I agree that providing an uncurrent limited -10v was a mistake.

Some suggestions:
1) A loose part (screw, nut, washer) that found itself a place
shorting the -10v seems likely
2) A cap failure - how long was the 8566 off - long enough for the cap
to depolarize.

Thoughts on how to proceed:
Isolate sections of the power distribution on the PCB -pull cards,
pull connectors, etc.
If something smoked, it will be either a component on a PCB or the
motherboard (There are a few). Or it could be a PCB trace (bad news
if it is in a relatively inaccessible place.

Hardest but most through is to remove all cards, test for appropriate
voltages and then plug in a selection of cards. I usually start with
the control section (CPU, etc), then RF, then M/N, then 20/30. Don't
forget the front pannel, but it is easy to isolate (don't remember if
-10v is used on FP - think it is not).

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-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070

Note that the battery is a coin cell with tabs that is soldered to the
main PCB. Would have been a lot nicer if they had used a battery
holder for the coin cell.

I understand that bit. On the HP 3478A DMM replacing the battery without maintaining voltage in the circuit caused loss of calibration and you have an inaccurate meter. If I just remove and replace the battery in the HP 54622D oscilloscope do I also lose calibration or something else important? Is it just keeping user preferences? My approach to replacement will depend on what is lost when the battery is disconnected.

If the battery runs down it will eventually leak and ruin the scope or DMM. I suggest you replace it.

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5082-2303 diode specifications:

??????????? Minimum breakdown voltage V_BR (V): 20

??????????? Minimum forward voltage V_F (mV): 400

??????????? V_F = 1V Max at forward current I_F (mA): 35

??????????? Maximum reverse leakage current : I_R (nA): 500 at V_R (V): 15

??????????? Maximum capacitance C_T (pF): 1.0

??????????? ???????????

5082-2308 diode pair matching test conditions:

Δ痴_f at I_f = 0.75V at 20 mA

Δ颁_o at f = 1.0 MHz

Greg

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Hi Joel, were you successful ? I have a very similar issue with a known working 8594E. I reset the default CAL, ran the CAL with -37Hz, but the CAL routine never finishes and stay stuck at "CAL: EMI bandwidth". And when I say stuck, it stays there after 14 hours of running and no updates on the screen, except it goes from -35 to -40Mhz back and forth, as if it was looking for something that never appears.

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I have started a new topic for my problem, you can reply there if you want to help.

Thank you.

Hi group ! I will start by saying that I really messed up here. I hope I will find help.

I noticed one day that my Analyzer was not reading the right amplitude in the 100Mhz range. It did read the correct amplitude at 300Mhz from the CAL output signal.

I decided to run the AMPTD CAL but it stopped with this error : AMPTD CAL : GAIN FAIL SRQ 110

Without fully reading the manuals, I then tried to run the CAL by centering to -37Hz. The AMPDT CAL then never finishes (after 12 hours of running).

I then restored the default CAL (I do have pictures of the CALS before I reloaded the default factory CALS).

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Now, I can't run the CAL process without entering -37Hz because I get "CAL SIGNAL NOT FOUND" which is a documented problem during the calibration of the instrument, the workaround being to do the CAL by centering to -37Hz before.

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Well, since centering to -37Hz is not working and now my CAL OUT at 300Mhz reads -50dbm instead of -20dmb, what can I do to fix this ?

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If I could get back to the primary issue, which gave me the "AMPDT GAIN FAIL" (which is the DAC gain set to 255 but amplitude reading is not within specs), I could restart from where the real issue was.

Thanks.

This fellow specializes in the 8640 and he rebuilds the frequency range gear assemblies.

I don’t have any connection with him except for buying a gear range assembly.