Author Topic: Tek TDS744 died 5 days after fixing the color issue  (Read 546 times)

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Offline H1t3ckTopic starter

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Tek TDS744 died 5 days after fixing the color issue
« on: March 07, 2023, 02:01:15 pm »
Well after enjoying the new to me TDS744 after fixing the color issue, five days later it died.  Upon turn it on the power supply would cycle on and off (the front panel LEDs would come on and off repeatedly every 3 to 5 seconds).

After further investigation found out the HV Power Supply was overloading the 25V supply as it tried to come up and the Main PS would shut down and repeat in an endless cycle.

By unplugging the connector to the HV supply then the system came up normally when turned on.

After some more in detail investigation of the HV supply I found the HV transformer pin3 was open which supplies the 75volts, no continuity between pin3 and pins 1,2 and 9.  However, looks like pin3 was now shorted to the primary pin 4.

So I was hoping to keep the scope in the original configuration, i.e. not switch to a LCD display.

Will have to see if I get lucky and find a HV transformer (120-1930-00) for a reasonable price.

Interestingly the HV transformer might had been replaced once in the past judging by the solder connections.

I guess having 30 yr old TE you have to expect issues.

Tony



 

Offline nctnico

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Re: Tek TDS744 died 5 days after fixing the color issue
« Reply #1 on: March 07, 2023, 02:48:22 pm »
This sucks....   I feel really sorry for you. Unfortunately these HV transformers are prone to failure. I have had a couple of these scopes through my hands with broken HV transformers. I got lucky once and managed to snatch up an entire CRT board for a low price on Ebay. Seller didn't know the actual worth...
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline TERRA Operative

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Re: Tek TDS744 died 5 days after fixing the color issue
« Reply #2 on: March 07, 2023, 03:12:33 pm »
I still have a spare CRT board you can have for cheap plus post from Japan if you want it. :)

Or I can pull and send just the transformer, whatevs.
Where does all this test equipment keep coming from?!?

https://www.youtube.com/NearFarMedia/
 


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