Re: IBM Thinkcentre S50 TYPE: 8086
Well, I just realized that vcc_ddr is fine - solid 2.6v with resistance of 30 ohms. So it might be that vcc-agp has no short - it's just that power is not delivered to it (0 volts), which could mean that powermos is fried. I need to check the gate voltage to know for sure, though (and that's probably pulse width modulated, so I'll need my oscilloscope).
Will post back when I'm done. Thanks momaka.
EDIT: If I'm not mistaken, I think that vcc_agp should be around 1.5v. Someone correct me if I am.
jimmy274
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Last Activity: 02-12-2025, 03:19 PM
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Location: Belgrade, Serbia
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Re: IBM Thinkcentre S50 TYPE: 8086
No thoughts on this whatsoever? Anyone?Leave a comment:
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Re: IBM Thinkcentre S50 TYPE: 8086
Checked! Very weird results - the readings are mismatched by 1 ohm:
1. Vcc_agp '+' to '-' (correct polarity): 41.1 ohms,
2. Vcc_agp '-' to '+' (reversed polarity): 42.1 ohms.
Vcc_agp is made from +5V and has one Ruby YXA 10v 470u on it's exit (and it's not him that's shorted, tried by removing it - good as new). Also, it's made by an SMPS - it has one switch (ic mosfet - has 2xmos inside - Nikos P2103HV), one choke and the before-mentioned output cap. It also has filtering all over the motherboard - some of it was done by one...Leave a comment:
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Re: IBM Thinkcentre S50 TYPE: 8086
Good point. Will check and post back.Leave a comment:
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Re: IBM Thinkcentre S50 TYPE: 8086
New info guys. Traces around the changed caps are fine, I did a recheck and could not find the damage. However... The Vcc_agp and Vcc_ddr are pretty much shorted - When I check + and - terminals across some caps (used to filter Vcc_agp and Vcc_ddr), I get 40 ohms and 30 ohms (no fluctuation - hard 40.2 and 29.8).
So either I've got something shorted or something was shorted all along. Suspects - bunch of Rubycon YXA and some ZL (yes, I know - hardly these are making problems), northbridge (the blue finish has gone a bit yellowish under it),...Leave a comment:
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Re: IBM Thinkcentre S50 TYPE: 8086
Yeah, Chemicons tend to do that. This S50 board had 3 KZEs, and even though they usually don't fail, I still replaced them with Panasonic FM (I get bad vibe from Chemicons).
Temporary fix? Why? These Panasonics are great (I also used NHG series for some of my diy audio stuff, but they're not low-ESR) - I would even go as far as saying that I like them better than Nichicons - I've seen a lot of failed Nichicons (some of them being in top of the range tube audio amps - these were not HM, they were PW or PM made in late 80s through early 90s),...Leave a comment:
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Re: IBM Thinkcentre S50 TYPE: 8086
Just a few more things before I post the pics (still hadn't gotten around to do so).
The CPU is Celeron D 2.4, and even though it's a Prescott core, the heatsink doesn't get too hot, but I probably will switch to Northwood as soon as the machine actually posts.
@bigbeark: Even though bunch of people think that TDP of ICH-5 is too low to be cooled, I agree with you - if you touch the surface with your finger and fire up (first ground yourself of course), you can't hold it there for very long - it gets very hot. I did use some...Leave a comment:
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Re: IBM Thinkcentre S50 TYPE: 8086
The board had the exact same symptoms before the recap, so... I don't think it's the trace. Will check, though. I must admit that some caps were tricky to get to and that I did burn the upper lacquer, but I got nowhere near the trace itself (copper is still well under the blue finish). I'll doublecheck with multimeter just to be sure, but I don't think this is the problem (as I said, I did quite a few recaps - there were a lot of them that looked much worse than this one and still functioning).
Btw, you're sure it's the same board? This...Leave a comment:
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Re: IBM Thinkcentre S50 TYPE: 8086
Forgot to say that I did that, does not help.Leave a comment:
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IBM Thinkcentre S50 TYPE: 8086
Hi all,
Ok, this is my first post/thread, but not my first job. I've only recently discovered this forum, before that I've done a lot of recaps on older boards, but this one has me stunned.
First, I did a search on this and a lot of other forums to no avail. Seems that no one had Thinkcentres in their workshop, which is cool for IBM, but unfortunately, these babies do fail and they fail big time - I did a full recap and I've still got nothing.
Since I don't have the board with me now (will have in a few hours), I'll just explain the symptoms and what's done and then upload...
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