| Author | Message | ||
| david anderson (Davidanderson)
Rating: N/A |
I'm working on a wiring project for the bus and needed two standard SPDT relays. I hooked it all together as per my designed wiring diagram. Poof the fuse blew and both relays are toast. Hmmm, I went back to the auto parts store and they were out so I went to an Autozone and bought 2 more relays. This time I pulled a bosch relay out of one of the bus wiring sockets and stuck the new one in it. Poof it heated up and died. Now, I'm pissed. I took the 2nd one and got my alligator clips and hooked 12v + to terminal 85 and 12v- to terminal 86. Poof, it melted my little alligator clip and died. I took these two back and got my money back. They didn't have any more. I went back to the original store and attempted to buy 2 more, as he had gotten 3 in his morning order. We tried all 3 and Poof they sparked and melted the alligator clip wiring. (I took in my Bosch and it worked fine on his battery) Now, I went to NAPA and the guy pulls out an identical chinese relay from the 1st two stores. This time I said, "I'm not buying this unless you test it. We hooked 2 alligator clips on it, one to #85 and one to #86 and to a 12 volt battery. Poof, it melted the alligator clip. I said, "no thanks" The guy put it back on the shelf. I gave up on all this baloney and scavenged two bosch relays off some unused circuits in the bus. I wired it all back together as per my original drawings and my project worked like a charm. So, I ordered 4 bosch relays from Wrico to finish the 2nd half of the project. Sometimes, the chinese screw things up. FYI, I am hooking up linear actuators for my double beds to slide them together, so my wife and I can snuggle when in the coach. Bed #1 works like a charm. When I get the relays, bed #2 will be hooked up. David Anderson | ||
| John MC9 Rating: N/A |
"I am hooking up linear actuators for my double beds to slide them together, so my wife and I can snuggle when in the coach. Bed #1 works like a charm. When I get the relays, bed #2 will be hooked up." So, just runnin' things by hand in the meantime? | ||
| David Hartley (Drdave)
Rating: N/A |
The mexican ones are better. Tyco brand The only other thing could have been that there were blocking diodes across the relay coils. If you hooked them up backwards "POOF" and a short. Did you check them with a DVM in diode mode before apply the power? The Bosch and Tyco don't have the diodes. Relays used in the newer computer controlled systems many times "DO" have blocking diodes to prevent damage to transistor output circuits. Once you let the smoke out it's real hard to get it back in.... | ||
| david anderson (Davidanderson)
Rating: N/A |
David, I plugged them into my docking light relay socket. 85 is +. 86 is -. All my OEM relay sockets on my Eagle are that way. If those relays had diodes in them, and each one's number 86 was + and 85 was -, then yes they could have been hooked up backwards, but who is to know? The wiring diagram on the chinese relays had the exact same symbols as my Bosch relays. I don't care now. The Bosch relays are on the way. David Anderson | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
David, do you still have one of the bad relays? I would like to disassemble it and determine why it went poof. That's a rare thing, and I'd sure like to know the reason. If you want to send me one, click my profile and email me, I'll give you my address.. gary | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Ok David, here's the scoop !! I got the two relays in the mail today from you and immediately started sleuthng... Basically it wasn't you.... Both relays have diodes installed across their coils to eliminate inductive kick...BOTH relays diodes were put in there BACKWARDS !! That said, I'm not absolutely sure that there is really a "standard" although this schematic from Bosch seems to agree with the way everyone hooks their relays up...except the Chinese I guess...  To compare, I took some Freightliner relays apart and instead of diodes, they have resistors across the coils. Also, in searching the internet, there appears to be a lot of relays with nothing at all across the coils. So there does not appear to be a true "standard" with the diodes, resistors, etc, but for the most part everyone pretty much seems to specify that 85 be hooked to (+) and 86 be hooked to (-) regardless what is inside. You were doing ok David, and simply got screwed by the import relays not adhering to the "normal" way of doing things. Other than that, both relays had respectably made guts and would have worked fine had the polarity been checked out first. So here's what happened to you David... (1) you hooked the relay up properly (2) you powered it up and since it's diode was backwards, it immediately shorted the diode out, meaning that now hooking it up either way would blow circuits because the relay is shorted in both directions (due to the shorted diode) So my advise to everyone would be to simply check first with an ohm-meter to figure out which way the diodes are (if they are in there at all), then hook it up accordingly. It never ends does it !!  | ||
| david anderson (Davidanderson)
Rating: N/A |
Thanks Gary, Too bad the relays I returned for refunds, the clerks just put them back on the self. BTW, the relays I got from Wrico specified "diode" and 85+ and 86-. David Anderson | ||
| David Hartley (Drdave)
Rating: N/A |
Ahh... Now for the fun part.. Some relays don't have diodes, They have MOV's which are non-polarized !  | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Hmmm Mr. hartley... ya got me.. I was looking at the Freightliner one(s) I took apart and it looked like 1/2 watt resistors in there, color codes and all, which didn't make a lot of sense at the time. My thoughts went "well, kinda lame, a resistor is better than nothing but not my component of choice"... I wasn't thinking MOV! (which would make a lot of sense) Now I'm gonna take one apart again and check it out just to make sure. I wasn't aware of MOV's manufactured to look just like an axial carbon film resistor... I learn every day..!!! | ||
| David Hartley (Drdave)
Rating: N/A |
Diodes short. Resistors Bleed. MOV's clamp ( Metal Oxide Varistors ) Been around this stuff for over 40 years and I am still amazed at what I learn sometimes. It's like trying to protect a transistor with a fast acting fuse. The transistor is "faster!" The impossible we do immediately, The difficult takes a little longer. |