Short to gnd display board Honeywell Relay Module

[WHaThEFLuX]

Re: Short to ground on display board, how to find the culprit?

JF1 pin voltage = ~30V, pictures of other boards coming right up.....

Trust me when I say make and model are unimportant, you will not find a schematic for these devices anywhere

[budm]

Re: Short to ground on display board, how to find the culprit?

"JF1 pin voltage = ~30V, " 30V source forcing current through a small inductor through shorted circuit, no wonder it blew up.
Well, you'll never know, but at least we will know what this device does; never under estimate Badcaps people, there are many people in many different fields here.
It is kind of like this thread which OP does not think the pictures will help:
Post 13 and later:
https://www.badcaps.net/forum/showthread.php?t=64179

[WHaThEFLuX]

Re: Short to ground on display board, how to find the culprit?

Here is how everything is connected.

In the last picture, the last pin on the right in the row of horizontal pins on the upper left of the board connects to JF1.

[R_J]

Re: Short to ground on display board, how to find the culprit?

In the last picture that JF1 pin (connected to burnt coil) seems to go to J4 (rj45) jack that has a blank rj45 plug in it, is it not normaly used and is it possible someone pluged in something they should'nt have blowing the inductor on the otherboard?

[WHaThEFLuX]

Re: Short to ground on display board, how to find the culprit?

Thanks for the input RJ, I believe that port is used for diagnostics, I have never used it myself, every unit I receive comes with the blank plug.

[budm]

Re: Short to ground on display board, how to find the culprit?

So what is this device is for? We still do not know what we are dealing with here.

[R_J]

Re: Short to ground on display board, how to find the culprit?

looks like it could be a second 4-20 ma current loop output like the other rj45, just not used in this application. did you ever clean up all the burnt carbon and try the board?

[WHaThEFLuX]

Re: Short to ground on display board, how to find the culprit?

I've had this same problem many times before and was never able to figure it out, no amount of cleaning will solve it. Whatever damage occurred causes false readings on most other components on the board, when removed they all test fine. The first component that made me realize this was the diode Z1, on the burnt board it reads in both directions while on a good one it does not.

Bud, this unit functions exactly the same as the honeywell in my other thread, but is a different brand and design:

https://customer.honeywell.com/resou...0s/65-0126.pdf