Re: TDS744A input failure.


Maybe you still have leakage currents from the electrolyte?
I washed the boards of my TDS544A really well with water and detergent.
Obvously I rinsed them to get the detergent off, and dried them before use.


On Tue, Apr 25, 2017 at 2:19 PM, 'Daveyk021 .' daveyk021@...
[TekScopes] <TekScopes@...> wrote:
Thank you. On my TDS544, I now have all four traces but the compensation
routine does not work, it ends in an error. Channel 1 and 2 are pretty
close but float from 0v a little. Traces 3 and 4 are pretty high above the
0v baseline.

Yesterday, I had a ACQ board out and examined every trace from every cap.
I found two questionable solder connections to the caps. There is not a
lot of leakage damaged to the board. I have cleaned all leaked areas (and
there was really only 3) with flux remover. I have flushed the entire
board with flux remover. All op amps have proper voltage rails.

I checked all the voltages coming out of the power supply and they are spot
on. What I didn't do was scope them for noise.

I'm not sure where to test the ACQ board for this problem. I tired to
include a picture of the ERROR screen of the scope and that didn't stay
with the email. I tried to upload the picture to the file upload section
and the upload does not complete. Some of the messages:
"ERROR: Cal meas clipped at max dig g... CH3 Balance Cal of Attenuator"
"ERROR: Insufficient differential responce CH1 Gain cal of M694 Stepgains"
"ERROR: Characterized values out of b...A/D biasing cal"
"ERROR: Characterized values out of b...Vertical"
"ERROR: 2260 Calibration failed"
"ERROR: 2260 Calibration failed"


On Tue, Apr 25, 2017 at 6:12 AM, David @DWH [TekScopes] <
TekScopes@...> wrote:

There is a TDS520B service manual which includes schematics giving a
good idea of what is in the attenuator hybrids.

On Mon, 24 Apr 2017 14:55:14 -0400, you wrote:

Are there schematics for those input boards/hybrids? With those somewhat
large relays soldered on them, I don't exactly think of them as hybrids.
they considered that, my guess is "no"?

Posted by: "Daveyk021 ." <daveyk021@...>


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