Guess not on this one!

Any direction on this would be appreciated. Is there a way to test the power supply by itself or does it need a load?

Thanks,

--Ed
 

kc8eyt

Experienced Member
Joined
Aug 7, 2020
Messages
323
Check the motherboard very carefully for blown tantalum caps. My Compaq III exhibited this same behavior and it ended up being a cap that was blown on the motherboard.
 

retro-pc_user

Veteran Member
Joined
Oct 13, 2017
Messages
703
Location
SE Michigan, USA
Also the CPU might be inserted in the wrong orientation (notch on the CPU or FPU not matching the notch on the CPU LIF socket/PLCC). I once inserted the FPU incorrectly on my 386 PC and a 486 CPU on another system and after powering off both machines and waiting for the discharge to complete, I reseated the FPU and CPU correctly and boots up fine.

My Portable 8088 has an issue where it would either power on without issues or not boot at all if the system froze due to a misconfigured floppy or hard drive setting.
 

eddieb76

New Member
Joined
Jun 15, 2020
Messages
5
Does anyone have the pinouts for the power connector to the Compaq Portable III ? Trying to test the PS..... Thanks
 

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eddieb76

New Member
Joined
Jun 15, 2020
Messages
5
Check the motherboard very carefully for blown tantalum caps. My Compaq III exhibited this same behavior and it ended up being a cap that was blown on the motherboard.

How did you isolate the bad cap? All of the ones on my MB look ok..... Thanks
 

Andrettigto

Experienced Member
Joined
Jan 9, 2017
Messages
50
Location
Toronto, Ontario
Does anyone have the pinouts for the power connector to the Compaq Portable III ? Trying to test the PS..... Thanks

I'd be interested in knowing the connector voltages too. My Portable III P/S is dead and 200v supplies are not exactly common :)
So now I'm thinking of installing an ATX supply for the motherboard and swapping out the plasma for an MCE2VGA & 10.1" IPS
 

resman

Veteran Member
Joined
Jan 1, 2014
Messages
522
Location
Lake Tahoe
I'd be interested in knowing the connector voltages too. My Portable III P/S is dead and 200v supplies are not exactly common :)
So now I'm thinking of installing an ATX supply for the motherboard and swapping out the plasma for an MCE2VGA & 10.1" IPS

I admit to gutting a dead Portable III, using the screen as a backup for my Portable 386, then swapping the screen for an LCD and the motherboard for a Jetson TX2. Just love the aesthetic of the Portables and gives the barebones Jetson MB a nice, compact, and portable platform.IMG_2604.jpg
 

Andrettigto

Experienced Member
Joined
Jan 9, 2017
Messages
50
Location
Toronto, Ontario
Nice! That Jetson TX2 is not exactly cheap and combined with the display makes it a big investment. It looks great and sure it performs well.
I might change course and look into using an old ASRock 880GM-LE I have. It would allow me to reuse most of the backplane giving it parallel and serial ports and offer a choice of XP or Win7.
 

Destiouj

New Member
Joined
Jun 2, 2022
Messages
2
I have one too but when I turn it on it turns back off and on again and again , i took a look inside and the caps where fine
 
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