Author Topic: Tektronix 5441 Power Supply Faulty?  (Read 212 times)

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Offline Dead1y_Wolf

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  • Country: at
Tektronix 5441 Power Supply Faulty?
« on: October 31, 2019, 08:57:54 pm »
Good evening guys,

i got this oscilloscope gifted from my father and i really like the CRT ones.

Only problem is it is not working properly.

I desoldered the power supply to check it, because a cap blew up constantly.

Following problems occur: The PSU can be adjusted by 2 variable resistors (on +30VDC and -30VDC) but turning those does nothing at all
                                       the -15VDC Testpoint measures with -34VDC (almost the same as -30VDC testpoint)
                                       the 200VDC output is at 200VDC directly after the rectifier but 240VDC at the testpoint

In the attachments are the board layout, the blank circuit and the blank circuit "colored" and filled in to give you guys more to work with.

If you have questions or want the detailed parts list or photos, just ask me.

I tried some measuring and testing myself to find out what the problem could be but it is not possible to me to understand the circuit enough to start troubleshooting.

Let's say that I am a "beginner" in electronics and also try to understand everything that makes that scope work, because i find it interesting and always  try to learn something new.
And I also know that this project is wayyyyy to big for a beginner but meh... i like the scope and wanna use it.

Thanks in advance for your help (if possible)


Offline randyhenke

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  • Posts: 4
Re: Tektronix 5441 Power Supply Faulty?
« Reply #1 on: November 07, 2019, 02:35:09 am »
Power off the scope and let the caps discharge and see if you have continuity from your testpoints to the bridge rectifier.  I'm thinking that your measuring the wrong testpoints.  If you don't have continuity then see if you can find a better schematic for your scope. If you have continuity between your test point and rectifier then I would remove the fuse from the circuit and measure voltage at your test point, and if so start tracing where that voltage could have come from.

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