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Thread: Blinking Power Lights on a Compaq Portable III

  1. #1

    Default Blinking Power Lights on a Compaq Portable III

    The seller of the machine said the computer worked fine until he turned it on one day and it popped. When I took the rear cover off the computer, I saw two busted Tantalum Capacitors, but I've heard that on some IBM machines they don't matter. It almost sounds like its under too much load and restarting constantly. I also checked the Power Supply, but everything looked fine in there. Here's a video of the symptoms.

    Thanks!

  2. #2
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    Quote Originally Posted by aguerrero810 View Post
    ... I saw two busted Tantalum Capacitors, but I've heard that on some IBM machines they don't matter.
    For the IBM machines that you write of, the capacitors that can be left out and not affect motherboard (repeat: motherboard) operation, are in specific locations within the circuit. Other capacitors on the same motherboards do have an effect. For example, the tantalum capacitors that service the RAM are very important (failure resulting in nil or flakey RAM operation).

  3. #3
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    I've got an IBM PS/2 Model 80 last year from a recycler. Computer was working perfect except it couldn't manage to keep CMOS settings despite the new battery. Then, I've carefully inspected the board and saw that none of the tantalums were in place They were all cut from their legs and discarded.

    My theory here is that after the explosion of few of them, somebody saw that the computer is working without them and then thought that they are unnecessary and removed all as a precautionary measure :P I've installed electrolytics (they were all three legged tantalums originally) and CMOS issue has then gone.
    IBM 5150 - IBM 5155 - IBM 5160 - IBM PS/2 Model-60 (8560-041) - IBM PS/2 Model 55 SX with 8503 - IBM PS/2 Model 35 - IBM PS/2 Model 80 (8580-X21, XGA2) - IBM PS/2 Model-30 (8530-021, IBM 8513) - IBM PS/2 Model-30/286 (8530-H31) - IBM PS/1 (2133-642) - IBM PS/1 (2155-593) - IBM PC 330 450DX2 (6571-KV1) - TANDY 1000 TL/2 - Turbo XT Clone - Wearnes Boldline (80286/16) - Hyundai SUPER386ST (386SX/25) - AST AdvantagePro! (486DX/33) - Olivetti PCS46/C (486DX2/50), - 386DX/40 System - AMD K6-2/400 System - Pentium PRO/200 System

  4. #4

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    So I got the computer to work after removing one of the Tantalums. I was working with it for a while then it stopped again. I think I'm going to do what you are saying. So they can just be replaced directly with electrolytics?

    Thanks!
    Anthony

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    So it means that the tantalum which you've removed was causing a short and kicking the short circuit protection of the power supply. Don't continue with them cause they may pop and make you a firework show

    You can safely replace tantalums with electrolytics having the same capacitance value and at least same voltage. They are long replaced with modern electrolyric/polymer caps and used rarely now. Just be careful about the polarity. In tantalums, marking is located for the positive pole but in electrolytics for the negative. I replace tantalums with eqivalent electrolytics all the time when they've failed.
    IBM 5150 - IBM 5155 - IBM 5160 - IBM PS/2 Model-60 (8560-041) - IBM PS/2 Model 55 SX with 8503 - IBM PS/2 Model 35 - IBM PS/2 Model 80 (8580-X21, XGA2) - IBM PS/2 Model-30 (8530-021, IBM 8513) - IBM PS/2 Model-30/286 (8530-H31) - IBM PS/1 (2133-642) - IBM PS/1 (2155-593) - IBM PC 330 450DX2 (6571-KV1) - TANDY 1000 TL/2 - Turbo XT Clone - Wearnes Boldline (80286/16) - Hyundai SUPER386ST (386SX/25) - AST AdvantagePro! (486DX/33) - Olivetti PCS46/C (486DX2/50), - 386DX/40 System - AMD K6-2/400 System - Pentium PRO/200 System

  6. #6

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    How do you get the cover off of the Power Supply? Thank you!

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