Re: Anyone out there fix a partially working 334A I need desperately to get it up and running!
On 4/7/20 12:04 PM, Jeremy Nichols wrote: Purely out of curiosity, what is the purpose of a chopper in a 334
distortion analyzer? HP used choppers in a lot of their DC voltmeters to
convert the DC to AC. They’d run the AC through some amplifiers and then
convert back to DC to run the meter. That took care of the old DC
amplifier drift problems. Since a distortion analyzer is already working
with AC, I would think a chopper wouldn’t be necessary. Obviously
there’s something I’m missing.? Unless my memory is failing, it's not strictly a chopper, but it's part of the automatic tuning system. The choppers are digitally-controlled switches, but I believe the LDR-based subsystem in the 33x distortion analyzers are more "analog" in nature, to follow the fundamental frequency automatically. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
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Re: Anyone out there fix a partially working 334A I need desperately to get it up and running!
Purely out of curiosity, what is the purpose of a chopper in a 334 distortion analyzer? HP used choppers in a lot of their DC voltmeters to convert the DC to AC. They’d run the AC through some amplifiers and then convert back to DC to run the meter. That took care of the old DC amplifier drift problems. Since a distortion analyzer is already working with AC, I would think a chopper wouldn’t be necessary. Obviously there’s something I’m missing.?
Jeremy?
-- Jeremy Nichols
6.
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hello Dave,
yes, specials:
The Power Line Supply is a Option and not always inside.
427A have a Set of 4 obsolete 6.75V mercury batterys,
if they are tired and there is no PSU, build it self.
The instrument needs ±13,5V.
Another way is to use 2 pcs. of 9V Blocks, it will work with them also.
Martin
Am 07.04.2020 um 06:17 schrieb Dave McGuire:
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On 4/7/20 12:14 AM, Paul Bicknell wrote:
Just switched on a 427A volt meter that I rescues a few weeks ago
Just wondering is their any think special about it and is it worth spending
any time on as it reads low I've never put my hands on one, but I checked out the specs a bit. It
doesn't seem particularly noteworthy in any specific way, but it sure
does look like a nice handy all-around bench meter with a nice big meter
face.
-Dave
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Re: Anyone out there fix a partially working 334A I need desperately to get it up and running!
Hello,
a dude named CarlsonLabs has had a 2h video on replacing these neons. Never sat through it all the way to the fartingsound, don?t have a link handy but wanted to mention it. If there is interest I can go hunt it down.
Tam
With best regards
Tam HANNA
Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at
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On 2020. 04. 07. 16:41, n4buq wrote: Same problem with neon-choppers as found in the 410C. HP replaced that with a fully solid-state board towards the end of production. I wonder if something similar could be done for the 334A?
Thanks,
Barry - N4BUQ
----- Original Message -----
From: "Chuck Harris" <cfharris@...>
To: [email protected]
Sent: Tuesday, April 7, 2020 8:52:18 AM
Subject: Re: [HP-Agilent-Keysight-equipment] Anyone out there fix a partially working 334A I need desperately to get
it up and running!
The killer problem I have found with 334A's, is they have an optically
driven chopper that relies on NE2 style neon bulbs, and CdS photo resistors
to do the chopping.
The problem is two fold: First, the neons get smoky inside, and don't put
out enough light to switch the photo resistors, and second, the CdS photo
resistors sometimes fail.
The neons used have a little radioactive material sintered into their
electrodes,
to make them dark fire reliably, and modern replacements don't. And, the
CdS photo resistors were selected and matched for maximum on/off resistance
spread. CdS photo resistors run afoul of the RoHS regulations because of the
Cadmium, and are very expensive, if you can get them at all. It is unlikely
you can find the super wide spread selected variety that HP used.
All of the other problems I have seen have been simple capacitor replacement
issues. The 334A is stocked full of TE/30D style electrolytic capacitors,
and
their rubber seals have pretty much all turned to stone by now.
Replacing the capacitors won't have any real effect on calibration.
-Chuck Harris
Steve wrote:
I have an Hp 334A that powers on and appears to function partially but I’m
not sure what all could be wrong with it. If anyone fixes these units at a
reasonable price I would be interested in having it put back in top notch
shape with a good calibration. I restore vintage hifi and I need to get it
up and going as quickly as possible.
|
Re: Anyone out there fix a partially working 334A I need desperately to get it up and running!
Certainly it could, but a bit of engineering time would be required
to make sure that none of the specifications were compromised...
-Chuck Harris
n4buq wrote:
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Same problem with neon-choppers as found in the 410C. HP replaced that with a fully solid-state board towards the end of production. I wonder if something similar could be done for the 334A?
Thanks,
Barry - N4BUQ
----- Original Message -----
From: "Chuck Harris" <cfharris@...>
To: [email protected]
Sent: Tuesday, April 7, 2020 8:52:18 AM
Subject: Re: [HP-Agilent-Keysight-equipment] Anyone out there fix a partially working 334A I need desperately to get
it up and running!
The killer problem I have found with 334A's, is they have an optically
driven chopper that relies on NE2 style neon bulbs, and CdS photo resistors
to do the chopping.
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Re: OT: Help identifying these mixers required - ADTEC
Tim,
The other device was made by ADTECH as you noted, later ECI, which was bought by Alpha Microwave (when Control Data owned them) and became the basis for their MMW mixer line. My first boss at Westinghouse Defense was one of the principles at ADTEC (all came from Johns Hopkins, including Merrill Skolnik and other notables). Really innovative MMW company in the early 60's.
IIRC, uses a MMW flat cartridge crystal, point contact type with a hand pointed Tungsten whisker (using HF) made by Frank Trageser (only guy who could do them right...).
If the diode tests good with a ohm-meter for some sort of front to back ratio then you are in business. Use typical precautions.? Mostly used in the harmonic mode with LO & IF diplexed together on the N connector, IF in the DC-several GHz (10 ?) range. If both ends open, you can use in fundamental mode mixing. NF ranged in the 15-20 dB area.
Should get you close.
BTW, if you decide to get rid of the ADTEC device, let me know, would like it for the collection.
Regards,
Jeff Kruth
In a message dated 4/7/2020 10:07:18 AM Eastern Standard Time, Brucekareen@... writes:
Tim,
Demornai-Bonardi 633 devices were directional couplers that coupled to a crystal detector on one coupled side and a flange on the other.? They were generally used with a reflecting cavity wavemeter on the flanged port to measure frequency.? The W version would have covered 90 to 140 GHz (WR-8).? These are fairly early designs and yours is probably at least fifty years old.? I am not familiar with the other device.
Bruce, KG6OJI
_._,_._,_
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Re: Anyone out there fix a partially working 334A I need desperately to get it up and running!
Same problem with neon-choppers as found in the 410C. HP replaced that with a fully solid-state board towards the end of production. I wonder if something similar could be done for the 334A?
Thanks,
Barry - N4BUQ
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----- Original Message ----- From: "Chuck Harris" <cfharris@...>
To: [email protected]
Sent: Tuesday, April 7, 2020 8:52:18 AM
Subject: Re: [HP-Agilent-Keysight-equipment] Anyone out there fix a partially working 334A I need desperately to get
it up and running!
The killer problem I have found with 334A's, is they have an optically
driven chopper that relies on NE2 style neon bulbs, and CdS photo resistors
to do the chopping.
The problem is two fold: First, the neons get smoky inside, and don't put
out enough light to switch the photo resistors, and second, the CdS photo
resistors sometimes fail.
The neons used have a little radioactive material sintered into their
electrodes,
to make them dark fire reliably, and modern replacements don't. And, the
CdS photo resistors were selected and matched for maximum on/off resistance
spread. CdS photo resistors run afoul of the RoHS regulations because of the
Cadmium, and are very expensive, if you can get them at all. It is unlikely
you can find the super wide spread selected variety that HP used.
All of the other problems I have seen have been simple capacitor replacement
issues. The 334A is stocked full of TE/30D style electrolytic capacitors,
and
their rubber seals have pretty much all turned to stone by now.
Replacing the capacitors won't have any real effect on calibration.
-Chuck Harris
Steve wrote:
I have an Hp 334A that powers on and appears to function partially but I’m
not sure what all could be wrong with it. If anyone fixes these units at a
reasonable price I would be interested in having it put back in top notch
shape with a good calibration. I restore vintage hifi and I need to get it
up and going as quickly as possible.
|
Re: OT: Help identifying these mixers required
Tim,
Demornai-Bonardi 633 devices were directional couplers that coupled to a crystal detector on one coupled side and a flange on the other.? They were generally used with a reflecting cavity wavemeter on the flanged port to measure frequency.? The W version would have covered 90 to 140 GHz (WR-8).? These are fairly early designs and yours is probably at least fifty years old.? I am not familiar with the other device.
Bruce, KG6OJI
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Re: Hints on removing burned tantalum residue
Thanks everyone for the great suggestions.? I will try them all. Starting with the simpler ones then moving up.? The RF board is just a simple D/C to DC power supply.? I shall report back.?
Thanks Dave
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On Apr 7, 2020, at 2:41 AM, Jan Weber via groups.io <jancarlweber@...> wrote:
? May I suggest using a glass fiber pen/brush for removing burnt-in particulate matter and charring?
I've used them in the past to clean corrosions caused by leaking batteries.?
Regards
Jan What a mess - it really did a number on that board section. I agree that acetone would be a pretty good solvent for some of the char, but unfortunately, it may not clean it all off. Some is likely carbon particles (from burning up the coating) and Ta oxides (from the cap guts) splattered onto (and into) the surfaces, and no conventional solvent will dissolve it. The good news is that even if you can't get it spic and span, any remaining residue probably won't hurt the circuit operation after cleaning and repair.
Besides some solvent action, good mechanical scrubbing should help. I'm not sure if your comment about IPA is a question (will it work?) or a statement (tried and it doesn't work). I'd start with IPA, if you haven't already. Paint thinner or acetone are logical next steps. Acetone may be a little too intense to leave on for very long.
Presuming you don't want to remove the board from the RF assembly, which appears to have its feed-throughs soldered to the board, the trick is to be able to work on board cleanup without getting anything bad into the RF. IPA and acetone would probably be best then, since they're miscible with water and will evaporate quickly, while paint thinner would be a bit messy and slow to depart.
If the board can be readily removed, you have more options such as aqueous washing with detergents, and some gentle abrasive action such as an opaque toothpaste worked with - of course - an old toothbrush, to scrape off the particles that aren't too tightly embedded in the surfaces. Regardless of the solvents and methods, I always use old toothbrushes for scrubbing. Higher intensity solvents may dissolve or degrade the bristles and heads, so you have to work fast in some cases.
Another option, if you have access to the appropriate equipment, is to skip solvents altogether and do purely mechanical cleaning, like with a soda or walnut shell blaster.
Good luck.
Ed
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Re: Hints on removing burned tantalum residue
Thanks Nigel, I have found the IFR group. I should have looked first. ? Thanks
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On Apr 7, 2020, at 2:50 AM, nigel adams via groups.io <nigel.adams@...> wrote:
?
Have you tried the IFR group as well - there are people who have this stuff and might be able to help.
Not directly HP related but this is where the knowledge is.
I am starting to repair an IFR-1200S that had an incident.
<IMG_0884.jpeg> <IMG_0886.jpeg>
A 150 uF 15V tantalum went up in smoke.
What is the best solvent to remove the residue on the rest of the PCB. Isopropyl does not take all of it off? Want to get it all clean before I replace parts and continue the repair.
Thanks
Dave?
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Re: Anyone out there fix a partially working 334A I need desperately to get it up and running!
The killer problem I have found with 334A's, is they have an optically
driven chopper that relies on NE2 style neon bulbs, and CdS photo resistors
to do the chopping.
The problem is two fold: First, the neons get smoky inside, and don't put
out enough light to switch the photo resistors, and second, the CdS photo
resistors sometimes fail.
The neons used have a little radioactive material sintered into their electrodes,
to make them dark fire reliably, and modern replacements don't. And, the
CdS photo resistors were selected and matched for maximum on/off resistance
spread. CdS photo resistors run afoul of the RoHS regulations because of the
Cadmium, and are very expensive, if you can get them at all. It is unlikely
you can find the super wide spread selected variety that HP used.
All of the other problems I have seen have been simple capacitor replacement
issues. The 334A is stocked full of TE/30D style electrolytic capacitors, and
their rubber seals have pretty much all turned to stone by now.
Replacing the capacitors won't have any real effect on calibration.
-Chuck Harris
Steve wrote:
toggle quoted message
Show quoted text
I have an Hp 334A that powers on and appears to function partially but I’m not sure what all could be wrong with it. If anyone fixes these units at a reasonable price I would be interested in having it put back in top notch shape with a good calibration. I restore vintage hifi and I need to get it up and going as quickly as possible.
|
Re: Ebay seller called m2wave
One trick that worked always for me:
Click on the rating score number:
The seller's profile will open.
Then click on 'contact member':
and check 'This is not about an item' box (important!):
This will let you get in contact with the seller directly, circumventing restrictions set with offered items.
?
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Re: Hints on removing burned tantalum residue
Have you tried the IFR group as well - there are people who have this stuff and might be able to help.
Not directly HP related but this is where the knowledge is.
I am starting to repair an IFR-1200S that had an incident.
 
A 150 uF 15V tantalum went up in smoke.
What is the best solvent to remove the residue on the rest of the PCB. Isopropyl does not take all of it off? Want to get it all clean before I replace parts and continue the repair.
Thanks
Dave?
|
Re: Hints on removing burned tantalum residue
May I suggest using a glass fiber pen/brush for removing burnt-in particulate matter and charring?
I've used them in the past to clean corrosions caused by leaking batteries.?
Regards
Jan
What a mess - it really did a number on that board section. I agree that acetone would be a pretty good solvent for some of the char, but unfortunately, it may not clean it all off. Some is likely carbon particles (from burning up the coating) and Ta oxides (from the cap guts) splattered onto (and into) the surfaces, and no conventional solvent will dissolve it. The good news is that even if you can't get it spic and span, any remaining residue probably won't hurt the circuit operation after cleaning and repair.
Besides some solvent action, good mechanical scrubbing should help. I'm not sure if your comment about IPA is a question (will it work?) or a statement (tried and it doesn't work). I'd start with IPA, if you haven't already. Paint thinner or acetone are logical next steps. Acetone may be a little too intense to leave on for very long.
Presuming you don't want to remove the board from the RF assembly, which appears to have its feed-throughs soldered to the board, the trick is to be able to work on board cleanup without getting anything bad into the RF. IPA and acetone would probably be best then, since they're miscible with water and will evaporate quickly, while paint thinner would be a bit messy and slow to depart.
If the board can be readily removed, you have more options such as aqueous washing with detergents, and some gentle abrasive action such as an opaque toothpaste worked with - of course - an old toothbrush, to scrape off the particles that aren't too tightly embedded in the surfaces. Regardless of the solvents and methods, I always use old toothbrushes for scrubbing. Higher intensity solvents may dissolve or degrade the bristles and heads, so you have to work fast in some cases.
Another option, if you have access to the appropriate equipment, is to skip solvents altogether and do purely mechanical cleaning, like with a soda or walnut shell blaster.
Good luck.
Ed
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Re: Optiion upgrade HP 8753C/B
so finally all option successfully installed, thank you all for your helping comments
PS: for those who don't want to waste time searching in the service manual I attached the procedure here?
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Re: Hints on removing burned tantalum residue
What a mess - it really did a number on that board section. I agree that acetone would be a pretty good solvent for some of the char, but unfortunately, it may not clean it all off. Some is likely carbon particles (from burning up the coating) and Ta oxides (from the cap guts) splattered onto (and into) the surfaces, and no conventional solvent will dissolve it. The good news is that even if you can't get it spic and span, any remaining residue probably won't hurt the circuit operation after cleaning and repair.
Besides some solvent action, good mechanical scrubbing should help. I'm not sure if your comment about IPA is a question (will it work?) or a statement (tried and it doesn't work). I'd start with IPA, if you haven't already. Paint thinner or acetone are logical next steps. Acetone may be a little too intense to leave on for very long.
Presuming you don't want to remove the board from the RF assembly, which appears to have its feed-throughs soldered to the board, the trick is to be able to work on board cleanup without getting anything bad into the RF. IPA and acetone would probably be best then, since they're miscible with water and will evaporate quickly, while paint thinner would be a bit messy and slow to depart.
If the board can be readily removed, you have more options such as aqueous washing with detergents, and some gentle abrasive action such as an opaque toothpaste worked with - of course - an old toothbrush, to scrape off the particles that aren't too tightly embedded in the surfaces. Regardless of the solvents and methods, I always use old toothbrushes for scrubbing. Higher intensity solvents may dissolve or degrade the bristles and heads, so you have to work fast in some cases.
Another option, if you have access to the appropriate equipment, is to skip solvents altogether and do purely mechanical cleaning, like with a soda or walnut shell blaster.
Good luck.
Ed
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Re: Optiion upgrade HP 8753C/B (CRT Focus)
My 8753A had a CRT with low intensity as well as beeing unfocused.
I have not tried to rejuvinate the CRT, but I took the monitor apart and made a deep
cleaning of the HV circuit board. Vacuuming of the electrostatic dust and then
wiping the board as clean as I could with a dampened cloth.
Also the CRT was taken out and cleaned.
The intensity is still low but the focus could then be adjusted to satisfaction.
I guess that leakage currents caused by the dust and dendrites formed
by pollution and moisture in a 30+ year old instrument can be a problem.
Cheers
Ulf Kylenfall
SM6GXV
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OT: Help identifying these mixers required
Hi all,
Pocking around one of my junk boxes I happened across a couple of
mixers I picked up on eBay I had completely forgotten about.
One is an ADTEC M-10 20, the other is a Demornay/Bonardi DBW-633
I'd greatly appreciate it if anyone has specifications or data of
any kind for these devices.
thanks
Tim
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Re: Hints on removing burned tantalum residue
Thanks guys, Good reminder on wooden Q tips. ? There is also Xylene. (Goof off) I shall go at it slowly. ?No rush Might have to wait as it’s sort of hard to just pop over to the local store as many are shut down.? Might also try Ultrasonic. ?
Thanks
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On Apr 6, 2020, at 10:38 PM, Bill via groups.io <ko4nrbs@...> wrote:
? Try Acetone.? I use it with q-tips and a rag.? Don't pour it on the equipment as it may melt some things.? Just dampen the q-tip or rag with it.? ?Have good ventilation and no open flames!!? That includes space heaters. Bill
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Re: Hints on removing burned tantalum residue
Make certain it is a wooden steam Q-tip. ?Acetone will melt the plastic ones.
Ken
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On 6Apr, 2020, at 11:37 PM, Bill via < ko4nrbs@...> wrote:
Try Acetone.? I use it with q-tips and a rag.? Don't pour it on the equipment as it may melt some things.? Just dampen the q-tip or rag with it.? ?Have good ventilation and no open flames!!? That includes space heaters. Bill
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Dave McGuire
Jeremy Nichols
ebrucehunter