LitOn PS-5900-2H

[aquamon]

from https://www.electro-tech-online.com...-and-current-supervisor-ic.106850/#post874642

I have a uc3845b to drive the main transformer but has no output.
pins:
1. 0.6V
2. 0.268V
3. 0.8mV
4. 2.287V
5. GROUND
6. 1.1mV
7. 12.5V
8. 4.97V

The FET is good.

Purchasing a replacement ATX PS is not an option.

Any ideas?

I'm currently thinking of replacing uc3845b but my cheapo replacement soldering iron is presently shocking me and I have no isolation Xformer.

317V on Fet's Drain...

 

[aquamon]

shouldn't pin 2 be higher than pin 1?

 

[aquamon]

replaced that IC, and today...

 

[aquamon]

Primary Circuit

Here's the primary side for your assistance, please.
https://www.eserviceinfo.com/download.php?fileid=56090

 

[aquamon]

Q303 & Q503 or PNP's, not NPN's.
Q303/Q503=A1015
Q301=C1815
corrected

 

[aquamon]

Well since you asked so nicely, I think to clear the faults, you use the remote pin.
According to data sheet.
But if whatever caused the fault condition still persist, then it will most likely return to the faulted state.

No fault remains.
I think that there is a typo about the capacitor used to reset.
How can the same size capacitor be used as in the no fault condition?

This is the part that I fail to understand, pg. 14:
"When the system has latched (either after overcurrent
or overvoltage condition), the system
needs to be reset via the Remote input. The C2
capacitor determines two different timings to the
Fault output :
C2=100nF => Trem1(ON to OFF)=8ms
C2=100nF => Trem2(OFF to ON)=24ms"