My clothes dryer keeps running and online posts indicate that I need to replace the relay in the first picture. My question is about the gel shone in the second picture - it covers the bottom of everything on the board.
Can I/do I just cut it away around the edge enough to get the board out of the tray? I assume I need to remove the board from the tray so I can un-solder the relay.
Did you try turning it off and back on again?
Yes I theory if you got the board out safely you could possibly defeat the epoxy and solder a new relay. I don’t think I could pull it off. The quick fix way is to replace the board. The crazymadscientist way would be to Dremel open the bad relay, take out all its guts. Then solder the new relay into the pins on the old relay. This method may not work. Honestly I’d just replace the board.
The on/off button doesn’t work when the relay is stuck. Unplugging the dryer for several minutes didn’t help - the dryer started running again as soon as it was plugged back in. Percussive maintenance does shut it off.
I’m sure you’re significantly more experienced in this area than I am: Do you expect that it will take a lot of time or is it really that tricky to do?
It appears this model is known to have this problem. If I just replace the board I’ll likely have to do it again if I keep the machine. I hate to reward companies for manufacturing bad products.
I’m like James on this. I’ve been known to try to replace components rather than entire boards, but mostly when a superior part can reduce the chance of a repetition of the failure or when a board is unavailable or crazy expensive.
Getting that board out of the epoxy looks like a lot of work with significant chance of damage to the rest of the circuit.
The likelihood of a New board failing is about the same as the new relay failing if replaced with the same part.
Maybe I’ll have to replace the board for now and see if I can get the relay off the current board. I can replace the relay 12 times or more for the price of the board, if the board fails again.
What is the purpose of the epoxy?
The on the books reason for the board being potted up with that much epoxy is probably to ensure no moisture gets to components.
The tin foil hat wearing conspiracy theory reason is to keep people from repairing the board themselves.
Truth is probably in the middle.
New boards are unavailable, so I ordered a used one. I may try cutting the relay off the current board to see if I have any success.
Thanks for the responses.
And as I clean up in my garage, Im keeping an eye out for my can of “conformal coating” just in case you are interested in recoating whatever repair you make IF that repair functions. It is the highest quality version of CC but that means it is toluene based silicone. And needs an outdoor drying cycle or a vented oven for drying it.
Conformal coatings are necessary in evirons where condensation can occur on the board. Protecting your copper traces and soldered leads. It also slows down heat rejection causing hot IC chips to overheat more often. Relays are typically not as prone to overheating but if made of really fine copper wire wraps … And or used in the frequent on off mode [like motorcycle voltage regulators] a relay certainly can be a serial overheat item. And replacement. In which case, speccing the relay and going with one with fatter wires in the windings might be a reliability option. I havent opened a relay catalog in decades and decades. Since college in the 80s.
I am a little bit experienced, but not as useful in board trouble shooting as component troubleshooting. The Electron Microscopy school I went to was attended almost exclusively by Integrated Circuit classmates. And so our classes focussed on that pov. Components QC. And I had already had related component troubleshooting training in the navy for old failed [EKG machines] … with discreet transistors and op-amps. Late 1970 electronics were “easier” by a long shot. Good learning oppo.
