Re: Thermal Couple attached to heat sink
Hello John, The usual insulator for thermocouples is mica. 73 de Brian, VK2GCE
----- Original Message -----
To: <[email protected]>
Cc:
Sent: Sat, 14 Sep 2024 17:49:28 -0700
Subject: Re: [HP-Agilent-Keysight-equipment] Thermal Couple attached to heat sink
Thanks Jim,
Does anyone know what would make a good spacer?
?
John
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Re: Thermal Couple attached to heat sink
Thanks Jim,
Does anyone know what would make a good spacer?
?
John
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Re: 8566B Attenuator Service
Vladan,
You're the boss! Okay, I'll not do that.
More tomorrow... I'm off to bed now.
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Re: 8566B Attenuator Service
Jinxie, don't touch those gold pads, just fix the o-rings. Gold is soft and it's supposed to smear a little by design.
?
Vladan
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Re: HP attenuator O-rings
On Sat, Sep 14, 2024 at 12:30 PM, Dan Rae wrote:
For those looking for O rings, ...
which are buna.
So good, if you want those.
The OP was asking about Viton.
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Re: 8566B Attenuator Service
Yes, I did notice those marks on the gold plating. I'll take a better look tomorrow under the stereoscope to see if they're invasive. I have some 24kt gold wire which I could use to sputter those pads if they're beyond repair - assuming that would adhere, of course. 25 mil wire coil @ 1000 amps should do it surely?
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Re: HP attenuator O-rings
For those looking for O rings, there was extensive discussion about them way back in 2016 of course on the Yahoo group which has now vanished I presume.? I did buy 800 of them from PAI, their Part number:
23-41 5747
70 Duro Black Buna N
In stock
C/s .023 ¡À .002 x ID .041 ¡À .003
Tasha Johnson
Customer Service Representative
Precision Associates Inc.
Direct: (612) 334-9120
Toll Free: (888) 724-4712
which I was able to pass on at $10 for 50 post paid, the hardest part of which was counting them...
No idea even if they are still in business.
Dan
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Re: 8566B Attenuator Service
Well done, gentlemen, loads of good suggestions here; plenty for me to get on with tomorrow when I next get a session in.
So here's where I am now. From the advice here it seems the best course is to replace the front panel of the attenuator so the contacts can bear against the pads. Then re-attach the ribbon cable to the motherboard. Both of these steps I have now taken. Tomorrow I'll squirt some RF and some DC (at different times!) through the input and monitor the output in the time and frequency domains. Seems that RF and DC show up different issues, so fine, I'll try both.
Now, the sharp-eyed (extremely sharp-eyed!) fellow who pointed out that O ring was perfectly correct. It is indeed heavily perished. One or two of the others are also showing signs of age, too, but that one is the worst by far.
Now I've had to remove A6A9 to get the attenuator out and detached some of its cables in the process. Will I be okay to turn the SA on with this section in this state? I would have thought so, but don't wish to fry something at this stage!
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Re: HP attenuator O-rings
On Sat, Sep 14, 2024 at 03:43 AM, Alan Bain wrote:
there are various comments that they need to be
Viton/FKM in order to last
Viton is type of fluoroelastomer.
It's a type of high-performance synthetic rubber, valued for its excellent resistance to heat/temperature... compared to buna
There are different grades of Viton; but AFAIK, all those grades of Viton outperform buna... unless there is some specific chemical that buna can resist, and Viton cannot.
?
I'm not sure (I haven't checked the posts) to know if it's the temperature that matters in this application... but, I assume it is.
That is... yes... buna degrades over time, much faster than Viton... but, so do we.
?
Anyway the 'longest lasting' synthetic rubbers are
viton, silicone, polyurethane,buna
?
I was able to find 'general purpose' 1.78 ID, 1.78 CS? Viton o-rings... here (not Europe) for 20 cents, at 100... net (not including shipping)
?
?
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Re: HP 141T Power Supply Help Needed
The worst bugs make the instrument diverge from the schematic, often in ways that would look like nonsense if you drew it there.
toggle quoted message
Show quoted text
"From
over 40 years of fault finding and repair experience in a wide range of electronic products, not just instrumentation, the weirdest symptoms often have a really simple root cause!"
?
This
has been my experience as well! Makes it very easy to go down a rabbit hole. Which is why I always do a thorough visual inspection first. Also checking mechanical components of switches, pots, etc. Giving them a good clean right off the bat and testing those
first can save you a lot of headache.
?
-Frank
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Re: 8566B Attenuator Service
There seem to my eye to be ridges on some of the gold plating on those pads.? This can cause issues.? Gentle use of a paper eraser can help here (but the gold is thin, don't over do it). I've also found deoxit gold can be helpful in cleaning the contacts.
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Re: HP 141T Power Supply Help Needed
Nice one Bill.
??? Dave B.
From: Bill
Berzinskas
Date: Sat, 14 Sep 2024 15:55:06 GMT
F4 had blown when I was getting 24v.??? I replaced it
and q4, soldering both pins of q4 temporarily.?? It's possible the
"one good" inseption clip was not.???
I'm just glad to be over that for now...
--
Created on and sent from a Unix like PC running and using open source software:
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Re: HP 141T Power Supply Help Needed
"From over 40 years of fault finding and repair experience in a wide range of electronic products, not just instrumentation, the weirdest symptoms often have a really simple root cause!"
?
This has been my experience as well! Makes it very easy to go down a rabbit hole. Which is why I always do a thorough visual inspection first. Also checking mechanical components of switches, pots, etc. Giving them a good clean right off the bat and testing those first can save you a lot of headache.
?
-Frank
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Re: 8566B Attenuator Service
Hard to be sure from the picture but how do the O-rings look, the
lower one on the far left actuator rod (the 'ribbon cable' end)
looks a bit odd?
Sometimes the O-rings go gooey and sometimes they harden, either way
it can affect the 'throw' of the actuator solenoid - especially the
lower one - which might lead to the symptoms you describe.
On 14/09/2024 17:03, Jinxie via
groups.io wrote:
toggle quoted message
Show quoted text
Hi all,
?
So I've removed the attenuator and stripped it down to a
point where I can see the important bits and I cannot, from
careful inspection alone, see anything amiss with it (photo
attached). The pads all look nice and there are 4 of them! I'm
guessing one 10dB and the rest 20dB ones. The longer ones
measure about 82 ohms each across their terminals with minor
variations between them and the shorter measures 52 ohms approx.
The springs underneath look like brand new and the plungers do
flip from on to off with just a bit of pressure from a
screwdriver but I haven't tried to actuate them under power
(24V) yet. I thought I'd best pause and get some suggestions
before I do something which could cause damage.
Some of you may recall from a previous thread that when the
attenuator was in circuit and I attempted the calibration
procedure, I saw no signal visible with the 0dB and 10dB
settings. The 20, 30, 40, 50 and 60dB settings seemed okayish
(some a bit noisy) but 70dB was *very* noisy.? Any suggestions
as to how to proceed?
?
Thanks,
?
J.
Attachments:
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Re: 8566B Attenuator Service
That's an old one! The newer versions have a PCB with one-shots on board. These attenuators are pulsed on/off so I'd be warry of using a bench supply to activate the solenoids; you might burn them up and then you're toast!
The better option is to plug it in to the unit and activate that way. You should be able to verify that the spring fingers are moving up and down.
With the pad assemble in place (just a few screws to hold it) you can do a few things. Place an ohmeter between the two ports and verify you have resistance (pretty low) for all combinations. Even better is to used an RF generator and a spectrum analyzer to
measure it. (a scope would also work)
You can try cleaning the springs and pads with IPA but be very careful!
Good luck.
Mark
toggle quoted message
Show quoted text
Hi all,
?
So I've removed the attenuator and stripped it down to a point where I can see the important bits and I cannot, from careful inspection alone, see anything amiss with it (photo attached). The pads all look nice and there are 4 of them! I'm guessing one
10dB and the rest 20dB ones. The longer ones measure about 82 ohms each across their terminals with minor variations between them and the shorter measures 52 ohms approx. The springs underneath look like brand new and the plungers do flip from on to off with
just a bit of pressure from a screwdriver but I haven't tried to actuate them under power (24V) yet. I thought I'd best pause and get some suggestions before I do something which could cause damage.
Some of you may recall from a previous thread that when the attenuator was in circuit and I attempted the calibration procedure, I saw no signal visible with the 0dB and 10dB settings. The 20, 30, 40, 50 and 60dB settings seemed okayish (some a bit noisy)
but 70dB was *very* noisy.? Any suggestions as to how to proceed?
?
Thanks,
?
J.
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Re: 8566B Attenuator Service
Hello Jinxie,
It seems you have indeed one 10dB, one 20 dB and two 20dB combined to make 40.
From what you say I'd think the 10dB is the culprit. 60 ok, 70 not?
Remember for the test what someone above suggested: Why not try it with low voltage CC? Very easy to measure the attenuation and to see on a scope if it's noisy!
Not much, just my 2€cents!
Best,
Renaud
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Re: HP 141T Power Supply Help Needed
Different load is very plausible, but if so, I'm disappointed they didn't annotate it.? Tsk.
Dave Wise
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Show quoted text
Re:-
"That discrepancy between A2Q9.C and Q4.C is certainly a typo, or
perhaps the two points were measured at different times and the mains
voltage changed, and no-one noticed that they're by definition the same."
Under different load conditions perhaps?? (Plug-ins present, or not.)
I see there is also mention of 2V ripple on the +ve unregulated side
(Q4.Q9 collector.)? Presumably when under some unspecified load.
(I don't have a copy of the full manual.)
Regards.
Dave B.
--
Created on and sent from a Unix like PC running and using open source software:
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Hi all,
?
So I've removed the attenuator and stripped it down to a point where I can see the important bits and I cannot, from careful inspection alone, see anything amiss with it (photo attached). The pads all look nice and there are 4 of them! I'm guessing one 10dB and the rest 20dB ones. The longer ones measure about 82 ohms each across their terminals with minor variations between them and the shorter measures 52 ohms approx. The springs underneath look like brand new and the plungers do flip from on to off with just a bit of pressure from a screwdriver but I haven't tried to actuate them under power (24V) yet. I thought I'd best pause and get some suggestions before I do something which could cause damage.
Some of you may recall from a previous thread that when the attenuator was in circuit and I attempted the calibration procedure, I saw no signal visible with the 0dB and 10dB settings. The 20, 30, 40, 50 and 60dB settings seemed okayish (some a bit noisy) but 70dB was *very* noisy.? Any suggestions as to how to proceed?
?
Thanks,
?
J.
|
Re: N9010A 32-bit XSA Software for Windows 7
Thanks Stan,
?
The unit can run the 32-bit version of Windows 7 - You can also get the custom devices to install by extracting the Windows XP drivers and then dropping the correct WDFCoInstaller DLL into the same directory (Don't know if they work as we didn't have the XSA App Running).
?
So it appears to be all ready except for the XSA app. I've heard that there were license key issues but, again, without a 32-bit version of the app I couldn't tell.
?
I'm not after any specific version of the XSA app so any one that you can find that is Windows 7 only would work - I do know that A.24.56 is a 64-bit version of the app so it should be earlier than that
?
Thanks,
?
TonyG
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Re: HP 141T Power Supply Help Needed
F4 had blown when I was getting 24v.??? I replaced it and q4, soldering both pins of q4 temporarily.?? It's possible the "one good" inseption clip was not.???
I'm just glad to be over that for now...
Hi again.
?From the above measurements, it looks like Q4 is bad (open collector?)?
But later it is said the -12.6 rail came good.
Intermittent connections around Q4, as someone (forget who) mentioned
happened due to a bad power transistor heatsink mounted socket, that I
too in the past have had troubles with, in other makers kit where they
were used for convenience.? Or other bad connection issue(s).
It would be worth checking F4 and it's holder or clips if PCB mounted,
and their soldering on the PCB too perhaps.
The + and - 100V rails don't seem too far out, for now.
The -24V episode on the -12V rail, might have damaged (for example)
flood gun filaments in the CRT (if your instrument has a storage tube.)?
There was I recall, one other who said they had a tube with burnt out
flood gun filaments.?? Or was that with F4 removed, and you saw that on
the transformer side of F4?
?From over 40 years of fault finding and repair experience in a wide
range of electronic products, not just instrumentation, the weirdest
symptoms often have a really simple root cause!
Regards to All.
Dave B.
--
Created on and sent from a Unix like PC running and using open source software:
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Brian
Jinxie
Frank Mashockie
