Model 500 Restore.....

[jstang]

Ok used a voltage drop test on my DMM. .97 for the MZ2361 and 1.08 for 2x1n4148s.

But keep in mind the 500 uses two of them back to back in one of the circuit.

So that is 1.94 vs 2.16.... .2v ..... Hmmm I doubt that is the issue.

I would like to resolve this, as semi's get noisier with age....

Jk

 

[Imike16]

Hi John,
I made a probe test ring my Model 500 output transistors beta 55/70 (I have just these transistors) Mz2361 2x4148, Sz51066k 3x4148, I looked good heat connention. I started and after 5 sec 1 pair transistor wrong. Take care for your Marantz 500 because this is good.

Thanks a lot,

Imi

 

[jstang]

To love the 500, you have to love electrical and mechanical challenges.....

 

[Imike16]

I hope in the future my Marantz will be good, too. :yes:

 

[Imike16]

To love the 500, you have to love electrical and mechanical challenges.....

Yes, Sir... :thmbsp:

 

[Imike16]

Ok... Yesterday I swapped out my MZ 2361s with the 2x1n4148 on one amp board and then spent an hour trouble shooting a blown rail fuse.

I was not in the mood to trouble shoot to see what caused the blown fuse with the 2x1n4148s in the circuit. Not realizing the fuse blew, I spent a hour lifting leads to try to understand why the 18v was not working. Then after track it down to the blown rail fuse, I normalized everything and put the MZs back in. Everything was fine. I was more interested in testing some different feedback cap combos. I swapped every other semi using my curve tracer characterization, first issue I have had with this amp's semi conductors and never blew a rail fuse with this process before. Need to look more closely at what is going on here.

May be the 2x1n4148 is a good replacement for 500's MZ2361s.... Maybe not.... Maybe I did some thing wrong installing the 2x1n4148s... Maybe not....

I usually double & triple check things and inspect closely my soldering, there were no issues... The fuse blew a little after power up and while I was checking voltages. I did not short anything with probing....

So I am thinking its back to drawing board on using 2x 1n4148s on the 500's amp boards.

Mike are you still blowing rail fuses?

Hi John,

I hope for your amp has not been serious trouble. I try to obtain MZ2361 diode.

Best regards,
Imi.

 

[USMC Spike]

Hi John,

You had issues with the 1n4148s * X quantity,
possibly causing trouble in your 500 above.

Did you resolve the issue?
What was the route cause?
What was the fix?

Thanks,

Spike

PS I sent you a PM in case you didn't see this thread.