No Power in Watlow 988 Series Temperature Controller (Epoxy To Fix Broken Track)
One of my customers brought in this Temperature and told me that is just stopped working and he need it urgently and he can’t afford to buy a new controller. I told him that I will try to repair it but there are no guaranties.
First thing I did was to power the unit up via my Isolation transformer and a light bulb. Sometime people may bring in equipment and there is nothing wrong with it and fault lie somewhere else. But in this case the unit was as the customer said No Power.
Then I open the unit for inspection…. I check on the power supply section and surrounding components and found a 10uf-35V tantalum capacitor and a 10 uf 35V electrolytic capacitor bad. See picture below:
The Electrolytic Capacitor next to the tantalum had leaked it electrolyte and shorted the Tantalum cap. I then remove the both Capacitor and notice that the leaking had also taken out the circuit trace for the tantalum Cap. I clean all the carbon from the trace. See picture below:
I decided to make a new trace using copper foil and conformal coating epoxy to glue the trace back to the circuit board to make it look original.
First I laid down some epoxy and the place the trace on the epoxy and using tape to hold it in place while it dries.
I let the epoxy dried for 24 hours and then I soldered the two pads together. I then install a through hole tantalum cap and then the Electrolytic cap and apply some more Epoxy over the solder pads.
I the assembled the unit back together and tested the unit to its full functions. I used my Transmation thermocouple calibrator for the input test and it worked perfectly. Left the unit running for 4 hours and it was working as it should. Job completed. I call the customer and he was delighted to hear the good news.
This article was prepared for you by Andre Gopee from Calitech Limited Trinidad West Indies.
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By the way if you have any good repair article that you want me to publish in this blog please do contact me HERE.
Note: Please check out his previous repair article below:
https://jestineyong.com/more-than-20-bad-components-found-in-amplifier-circuit-board/
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Yogesh Panchal
September 24, 2018 at 9:33 pm
Andre Gopee,
Good repair!
Albert van Bemmelen
September 24, 2018 at 11:10 pm
Nice work with professional pcb repair! Thanks for sharing. I've never used epoxy glue but maybe I should give it a try one day? I would like to know about using it, in what form you buy it, and more about how you keep it in store for a long time before it is needed. After all, they are 2-component chemicals?
Andre Gopee
September 25, 2018 at 9:22 pm
Thanks Albert, The Epoxy I used was CW Epoxy (Circuit Works) from Digikey Electronics. I store it in my refrigerator and it stays for a very long time.Its a two part Epoxy especially made for electronics. It is really known as under-boding epoxy.
Albert van Bemmelen
September 27, 2018 at 3:08 am
Thanks Andre for that information. Will have a look where to buy it the cheapest!
Glad you gave that specifics!
Robert Calk Jr.
September 24, 2018 at 11:34 pm
Nice work, Andre. Thanks.
Parasuraman S
September 24, 2018 at 11:36 pm
Excellent! But beyond my scope, this epoxy, re-fixing the track etc.
Mark
September 25, 2018 at 7:30 am
Well done Andre,
Good repair - thinking outside the box!
Andre Gopee
September 25, 2018 at 9:24 pm
Thanks Guys.
Mason Sarles
September 25, 2018 at 10:46 pm
Andre,
Very nice PCB board repair. Thank you for sharing your repair.
Mason Sarles
Texas
Humberto
September 25, 2018 at 11:56 pm
Great repair of the PCB. Congrats.