HP cables free for cost of shipping
I have four (4) HP cables with Centronics-style cables, free for the cost of shipping (USPS Medium flat-rate box will hold all 4 cables). PayPal $20 to jn6wfo@....?
Cables are untested but appear to be undamaged.
- HP-44744B, 50-pin male-male Centronics, quantity 2, one about 12 feet long, the other about 6 feet long. Purpose: The 1989 HP catalog (page 626) shows this cable is used to connect the HP44702A/B High-speed Voltmeter to the HP-98622A GPIO Interface for the HP-200 series computer.
- HP-562A-16C,
50-pin male-male Centronics, quantity 2, each about 6 feet long. Purpose: Connects HP-5326/27
(Option B)
series Counter-DVM to HP-5050B Digital Recorder.
Jeremy Nichols,N6WFO? Santa Rosa, California
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Re: 8566B Attenuator Service
I thought you had a problem with a coil staying energised as though its switch was not opening, as opposed to one not being able to switch back as the switch that needs to be closed to allow the current though it is not closing properly?? Maybe I’m getting confused! ? I have been following this thread with much intertest and I am impressed by your determination and the amazing help here! ? 73, Mike, Mike Stevens, G8CUL/F4VRB. ?
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From: [email protected] <[email protected]> On Behalf Of Jinxie via groups.io
Sent: 15 September 2024 18:46
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] 8566B Attenuator Service? Yes, we are on the same page! I'm going to try Adrian's suggestion of alcohol-soaked paper and if that doesn't work, I'll consider using very fine abrasive paper - say 2500 grade to begin with.
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Re: 8566B Attenuator Service
Thumbs up! And Robert is correct about burning these out. They are designed to be pulsed to one direction or the other.
And if it's always energized, then something is clearly wrong!
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@Mark
Yes, we are on the same page! I'm going to try Adrian's suggestion of alcohol-soaked paper and if
that doesn't work, I'll consider using very fine abrasive paper - say 2500 grade to begin with.
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Re: 8566B Attenuator Service
@Mark
Yes, we are on the same page! I'm going to try Adrian's suggestion of alcohol-soaked paper and if that doesn't work, I'll consider using very fine abrasive paper - say 2500 grade to begin with.
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Re: 8566B Attenuator Service
@Robert:
Well, I would have thought so too. However, it seems quite happy to remain energized indefinitely (fortunately!) Perhaps this (somewhat less common) attenuator is designed to operate that way? After all, it would provide a far more definite on/off than relying on some sort of spring mechanism.
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Re: 8566B Attenuator Service
I wish I knew! Unfortunately I cannot see from any available angle if the leaves are parallel with one another. But even if they're not, there should still be some degree of contact sufficient to provide a short. Anyway, they look fine visually. Thanks for the tip about using paper. I hadn't thought of that. I'll give it a try with some IPA soaked in.
The weird thing is that this fault is so reliable and repeatable. It's not an intermediate contact as one might expect. It's just there 100% the time by default it seems.
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Re: 8566B Attenuator Service
In fact, the tiny pin that pushes the two leaves apart is coated in glass and the pin is then an insulator when placed between the leaves...
?
Dan in Chandler, AZ
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Re: 8566B Attenuator Service
If the coil is staying energised than the control contact is falty or not being actuated. When the armature move it shoul cause the circuit to the coil should be broken. The coils are not designed to be be permanently energised and can be burnt out if left energised.
?
Robert.
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Re: Thermal Couple attached to heat sink
Thanks. I have the thermal couple? thermocouple :-)? ?It is the spacer that is under it that I'm looking for - or at least it's function, whether it is intended to conduct heat or just hold the tc against the heat sink. I found a clue: the service manual describes it as "Foam Pad".? I'm going to guess that it is not intended to conduct heat. That would make more sense, as its function is to measure the temperature of the heat sink.
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Re: 8566B Attenuator Service
I want to make sure we're on the same page here.
In the image below, the RED circles are the switch contacts CLOSED.
The YELLOW circles are the switch contacts OPEN.
If you get no continuity between the two spring contacts when closed (red) then yes, that's a problem.
If that's the case and cleaning is no help, you could try come light abrasive on them.
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Thank you, Greg. I would follow your suggestion, but I'm not about to give up all hope at the prospect of fixing a pair of leaf springs!!
I've cleaned those springs with three different solvents but they still
won't make electrical contact. There is plenty of 'spring' in them to make a good contact with each other, but it's just not happening. I've never had this before. Ever. Ideally I'd like to remove this pair and examine them under the stereoscope, but that's
not possible. The only other thing I can try (and I'm fast running out of ideas) is abrasive paper. I have the full range of grades here from coarse to ultra-fine. Does anyone know what these springs are made from? I don't wish to rub through some delicate
plating and make the situation even worse!
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Re: 8566B Attenuator Service
Hmmm, fussy things them electrons!
You are right, that's weird!
Desperate ideas to follow:
Have you got/tried Deoxit gold contact cleaner or something like it?
A very mild abrasive is a tiny strip of copier paper soaked in
contact cleaner and carefully drawn through the closed contacts
(downwards in this case)
Are the two leaves of the contact parallel to each other or has one
twisted slightly?
Has a tiny flake of the insulation on the actuator pin somehow
rubbed off and got stuck to the contact face?
.... I'll keep thinking...
On 15/09/2024 17:49, Jinxie via
groups.io wrote:
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Adrian,
Yes, light pressure and they do make short-circuit contact.
However, the next actuation and it's gone again. Yet there is
sufficient springiness there to provide physical
contact - just not electrical!
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Re: 8566B Attenuator Service
Adrian,
Yes, light pressure and they do make short-circuit contact. However, the next actuation and it's gone again. Yet there is sufficient springiness there to provide physical contact - just not electrical!
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Re: 8566B Attenuator Service
Thank you, Greg. I would follow your suggestion, but I'm not about to give up all hope at the prospect of fixing a pair of leaf springs!!
I've cleaned those springs with three different solvents but they still won't make electrical contact. There is plenty of 'spring' in them to make a good contact with each other, but it's just not happening. I've never had this before. Ever. Ideally I'd like to remove this pair and examine them under the stereoscope, but that's not possible. The only other thing I can try (and I'm fast running out of ideas) is abrasive paper. I have the full range of grades here from coarse to ultra-fine. Does anyone know what these springs are made from? I don't wish to rub through some delicate plating and make the situation even worse!
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Re: 8566B Attenuator Service
Where are you measuring from/to?
It looks like the solder tags sticking downwards, where the wires
are soldered on also terminate the solenoid winding wires - which is
logical - is it possible that the soldered joint has failed in some
weird way there? Can you probe (very carefully!) across the contacts
at the point they bend horizontally and disappear into the black
plastic supports??
On 15/09/2024 16:25, Jinxie via
groups.io wrote:
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Update: I've just also tried isopropyl alcohol. No
difference. Then I tried Servisol switch cleaning lubricant.
Still not making contact! It's as if there's an insulating layer
between those leaves. This is just weird.
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Re: 8566B Attenuator Service
When I started see anomalous operation of the attenuator in my HP spectrum analyzer I removed it and took off the cover to peek inside. I quickly realized that the sensitivity to any neophyte attempts to repair it would probably end in disaster. So I sent it out to Test Equipment Plus in Mississippi. It was returned repaired back to HP factory specs with a complete set of network analyzer test result documents.
Yes, it was expensive but I feel that it averted a possible disaster.
Greg
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Re: 8566B Attenuator Service
OH! I remember now after seeing a picture. The insulator on the pin is in fact what OPENS the switch. When the pins moves away. the two spring fingers make contact and THAT is what closes the switch.
Mystery solved.
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It's been years but I seem to recall some insulating material on those ... somewhere for some reason!
Update: I've just also tried isopropyl alcohol. No difference. Then I tried Servisol switch cleaning lubricant. Still not making contact! It's as if there's an insulating layer between those leaves. This is just
weird.
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Re: Agilent E4406 fails to turn on
Had a problem...+15V standby DC-DC converet. Small verticaly moumter piggy board on main PSU. Replace all (2or3) electrolitic condesators.
Milan
On Sun, 15 Sep 2024, 17:09 hardyhansendk via , <hardyhansen= [email protected]> wrote: Hi
I have experienced the same no turn on,it began to take a while before start up-later it would not at start at all.Replaced the input caps-and it worksl.
David..we have also have the schematics for RF board and Synthesizer and maybe Tim would be interested in VSA software 89601A??
Regards
Hardy? ?
-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af David C. Partridge
Sendt: 15. september 2024 16:11
Til: [email protected]
Emne: Re: [HP-Agilent-Keysight-equipment] Agilent E4406 fails to turn on
If you want a schematic of the fan board send an email offline.
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Tim Tuck
Sent: 15 September 2024 13:07
To: [email protected]
Subject: [HP-Agilent-Keysight-equipment] Agilent E4406 fails to turn on
Hi all,
My E4406 won't turn on so I've pulled it out the PSU, and apart from some suspicious RIFA caps it appears OK.
I've also gone over the Fan control board on the suggestion that some 10k or 100k resistors might be open circuit but a simple in circuit test shows them to be OK.
While this might be not sufficient to reveal an open circuit device since the surrounding circuit might provide the return path for a resistance measurement of near value, if someone knows which resistors I should de-solder to check, please tell :)
Any other pointers to common faults to look for or a path to take would be great.
thanks
Tim
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Re: 8566B Attenuator Service
It's been years but I seem to recall some insulating material on those ... somewhere for some reason!
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Update: I've just also tried isopropyl alcohol. No difference. Then I tried Servisol switch cleaning lubricant. Still not making contact! It's as if there's an insulating layer between those leaves. This is just
weird.
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Re: 8566B Attenuator Service
This really makes no sense. Let's say it gets the signal to turn 'out' (up). Then the switch to turn 'in' (down) should make contact and the out/up switch should be open. SO at this point, neither coil should be ON and you should be able to move the solenoid
by hand. (those magnets are strong so it takes some effort) If the OUT/UP signal is stuck on, the solenoid would move right back into position.
You might just have to carefully test it with a bench power supply per previous discussions.
I have attached the datasheet just in case you need it.
Mark
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For some reason, the lower contact pair of Y leaves will *not* make contact. They
appear to be making contact visually, but it's open circuit every time. I've tried shaving down a toothpick and cleaning the inside contact areas with ethanol but it's made NO difference at all. If I jiggle them, I can get them to make electrical contact,
but then it's lost again a moment later. Never experienced this before! Could this explain why this attenuator is permanently stuck 'on' once actuated?
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Re: 8566B Attenuator Service
Update: I've just also tried isopropyl alcohol. No difference. Then I tried Servisol switch cleaning lubricant. Still not making contact! It's as if there's an insulating layer between those leaves. This is just weird.
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Jeremy Nichols
Jinxie