1996 U320 40', The Automatic Transfer Switch is a MagneTek ATS 100
On shore power the remote panel's charge and invert LEDs were flashing like a lightbar in your rearview mirror.
The suspected cause is a backfeed current.
After shutting the shore power off any attempt to turn the shore power on causes the shore power source GFI to pop.
I isolated the bridge diode and the MOV from each other and the circuit. Testing the diodes, with a diode tester, shows three diodes at about 0.5 V DC the fourth diode shows 1.002 V DC. A resistance test shows three diodes at 235 +/- K ohms, the forth diode shows 477 +/- K ohms.
The MOV measures as an open loop (OL).
The purpose of the bridge diode appears to be to supply the switch with DC current to actuate the relays, no 60 Hz hum.
Any ideas? Do I have a bad bridge diode? Should I burn the coach down?
Tim
Don't burn the coach down.
I have very little experience with these. Many have had corroded or burned contacts and have had some luck filing or sandpapering them clean and trying again. It may be that the prudent way to deal with this is to replace it. I can't fine MagnaTek ATS100 anywhere or a user manual. This may not be what came in your coach although there are several references to it in a search.
This one has 12 v coils
Amazon.com: Progressive Dynamics PD52DCSV Surge Protected Transfer: Automotive (https://amazon.com/Progressive-Dynamics-PD52DCSV-Transfer-Protected/dp/B0136U0QU4/ref=sr_1_19?crid=16A621WBJ4DWC&dchild=1&keywords=automatic+transfer+switch+50+amp&qid=1592853736&sprefix=automatic+transfer+switch%2Caps%2C260&sr=8-19)
See Lessons learned RE Transfer swith (https://www.foreforums.com/index.php?topic=1071.msg3346#msg3346)
50 AMP TRANSFER SWITCH LPT50CA replaced by the LPT50BRD
50 AMP TRANSFER SWITCH LPT50CA replaced by the LPT50BRD (https://dan-marcrvparts.com/product/50-amp-transfer-switch-lpt50ca-replaced-by-the-lpt50brd/)
Amazon.com: Esco LPT50BRD Generator 50A 120/240V Relay Base Automatic... (https://www.amazon.com/Esco-LPT50BRD-Generator-Automatic-Transfer/dp/B008VF91ME/ref=sr_1_4?dchild=1&keywords=LPT50BRD&qid=1592854458&sr=8-4)
Amazon.com: Elkhart (LPT50BRD 50 Amp Automatic Transfer Switch: Automotive (https://www.amazon.com/Elkhart-LPT50BRD-Automatic-Transfer-Switch/dp/B007HS0ONG/ref=sr_1_1?dchild=1&keywords=LPT50BRD&qid=1592854342&sr=8-1)
This is recent post from John Morales that recently replaced his ATS with the same one I did 3 years ago, a Progressive Dynamics PD52. It is of similar size, a quiet quality unit. I have no regrets using it. He and I both installed the PD52 units ourselves.
Transfer switch Question (https://www.foreforums.com/index.php?topic=39610.0)
This is what we both used. He bought two.
Amazon.com: Progressive Dynamics PD52V 5200 Series Automatic Transfer Switch... (https://www.amazon.com/dp/B003VAWNVK/ref=cm_sw_r_em_apa_i_ZYq8EbNJF9583)
They do make a DC coil version, that Roger gave a link to above, that is little bit bigger, it is designed to be quieter, and is more expensive. I am having no issue with noise on my new unit, the PD52.
Amazon.com: Progressive Dynamics PD52DCSV Surge Protected Transfer: Automotive (https://www.amazon.com/dp/B0136U0QU4/ref=cm_sw_r_em_apa_i_89q8EbCQ7FR22)