Author Topic: Dead Tektronix TDS3034 (solved)  (Read 481 times)

0 Members and 1 Guest are viewing this topic.

Offline John.S

  • Contributor
  • Posts: 11
  • Country: nl
Dead Tektronix TDS3034 (solved)
« on: June 08, 2019, 02:49:15 pm »
Yesterday I grabbed my scope to do some measurement on my Modbus Arduino project.
Put in the power cord, push the start button and……. nothing happened.

First challenge, how to open this puppy.

Well..... YouTube is your friend, after 2 videos that shows absolutly nothing, I found one that explains everything, how can you even design something like that :P

So, after removing the housing it is all nice and well reachable.
First remove the part with the fan, pre power supply and regulator board with only three screws.
Then seperate the pre regulator board.
The service manual says that you can power up the pre regulator, and it should give you 15 Volts DC.
So I did that, and it gives me absolutely nothing. I was happy with that, it seems to me the easiest part of this scope to repair.

Fuse was OK, and little over 400V DC on the main capacitor, so no worries there. Main switching mosfet also looks OK.
Also no leaking or bulged capacitors so no obvious culprits on the board.
Becouse the amount of components is not that much I started poking around with the ohm meter to check for shorts or open circuits.
I was lucky, one of the first things I measured was the 2 resistors in series at the place of R2 (2 x 390kohm in series)
One of these 2 was open circuit !!
I did not have resistors of this size in my parts box, but decided to put 3 270kohm resistors in series and solder them in for testing.


I conncted the power leads back an and put 230Vac on the board and got 15 Vdc on pin 1 and 6 on the connector. So its alive again :-+

Put everything back together, and powered the scope op, and luckily it is up and running again.

I did order new resistors of the right value and size, when in I will change my bodge resistors for the new ones.

So at the end it is a verry simple repair, but becouse there is not so much to vind about these scopes i post it anyway.
Mayby it can help other people.


Greetings
John.
Don't think in problems, think in solutions....
 
The following users thanked this post: Neomys Sapiens

Offline Jay_Diddy_B

  • Super Contributor
  • ***
  • Posts: 1851
  • Country: ca
Re: Dead Tektronix TDS3034 (solved)
« Reply #1 on: June 08, 2019, 03:20:06 pm »
Hi,

If you want to know more about this power supply, including a partial schematic, look here:

Link: https://www.eevblog.com/forum/repair/a-tektronix-tds3014b-with-two-strange-issues/msg991612/#msg991612

I have seen this fault before.

Regards,
Jay_Diddy_B
 
The following users thanked this post: Neomys Sapiens

Offline John.S

  • Contributor
  • Posts: 11
  • Country: nl
Re: Dead Tektronix TDS3034 (solved)
« Reply #2 on: June 08, 2019, 04:46:42 pm »
Hi,
Thanks for the link.
It is now obvious why the supply was completely dead with R2 open circuit.
With this fault it is also clear why nothing else is damaged.

greetings
John.

Don't think in problems, think in solutions....
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf