m923a2 PCB testing per TM opinions much appreciated

[ghettoct]

first i wanted to say thanks to CPDOG and 74M35A2 for their help on alternator problems and CPDOG for pointing me in the direction of the PCB.

i have had an issue with intermittent overcharging from alternator, took to a reputable alternator shop here that does trucks and industrial equipment and they found my 60 amp greek alternator's regulator to be bad. they serviced the alternator, and changed out the regulator with one they had in stock. benched tested it and it was good. brought home put on truck idled for a while shut off then took truck out for spin. ABS light came on and i noticed the voltage was overcharging all the time vs the last time the old one was intermittent, took home and called shop and they said to bring in. i have since gone through truck checking grounds and for abrasions etc.

brought back alternator and they benched tested it and it was wide open and would have to order a new regulator. they called back a few days later that it was ready, picked it up and they said they put a new regulator on it, checked the windings etc and benched tested it under load for 30 mins and it didn't fry out. brought back put in truck and after talking to CPDOG whom had similar issues of over charging he said to test the PCB, which i got to do today:

here are the results of TM9-2320-272-23-1 page 0100 PCB assembly test. using DVM (batteries are disconnected, battery and ignition switch in off position)

PCB is NSN 6110-01-144-8674 on label on it but original box it was in was labeled 2929-01-144-8674

step1:ground

red dvm to PCB pin E, black dvm ground (should be less than 200 ohms)

dvm 200 setting i get 52.9 ohms. under 200 pass

step2: no continuity PCB Pins B and D

red dvm to PCB pin B, black to PCB pin D (should be less than 200 ohms)

dvm 200 setting i get: no dvm change, no continuity pass

step3: no continuity PCB Pins C and D

red dvm to PCB pin C, black to PCB pin D (should be less than 200 ohms)

dvm 200 setting i get: no dvm change, no continuity pass

step4: no continuity PCB Pins A and ground (FAILED??)

red dvm to PCB pin A, black to ground (should be less than 1000 ohms)

dvm 2K setting i get: .052 ohms (CONTINUITY, fail?? )

step 5: no continuity PCB Pins B and ground

red dvm to PCB pin B, black to ground (should be greater than 10,000 ohms)

dvm 20K setting i get:no dvm change, no continuity pass

step6: no continuity PCB Pins C and ground

red dvm to PCB pin C, black ground (should be greater than 10,000 ohms)

dvm 20K setting i get: no dvm change, no continuity pass

step7: no continuity PCB Pins D and ground

red dvm to PCB pin D, black to ground (should be about 1000 ohms)

dvm 2K setting i get: no dvm change, no continuity pass

i didn't proceed the rest of testing because my batteries were disconnected.

can someone look over the info and verify if sam correct in my findings? i assume that test 4 failed and need new PCB?

i assume that test 4 failed because it showed continuity? i turn wrenches and not that smart with meters and such. my dvm had only selections of 200, 2K, 20K, 200K, and 2M ohms. so i selected the 2K ohms (Tm stated that reading should be about 1000 ohms) and measured and got .052. which i assume represents continuity. so i am totally confused. help. lol

i found a drawing here on searching and it shows a PCB circuit board and the relationship of Pin A is from battery switch #459. and since i had problems with alternator overcharging (replaced and checked out regulator at shop) would this test failure if a failure wold cause alternator problems.

in the same drawing PCB Pin F goes to the alternator (i assume a sensing wire to alternator? ) the TM test above did not even test Pin F. so in a nut shell am i over thinking this?? i am confused as a blond in store with mirrors.

any help is appreciated.


ps the previous owner had changed this out about 3 years ago with a new in box PCB, when he picked up the truck at auction, someone had swapped the PCB (his truck started and ran with PCB that wouldn't start and run) he had someone at avionics shop look at it and repaired it, i tested it as the one in question and it passed all the steps. its an open box and can see all the guts but Pin F is not connected to anything inside nor is Pin G ) it has these numbers stamped on the box "19207-12450333 mfr 51319" isn't Pin F in relations to alternator? sam not even sure if this PCB will work on the 923a2? again thanks. james

 

[73m819]

Just remember that a 939 pcb WILL work on a 809 series, a 809 series pcb WILL NOT work on a 939 series,, If I had pcb problems I would just get rid of it, its main purpose is to keep a young driver from starting the truck in gear and if it is already running. replace it with a high amp solenoid to turn things on (39 series had this), the starter straight from the start switch, also the fuel solenoid straight from the start switch. A LOT LESS HASSLE and a lot easier to trouble shoot.