VOGONS


First post, by RogrWilco

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Hi! So, as part of my journey into retro computing I bought an IBM PS/1 2011 off eBay. This was the first PC my family owned, so I thought it would be a great place to start a possible collection. Maybe not, it seems. Though it was tested as working by the seller, powering on and booting up successfully, it didn't work when I took it out of the box. It won't even power on. I have a hunch it's the power supply, which is built into the monitor of this model, but I have no way to really know. See, while I have a fair bit of know-how when it comes to computers, I know almost nothing about electronics. If I opened up the monitor I wouldn't really know what to look for or how to fix it. I'm happy to try to learn, but don't really know where to start. I'm hoping someone here might be able to help me diagnose the problem and point me in the right direction toward fixing it.

https://youtu.be/L_-Q3hw090Y

This video shows what happens when I try to power it up. No lights, no fans, but, the first time you turn it on, it makes this electric twang or very brief hum, as heard in the video. It doesn't make this sound on successive tries, unless you leave it for 15 minutes or so, in which case you can hear the electric twang again. This is the only clue I have as to what might be wrong. I'm willing to open up the monitor, though I've been kind of scared off by what I've read online about possibly killing myself by touching an anode on the monitor or capacitor in the power supply. Still, I'd do it if it'll help figure out what's wrong with this thing and possibly fix it.

Wasn't looking to get so into the weeds so soon after first diving into this hobby, but here we are. Hoping you folks can help.

Reply 1 of 6, by pentiumspeed

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Have a electronics repair shop who knows their stuff to look into rebuilding the power circuits in your monitor you can try turning on monitor with video and power connector disconnected from the computer box to rule out shorted computer before sending off the PS1 monitor to electronics repair shop.

I had a PS/1 2011 with monochrome monitor once when I was a student, mainly to log into college's vax via serial connection just like terminal, in 3rd quarter of '93.

Cheers, pentiumspeed

Great Northern aka Canada.

Reply 2 of 6, by RogrWilco

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Thanks, pentiumspeed. The problem does persist when it's not connected to the main box, so I believe it's one of the circuits in the monitor. Good suggestion about finding a repair shop. I already spoke to someone that may be able to help. I may also just return it to the seller, if I can. Thanks again.

Reply 3 of 6, by pentiumspeed

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I suggest not to return it. Too rare and expensive if you find another. Go ahead and get the monitor repaired.

That computer without a monitor as power supplly is useless. Unless someone knows the pinout of that connector to make external power supply to juice the computer itself and use regular vga monitor or LCD with vga input. That is done easily if repair shop cannot repair the monitor but having them analyze the pinout of the cable and cut off from monitor and make a power supply for it.

Cheers, Jason

Great Northern aka Canada.

Reply 4 of 6, by pentiumspeed

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http://oldcomputer.info/pc/ps1_2121/index.htm

Pinout for power connector in this website. 36V around 2A or so. 36V is correct since from other document IBM published.

https://ps1stuff.wordpress.com/page/4/ more documents.

Cheers, Pentiumspeed

Great Northern aka Canada.

Reply 5 of 6, by RogrWilco

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Thanks, Pentiumspeed. I hadn't see that first resource. I've already started the return process on eBay and there is currently another unit for sale that seems to be in better condition, so I may just proceed down that route. But I'll post the outcome here if I decide to keep it and get it fixed. Thanks again.

Reply 6 of 6, by StEeLz

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Hey, I may be late to the party but I fixed mine.
I had exactly the same symptoms, turning on will get the LED flash for a split second and go dead.

I took the Power Supply from the monitor out and probed around, and noticed that the Switching from the SMPS was propagating to the DC side on the 36V connector.
I suspected a bad cap and first component I'm checking is the culprit!

C43 was dead short!
1500uF 50V

Even if you already sent the machine back, hope it can help someone else with a similar issue! It could be that those SEMCO caps are a common failure?