开云体育

Calling Tektronix repair experts. I have a TDS340A where the ZYTEC 2291739 Power Supply literally blew/burnt like 5 component beyond recognition. A little hard work looking at a lots of post and pictures I manage to find all values except for one ZENER DIODE - VR9.

Does anyone have an idea of what voltage this should be? (I assume due to the VR that it is a Zener diode).

added some pictures for the VR9 ZENER diode that I can't find value on as blown and no schematics.





My guess could be 6.2V or 20V? likely a 1N5243B/1N52343 based on a LeCroy schematic for a "similar" PS but not same. Any ideas?

Thank you.

On Sun, Jan 26, 2025 at 10:14 AM, Mr Lurpak's Electronics Rescue wrote:

Does anyone have an idea of what voltage this should be?

With one end removed from the board and checked on a 576 curve tracer it has zener voltage of 17.4V

/H?kan

On Wed, Jan 29, 2025 at 09:12 AM, Mr Lurpak's Electronics Rescue wrote:

added some pictures

I noticed on your picture that the large ceramic resistor has burned the board.
This is/was a common problem on these supplies. It was due to too high voltage
across the resistor when in standby mode. Most of the times the supply could be
fixed and other times the board was too damaged so the supply had to be replaced.
It is best to avoid having these scopes om standby for longer periods of time.

This document might be of help on further trouble shooting:


/H?kan

Thanks that is very good information. My guess would have been in the 20V but this is better. Thanks a lot.

Yes, it is exactly what happened. The resistor burned, the big capacitor also destroyed and the BUZ355 cracked along with a few other components like the VR9. I did read about not having it in standby mode and some work around. But for now fixing it to see if it actually works is step 1. So your help is very much appreciated, and downloaded the PDF - looks like a good read.

Cheers.