|
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.?
|
I would think that a lot of the answer depends on where you are located. If the meter has to be shipped twice the cost could be very high depending on locations.
Stuart K6YAZ
Los Angeles, USA
|
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.
|
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
toggle quoted message
Show quoted text
----- 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.
|
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:
toggle quoted message
Show quoted text
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.
|
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
toggle quoted message
Show quoted text
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.
|
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.
|
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
|
Jeremy,
>Purely out of curiosity, what is the purpose? >of a chopper in a 334 distortion analyzer?
Auto null.
------ Best regards, Goran Finnberg The Mastering Room AB Goteborg Sweden E-mail: mastering@... Learn from the mistakes of others, you can never live long enough to make them all yourself.??? -?? John Luther (\__/) (='.'=) (")_(") Aron, VovVov, Nero & Smurfen:RIP
|
Jeremy,
>Purely out of curiosity, what is the purpose?
>of a chopper in a 334 distortion analyzer?
Auto null.
The neons and light sensitive resistors are used? in a Wien bridge to automatically balance the null.
Page 4.2 onwards describes the circuit in detail.
Loss of a neon and its back to manual tuning.
---------
Best regards,
Goran Finnberg
The Mastering Room AB
Goteborg
Sweden
E-mail: mastering@...
Learn from the mistakes of others, you can never live long enough to
make them all yourself.??? -?? John Luther
(\__/)
(='.'=)
(")_(") Aron, VovVov, Nero & Smurfen:RIP
|
You are right, there are 3 CdS cells, and two lamps that are
used to operate a Wein bridge that performs the auto null function.
The last 334 that was in my shop had one bad CdS cell, and the bridge
could not balance... And no substitute CdS I could find would quite
do the job. As I recall they were large, perhaps 5/8" diameter, CdS
cells.
There are 35 TE/30D type capacitors on the A2, A3, and A5 boards, and
two incandescent lamps. Odds are very large that several of the TE
style capacitors will bad. Several are 3V, and 6V types, and they are
always bad in my experience.
That is where I would start.
-Chuck Harris
Dave McGuire wrote:
toggle quoted message
Show quoted text
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
|
Is it the video on the HP 419 meter? "
toggle quoted message
Show quoted text
On 2020-04-07 11:35 a.m., Tam Hanna wrote: 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
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.
--
This email has been checked for viruses by AVG.
|
Yes!!! You are a truffle pig!
Tam
With best regards
Tam HANNA
Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at
toggle quoted message
Show quoted text
On 2020. 04. 07. 21:05, Merchison Burke via groups.io wrote: Is it the video on the HP 419 meter? "
On 2020-04-07 11:35 a.m., Tam Hanna wrote:
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
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.
|
Thanks, all! I forgot about the Auto Null function.
On Tue, Apr 7, 2020 at 12:22 PM Tam Hanna < tamhan@...> wrote: Yes!!! You are a truffle pig!
Tam
With best regards
Tam HANNA
Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at
On 2020. 04. 07. 21:05, Merchison Burke via wrote:
> Is it the video on the HP 419 meter? ""
>
> On 2020-04-07 11:35 a.m., Tam Hanna wrote:
>> 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
>>
>> 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.
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>
>
|
I haven't used it in a while, I've been using a leader LDM-170 but feel more confident in triusting the 334A. First problem is that you can't "Set" anything unless you have an extremely high voltage signal going in @1VAC then you can fake go through all the steps. second, the auto function works but I'm not sure if it's 100% or not. I'm in Knoxville Tn.
|
The 334 has an Automatic Nulling (A6 board) circuit which uses lamps and a single detector. I see no chopper.
On Tue, Apr 7, 2020 at 12:04 PM Jeremy Nichols < jn6wfo@...> 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.?
Jeremy?
--
Jeremy Nichols
6.
|
Collective wisdom, y'all.
Stay safe...now that Jzonsson de Peffel also got ill, I am
starting to worry a bit. To me, he appeared as the pinnacle of a
healthy happy strong man...
With best regards
Tam HANNA
Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at
On 2020. 04. 07. 22:06, Jeremy Nichols
wrote:
toggle quoted message
Show quoted text
Thanks, all! I forgot about the Auto Null
function.
On Tue, Apr 7, 2020 at 12:22
PM Tam Hanna < tamhan@...>
wrote:
Yes!!! You
are a truffle pig!
Tam
With best regards
Tam HANNA
Enjoy electronics? Join 15k7 other followers by visiting the
Crazy Electronics Lab at
On 2020. 04. 07. 21:05, Merchison Burke via wrote:
> Is it the video on the HP 419 meter? ""
>
> On 2020-04-07 11:35 a.m., Tam Hanna wrote:
>> 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
>>
>> 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.
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>
>
--
Jeremy Nichols
6.
|
I'm sorry Michael, I misremembered. Before I looked in the
manual, I remembered lamps, of some sort, and CdS photoresistors,
and it registered as a choppers.
It is actually a Wien Bridge. Three of the four legs are CdS
photoresistors. One lamp feeds two of the photoresistors, and
the other feeds a single photoresistor.
The last time I worked on 334's was about 1984. I am surprised that
I remembered as much as I do.
-Chuck Harris
Michael A. Terrell wrote:
toggle quoted message
Show quoted text
The 334 has an Automatic Nulling (A6 board) circuit which uses lamps and a
single detector. I see no chopper.
On Tue, Apr 7, 2020 at 12:04 PM Jeremy Nichols <jn6wfo@...> 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.
Jeremy
--
Jeremy Nichols
|
Not that it means anything but I do see a neon glow from the photo cells and it appears to be glowing bright. It looks as if someone has worked on this thing at some point because wire positions are written in pencil on the inside chassis. Also, I'm supposed to have 2 volts on one of the first two test points but it's not there. I do have an adjustable positive power supply but the negative is low and will not adjust in either direction. Man, I'm putting way too many irons in the fire at the moment, I also have an Hp 652A that needs some work. The 652 may be simple in it's engineering and circuitry but it's baffling the heck out of me. I had to replace 6 of the 3904's in the power supply to get it to work and the expand WAS working now the expand operation is dead again. I wonder if these two would make either good door stops or boat anchors? If good door stops that would at least make for a good conversation piece!
|
I have both of those models as well that I purchased very inexpensively at an estate sale a few years ago and this conversation has prompted me to drag those out and see the operational status of both.
My 334A seems to work well enough (although the balance controls need some TLC as they've gone "scratchy"); however, I did check the PS rails and both were extremely close to +/- 25VDC. The AUTOMATIC function doesn't appear to work correctly. If I switch to AUTOMATIC, the meter starts to drift off of "balanced" so something may be wrong there. I haven't checked too much else on it.
My 652A's EXPAND function does not work and I intend to investigate that soon. The A3 board is certainly in a convenient place to check that so maybe I can get that functional without too much trouble.
Thanks,
Barry - N4BUQ
toggle quoted message
Show quoted text
----- Original Message ----- From: "Steve" <roadkill71@...>
To: [email protected]
Sent: Thursday, April 9, 2020 8:34:52 AM
Subject: Re: [HP-Agilent-Keysight-equipment] Anyone out there fix a partially working 334A I need desperately to get
it up and running!
Not that it means anything but I do see a neon glow from the photo cells and
it appears to be glowing bright. It looks as if someone has worked on this
thing at some point because wire positions are written in pencil on the
inside chassis. Also, I'm supposed to have 2 volts on one of the first two
test points but it's not there. I do have an adjustable positive power
supply but the negative is low and will not adjust in either direction. Man,
I'm putting way too many irons in the fire at the moment, I also have an Hp
652A that needs some work. The 652 may be simple in it's engineering and
circuitry but it's baffling the heck out of me. I had to replace 6 of the
3904's in the power supply to get it to work and the expand WAS working now
the expand operation is dead again. I wonder if these two would make either
good door stops or boat anchors? If good door stops that would at least make
for a good conversation piece!
|
Steve
Jeremy Nichols
Dave McGuire
Michael A. Terrell