Anyone have information on this (rectifier)

[richard5933]

This is listed as "in-line diode rectifier assembly", which connects through a 6-amp line fuse to terminal #14, which has something to do with the headlights/dimmer.

The part is burned out and the 6-amp fuse is blown. Headlights still function.

Anyone know specifically what this is? Maybe someone can help me figure out the value of the part?

Luke has nothing on this. Only marking on the outer vinyl cover is 'Jayco 101'

[sledhead]

it is probably for the dash lights so you can dim them if you want

dave

[Gerry H]

Richard: Take the cover off from it and see if you can read any numbers on it so it can be identified. Gerry H

[richard5933]

So now I've gone and voided my warranty by cutting it open.. M

This was inside a cardboard tube inside the vinyl cover.

Still no markings.

[buswarrior]

Back to the religious writings?

Where is it in the schematic?

Happy coaching!
Buswarrior

[richard5933]

Back to the religious writings?

Where is it in the schematic?

Happy coaching!
Buswarrior

I've looked at all the various pages in the wiring diagram book that discuss this, and none of them seem to give a clear picture of what it does. I'll try and summarize the various possibilities tomorrow when I'm more clear-headed. It is listed in the parts book as: RECTIFIER-Head lamp low beam. Since my low beam lights work even with this burned out, I'm not really sure how the name of the part fits.

The wiring diagrams for this coach include three variations: Standard, RPO, and SEO. The last two are for various option packages which were available from the factory. I know that I have equipment beyond the Standard, but neither of the other two options seem to fit for all the various systems. Since our coach was ordered directly from GMC by a charter bus company specifically to be converted by Custom Coach, and because I know of at least a few non-standard options that were ordered, I'm wondering if our coach doesn't fit any of the wiring diagrams directly.

Keep in mind that in all this I'm speaking specifically about the bus portion of the vehicle, which is still largely intact and not altered from how it left the factory. Custom Coach did a good job of keeping their wiring separate and distinct from what came with the bus. They also included a separate book of wiring diagrams for the house systems (which I'm updating as I make changes.)

[Geoff]

That looks like a diode.  A rectifier works off a magnetic coil and turns AC volts into DC volts, and if the rectifier is also a regulator, it keeps the battery from overcharging.  The diode is there so you don't get voltage feedback.

I have no idea how this information fits into your headlights.

[Dave5Cs]

Like an Electrical check valve.

[richard5933]

Electrical check valve almost makes sense. I'm not positive, but it looks like one end of this rectifier/diode goes to the same terminal where the electric speedometer gets its signal from the bus alternator. Could be there to prevent a feedback loop and a false speed reading.

Let's try that again...

I just re-read the manual section which talks about the speedometer. "A permanent magnet AC generator (sending unit) is mounted on the transmission...Generator supplies a signal...This signal is rectified to direct current (DC), smoothed and fed to meter movement of speedometer..."

Maybe this piece being blown would explain why my speedometer is inaccurate. The faster I go the more inaccurate it is.

Two questions now...
1) Why did this blow in the first place, and
2) What was the size/value of the part?

I'd like to replace it but the specific one I need is not available. My bus needs a part with the two pigtail leads as shown in the photo. Luke says it's no longer available. If I had the specs on the part it's likely I could get something to do the job. The other option is that the equivalent part for the 4905 is available (possibly), but the 4905 uses screw posts for its terminals and not the push-on connectors like the 4108a. The part for the 4905 could most likely be adapted to work physically, but I still won't know if the electrical specs are the same.

Any thoughts or suggestions? So far you all have helped me screw my head on and find some good information. Now that I'm this close I'd like to figure out the rest.

[chessie4905]

If its a diode, check it with a vometer. should show continuity one direction and no continuity in the other direction. If it is truly bad, try getting a generic diode with a good reverse current rating. They are cheap. show your pictures to an old tv repairman that worked on the old tube type tvs. He can help.

[Iceni John]

If its a diode, check it with a vometer. should show continuity one direction and no continuity in the other direction. If it is truly bad, try getting a generic diode with a good reverse current rating. They are cheap. show your pictures to an old tv repairman that worked on the old tube type tvs. He can help.

Otherwise, do you have a real electronics store nearby?   (No, not a Radio Shack!)   The folk there should know what your mystery widget is.   However, one single diode won't make smooth DC from AC  -  it will make chopped-up intermittent DC, probably not what a speedometer needs.   If you know the make and model of your speedometer, is there still anything online about it?   Or just buy a new speedometer  -  I'm gradually replacing some of my original Teleflex gauges with new Speedhut ones that are much better.

John

[richard5933]

No point checking this one. The burn mark indicates it got pretty darn hot. I've got one coming from Luke, although it's the one intended for the 4905 and not the 4108. I'll do what I can to adapt it to the push-on connectors.

Surprisingly, the speedo works. Not terribly accurate once above 45 mph, but it works. If this doesn't make any difference, I'll probably just go with the Speed Hut GPS speedo like I did on the 4106. Not an urgent need since I have the Garmin in front of me, but eventually I'd like to have the speedo be more accurate. I just called Speed Hut, and apparently it's possible to order one with the odometer set to the reading on the speedo being replaced, so that the new speedo will show actual miles. Since ours only has 41,000 actual miles I kind of want to keep that.

[Gerry H]

Richard: That's a big diode. band denotes cathode - if there are no markings, I would expect a 1Nxxxx number somewhere on it. If not, reverse logic, 6 amp fuse is suppose to protect it, so it should be more than 6 amps with some headroom. Fuse should blow before the diode to protect it. Possible it's a zener (voltage regulator) type. More info needed. Do you know what voltage feeds it? AC or DC 12V or 24? Whatever still works is probably not a part of the diode circuit. Something is gonna be dead because of it. Gerry H

[richard5933]

Richard: That's a big diode. band denotes cathode - if there are no markings, I would expect a 1Nxxxx number somewhere on it. If not, reverse logic, 6 amp fuse is suppose to protect it, so it should be more than 6 amps with some headroom. Fuse should blow before the diode to protect it. Possible it's a zener (voltage regulator) type. More info needed. Do you know what voltage feeds it? AC or DC 12V or 24? Whatever still works is probably not a part of the diode circuit. Something is gonna be dead because of it. Gerry H

Wish I had answers to your questions - it would make this much easier.

Best I can tell, the part has something to do with the AC signal coming from the signal generator mounted on the transmission. If this is the case, the signal is headed to the speedo. Speedo still works, so I'm not exactly sure what the purpose was. Guess is that it has something to do with the following found in the manual, "...This signal is rectified to direct current (DC), smoothed and fed to meter movement of speedometer..." Maybe the lack of this part is why my speedo is not accurate.

It and the fuse were dead. Not sure the exact voltage of the signal coming through. I'd have to rig up a multimeter to work while driving to try and get a read on the signal since it won't generate until the transmission is in motion. I doubt that the voltage is all that high.

I've got one coming to me from Luke that shows a similar purpose, even though the part number and mounting style are not the same. I'm hoping that I can make it work. I'm not really stressed over this, but the mystery does confound me.

[buswarrior]

Back to the religious scribings?

Headlights, speedometer...

Third time's the charm?

Happy coaching?
Buswarior