RE. Metcal MX500 repair

[skrr]

Can anyone help me solve a problem with an MX500? About a year ago mine failed so I downloaded the schematics mentioned in another thread and found that U4 had died, I replaced it and all was well until last week when the unit failed again. I found that R1 had smoked and Q1 had blown to pieces,so I replaced them, checked surrounding components and plugged the unit in. All looked well so I turned it on, the yellow LED came on for a few seconds and then R1 and Q1 died again. I am a bit flummoxed

 

[metcalman]

You should check with the factory, they have a 4 or 5 year warranty and they are pretty flexible.

 

[Joshua Bretz]

I had the same problem. Replaced Q1 only to have it smoke again.

Debugged to C24. Replaced C24 with metallized polypropylene X2 capacitor 100nF Kemet PHE850ED6100MD18 (https://www.digikey.com/product-search/en?lang=en&site=us&KeyWords=PHE850ED6100MD18&x=0&y=0)

Also replaced Q1 with Fairchild KSA473YTU which has a different pinout but no rinky-dink plastic heatsink. (https://www.digikey.com/product-detail/en/KSA473YTU/KSA473YTU-ND/1051643)

Can anyone help me solve a problem with an MX500? About a year ago mine failed so I downloaded the schematics mentioned in another thread and found that U4 had died, I replaced it and all was well until last week when the unit failed again. I found that R1 had smoked and Q1 had blown to pieces,so I replaced them, checked surrounding components and plugged the unit in. All looked well so I turned it on, the yellow LED came on for a few seconds and then R1 and Q1 died again. I am a bit flummoxed

 

[metcalman]

Don't forget about the 4 year warranty AND they are selling refirbished systems in their web store.