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8116A Code 42

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Mick B:
I found the problem..... it's the wire harness. I might have found a new one complete with A6 pod, will see I'm waiting for them to get back to me. I'm also looking into making a new one its only 3 wires between the A6 board and A3 board Red, White, & Black. In the A6 Pod Green, yellow and red go through several RC circuits and come out as 2 wires and a ground.

Mick B:
Hello Mark, while trying to calibrate this HP 8116A I've run into a problem. Perhaps you can steer me in the right direction. 
when setting up the voltages IE: Square High Amplitude & Offset Pg. 9.4-5 It would seem I have a LARGE Over-Under shoot issue
In the picture the AMP is set to +10V. at +16V it is off the screen. At +10V you can see the P-P voltage is +13.44
the brown lines are indicators for the Setting VMAX & VMIN the overshoot is in the 30s% and not <4% making it impossible to set.
This is one of the first adjustments. This was not like this when I started, I made it all the way through the calibration and checked to see if the frequency and voltage levels were good, and I found this. :-BROKE
Do you see a place to start?

MarkL:
First, I would try a quick check to make sure it's not a measurement issue.  Move your cable to the trigger output and make sure it's a clean square wave on your scope.  Levels will be at 0V and 2.5V.  Assuming that's ok...

What do those spikes look like if you reduce the time/div?  Is it a simple overshoot or is it ringing?  Is it the same in complement mode?

Are the "Overshoot and Transition Time Adjustments" starting on page 9-6 still within acceptable limits?

If everything there appears to be ok, I would verify any adjustments having to do with frequency response, like flatness or distortion.  Anything timing related like frequency or width are probably not involved in the overshoot.

Failing all that, I would take a look at TP4 and see if it has the same shape of waveform as the output.  If it does, the output amplifier is being true to the shaper output and the problem adjustment is probably in the shaper area.  Otherwise, it's an adjustment further downstream in the output amplifier.  (Assuming the current issue is introduced by a change in adjustment.)


As a future hint, one thing to do is carefully mark all adjustments with a fine Sharpie before changing anything.  That way you can at least get back to where you started, and you are more free to experiment with any adjustments.  The marks can be removed with isopropyl and a q-tip, if needed/desired.  High-res photo(s) can also work, as long as they show everything.

Mick B:
Starting over all pots at center, as per the instructions. The previous owner did this. I have to go with it,4 chips and the main board were replaced.

Resistance measured on an HP 34401A

Picture's 1~4
 
1. This a 50.3 ohm terminated BNC TEE. With the 3ft cable the resistance is 50.65 through a banana adaptor
 
2. This a picture of a new BNC cable with a 50.1-ohm 2W pass through resistor on the trigger output (perfect)

3. This is the something but with the cable I was using for the main output.

4. This is the same cable as picture 3 but with the 50 ohm terminator resistor from picture 1 :wtf:

This does not do this all the time. It could be doing this with the pass through I just can't get it to do it now
adjustment on page 9-4.5 to 9-4.15 came out perfectly.
What could make this do this? I have been messing with this for hour-----days before I stumbled onto this

I'm going to do the calibration to the end again, using just pass through on the main output and a 20 dBm on the trigger output. on the scope, for adjustments that use the trigger output on my counter HP 5334A has a 50 ohm / Z button do you see a problem with this idea?

 

Mick B:
Hello all, well it made it through the calibration as before, everything is working as it should. It sucks a faulty 50-ohm termination that breaks down under load caused this.

On to making a cable for my HP 50005A I can't find one, it looks like three RG-316 coax in a sheath.
Anyone seen such a thing?

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