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Electronics => Repair => Topic started by: JacquesBBB on September 24, 2016, 09:51:58 am

Title: TDS3012b repair tentative. Help needed.
Post by: JacquesBBB on September 24, 2016, 09:51:58 am

Hi All,

I have scored a non functioning TDS3012b for free, and I am trying to bring it back to life.

The power supply seems to work, and I have all proper voltages at the BNC connector (+5.1V,+15V, -15V, -5V).
The symptom is a blank  screen.

I  have followed the procedure in the service manual I have
http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%20TDS%203000%20series%20Service.pdf (http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%20TDS%203000%20series%20Service.pdf)

but it does not fit with my device.

The J900 connector of the main board ( 26 pins)  is different from the one in the manual (12 pins)
so I do not know how to proceed.

- Does anybody has the proper service manual with the 26 pins J900 connector ?

- Does anybody  have an idea of what is wrong with this unit ?

Thanks
 

Title: Re: TDS3012b repair tentative. Help needed.
Post by: JacquesBBB on September 24, 2016, 10:51:56 am

Now I see that the manual I had  was for the TDS3000 and not TDS3000b

Now I have found the TDS3000b manual
http://www.pewa.de/DATENBLATT/DBL_TEK_TDS3000-SERVICE-MANUAL_ENGLISCH.PDF (http://www.pewa.de/DATENBLATT/DBL_TEK_TDS3000-SERVICE-MANUAL_ENGLISCH.PDF)

And indeed the J900 connector is different.
But unfortunately,  the troubleshooting procedure is now reduced to the minimal,  made for a technician  that
knows nothing in electronics.

 (https://www.eevblog.com/forum/repair/tds3012b-repair-tentative-help-needed/?action=dlattach;attach=258065)

I checked, and have effectively 15V between 1 and 6, which is expected from the previous procedure,
but now they do not go further, they just  tell to send the device to Tektronix for repair. What a shame !

Title: Re: TDS3012b repair tentative. Help needed.
Post by: HighVoltage on September 24, 2016, 12:44:20 pm

I had several TDS3000 scopes fail on me, A,B and C series
Every single time it was a power supply issue.
Make sure to load the rail with a little current, to see if it stays stable on all voltages.
And also look for ripple on the rails.

Sorry, I have no more manuals for these scopes since I don't own one anymore.

Title: Re: TDS3012b repair tentative. Help needed.
Post by: TopLoser on September 24, 2016, 12:56:36 pm

I bought and sold 10 or 20 of these, and I always kept a stock of spare power supplies.

I think I still have one somewhere, they were only about £30 from Tek.

Title: Re: TDS3012b repair tentative. Help needed.
Post by: JacquesBBB on September 24, 2016, 03:17:01 pm

Thanks for the feed back.

I was hoping it was the PSU, but as far as I can see with my limited knowledge, it seems that the fault
is elsewhere.

I have measures again the output of the PSU. I have 14.89 V  with 100mV ripple with no load
and 20mV ripple with a 100 ohm resistor load.