Ok.? Just wondering because it seems whenever I need one, all I have is the other!? So tempting to just turn it upside down....

Jim

Sent from my T-Mobile 4G LTE Device

-------- Original message --------

From: 搁别苍é别 <k6fsb.1@...>

Date: 3/1/22 2:30 PM (GMT-08:00)

To: [email protected]

Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up

works for me, although seems the condensation is worse with canned air, may be my imagination.
搁别苍é别

On 3/1/22 12:42 PM, Jim Ford wrote:

Say, anybody know any disadvantages of using freeze spray as a duster or a duster as freeze spray?? Turn one upside-down to make it work as the other, of course.? TIA.

Thanks for all the tips, guys; really helpful.
I've found a very readable and comprehensible description of the various functional blocks concerned and how they inter-relate to one another in the Analog Troubleshooting section of the diagnostics manual. I'll be getting to grips with that over the next few days as there are clearly many missing parts to my understanding of the circuitry used in this analyzer. If I have any problems I'll check back with you all.
I'm not sure yet if the REF unlock message was just a result of a cold oven; will have to go back over that aspect when time permits, but thanks for pointing out the possibility!

Say, anybody know any disadvantages of using freeze spray as a duster or a duster as freeze spray?? Turn one upside-down to make it work as the other, of course.? TIA.

Jim Ford

Sent from my T-Mobile 4G LTE Device

-------- Original message --------

From: Flannel Tuba <flanneltuba@...>

Date: 3/1/22 12:12 PM (GMT-08:00)

To: [email protected]

Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up

@Jim: I too am a big fan of freeze spray. It can really root out faults that would otherwise be very difficult to diagnose with bench equipment, especially intermittent issues like this. I gave each of the regulator sections a nice dose of freeze spray, without any revealing results, except for the one drawback of such techniques, namely the condensation that can result after cooling the boards, which in this case would throw the regulators off until they'd dried off. Ordinarily, I avoid freezing entire sections of a circuit at once, preferring to freeze each component separately with a nice steady and directed drip from the freeze can. This not only helps eliminate the condensation issue, but saves on the freeze spray, which is not inconsequentially pricy. Unfortunately, without any extender cards, it's nearly impossible to just freeze a specific component at a time, so, firehose freeze spray it is! Anyway, it didn't expose any temperature sensitive issues on the regulator cards.

@George: I definitely plan to re-flow all of the TO3 connections, and clean the sockets and pins. Even if it doesn't fix this issue, it's good hardware hygiene in any case. I'll put all of the power transistors on a curve tracer too, and run them through a wide temperature sweep. None of them generated any notable heat while in circuit, but a flakey P/N junction can decide to fail at relative room temperatures. I will say, the day this failed, the temperature in my shop (uninsulated barn actually) was probably in the mid 40°s, F. Admittedly a silly temperature to be aligning a receiver, but it was intended to be a rough alignment. I was bored, what can I say?

@Dave: As long as I've had this 8640, is has always been positioned horizontally, so I would hope this would preclude the possibility of the lubricant creeping into the electronics. I do agree that the behavior of the 44.6V supply floating high when the oscillation stops, seems like the regulator's reaction to being underloaded, perhaps when the circuits it supplies, take a nap. Thanks for the tips on where these los might reside.?

I really need to make or buy some 15 pin extender cards. Troubleshooting such circuits without, is like trying to fish coins out of a storm drain. Anyone know a good source of such, that aren't priced by concert scalpers?

Say, anybody know any disadvantages of using freeze spray as a duster or a duster as freeze spray?? Turn one upside-down to make it work as the other, of course.? TIA.

Jim Ford

Sent from my T-Mobile 4G LTE Device

-------- Original message --------

From: Flannel Tuba <flanneltuba@...>

Date: 3/1/22 12:12 PM (GMT-08:00)

To: [email protected]

Subject: Re: [HP-Agilent-Keysight-equipment] HP8640B RF Fails Several Seconds After Power Up

@Jim: I too am a big fan of freeze spray. It can really root out faults that would otherwise be very difficult to diagnose with bench equipment, especially intermittent issues like this. I gave each of the regulator sections a nice dose of freeze spray, without any revealing results, except for the one drawback of such techniques, namely the condensation that can result after cooling the boards, which in this case would throw the regulators off until they'd dried off. Ordinarily, I avoid freezing entire sections of a circuit at once, preferring to freeze each component separately with a nice steady and directed drip from the freeze can. This not only helps eliminate the condensation issue, but saves on the freeze spray, which is not inconsequentially pricy. Unfortunately, without any extender cards, it's nearly impossible to just freeze a specific component at a time, so, firehose freeze spray it is! Anyway, it didn't expose any temperature sensitive issues on the regulator cards.

@George: I definitely plan to re-flow all of the TO3 connections, and clean the sockets and pins. Even if it doesn't fix this issue, it's good hardware hygiene in any case. I'll put all of the power transistors on a curve tracer too, and run them through a wide temperature sweep. None of them generated any notable heat while in circuit, but a flakey P/N junction can decide to fail at relative room temperatures. I will say, the day this failed, the temperature in my shop (uninsulated barn actually) was probably in the mid 40°s, F. Admittedly a silly temperature to be aligning a receiver, but it was intended to be a rough alignment. I was bored, what can I say?

@Dave: As long as I've had this 8640, is has always been positioned horizontally, so I would hope this would preclude the possibility of the lubricant creeping into the electronics. I do agree that the behavior of the 44.6V supply floating high when the oscillation stops, seems like the regulator's reaction to being underloaded, perhaps when the circuits it supplies, take a nap. Thanks for the tips on where these los might reside.?

I really need to make or buy some 15 pin extender cards. Troubleshooting such circuits without, is like trying to fish coins out of a storm drain. Anyone know a good source of such, that aren't priced by concert scalpers?

@Jim: I too am a big fan of freeze spray. It can really root out faults that would otherwise be very difficult to diagnose with bench equipment, especially intermittent issues like this. I gave each of the regulator sections a nice dose of freeze spray, without any revealing results, except for the one drawback of such techniques, namely the condensation that can result after cooling the boards, which in this case would throw the regulators off until they'd dried off. Ordinarily, I avoid freezing entire sections of a circuit at once, preferring to freeze each component separately with a nice steady and directed drip from the freeze can. This not only helps eliminate the condensation issue, but saves on the freeze spray, which is not inconsequentially pricy. Unfortunately, without any extender cards, it's nearly impossible to just freeze a specific component at a time, so, firehose freeze spray it is! Anyway, it didn't expose any temperature sensitive issues on the regulator cards.

@George: I definitely plan to re-flow all of the TO3 connections, and clean the sockets and pins. Even if it doesn't fix this issue, it's good hardware hygiene in any case. I'll put all of the power transistors on a curve tracer too, and run them through a wide temperature sweep. None of them generated any notable heat while in circuit, but a flakey P/N junction can decide to fail at relative room temperatures. I will say, the day this failed, the temperature in my shop (uninsulated barn actually) was probably in the mid 40°s, F. Admittedly a silly temperature to be aligning a receiver, but it was intended to be a rough alignment. I was bored, what can I say?

@Dave: As long as I've had this 8640, is has always been positioned horizontally, so I would hope this would preclude the possibility of the lubricant creeping into the electronics. I do agree that the behavior of the 44.6V supply floating high when the oscillation stops, seems like the regulator's reaction to being underloaded, perhaps when the circuits it supplies, take a nap. Thanks for the tips on where these los might reside.?

I really need to make or buy some 15 pin extender cards. Troubleshooting such circuits without, is like trying to fish coins out of a storm drain. Anyone know a good source of such, that aren't priced by concert scalpers?

To add to Bruce's answer: the REF unlock can occur when the OCXO oven is
warming up. If the unit has been plugged in (doesn't need to be powered
on, since the oven supply is active anytime the instrument is connected
to mains) more than ~10min or so and the annunciator is still there,
that's an indication there's an issue. FYI although the oven supply is
always present when plugged in, the oscillator supply isn't. You'll need
to power on the unit to see the 10 MHz signal.

I would start by just checking to make sure this 10 MHz signal is
present. You don't need to open the instrument, it's available on the
back panel. Any oscilloscope should be able to tell you whether the
reference signal is present or not. I got a ref unlock on an 8340 (same
reference as the 8566) and it was caused by a dead reference.

If the reference is dead, you can test the rest of the instrument by
providing an external 10 MHz reference. Check the manual to ensure the
power level is appropriate. If you're not getting a 10 MHz signal,
before ultimately implicating the reference, you should ensure all
interface signals to the reference (including both the oven and
oscillator supplies) are correct.

If the reference is present but you still see the REF unlock that will
require some additional troubleshooting.

Good luck,
Matt

To add to Bruce's answer: the REF unlock can occur when the OCXO oven is
warming up. If the unit has been plugged in (doesn't need to be powered
on, since the oven supply is active anytime the instrument is connected
to mains) more than ~10min or so and the annunciator is still there,
that's an indication there's an issue. FYI although the oven supply is
always present when plugged in, the oscillator supply isn't. You'll need
to power on the unit to see the 10 MHz signal.

I would start by just checking to make sure this 10 MHz signal is
present. You don't need to open the instrument, it's available on the
back panel. Any oscilloscope should be able to tell you whether the
reference signal is present or not. I got a ref unlock on an 8340 (same
reference as the 8566) and it was caused by a dead reference.

If the reference is dead, you can test the rest of the instrument by
providing an external 10 MHz reference. Check the manual to ensure the
power level is appropriate. If you're not getting a 10 MHz signal,
before ultimately implicating the reference, you should ensure all
interface signals to the reference (including both the oven and
oscillator supplies) are correct.

If the reference is present but you still see the REF unlock that will
require some additional troubleshooting.

Good luck,
Matt

From: "Askild" <megafluffy@...>
To: "HP-Agilent-Keysight-equipment" <[email protected]>
Sent: Tuesday, March 1, 2022 12:52:45 PM
Subject: Re: [HP-Agilent-Keysight-equipment] HP 410B probe wire

@Bruce
I only had very little time this evening to investigate further, I'm afraid. Not even enough time to try shortening the ground clip lead! I will try out everyone's suggestions in due course, however.
As things stand, I was able to observe that the screen is showing three errors in all now: Battery, YTO Unlock and REF Unlock. I don't recall that last one being there previously. There are three LEDs lit on the stack of modules criss-crossed by the press-on patch leads. I think these are the ones you were referring to:
ON=PLL3 Lock
ON=PLL1 Lock
ON=HET
As I say, all three are lit. Can't see any LED for PLL2, though!
After trying everyone's suggestions I plan to work through the steps suggested in the troubleshooting & diagnostics manual. It's probably going to be above my pay-grade, but nothing to lose by at least trying I guess.