Howdy folks,
I recently got this PSU to replace the 250W Delta unit in my "Retro-PC workhorse" - the rig that I'm using for testing most of my retro stuff.
https://www.badcaps.net/forum/attach...1&d=1648432776
https://www.badcaps.net/forum/attach...1&d=1648432776
https://www.badcaps.net/forum/attach...1&d=1648432776
Cleaned it good (wasn't too dirty to begin with) then proceeded to test it with a minimal load (two old hard drives). Everything looked OK, all voltages in spec except the pwr_ok signal that fluctuates somewhere between 0 and 0.4 volts.
Despite this, I used it to power the "workhorse" and surprisingly it started and ran as usual (pwr_ok still low), but I'm wary of using it like this on a test system so I reverted to the old 250W supply.
Took it apart again, desoldered the small daughterboard/control board to check for problems. At first I thought it was soaked in electrolyte from supposedly bad capacitors, but this proved to be only an excess of flux from manufacturing, which was easy to clean with iso alcohol.
One of the small elkos on the board (nichicon PW 10uF/25V) seemed to have a high-ish ESR (a bit over 4 ohm) so I replaced it with a 10uF/35V from the same series (around 1 ohm I think). However, after putting it all together it didn't change anything. Voltages still in spec, pwr_ok missing.
The three chips on the small board are two LM339 (one DIP, one SOIC) and a TSM1002DS which I suspect could be a custom Delta chip. All capacitors are from reputable brands (NCC primary, mostly Rubycon on the main board, Nichicon on the daughterboard). Lacking a schematic (and experience) I'm at a loss, so any advice/idea/hint will be greatly appreciated.
Thanks!
I recently got this PSU to replace the 250W Delta unit in my "Retro-PC workhorse" - the rig that I'm using for testing most of my retro stuff.
https://www.badcaps.net/forum/attach...1&d=1648432776
https://www.badcaps.net/forum/attach...1&d=1648432776
https://www.badcaps.net/forum/attach...1&d=1648432776
Cleaned it good (wasn't too dirty to begin with) then proceeded to test it with a minimal load (two old hard drives). Everything looked OK, all voltages in spec except the pwr_ok signal that fluctuates somewhere between 0 and 0.4 volts.
Despite this, I used it to power the "workhorse" and surprisingly it started and ran as usual (pwr_ok still low), but I'm wary of using it like this on a test system so I reverted to the old 250W supply.
Took it apart again, desoldered the small daughterboard/control board to check for problems. At first I thought it was soaked in electrolyte from supposedly bad capacitors, but this proved to be only an excess of flux from manufacturing, which was easy to clean with iso alcohol.
One of the small elkos on the board (nichicon PW 10uF/25V) seemed to have a high-ish ESR (a bit over 4 ohm) so I replaced it with a 10uF/35V from the same series (around 1 ohm I think). However, after putting it all together it didn't change anything. Voltages still in spec, pwr_ok missing.
The three chips on the small board are two LM339 (one DIP, one SOIC) and a TSM1002DS which I suspect could be a custom Delta chip. All capacitors are from reputable brands (NCC primary, mostly Rubycon on the main board, Nichicon on the daughterboard). Lacking a schematic (and experience) I'm at a loss, so any advice/idea/hint will be greatly appreciated.
Thanks!
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