hideehoo
Experienced Member
Picked up a 8032 with bad transformer a while back, my son posted about it here.
http://www.vcfed.org/forum/showthre...e-CBM-8032-Transformer-Problem&highlight=8032
Primary winding is open circuit, didn't see a thermal fuse anywhere. Bottom line is fixing the transformer seems like a non-starter, exact replacements are unobtainium and likely failure prone during the shipping process (old and heavy), and individual transformers of sufficient amp ratings are expensive and I'm not sure I can actually fit them all given the all the different voltages needed here at sufficient amperage.
So, as much as it pains me to hack this up, I'm thinking of going with an +18V AC-DC SMPS to feed the monitor, and then some DC-DC buck converters (probably xl4016 based) downstream to get +12V and +5V, and finally a LM2662 based negative converter to get the -5V for the DRAM. Total cost via my favorite Chinese vendors is around $20. Judging by the max current delivery capacity of the existing linear regs, I'm guessing a 18V 10A supply, two 8A bucks for +12V and +5V, and finally 200ma for -5V should easily do the job, even factoring in Chinese amp ratings
Will need to pull the linear regulators, some of the existing buffer/storage caps (to prevent inrush surge currents at power up), and the rectifier bridges so I can reuse the transformer connector block to make things look somewhat tidy.
Thoughts? I feel dirty already, but a working computer in this case seems better than one just collecting dust.
http://www.vcfed.org/forum/showthre...e-CBM-8032-Transformer-Problem&highlight=8032
Primary winding is open circuit, didn't see a thermal fuse anywhere. Bottom line is fixing the transformer seems like a non-starter, exact replacements are unobtainium and likely failure prone during the shipping process (old and heavy), and individual transformers of sufficient amp ratings are expensive and I'm not sure I can actually fit them all given the all the different voltages needed here at sufficient amperage.
So, as much as it pains me to hack this up, I'm thinking of going with an +18V AC-DC SMPS to feed the monitor, and then some DC-DC buck converters (probably xl4016 based) downstream to get +12V and +5V, and finally a LM2662 based negative converter to get the -5V for the DRAM. Total cost via my favorite Chinese vendors is around $20. Judging by the max current delivery capacity of the existing linear regs, I'm guessing a 18V 10A supply, two 8A bucks for +12V and +5V, and finally 200ma for -5V should easily do the job, even factoring in Chinese amp ratings
Will need to pull the linear regulators, some of the existing buffer/storage caps (to prevent inrush surge currents at power up), and the rectifier bridges so I can reuse the transformer connector block to make things look somewhat tidy.
Thoughts? I feel dirty already, but a working computer in this case seems better than one just collecting dust.