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Re: HP 8350B sweeper behavior

 

Some more pics of the broken CW-Filter capacitor.

I made some experiments to measure the effect of CW filtering on frequency:
CW 1000 MHz (after 2 hours with CW filter on), frequency CAL'd to 1GHz: CW Filter to off: +5kHz.
CW 10 MHz (after 30 min later): frequency -75kHz, CW Filter to off: +2 kHz
CW 2400 MHz (immediately after): frequency -2MHz, CW Filter to off: +15kHz
CW 2400 MHz (after 90 minutes): frequency -48kHz, CW Filter to off: +10kHz

Its interesting to see the charging and forming effect on the cap as the delta between CW filter on and off gets smaller. But these variations are much smaller than the variation of nearly 2MHz I get when the current through the YTO changes and probably heats it up a little. All in all I cannot see why this capacitor is critical, except if you do not want to see the slightes change in frequency when turning CW filter on or off. Why do that in CW mode? In sweep-mode CW filter is turned off anyway.

BTW, does the older 86222B has a CW filter, too? There is nothing on the front panel, its output in CW mode is comparable to the 83522A with CW filter on.

cheers
Martin

P1020616 _21.11.2023 - 17h30_.jpg
P1020621 _21.11.2023 - 17h33_.jpg
P1020627 _21.11.2023 - 17h35_.jpg

Re: HP 8350B sweeper behavior

 

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Hi,

?

I have 3 plug-ins, and for the 83522A, I know that it is the original capacitor, since it was purchased new from HP at the time, and I was the only user of this device. I bought it when the company ceased operations.

?

So for the 83522A and 83540A, the capacitor is on A6. For the 83595A, the capacitor is on A8. I removed the 300uF capacitor on the 83595A and noticed right away that it was much heavier than a 330UF 40V capacitor. Having no performance problem, I put the original capacitor back in place after inspection.

?

De?: [email protected] <[email protected]> De la part de Jim Adney
·¡²Ô±¹´Ç²â¨¦?: 21 novembre 2023 08:32
??: [email protected]
Objet?: Re: [HP-Agilent-Keysight-equipment] HP 8350B sweeper behavior

?

On Mon, Nov 20, 2023 at 02:09 PM, Martin wrote:


I can hardly believe what I saw when I took out the A6-board. A capacitor with only one leg... what the heck is so special about this one that its so different to all the others - and leaking, too!

?

?

The wet Ta caps that I'm familiar with, and like to use, have a glass seal around the pos. lead. This one appears to have a rubber seal, but the odd thing is that the leak appears to have been at the neg, case, end. How does this happen? Is this a typical failure mode?

Are we SURE this is actually a Ta cap? I'd like to see a better photo of the writing on the case.

I've never seen one of the glass sealed Ta caps leak. Does it happen occasionally?

Capacitor_CW filter.jpg

Re: HP 8350B sweeper behavior

 

On Mon, Nov 20, 2023 at 02:09 PM, Martin wrote:

I can hardly believe what I saw when I took out the A6-board. A capacitor with only one leg... what the heck is so special about this one that its so different to all the others - and leaking, too!

?

?
The wet Ta caps that I'm familiar with, and like to use, have a glass seal around the pos. lead. This one appears to have a rubber seal, but the odd thing is that the leak appears to have been at the neg, case, end. How does this happen? Is this a typical failure mode?

Are we SURE this is actually a Ta cap? I'd like to see a better photo of the writing on the case.

I've never seen one of the glass sealed Ta caps leak. Does it happen occasionally?
Re: HP 8350B sweeper behavior

 

On 21. Nov 2023, at 02:32, Ed Breya via groups.io <edbreya@...> wrote:
If finding reasonable wet Ta caps is difficult or outrageous, you can do some experiments with Al types, with proper selection and testing, and acceptance of good but not necessarily perfect original performance...
I did a very thorough selection before choosing the cap with the best dimensions ;-)

Do you know the magnitude of currents going into the YTO's coil? Since the capacitor is in parallel to the coil, the voltage-to-current converter is unable to see and correct for its leakage. As a consequence: higher CW frequency -> higher current -> higher voltage -> higher leakage -> higher shift in frequency when I switch CW-filter on and off.

I'll check that today once the unit is stable (takes an hour or two).

cheers
Martin
Re: HP 8350B sweeper behavior

 

¿ªÔÆÌåÓý

On 20. Nov 2023, at 21:42, paulswed <paulswedb@...> wrote:
Those are very very special caps. They are made to insure that the equipment?fails after a number of years.?

:-)

The acid that leaks out will dissolve?PC traces...

Apparently there is no damage to the traces. I used a glassfibre-brush to get the dirt off. These traces only lead to the test points, so no functional impact.?

cheers
Martin
Re: HP 16500C looking for logic analyser boards that are functional

 

I just wanted to be clear that when we were talking about the various VIA on the board this is the sort of problem I should be going after? I put red circles next to the things I was planning to go at with the solder sucker when it arrives.



Should I just go after basically all the through hole VIA in the area? What makes it confusing is they put some sort of green coating on the via which makes it hard to tell what is corrosion and what isn't!?



On Tue, Nov 21, 2023 at 11:34?AM Damien Towning via <connolly.damien=[email protected]> wrote:
I have two things. The users reference and the programmers guide. From what I can glean in the users reference it should pop up some sort of programing interface via telnet.?

From the user guide,?

"? Telnet or ftp: Initiate a session from your controlling computer. If you are using telnet, be sure to specify socket 5025. If you are using ftp, log in as control."?

"Telnet: Type programming commands in directly."?

It will also remote xterm but it seemed simpler just to get Telnet going first. I wonder if that functionality needed to come off something that needs to be installed via disk. The programming guide seems to imply one is sitting in a terminal and able to issue various instructions. Contains example code to feed it.?


On Tue, Nov 21, 2023 at 11:03?AM Adrian Godwin <artgodwin@...> wrote:
I think the 16700 and possibly the 16600, which run HPUX on a PA-RISC processor have a telnet client but not the 16500.
It does have some open ports but they don't respond to what i've tried (SCPI commands).
Something I saw while looking for strings in the binary system files indicated they might provide an RPC interface.



--
Damien Towning

?



--
Damien Towning

?
Re: HP 8350B sweeper behavior

 

If finding reasonable wet Ta caps is difficult or outrageous, you can do some experiments with Al types, with proper selection and testing, and acceptance of good but not necessarily perfect original performance. First, try to get a bunch of brand-new, good quality Al caps in the right size and voltage range, and with specified DC leakage (will be temperature dependent too, usually spec'd). You'd want to select types/brands with lowest leakage specs, and about 2-3 times the original C value - maybe 680-1,000 uF in this case, and 30 VDC rating (same as original). Then set them all up with feed from a 30 V PS to form to the maximum expected operating voltage, for maybe a few days. If you want, you can do a "before" picture for comparison, and measure and record the DC leakage of each one. After the forming time, measure the leakages, and pick the one with the least to use as the replacement cap.

You can go with bigger C to get lower ESR and better filtering, but the leakage goes up in proportion. And of course, the part(s) have to fit the allowable space. Note - don't bother with OSCON types - they are way worst for leakage, but best for ESR.

In long periods of non-use, the leakage will increase, so next time it's used, you can reform them somewhat if desired by setting CW output at the highest possible YTO frequency (maximum coil thus forming voltage), for maybe a few hours to overnight. You probably wouldn't notice any difference in sweepers like these anyway, but at least you know the leakage can be reduced some amount.

Ed
Re: How do I update HP 3488A manuals in the Wiki?

 

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Does Artek have it?

DaveD

On Nov 20, 2023, at 19:59, Steve Holland via groups.io <sholland@...> wrote:

?

I bought a HP 3488A Switch/Control unit. Our Wiki has a 3499 manual with the 3488 manuals, and I have seen better versions of the manuals.?


Since I own a unit I thought I¡¯d take ownership of the issues, to the extent I¡¯m allowed. How do I help with the manuals?

Steve
How do I update HP 3488A manuals in the Wiki?

 

I bought a HP 3488A Switch/Control unit. Our Wiki has a 3499 manual with the 3488 manuals, and I have seen better versions of the manuals.?


Since I own a unit I thought I¡¯d take ownership of the issues, to the extent I¡¯m allowed. How do I help with the manuals?

Steve
Re: HP3400A Nonlinearities

 

Thank you - if I had took a few to actually think it over that would have been kinda obvious.? Thanks for being patient and answering ;-)

Hal
Re: HP 16500C looking for logic analyser boards that are functional

 

I have two things. The users reference and the programmers guide. From what I can glean in the users reference it should pop up some sort of programing interface via telnet.?

From the user guide,?

"? Telnet or ftp: Initiate a session from your controlling computer. If you are using telnet, be sure to specify socket 5025. If you are using ftp, log in as control."?

"Telnet: Type programming commands in directly."?

It will also remote xterm but it seemed simpler just to get Telnet going first. I wonder if that functionality needed to come off something that needs to be installed via disk. The programming guide seems to imply one is sitting in a terminal and able to issue various instructions. Contains example code to feed it.?


On Tue, Nov 21, 2023 at 11:03?AM Adrian Godwin <artgodwin@...> wrote:
I think the 16700 and possibly the 16600, which run HPUX on a PA-RISC processor have a telnet client but not the 16500.
It does have some open ports but they don't respond to what i've tried (SCPI commands).
Something I saw while looking for strings in the binary system files indicated they might provide an RPC interface.



--
Damien Towning

?
Re: HP 16500C looking for logic analyser boards that are functional

 

I think the 16700 and possibly the 16600, which run HPUX on a PA-RISC processor have a telnet client but not the 16500.
It does have some open ports but they don't respond to what i've tried (SCPI commands).
Something I saw while looking for strings in the binary system files indicated they might provide an RPC interface.
Re: HP 3400A Upgrade PCBs Available

 

On Mon, Nov 20, 2023 at 04:01 PM, factory wrote:
it confirms the 1826-1381 for U602
Which is an LT1012 - I was very surprised to see that they used such a precision amp on purpose - the precision is not needed there other than to possibly not have a negative output; even in the 3400B they used one section of a LM324. Doesn't hurt but just seems like an unnecessary expense and a departure from any other in the series.

Hal
Re: HP 8350B sweeper behavior

 

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After all of this, I need to:

  1. remove/replace the battery
  2. check/replace that cap

Mark


From: [email protected] <[email protected]> on behalf of Ed Breya via groups.io <edbreya@...>
Sent: Monday, November 20, 2023 1:17 PM
To: [email protected] <[email protected]>
Subject: Re: [HP-Agilent-Keysight-equipment] HP 8350B sweeper behavior
?
Just from your description I knew it's a wet-slug Ta type. These were used in certain spots where fairly high capacitance is needed, with low leakage. When it opened up, there went the CW filter function. The fresh cap seems to show that it can work, but a regular Al electrolytic is not the proper part here. Ideally and officially it should be another wet Ta for best performance.

But, who cares after fifty years? It's not like it will need to run like new, and over a fully specified temperature range. if you really do want or need it to be like new in this respect, the cap should be the original type, which would be very expensive to get new. The next best would be to find used or NOS ones that are still good, and after that would be a bunch of solid Ta caps in parallel. An even better than original, and permanent solution would be 300 uF-worth of plastic caps, but that's physically impractical.

Ed

Re: HP 3400A Upgrade PCBs Available

 

On Mon, Nov 20, 2023 at 09:32 PM, Harold Foster wrote:

My board was a revision "D" and I uploaded pictures to the 3400A area of the files section.

Hal
Thank you Hal, those pictures should have all the missing information, I can see they removed a double thickness ground trace from the front and made a much wider trace on the back, it confirms the 1826-1381 for U602. I'll check the resistors another night, getting late tonight here in the UK.

And Artek did have the correct manual, very quick response to my email and I now have an excellent quality manual covering the 1982-84 versions.


David
Re: HP 3400A Upgrade PCBs Available

 


My board was a revision "D" and I uploaded pictures to the 3400A area of the files section.

Hal
Re: HP 8350B sweeper behavior

 

Just from your description I knew it's a wet-slug Ta type. These were used in certain spots where fairly high capacitance is needed, with low leakage. When it opened up, there went the CW filter function. The fresh cap seems to show that it can work, but a regular Al electrolytic is not the proper part here. Ideally and officially it should be another wet Ta for best performance.

But, who cares after fifty years? It's not like it will need to run like new, and over a fully specified temperature range. if you really do want or need it to be like new in this respect, the cap should be the original type, which would be very expensive to get new. The next best would be to find used or NOS ones that are still good, and after that would be a bunch of solid Ta caps in parallel. An even better than original, and permanent solution would be 300 uF-worth of plastic caps, but that's physically impractical.

Ed
Re: HP 8350B sweeper behavior

 

Those are very very special caps. They are made to insure that the equipment?fails after a number of years.?
The acid that leaks out will dissolve?PC traces. Make sure you clean any residue off. I use a bit of baking soda and water. Sort of a soupy paste.
Then clean off with water. Save those traces.
Regards
Paul
WB8TSL
Re: HP 3400A Upgrade PCBs Available

 

Below is a partial screengrab showing what the dropbox email from Artek contained, from this you should be able to make out the Agilent front page on the second file, I've sent a message, hopefully they still have the scan they did, also odd as I didn't buy the first manual.


David
Re: HP 3400A Upgrade PCBs Available

 

Thanks to both Hal & David for info.

The 03400-60013 manual covers 03400-66512 Rev A (prefix 2225) & Rev C (prefix 2415).
As has been suggested elsewhere, it's most possible the Rev D was only covered in a service note, there is a low resolution picture of this board on the web with 2713 on the sticker (1987 date?).

I've added pictures of several A6 boards I own here; https://www.eevblog.com/forum/repair/hp-3400a-ldrs-replacement/msg5015905/#msg5015905

For my new board, I'm very much in design stage, about 75% done in KiCAD, using my Rev C board as a guide.
The Rev D has minor component differences (two removed) around the meter amp U602, plus minor differences I can see to the traces above the edge connector, I want to keep to through-hole parts.
Also wanted to confirm the U602 part number (think it's 1826-1381 aka LT1012, but not 100% sure from the low res picture), less critical at the moment is knowing any resistor value changes, this can be done afterwards.

Need to ask Artek about the correct manual, I ordered the 03400-60013 at $9.95, but for some odd reason the dropbox zipped file contained the 3400A-OSM-90008 (an excellent scan from Artek) and that Agilent branded 03400-90013 pdf of poor quality.

David
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