Alternator continues to fail after new installs

[Max]

Have you been running DC/AC inverters, a winch, huge music amps or had repeated jump starts?

[aquanaut20]

Anyone who diagnosed a burned diode without first dis-assembling the alternator has his head up his ass.

Each diode MUST be disconnected to test. Philip

[rmjindls12]

Originally Posted by Max

Have you been running DC/AC inverters, a winch, huge music amps or had repeated jump starts?

none of the above.

Originally Posted by aquanaut20

Anyone who diagnosed a burned diode without first dis-assembling the alternator has his head up his ass.

Each diode MUST be disconnected to test. Philip

wow, harsh. I don't think I said anyone diagnosed a burned diode. I did mention that AZ put the car on their tester and it showed a bad diode. Now they may be the same, but I'm not a mechanic and I thought the tester AZ uses was supposed to be accurate. But I do understand what you are saying, never the less.

[aquanaut20]

Automotive alternators are generally 3 phase A/C, using diodes to clip the A/C to 1/2 wave. This requires 6 diodes 3 each of + collector and 3 of negative. Each of these banks are assembled in parallel and in series with the stator coils. So if one diode goes open it is not discovered unless dismantled, if on the other hand a diode shorts the whole bank will show the short.... again to test it must be dismantled.... Philip

[rmjindls12]

Originally Posted by aquanaut20

Automotive alternators are generally 3 phase A/C, using diodes to clip the A/C to 1/2 wave. This requires 6 diodes 3 each of + collector and 3 of negative. Each of these banks are assembled in parallel and in series with the stator coils. So if one diode goes open it is not discovered unless dismantled, if on the other hand a diode shorts the whole bank will show the short.... again to test it must be dismantled.... Philip

The jpg was very helpful. I will hold onto it as well as all the replies and find an auto electrician. Hopefully I can get this thing resolved and I don't have to look for a different auto.

[fordem]

Phil - have you ever scoped the alternator output? In theory at least, an open diode should result in increased ripple on the output, I'd like to think it would be visible if scoped with a suitable load.

Having said that - I have no idea what the AutoZone tester is capable of.

[aquanaut20]

Originally Posted by fordem

Phil - have you ever scoped the alternator output? In theory at least, an open diode should result in increased ripple on the output, I'd like to think it would be visible if scoped with a suitable load.

Having said that - I have no idea what the AutoZone tester is capable of.

I have a MIL spec scope ($10,000) that does detect the ripple, but I also have a retail spec scope that does not. My guess is that the autostore would not have a MIL scope and the employees would not be trained in its use......
I have seen some of the equipment they use, a computerized Volt meter(2x5amp clams, direct to power source) that used a logics table to calculate load..Yes light/good, no light/bad.....Philip

[drowan]

Did you find an answer jm? I am in the midst of removing my fourth alternator in 8-9 months. 2001 GV 2.5. 1st was rebuilt by a local independent, second was reconditioned from AZ, 3rd was it's warranty replacement.