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File: ibm5150.jpg (2.45 MB, 4032x3024)
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I found an old 5150 and monochrome monitor that won't start up. I have done some troubleshooting and I am pretty certain that the power supply is not functioning correctly. I am having trouble finding PSU repair information online. Do any of you have any guidance on this?
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I also have tested the PSU by disconnecting the motherboard but left the floppy drives connected in order to see if the mobo was shorting the supply. I have a DMM and tantalum capacitors coming in early next week.
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fuck cern
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I assume there's a good reason it has to be this one and can't be replaced by an out of the box el-cheapo pc?
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>>1998350
My old job involved keeping computers alive well past their expected lifespans, although I didn't work anything quite this old. I am an 80s computer hobbyist though. Can you post some pictures of the power supply removed from the case? How about some good in-focus pics of the motherboard too? And do you mean that the monitor itself also won't power on?
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>>1998424
I would prefer to keep it as original as possible. I also want to work on my power systems knowledge. I am an electrical engineer by trade, but I work mostly on software.

>>1998448
I will have to get back to you on this next Tuesday as I am on vacation. I was getting antsy and wanted to get the thread going. I got some videos of the insides, but I didn't have enough time to get it all apart before I left.
The monitor is not starting up, correct. The PSU fan spins, but I've read that it is likely ac powered, and not a symptom of a working PSU.
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>>1998350
ask /g
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Try hacking at the case with a dremel for no reason
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Travel through time with it
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>>1998350
fuck off time traveler. if we're stuck here so are you.
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tons online, with mentions the psu may not always start it. maybe start by identifying your variant. i typed 5150 psu and got tons of hits. theres entire forums dedicated to that stuff.

post variant and findings. make this thread worth a damn.
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>>1998350
>I also have tested the PSU by disconnecting the motherboard

IIRC, one of the pins on one of the motherboard plugs is a "Power Good" signal. Unless it is connected (through the motherboard) to some other PS pin (not sure which), the PS doesn't completely "turn on".

It's been years since I've messed with these. Google for specifics.
>>
find another power supply and try to back-feed it through 2 molex connectors and bits of wire
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>>2001237
>/g
Why newfag, so they can tell him to buy an iPhone?
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Replace ALL of the electrolytic and tantalum caps before anything else. If any areas of the board look dark or burnt, check resistors in that area. Check your fuses and switches too.
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>>1998350
Nice AT&T bomber beer.
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>>1998448
>>2002873
>>2002884
>>2003111
OP here. So my focus shifted away from the PSU and to the tantalums. The 12v rail has been shutting down the PSU. The PSU will run when the molex for 12V is not connected. I will keep everyone updated when I change the caps tomorrow. Here are some of the innards. Also, I am using other resources as well to fix this.
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So dusty
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>>2003719
To clarify, it seems that the 5V runs correctly, but I will probably recap the whole board. The only issue is that my right hand is unusable since I fucked it up skiing
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>>2003719
>>2003720
>>2003721
Tantalums usually fail short i.e. they explode when powered. Definitely remove old solder from connectors and add new to eliminate cold joints. If you get it powered up and it still doesn't work, use a logic probe across the parallel logic chips to pinpoint duds. Check crystals/oscillators for drift too.
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>>2002893
This is probably the worst suggestion.
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>>2003182
Gen X is the worst Generation.
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>>2003924
Only faggy millennials believe that.
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>>2003789
This PSU is only 63W, the tants don't usually explode even if they failed. I am going to replace them today regardless. Ill update later.
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>>2003941
Pay close attention to your interconnects for corrosion and loose pins/bad contact. Butter 'em up with contact cleaner or a fiberglass pen to get them shiny.
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>>2001239
lol and short random shit
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My fucking package of tantalums got lost so I am going to microcenter tomorrow to get more tantalums. I'm going to have to learn how to solder with one arm, so I think that will be the biggest challenge here
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>>2004477
OP here. Im thinking it could be the RAM in Bank 0, going to try piggybacking it with some 4116 ram that I found online.
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>>1998350
Does it beep upon startup? Do you get fanspin? Give us some details? There are a bunch of dip switches inside which have to be changed along with different RAM and hardware configurations, so you could start there.
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>>1998350
Please take me with you
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>>2008602
OP broke his other arm on the monitor. He's never coming back. RIP in peperoni
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>>2009242
Help John Titor play Oregon Trail.





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