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Electronics => Repair => Topic started by: lihach on December 28, 2017, 08:20:27 am

Title: power unit repair TEKTRONIX TDS 460A
Post by: lihach on December 28, 2017, 08:20:27 am

During operation, there was a short circuit in the power board (119-3939-01)
At the same time, some of the elements burned, which I had already made. Help determine the value of the burned resistor P-25. Maybe someone will take a photo of the site. The gratitude is grateful.

Title: Re: power unit repair TEKTRONIX TDS 460A
Post by: shakalnokturn on December 28, 2017, 11:23:16 am

I followed your topic on the Tek group too. I do not have the same model PSU, but a lot of Power Systems Inc. PSUs are very similar.
Any way you could take clearer photos, including copper side?
I think your R25 is linked on one side to the large ceramic resistor (0.22ohm?) and switching transistor emitter, other side to optocoupler and green module pin8. Can you confirm?
Check large ceramic resistor between primary ground and switching transistor emitter is not open, if it did open check for burn marks near pin8 on green module.

Title: Re: power unit repair TEKTRONIX TDS 460A
Post by: lihach on December 28, 2017, 01:55:01 pm

I think the green module is working. After the resistor 25 burns, the oscilloscope is fully operational before being turned off by the button. Burned R-25 and controlled zener VR-3
Need photo R-25

Title: Re: power unit repair TEKTRONIX TDS 460A
Post by: lihach on December 29, 2017, 09:05:13 am

I CAN DRAW THE DIAGRAM OF THIS SITE BUT IT SHE WILL NOT SAVE ME IN THIS CASE.
THIS IS THE RESISTANCE NOT IN THE CHAINS THAT YOU DESCRIBED

Title: Re: power unit repair TEKTRONIX TDS 460A
Post by: Armadillo on December 29, 2017, 09:47:20 am

https://www.eevblog.com/forum/repair/help-needed-to-identify-component-in-tds460-power-supply/msg1386184/#msg1386184 (https://www.eevblog.com/forum/repair/help-needed-to-identify-component-in-tds460-power-supply/msg1386184/#msg1386184)

You can request from him since he had his opened up as well.

(https://www.eevblog.com/forum/repair/help-needed-to-identify-component-in-tds460-power-supply/?action=dlattach;attach=382369)

Title: Re: power unit repair TEKTRONIX TDS 460A
Post by: JacquesBBB on December 29, 2017, 01:18:19 pm

Yes,
I answered on my post. Its a 1.33k resistor.

Title: Re: power unit repair TEKTRONIX TDS 460A
Post by: lihach on December 29, 2017, 01:26:27 pm

Thank you very much. I no longer hoped that somewhere I can find such information. Because this requires disassembling the device. I am ready to answer all your questions. Why did you come to repair your power supply unit?

Title: Re: power unit repair TEKTRONIX TDS 460A
Post by: andy2000 on December 31, 2017, 04:53:23 pm

I recently repaired a TDS460, and the power supply was full of leaking caps.  Many of them weren't obvious, but there was electrolyte underneath them.  It may be related to your failure.

Title: Re: power unit repair TEKTRONIX TDS 460A
Post by: lihach on January 01, 2018, 08:36:08 pm

I myself am to blame. Conducted measurements without galvanic isolation