Hi; One way I have been able to detect a bad diode is using a digital volt ohm meter. With the car running set meter to AC volts attach 1 lead to output on alternator and other to ground, if you have a reading that means you have a bad diode or diodes. Remember an alternator without diodes produces AC current the diodes change it to DC current. Mel. Stoltzman From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of John Grady jkg@xxxxxxxxxxxxxxxxx [Chrysler300]
Sent: Saturday, June 13, 2015 4:15 PM
To: RICK AND DEBBIE CLAPHAM
Cc: Don Verity; chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] Voltage regulating It is not so easy to find an open diode without an oscilloscope . ( EE hat on) --which someone noted and that is correct . ( DC waveform is assymetric) Now: which of the 6 or 9 diodes is it ? And It will still work on car , almost ok , with one out . (open) But some good bad / tester would sell a lot of "rebuilt" regulators and alternators. Both , in two rounds. After three or four you might get a good one . You can just change all the stuff without a tester. Maybe how it is in 2015 . When you rebuild alternators , it is part of that to change diodes or test them one by one . Wires are off them then. How is elsewhere . I have gotten into rebuilts that did not work . Especially starters .. Loose screws , incorrect assembly , you name it . Little faith in that now .. All done in far east . And you can do it . A tester can tell you charging not working right (we know that) and spot totally bad vr or alternator. Despite that magic , we all STILL have a widespread problem with wavering charge , to some degree or other . And for a reason . Our vr and alternator are usually good .. And swapping does not fix it always.
Mileage on this really does vary. My .02 , most mopar alternator issues are the brush is stuck in the slide or usually just worn out. Storage plays a role . And in attempting to remove the corroded brush screw the casting breaks easily .. Leading to lots of ingenuity --and new words .
On Jun 13, 2015, at 11:50 AM, RICK AND DEBBIE CLAPHAM <rixpac@xxxxxxx> wrote: FYI diodes and stators can be tested while engine is running. Sun equipment had test equipment 40+ years ago. I am sure most parts stores today have hand held devices and can test you whole charging, cranking, regulator and battery in the parking lot.
CC: Chrysler300@xxxxxxxxxxxxxxx
To: d.verity@xxxxxxx
From: Chrysler300-noreply@xxxxxxxxxxxxxxx
Date: Fri, 12 Jun 2015 22:09:38 -0400
Subject: Re: [Chrysler300] Voltage regulating
Hi Don .. On I phone now .. Longer response later . I just want to point out that when charging increases ( in amps ) the voltage at the ign terminal of VR rises .. And the VR then cuts back . How much it cuts is a parameter G ( gain) and a time delay ( how fast ). ( complicated and for later ) . But anything that lets that voltage right there rise more than normal per amp of charge will cause cycling . That means bulkhead connectors ( replace with #10 solid wire on cars trucks with them --endemic problem 70's dodge trucks--wire burns at poor contact flag terminal ) and block to frame ground jumper is critical . I have used in adition two wire (-) cables , grounding battery (-) to body at radiator . Also a battery with high internal resistance (old) adds to this . It is somewhat normal . Design of regulator , especially time constant , any added loads on ignition terminal etc . I have had miswiring of ballast resistor where vr is fed off wrong end (lower v = excessive charge!) and had swapped wires on new ign switch ( ign s and s, 67 dart ) cause problems . Many cars have been messed with . A more powerful ( thicker core ? ) alternator will output more amps for same field v . That can screw up G factor . Cause overshoots in Vand cycling as it ( correctly) cuts back as V goes up too fast . Understanding how it works is step one ? A simple thing like poor battery post connections can cause this . Adding loads ( headlights ) damps the rise in V .. it may calm down . Your suggestion about a scope for checking electrical output is a good one. I have an old Bear scope (the big as a small car kind) that I picked up years ago. Unfortunately it takes up to much room in my garage and has been moved to the “tent” for years now. Diodes can be checked while the alternator is out, and should have been done on the dealer replacement. Dealer rebuilt parts are not always reliable though. I had the flickering gage thing at times on my G. It had an electronic regulator on it too. The problem I found with it was that the field terminal on the regulator was only fastened by one rivet, and would get loose over time. Moving it around some stopped the swinging needle. Connections that appear to be tight may not be good conductors either. Over time they oxidize and don’t work as well. Sometimes it just takes removing the wire and plugging it back in to fix. Other times the connector must be replaced. The firewall plugs are the worst for this. Sent: Thursday, June 11, 2015 9:59 PM Subject: [Chrysler300] Voltage regulating I have read with great interest the various e-mails on the above subject. This has been discussed years previously, without successfully resolving the issue, I think. I have a 300-K on hand, plus a 1968 New Yorker. Previously had another 300-K. Only the latter did not “blink” its headlights as it went down the highway! Naturally the pulsing ammeter accompanied the blinking. The one that did not blink/pulse had a mechanical voltage regulator (I believe original Chrysler manufacture!). The other two now have the electronic version (IF I remember correctly these were available through our club member who is now gone) which helps but does not eliminate the issue. Both only pulse the ammeter when the headlights are “on”. High beams make the situation worse on the 1964, but tend to smooth out the blinking/pulsing on the 1968. Both have had a special ground wire run from the voltage regulator case to the bulk head ground where the ground wire from the engine goes to the chassis. NO improvement. Now of the two, I have had the 1968 since my Granddad died and left it for me in 1971. For MANY years it was OK. Then the ammeter failed and I replaced it (another story about a parts man who felt nothing could fail in the ammeter). Still no issue with pulsing until the ALTERNATOR was replaced (Chrysler Corp rebuilt unit, not a bargain parts store piece)! Once that happened, I had the pulsing at the ammeter under most driving conditions. The electronic voltage regulator tended to reduce that except when I am driving with low beams on. I went through quite a few mechanical and one other electronic voltage regulators trying to “fix” the problem. I am not an electronics engineer. I DO have an opinion! I am of the opinion the three diodes are not fully functioning correctly on the alternator and a less than smooth current is produced (three phased currents to look like a smooth 13 volt current or there abouts). I do not know anyone that has the ability/equipment/knowledge to check this. I should think a good EE with an oscilloscope could do so. By no means is it unique. My friend, Galen Wollbrink, has it with his several old Chryslers. Almost looks like these pulsing headlights on motorcycles these days. Anyone with a good solution would surely be welcome to solve this issue! Most of what I read and what I have tried only address accomodating and lessening the issue, not really fixing it. Thank you for hearing yet another “opinion”!
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Posted by: "Melvin Stoltzman" <mlstoltzman@xxxxxxxxxxx>
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