Servicing Frontech ATX Power Supply
This SMPS was brought to me with the complaint that it was dead. This was removed from a computer belonging to a friend of mine. So, I gave him a standby from my stock. When I opened the top cover, just see what fell out:
My service room got filled up with nauseating smell and I grabbed a towel to cover my nose! Look at the stain it had left on the top cover! Probably it had got stuck there and fell off when I opened the cover!
Disposed of the carcass, took the SMPS outside and cleaned the inner side of the top cover as well as the top side of the PCB using IPA. I had to repeat this a few times, until the stains were removed. Brought it back to my service table and removed the PCB. Just see another surprise that I had:
My service room got filled up (or was it my feeling?) with foul smell once again. This is the first time, I found two dead Geckos in a device! This was the culprit, who caused failure of the SMPS, as you can see; it had got stuck at the High Voltage side of the Board! The bottom cover also had got stained! So, I rushed outside and repeated my cleaning works thoroughly and brought back for investigating the extent of damage done!
The fuse was blown. When I checked the components, I found that both transistors MJE13007 were dead short! Removed the fuse. But removing the transistors was possible only after taking out the two Filter Electrolytic Capacitors, as the mounting screws are obstructed by these.
As I observed dry solder all around, started patching it up. Remembered to take this snap before I completed:
Completed retouching all solder joints on the PCB. Checked for any other defective components on primary and secondary side. Could not find any. Checked ESR of capacitors and found these to be ok. Blue Ring Test of SMPS transformer was also ok. Connected a Bulb in place of fuse and checked. The Bulb glowed for a second and got off; indicating that no component was shorting on the Primary side of Board.
Connected the fan and it worked well. Left it running for a few minutes. Then disconnected, discharged the two High Voltage Caps and assembled the PCB back to its case.
Checked the unit once again, put back the cover and connected to mains, the Fan spun smoothly and when I checked the voltages, it was 12.20V. The other volts like 5V and 3.3V were also checked by me before putting the PCBs back.
You will notice that this SMPS has worked from 4th September, 2012 until recently, when these two Geckos decided to put a break!
Another job completed satisfactorily, though, being a strict vegetarian, it was disgusting for me to handle the dead Geckos! In fact, I wondered amusingly, what Karmic accounts that I had created to have to handle these things! Anyhow, it could be getting over soon, with a few more numbers of ‘double’ Geckos! (LOL)
This article was prepared for you by Parasuraman Subramanian from India. He is 66 years old and has more than 30 years’ experience in handling antiques equipment Valve Radio, Amps, Reel Tape Recorders and currently studying latest techs classes conduct by Kerala State Electronics Technicians’ Association. He was a BBA graduate, retired as MD of a USA company.
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