Bridgestone Motorcycle Parts Discussion Board

Bridgestone Tech Talk => 175 & 200 Talk => Topic started by: steelr86 on May 08, 2013, 03:41:31 PM

Title: rectifier
Post by: steelr86 on May 08, 2013, 03:41:31 PM

Hi All, I'm trying to get my Dt175 running for the first time. So far I have changed out just about everything! Battery, switch, coils.... So here's the question, when I turn the switch on after a second or two the rectifier starts smoking. I don't know if it is dirt, or the fact that the previous owner painted it or if there is something wrong with the wiring? Any help is appreciated

Title: Re: rectifier
Post by: Colin on May 08, 2013, 04:40:53 PM

Check all the wiring especially earths, test the battery voltage it should be in the region of 12.4, use the same meter to test the rectifier output, if its up about 17 volts or similar then it's needing replaced, they do go bad.
I had one go on a Suzuki, started smoking one day, it killed the battery too so don't go switching it on when you don't have too.
It may be the paint because rectifiers do generate heat, try cleaning it off if possible before you do anything else.
Colin.

Title: Re: rectifier
Post by: OldSwartout on May 10, 2013, 08:12:24 AM

If it smokes when you turn the key on, before it is running, it is either shorted out or the polarity is backwards. If it is shorted out, it can't be repaired.

Here's the test to see if it is good:

BS 175/350 rectifier testing:

A digital multimeter doesn't work well to check those old
selenium rectifiers as the meters don't provide enough current to
distiguish well between good and bad junctions. You need an old analog
meter or a battery and test light. To fully check the rectifier(with
all wires disconnected)using a battery and test light:

1. Connect battery Negative to rectifier Black: test light connected
to battery Positive should NOT light when touched to each of the
other four terminals.

2. Connect battery Negative to rectifier Red: test light connected to
battery Positive should light when touched to each of the other four
terminals.

3. Connect battery Positive to rectifier Black: test light connected
to battery Negative should light when touched to each of the other
four terminals.

4. Connect battery Positive to rectifier Red: test light connected to
battery Negative should NOT light when touched to each of the other
four terminals.

Title: Re: rectifier
Post by: duckman86 on May 10, 2013, 11:37:41 AM

Going to print this out! Awesome info.

Title: Re: rectifier
Post by: CL-100 on May 10, 2013, 04:55:06 PM

Ken S.

Thanks for taking the time to write out how to test the rectifiers.  Step by step directions are very helpful and gives me some insight on how/why the rectifier works.  Great info that I've printed and will add to my BS service docs. 

Title: Re: rectifier
Post by: Colin on May 10, 2013, 05:55:54 PM

Great answer old, I usually just junk them and put a new one on.

Title: Re: rectifier
Post by: OldSwartout on May 11, 2013, 01:25:41 PM

Quote from: Colin on May 10, 2013, 05:55:54 PM

Great answer old, I usually just junk them and put a new one on.

Me too, but I don't' know how many new ones are left.  I even went thru several used old ones that I thought were still good the last time I needed one, but found out unheated storage in the barn didn't keep them from getting corrosion in the junctions between plates and only found one good one.  A guy can always make a replacement from Radio Shack parts. It takes 3 pair of diodes, since there are 3 windings in the alternator.

I think something like this is the answer when new parts are gone, but haven't actually tried one (3 phase bridge rectifier):

http://www.amazon.com/Amico-1000V-Phase-Bridge-Rectifier/dp/B00A74HHT6/ref=sr_1_1?m=A1THAZDOWP300U&s=merchant-items&ie=UTF8&qid=1368292601&sr=1-1&keywords=Amico+SQL+100A+Amp+1000V+3+Phase+Diode (http://www.amazon.com/Amico-1000V-Phase-Bridge-Rectifier/dp/B00A74HHT6/ref=sr_1_1?m=A1THAZDOWP300U&s=merchant-items&ie=UTF8&qid=1368292601&sr=1-1&keywords=Amico+SQL+100A+Amp+1000V+3+Phase+Diode)

Title: Re: rectifier
Post by: disc_valve on May 13, 2013, 06:17:20 AM

I've been running my 175 and 350 Bridgestones with a Radio Shack solid state rectifier pack for around 30 years now with no problems. They don't look original, but they are hidden away on the twins so nobody is going to see 'em.

In my case, I used two single phase rectifier packs, wired together with short jump wires to create a 3-phase bridge rectifier (simple enough to work out the connections for those with some knowledge of high school physics), but the 3-phase pack shown would be electrically the same, just all contained in one box.

Unless you're a stickler for originallity, I'd go for the modern "potted" unit every time.

Graham
 

Title: Re: rectifier
Post by: Steve S. on May 13, 2013, 03:13:36 PM

Here's one I made up using the Radio Shack parts.(http://i559.photobucket.com/albums/ss38/batcarman/rectifier1.jpg) (http://s559.photobucket.com/user/batcarman/media/rectifier1.jpg.html)(http://i559.photobucket.com/albums/ss38/batcarman/rectifier2.jpg) (http://s559.photobucket.com/user/batcarman/media/rectifier2.jpg.html)(http://i559.photobucket.com/albums/ss38/batcarman/rectifier3.jpg) (http://s559.photobucket.com/user/batcarman/media/rectifier3.jpg.html)