Author Topic: Tek TDS 754D service manual? diagrams?  (Read 379 times)

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Offline Tracker

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Tek TDS 754D service manual? diagrams?
« on: June 21, 2019, 06:55:39 pm »
Hello kind forum people!

Looking for a set of diagrams for the Tektronix TDS 754D ?
A Google search came up with a so called 'service manual', but it only has block diagrams, no schematic or parts list.

I received this unit from a nice donor, however it seems to have a PSU problem.

On power on it goes into a 1 second cycle of flashing it's button lights and attempts to illuminate screen, then dies and repeats.
I guess something is pulling the PSU down and triggering a reboot.

Thanks in advance for any tips or links to the wanted manual.

Regards
Tracker

 
 
« Last Edit: February 29, 2020, 09:10:37 am by Tracker »
 

Offline Tracker

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Re: Tek TDS 754D service manual? diagrams?
« Reply #1 on: June 21, 2019, 07:56:19 pm »
Took a quick look inside and found the smoking gun so to speak.... :-+

There is a power regulator on a digital board (underside of scope) which has released its smoke!
The damage to the device is quite bad, making identification difficult...

And when I unplug the digital board the scope powers up fine, but without any display data.

Can anyone here tell what this Dpak part might be?

I suspect its a 12v regulator 78M12 ?? the number 12 is visible top right, buy we also have 09 on lower right, but that might be the date code?
Powering up the scope and measuring the input of the IC I can measure about +12v momentarily just before the scope cycles again, it might be higher than 12v but my meter cant quite catch it.
I may need to scope it!

It is identified as U1420 on the digital PCB.




PCB image, damaged IC is middle image/right side of the pic.

« Last Edit: June 21, 2019, 08:42:33 pm by Tracker »
 

Offline PepaZdepa

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Re: Tek TDS 754D service manual? diagrams?
« Reply #2 on: June 24, 2019, 09:09:18 pm »
Hi,  the pictures are invisible, send them again :)
 

Offline PepaZdepa

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Re: Tek TDS 754D service manual? diagrams?
« Reply #3 on: June 24, 2019, 09:15:08 pm »
This one?
« Last Edit: June 24, 2019, 09:29:21 pm by PepaZdepa »
 

Offline Tracker

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Re: Tek TDS 754D service manual? diagrams?
« Reply #4 on: June 24, 2019, 10:21:21 pm »
Oh wow, thanks a million mate. I had ordered the 78m12 ... Just as well you replied. I could have fried the downstream circuit. 79m12 was unexpected.
 

Offline PepaZdepa

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Re: Tek TDS 754D service manual? diagrams?
« Reply #5 on: June 24, 2019, 10:37:48 pm »
You're welcome  :)
The pic is from my 754D, schematic from TDS520 which is similar
 


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