Products > Test Equipment
Tektronix TDS220 repair
tautech:
--- Quote from: JFJ on August 26, 2016, 07:18:21 pm ---I found this thread while searching, unsuccessfully, for a supplier of the 4-ground pin BNC connectors that are pictured in Reply #3, above. Can anybody tell me the name of the manufacturer of those connectors?
The 2-ground pin type that are used on earlier versions of the TDS220/210 main board, are made by AMP/TE Connectivity, but I can't find the type pictured above in their catalogue.
--- End quote ---
On a 210 that I repaired some time ago I used the 2 leg sockets as replacements as they are "drop in".
Sure they are a weak point in these models if excessive stress is applied to the input connectors but there is another mod one can do to strengthen the BNC inputs. There is a good ground plane either side of the inputs, scrape away the coating and solder a 5mm wide copper strap up and over the input sockets. IIRC there was plenty of room to do this mod and it adds good strength to the connectors, the only tricky bit is you will need a soldering iron with a bit of grunt. Never took pics back then so sorry I have nothing more to share. :(
sbeube02:
First sorry for the late reply.
I put the oscilloscope on shelf and didn't use it since two years.
I decided to give it a try and followed your advice.
I first changed the OpAmp U110. I still had the same voltage reading, with 0V at U110 pin 2.
I made resistor measurements and R222 was 48.5kohm witch is really different from your board.
I desoldered R222 and it was open circuit, broken in two!
@JFJ, your resistance values were read directly on the resistor body or taken by measurement?
My resistors does not have any values marked on them.
JFJ:
--- Quote from: sbeube02 on July 27, 2019, 12:13:27 pm ---... @JFJ, your resistance values were read directly on the resistor body or taken by measurement?
--- End quote ---
The resistance values of R222 and R224 were read directly from the codes printed on their bodies. Those values are commensurate with the calculated output voltage of Q110, which is close to the measured emitter voltage on my board:
sbeube02:
Thank you so much!
I replaced R222 with a 12 kohm because I don't have a 12.1 kohm.
I now have 3.25V at Q110 witch is close from yours.
But... I still have the Channel 1 and 2 acquisition failed message on boot screen... >:(
The probe comp signal goes from 5kHz to 4 kHz then 3 kHz and stays at 3 kHz. Anyone have information about this startup sequence?
I fear the ADG422 is shoot because of the over voltage from the bad resistor causing it to be powered with more than 4 V instead of 3.3 V.
sbeube02:
When I check the error log, I always get a "Line trigger diag failled" message.
I started checking the voltages at J131 as per the service manual:
Everything is good, except pin 7 witch only gave me 1 Vpp:
I drawn the line trigger part of the power supply:
And when I desoldered R29 to R32 for measurement, R29 was broken in two!
I will replace this resistor and check if the error disappear.
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