Compaq Portable 386 PSU burn

[mdx]

Hi All,

I have a Compaq portable 386 that works perfectly. Well, except for the fact that it started smelling burned a few days ago. I took everything apart and found inside the PSU some parts with burn/melt marks (R8 and CR3, mainly.)
Any ideas as to why this suddenly started and what could be done to cure it? The fan is running fine.
Does anyone have schematics for the PSU or at least the values for the parts? (at least CR3 looks like it should be replaced, even if the whole things still runs.)

Any help appreciated!

PS: I can upload some pictures of the parts later if that helps.

 

[mdx]

Never mind about the values, I was able to read/google/measure them. R8 is 1kOhm Vishay FP3 3W/500V, CR3 is MUR 480 4A/800V. I will try to replace these with similar high power parts...

I am still interested in any ideas on why this might have happened and in the schematics in case I end up frying more components...

 

[mdx]

Hi All,

just an update. I replaced the parts and everything seems to be working again. Here are some pictures.



Now there is one more problem. When booting, sometimes (but not very often) the compaq will show error 601 (floppy controller error).
Any suggestions welcome ofcourse ;-)

 

[george]

Check FDD cables (power & data), check for stable +12V when FDD is accessed, check the fdd mechanics and if necessary clean and lubricate heads positioning mechanism.

 

[mdx]

Check FDD cables (power & data), check for stable +12V when FDD is accessed, check the fdd mechanics and if necessary clean and lubricate heads positioning mechanism.

Good point about power stability, since I had trouble with the PSU already. Some of the larger capacitors in the PSU are outside the range of my meter so I couldn't check them. If it's not the power supply then I will just replace the floppy drive and see if it helps. I have some spares lying around. (I am currently trying to get an IBM P70's floppy drive to work again so I don't want to spend too much time on this 'standard' one...)

Thanks, I'll report back soon ;-)