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Date
Re: Maximum depth of HP rack mountable gear?

 

As already mentioned, the 8664A and 8665A/B signal generators have to be some of the deepest products that HP made.? This is especially true if you have an option -010 unit: the low rf leakage version.? They're heavy too, like a sack of cement!? Mine still have the yellow, "two person lift" safety labels attached to the cabinets.? Lots of good exercise in moving these beasts around.? Since purchasing the units, I was able to save money by canceling my gym membership! :-)
Re: Fixing a sick 4332A LCR meter

 

Hello again Sean,

Indeed, Artek has a good manual (actually, I was the one who lent them a paper copy for scanning).

The R36 burn may have occurred when someone accidentally fed an external voltage to the Guard terminal. This voltage would have been fed to R36 directly via the S1A(R) function switch. If this is what happened, obviously the cause of the burn is not within the meter, and replacing R36 will take care of this failure.

Then, of course, the real repair project starts ! I would think along these lines:
- First, are there any functions that DO work ? Try R, L, C, try several ranges, and see what happens.
- Since the power supplies are OK, the next step would be to check whether the oscillator and output amplifier are working. Set the function to Capacitance, and connect an oscilloscope at the HIGH input terminal. You should see a nice sine wave at 1 kHz or 100 kHz depending on range, with 77 mV RMS amplitude.
If you don't see this sinewave, then the problem is either in the oscillator (look at the emitter of A2Q2) or the low-Zout amplifier (A1 IC5).

If the sine wave on the HIGH output is OK, we'll continue the search in the measurement circuits. So, please let me know what you see... I'm more than happy to share the fun !!!

Sincerely,

Joel
Re: HP 3455a DVM repair

 

Like most DVM's, there is a relay between the terminals on the
front panel, and the internal circuitry. If that relay is not
closing... for whatever reason... you would have behavior like
you are describing.

I have found lots of relay failures on the sorts of reed relays
that are used in the 3456 and 3455. I would suggest looking
there.

-Chuck Harris

Bob Albert via groups.io wrote:

How do I know if the tests fail?? It just presents the test number and that changes each time I press TEST.
My level of hope has been raised.? I think this is repairable.? Yes, Inguard to Ourguard communication seems to be the clue.? When I put a signal in it does not change ranges.? The Auto range takes it to the lowest range every time, regardless.
Bob On Wednesday, April 1, 2020, 11:18:39 AM PDT, Orin Eman <orin.eman@...> wrote:

Figure 8-H-1 in my manual shows where the assemblies and test points are.
Do all the tests 11 down to 0 fail?
I'd do the cal constant tests (Section 8-B-11), monitoring A10 TP4 () to see if the right voltages are getting to the AtoD.? Table 8-B-5 has the voltages to look for.? The procedure is a little tricky, but you are looking to see if A10 TP4 gets different voltages as you step through the constants at this stage.
If these voltages look reasonable, I'd look at the inguard to outguard communication - there are test points on A3 in the outguard section.

On Wed, Apr 1, 2020 at 10:36 AM Bob Albert via groups.io <bob91343@...> wrote:

Well Chuck, I don't know what to do next with this beast.? It acts as though it works but the display gives nothing useful.? Yet the display electronics seem to be working okay.
If I put a signal in, it ignores it.? Open or short on Ohms, voltage or no on volts, gives zeros and no autorange activity.? So perhaps it's an input circuit issue.? In Test I get error 11.? I press test repeatedly and it gives error numbers 10, 9, etc down to 0.
The manual sucks.? It tells me to look on module such and such but nowhere does it seem to show me which module is where.
Bob
On Wednesday, April 1, 2020, 10:22:56 AM PDT, Chuck Harris <cfharris@...> wrote:

Hi Bob,

I don't see how you can come to that conclusion.

The 3455A is highly reparable, and should be well
within your abilities.? Lots of people have fixed
their own successfully.

What you won't be able to do is send its calibration
module out for calibration.? You will have to do that
yourself.? But, it is not any more difficult to
calibrate than the 3456A.

It is not my meter of choice, as I greatly prefer
the 3456A, but for many, it is a useful addition to
their labs.

-Chuck Harris

Bob Albert via groups.io wrote:
? I don't see a whole lot of encouragement here regarding the possibility of getting my 3455A working.? Maybe I will just put it aside and wait for a scrap unit to swap out boards or parts.? My 3456A still works so I am grateful for that.
Bob
? ? On Wednesday, April 1, 2020, 06:40:17 AM PDT, Chuck Harris <cfharris@...> wrote:

? The 3455A was a dinosaur when it was first released.

The 3455A and 3456A were sold side by side, with the
3455A being about twice as expensive as the much more
capable 3456A.? The 3455A's interesting feature was
it was supposed to be cheap to calibrate.? All you
had to do to do a complete calibration was to unplug
the module in the back panel, and replace it with a
recently calibrated module.? The idea was you could
order up a calibration by mail, and return your old
calibration module as a core... never having to send
the full meter in for calibration.

Interesting idea, but surely not worth twice the price
of a 3456A.

I say it was a dinosaur, because it used all small
scale logic rather than large highly capable hybrid
circuitry, like the 3456A.? It should be much easier
to repair, but it should also be much less reliable.

And, that is my experience with the two units.

-Chuck Harris

paul swedberg wrote:
With respect to the 3455 and 3456 the difference is night and day. I have
numbers of 3456s and was given a seriously troubled 3455. Quite a
interesting meter.
Replaced at least 11 actually malfunctioning chips on the logic board. The
logics simple so easy to verify the chips were bad. No shot gunning
involved. Never really did get it working but ended up with a different
3455 that needed help and the AC board and it is in fine shape. With
respect to the old 3455 it has both a logic and voltmeter issue. The 3455
uses an unusual processor and teh DVM uses the same proc and a masked eprom
that is known to go bad. It acts as a state machine.
The 3456s are losing there eproms and copies can be found on the net. Thank
heavens.
Regards
Paul
WB8TSL
Re: HP 3455a DVM repair

 

Its been years since I've repaired one of these, but it sounds like the opto coupler may be a problem.
Quoting Orin Eman <orin.eman@...>:

The test number is the test that failed. If you press test, it goes onto
the next test - so all the numbers it displays are failures.

It does sound like it's getting all zeros from the inguard. A10 TP4 will
tell if anything is getting close to the AtoD.

On Wed, Apr 1, 2020 at 11:34 AM Bob Albert via groups.io <bob91343=
[email protected]> wrote:

How do I know if the tests fail? It just presents the test number and
that changes each time I press TEST.

My level of hope has been raised. I think this is repairable. Yes,
Inguard to Ourguard communication seems to be the clue. When I put a
signal in it does not change ranges. The Auto range takes it to the lowest
range every time, regardless.

Bob
On Wednesday, April 1, 2020, 11:18:39 AM PDT, Orin Eman <
orin.eman@...> wrote:


Figure 8-H-1 in my manual shows where the assemblies and test points are.

Do all the tests 11 down to 0 fail?

I'd do the cal constant tests (Section 8-B-11), monitoring A10 TP4 () to
see if the right voltages are getting to the AtoD. Table 8-B-5 has the
voltages to look for. The procedure is a little tricky, but you are
looking to see if A10 TP4 gets different voltages as you step through the
constants at this stage.

If these voltages look reasonable, I'd look at the inguard to outguard
communication - there are test points on A3 in the outguard section.


On Wed, Apr 1, 2020 at 10:36 AM Bob Albert via groups.io <bob91343=
[email protected]> wrote:

Well Chuck, I don't know what to do next with this beast. It acts as
though it works but the display gives nothing useful. Yet the display
electronics seem to be working okay.

If I put a signal in, it ignores it. Open or short on Ohms, voltage or no
on volts, gives zeros and no autorange activity. So perhaps it's an input
circuit issue. In Test I get error 11. I press test repeatedly and it
gives error numbers 10, 9, etc down to 0.

The manual sucks. It tells me to look on module such and such but nowhere
does it seem to show me which module is where.

Bob

On Wednesday, April 1, 2020, 10:22:56 AM PDT, Chuck Harris <
cfharris@...> wrote:


Hi Bob,

I don't see how you can come to that conclusion.

The 3455A is highly reparable, and should be well
within your abilities. Lots of people have fixed
their own successfully.

What you won't be able to do is send its calibration
module out for calibration. You will have to do that
yourself. But, it is not any more difficult to
calibrate than the 3456A.

It is not my meter of choice, as I greatly prefer
the 3456A, but for many, it is a useful addition to
their labs.

-Chuck Harris

Bob Albert via groups.io wrote:
I don't see a whole lot of encouragement here regarding the possibility
of getting my 3455A working. Maybe I will just put it aside and wait for a
scrap unit to swap out boards or parts. My 3456A still works so I am
grateful for that.
Bob
On Wednesday, April 1, 2020, 06:40:17 AM PDT, Chuck Harris <
cfharris@...> wrote:

The 3455A was a dinosaur when it was first released.

The 3455A and 3456A were sold side by side, with the
3455A being about twice as expensive as the much more
capable 3456A. The 3455A's interesting feature was
it was supposed to be cheap to calibrate. All you
had to do to do a complete calibration was to unplug
the module in the back panel, and replace it with a
recently calibrated module. The idea was you could
order up a calibration by mail, and return your old
calibration module as a core... never having to send
the full meter in for calibration.

Interesting idea, but surely not worth twice the price
of a 3456A.

I say it was a dinosaur, because it used all small
scale logic rather than large highly capable hybrid
circuitry, like the 3456A. It should be much easier
to repair, but it should also be much less reliable.

And, that is my experience with the two units.

-Chuck Harris

paul swedberg wrote:
With respect to the 3455 and 3456 the difference is night and day. I
have
numbers of 3456s and was given a seriously troubled 3455. Quite a
interesting meter.
Replaced at least 11 actually malfunctioning chips on the logic board.
The
logics simple so easy to verify the chips were bad. No shot gunning
involved. Never really did get it working but ended up with a different
3455 that needed help and the AC board and it is in fine shape. With
respect to the old 3455 it has both a logic and voltmeter issue. The
3455
uses an unusual processor and teh DVM uses the same proc and a masked
eprom
that is known to go bad. It acts as a state machine.
The 3456s are losing there eproms and copies can be found on the net.
Thank
heavens.
Regards
Paul
WB8TSL
Re: HP 3455a DVM repair

 

The test number is the test that failed.? If you press test, it goes onto the next test - so all the numbers it displays are failures.

It does sound like it's getting all zeros from the inguard.? A10 TP4 will tell if anything is getting close to the AtoD.

On Wed, Apr 1, 2020 at 11:34 AM Bob Albert via <bob91343=[email protected]> wrote:
How do I know if the tests fail?? It just presents the test number and that changes each time I press TEST.

My level of hope has been raised.? I think this is repairable.? Yes, Inguard to Ourguard communication seems to be the clue.? When I put a signal in it does not change ranges.? The Auto range takes it to the lowest range every time, regardless.

Bob
On Wednesday, April 1, 2020, 11:18:39 AM PDT, Orin Eman <orin.eman@...> wrote:


Figure 8-H-1 in my manual shows where the assemblies and test points are.

Do all the tests 11 down to 0 fail?

I'd do the cal constant tests (Section 8-B-11), monitoring A10 TP4 () to see if the right voltages are getting to the AtoD.? Table 8-B-5 has the voltages to look for.? The procedure is a little tricky, but you are looking to see if A10 TP4 gets different voltages as you step through the constants at this stage.

If these voltages look reasonable, I'd look at the inguard to outguard communication - there are test points on A3 in the outguard section.


On Wed, Apr 1, 2020 at 10:36 AM Bob Albert via <bob91343=[email protected]> wrote:
Well Chuck, I don't know what to do next with this beast.? It acts as though it works but the display gives nothing useful.? Yet the display electronics seem to be working okay.

If I put a signal in, it ignores it.? Open or short on Ohms, voltage or no on volts, gives zeros and no autorange activity.? So perhaps it's an input circuit issue.? In Test I get error 11.? I press test repeatedly and it gives error numbers 10, 9, etc down to 0.

The manual sucks.? It tells me to look on module such and such but nowhere does it seem to show me which module is where.

Bob

On Wednesday, April 1, 2020, 10:22:56 AM PDT, Chuck Harris <cfharris@...> wrote:


Hi Bob,

I don't see how you can come to that conclusion.

The 3455A is highly reparable, and should be well
within your abilities.? Lots of people have fixed
their own successfully.

What you won't be able to do is send its calibration
module out for calibration.? You will have to do that
yourself.? But, it is not any more difficult to
calibrate than the 3456A.

It is not my meter of choice, as I greatly prefer
the 3456A, but for many, it is a useful addition to
their labs.

-Chuck Harris

Bob Albert via wrote:
>? I don't see a whole lot of encouragement here regarding the possibility of getting my 3455A working.? Maybe I will just put it aside and wait for a scrap unit to swap out boards or parts.? My 3456A still works so I am grateful for that.
> Bob
>? ? On Wednesday, April 1, 2020, 06:40:17 AM PDT, Chuck Harris <cfharris@...> wrote:
>
>? The 3455A was a dinosaur when it was first released.
>
> The 3455A and 3456A were sold side by side, with the
> 3455A being about twice as expensive as the much more
> capable 3456A.? The 3455A's interesting feature was
> it was supposed to be cheap to calibrate.? All you
> had to do to do a complete calibration was to unplug
> the module in the back panel, and replace it with a
> recently calibrated module.? The idea was you could
> order up a calibration by mail, and return your old
> calibration module as a core... never having to send
> the full meter in for calibration.
>
> Interesting idea, but surely not worth twice the price
> of a 3456A.
>
> I say it was a dinosaur, because it used all small
> scale logic rather than large highly capable hybrid
> circuitry, like the 3456A.? It should be much easier
> to repair, but it should also be much less reliable.
>
> And, that is my experience with the two units.
>
> -Chuck Harris
>
> paul swedberg wrote:
>> With respect to the 3455 and 3456 the difference is night and day. I have
>> numbers of 3456s and was given a seriously troubled 3455. Quite a
>> interesting meter.
>> Replaced at least 11 actually malfunctioning chips on the logic board. The
>> logics simple so easy to verify the chips were bad. No shot gunning
>> involved. Never really did get it working but ended up with a different
>> 3455 that needed help and the AC board and it is in fine shape. With
>> respect to the old 3455 it has both a logic and voltmeter issue. The 3455
>> uses an unusual processor and teh DVM uses the same proc and a masked eprom
>> that is known to go bad. It acts as a state machine.
>> The 3456s are losing there eproms and copies can be found on the net. Thank
>> heavens.
>> Regards
>> Paul
>> WB8TSL
>>
>>
>>
>>
>
>
>
>
>
>
>
>
Re: HP 3455a DVM repair

Bob Albert
 

How do I know if the tests fail?? It just presents the test number and that changes each time I press TEST.

My level of hope has been raised.? I think this is repairable.? Yes, Inguard to Ourguard communication seems to be the clue.? When I put a signal in it does not change ranges.? The Auto range takes it to the lowest range every time, regardless.

Bob
On Wednesday, April 1, 2020, 11:18:39 AM PDT, Orin Eman <orin.eman@...> wrote:


Figure 8-H-1 in my manual shows where the assemblies and test points are.

Do all the tests 11 down to 0 fail?

I'd do the cal constant tests (Section 8-B-11), monitoring A10 TP4 () to see if the right voltages are getting to the AtoD.? Table 8-B-5 has the voltages to look for.? The procedure is a little tricky, but you are looking to see if A10 TP4 gets different voltages as you step through the constants at this stage.

If these voltages look reasonable, I'd look at the inguard to outguard communication - there are test points on A3 in the outguard section.


On Wed, Apr 1, 2020 at 10:36 AM Bob Albert via <bob91343=[email protected]> wrote:
Well Chuck, I don't know what to do next with this beast.? It acts as though it works but the display gives nothing useful.? Yet the display electronics seem to be working okay.

If I put a signal in, it ignores it.? Open or short on Ohms, voltage or no on volts, gives zeros and no autorange activity.? So perhaps it's an input circuit issue.? In Test I get error 11.? I press test repeatedly and it gives error numbers 10, 9, etc down to 0.

The manual sucks.? It tells me to look on module such and such but nowhere does it seem to show me which module is where.

Bob

On Wednesday, April 1, 2020, 10:22:56 AM PDT, Chuck Harris <cfharris@...> wrote:


Hi Bob,

I don't see how you can come to that conclusion.

The 3455A is highly reparable, and should be well
within your abilities.? Lots of people have fixed
their own successfully.

What you won't be able to do is send its calibration
module out for calibration.? You will have to do that
yourself.? But, it is not any more difficult to
calibrate than the 3456A.

It is not my meter of choice, as I greatly prefer
the 3456A, but for many, it is a useful addition to
their labs.

-Chuck Harris

Bob Albert via wrote:
>? I don't see a whole lot of encouragement here regarding the possibility of getting my 3455A working.? Maybe I will just put it aside and wait for a scrap unit to swap out boards or parts.? My 3456A still works so I am grateful for that.
> Bob
>? ? On Wednesday, April 1, 2020, 06:40:17 AM PDT, Chuck Harris <cfharris@...> wrote:
>
>? The 3455A was a dinosaur when it was first released.
>
> The 3455A and 3456A were sold side by side, with the
> 3455A being about twice as expensive as the much more
> capable 3456A.? The 3455A's interesting feature was
> it was supposed to be cheap to calibrate.? All you
> had to do to do a complete calibration was to unplug
> the module in the back panel, and replace it with a
> recently calibrated module.? The idea was you could
> order up a calibration by mail, and return your old
> calibration module as a core... never having to send
> the full meter in for calibration.
>
> Interesting idea, but surely not worth twice the price
> of a 3456A.
>
> I say it was a dinosaur, because it used all small
> scale logic rather than large highly capable hybrid
> circuitry, like the 3456A.? It should be much easier
> to repair, but it should also be much less reliable.
>
> And, that is my experience with the two units.
>
> -Chuck Harris
>
> paul swedberg wrote:
>> With respect to the 3455 and 3456 the difference is night and day. I have
>> numbers of 3456s and was given a seriously troubled 3455. Quite a
>> interesting meter.
>> Replaced at least 11 actually malfunctioning chips on the logic board. The
>> logics simple so easy to verify the chips were bad. No shot gunning
>> involved. Never really did get it working but ended up with a different
>> 3455 that needed help and the AC board and it is in fine shape. With
>> respect to the old 3455 it has both a logic and voltmeter issue. The 3455
>> uses an unusual processor and teh DVM uses the same proc and a masked eprom
>> that is known to go bad. It acts as a state machine.
>> The 3456s are losing there eproms and copies can be found on the net. Thank
>> heavens.
>> Regards
>> Paul
>> WB8TSL
>>
>>
>>
>>
>
>
>
>
>
>
>
>
HP 209A

 

¿ªÔÆÌåÓý

Hello, Glenn--
You wrote...

"Has anyone seen abnormalities at 60, 120 and 180 Hz sine wave output?
Specifically AM modulation or changing amplitude."

The oscillator design is a Wien bridge, and I dimly recall reading something
about the sensitivity of the bridge circuit at the dialed-in frequency. Specifically, at a 60 Hz
frequency setting, any stray 60 Hz pickup will interact? with the 60 Hz oscillation frequency
setting and exhibit "pulling" or modulation of the desired 60 Hz output. I've seen this
effect many years ago with an older tubed HP oscillator (a HP 200CD).

The 120 Hz and 180 Hz frequencies are harmonics of 60 Hz and may be exhibiting
the same "beat" with stray 60 Hz fields.

So, I'm not sure if the effect is a "feature" or a "bug", but I'd check the 209A's power supply
for ripple, and if there are screws that connect the PC boards' ground planes to the
chassis, make sure that they're tightened.

Perhaps someone in the group can offer further insights?

73--

Brad? AA1IP

*??? *?? *
For some April 1st fun, go to...

..
Re: HP 3455a DVM repair

 

Figure 8-H-1 in my manual shows where the assemblies and test points are.

Do all the tests 11 down to 0 fail?

I'd do the cal constant tests (Section 8-B-11), monitoring A10 TP4 () to see if the right voltages are getting to the AtoD.? Table 8-B-5 has the voltages to look for.? The procedure is a little tricky, but you are looking to see if A10 TP4 gets different voltages as you step through the constants at this stage.

If these voltages look reasonable, I'd look at the inguard to outguard communication - there are test points on A3 in the outguard section.


On Wed, Apr 1, 2020 at 10:36 AM Bob Albert via <bob91343=[email protected]> wrote:
Well Chuck, I don't know what to do next with this beast.? It acts as though it works but the display gives nothing useful.? Yet the display electronics seem to be working okay.

If I put a signal in, it ignores it.? Open or short on Ohms, voltage or no on volts, gives zeros and no autorange activity.? So perhaps it's an input circuit issue.? In Test I get error 11.? I press test repeatedly and it gives error numbers 10, 9, etc down to 0.

The manual sucks.? It tells me to look on module such and such but nowhere does it seem to show me which module is where.

Bob

On Wednesday, April 1, 2020, 10:22:56 AM PDT, Chuck Harris <cfharris@...> wrote:


Hi Bob,

I don't see how you can come to that conclusion.

The 3455A is highly reparable, and should be well
within your abilities.? Lots of people have fixed
their own successfully.

What you won't be able to do is send its calibration
module out for calibration.? You will have to do that
yourself.? But, it is not any more difficult to
calibrate than the 3456A.

It is not my meter of choice, as I greatly prefer
the 3456A, but for many, it is a useful addition to
their labs.

-Chuck Harris

Bob Albert via wrote:
>? I don't see a whole lot of encouragement here regarding the possibility of getting my 3455A working.? Maybe I will just put it aside and wait for a scrap unit to swap out boards or parts.? My 3456A still works so I am grateful for that.
> Bob
>? ? On Wednesday, April 1, 2020, 06:40:17 AM PDT, Chuck Harris <cfharris@...> wrote:
>
>? The 3455A was a dinosaur when it was first released.
>
> The 3455A and 3456A were sold side by side, with the
> 3455A being about twice as expensive as the much more
> capable 3456A.? The 3455A's interesting feature was
> it was supposed to be cheap to calibrate.? All you
> had to do to do a complete calibration was to unplug
> the module in the back panel, and replace it with a
> recently calibrated module.? The idea was you could
> order up a calibration by mail, and return your old
> calibration module as a core... never having to send
> the full meter in for calibration.
>
> Interesting idea, but surely not worth twice the price
> of a 3456A.
>
> I say it was a dinosaur, because it used all small
> scale logic rather than large highly capable hybrid
> circuitry, like the 3456A.? It should be much easier
> to repair, but it should also be much less reliable.
>
> And, that is my experience with the two units.
>
> -Chuck Harris
>
> paul swedberg wrote:
>> With respect to the 3455 and 3456 the difference is night and day. I have
>> numbers of 3456s and was given a seriously troubled 3455. Quite a
>> interesting meter.
>> Replaced at least 11 actually malfunctioning chips on the logic board. The
>> logics simple so easy to verify the chips were bad. No shot gunning
>> involved. Never really did get it working but ended up with a different
>> 3455 that needed help and the AC board and it is in fine shape. With
>> respect to the old 3455 it has both a logic and voltmeter issue. The 3455
>> uses an unusual processor and teh DVM uses the same proc and a masked eprom
>> that is known to go bad. It acts as a state machine.
>> The 3456s are losing there eproms and copies can be found on the net. Thank
>> heavens.
>> Regards
>> Paul
>> WB8TSL
>>
>>
>>
>>
>
>
>
>
>
>
>
>
Re: HP 209A issues

 

On 4/1/20 1:45 PM, Glenn Little wrote:
Has anyone seen abnormalities at 60, 120 and 180 Hz sine wave output?
Specifically AM modulation or changing amplitude.
Hmm, suspicious! Heterodyning with AC ripple from dried-out filter
capacitors in the power supply?

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
HP 209A issues

 

Has anyone seen abnormalities at 60, 120 and 180 Hz sine wave output?
Specifically AM modulation or changing amplitude.

Glenn

--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
Re: HP 3455a DVM repair

Bob Albert
 

I just made an interesting test.? In Ohms it does put out a test current to the front panel terminals.? So it's trying to make a measurement.? It appears to be a voltmeter issue, at the input to the machine, since it ignores the input.? It even puts out a current in the 4-terminal Ohms mode (from the other pair of terminals).

Bob

On Wednesday, April 1, 2020, 10:36:17 AM PDT, Bob Albert via groups.io <bob91343@...> wrote:


Well Chuck, I don't know what to do next with this beast.? It acts as though it works but the display gives nothing useful.? Yet the display electronics seem to be working okay.

If I put a signal in, it ignores it.? Open or short on Ohms, voltage or no on volts, gives zeros and no autorange activity.? So perhaps it's an input circuit issue.? In Test I get error 11.? I press test repeatedly and it gives error numbers 10, 9, etc down to 0.

The manual sucks.? It tells me to look on module such and such but nowhere does it seem to show me which module is where.

Bob

On Wednesday, April 1, 2020, 10:22:56 AM PDT, Chuck Harris <cfharris@...> wrote:


Hi Bob,

I don't see how you can come to that conclusion.

The 3455A is highly reparable, and should be well
within your abilities.? Lots of people have fixed
their own successfully.

What you won't be able to do is send its calibration
module out for calibration.? You will have to do that
yourself.? But, it is not any more difficult to
calibrate than the 3456A.

It is not my meter of choice, as I greatly prefer
the 3456A, but for many, it is a useful addition to
their labs.

-Chuck Harris

Bob Albert via groups.io wrote:
>? I don't see a whole lot of encouragement here regarding the possibility of getting my 3455A working.? Maybe I will just put it aside and wait for a scrap unit to swap out boards or parts.? My 3456A still works so I am grateful for that.
> Bob
>? ? On Wednesday, April 1, 2020, 06:40:17 AM PDT, Chuck Harris <cfharris@...> wrote:
>
>? The 3455A was a dinosaur when it was first released.
>
> The 3455A and 3456A were sold side by side, with the
> 3455A being about twice as expensive as the much more
> capable 3456A.? The 3455A's interesting feature was
> it was supposed to be cheap to calibrate.? All you
> had to do to do a complete calibration was to unplug
> the module in the back panel, and replace it with a
> recently calibrated module.? The idea was you could
> order up a calibration by mail, and return your old
> calibration module as a core... never having to send
> the full meter in for calibration.
>
> Interesting idea, but surely not worth twice the price
> of a 3456A.
>
> I say it was a dinosaur, because it used all small
> scale logic rather than large highly capable hybrid
> circuitry, like the 3456A.? It should be much easier
> to repair, but it should also be much less reliable.
>
> And, that is my experience with the two units.
>
> -Chuck Harris
>
> paul swedberg wrote:
>> With respect to the 3455 and 3456 the difference is night and day. I have
>> numbers of 3456s and was given a seriously troubled 3455. Quite a
>> interesting meter.
>> Replaced at least 11 actually malfunctioning chips on the logic board. The
>> logics simple so easy to verify the chips were bad. No shot gunning
>> involved. Never really did get it working but ended up with a different
>> 3455 that needed help and the AC board and it is in fine shape. With
>> respect to the old 3455 it has both a logic and voltmeter issue. The 3455
>> uses an unusual processor and teh DVM uses the same proc and a masked eprom
>> that is known to go bad. It acts as a state machine.
>> The 3456s are losing there eproms and copies can be found on the net. Thank
>> heavens.
>> Regards
>> Paul
>> WB8TSL
>>
>>
>>
>>
>
>
>
>
>
>
>
>
Re: HP 3455a DVM repair

Bob Albert
 

Well Chuck, I don't know what to do next with this beast.? It acts as though it works but the display gives nothing useful.? Yet the display electronics seem to be working okay.

If I put a signal in, it ignores it.? Open or short on Ohms, voltage or no on volts, gives zeros and no autorange activity.? So perhaps it's an input circuit issue.? In Test I get error 11.? I press test repeatedly and it gives error numbers 10, 9, etc down to 0.

The manual sucks.? It tells me to look on module such and such but nowhere does it seem to show me which module is where.

Bob

On Wednesday, April 1, 2020, 10:22:56 AM PDT, Chuck Harris <cfharris@...> wrote:


Hi Bob,

I don't see how you can come to that conclusion.

The 3455A is highly reparable, and should be well
within your abilities.? Lots of people have fixed
their own successfully.

What you won't be able to do is send its calibration
module out for calibration.? You will have to do that
yourself.? But, it is not any more difficult to
calibrate than the 3456A.

It is not my meter of choice, as I greatly prefer
the 3456A, but for many, it is a useful addition to
their labs.

-Chuck Harris

Bob Albert via groups.io wrote:
>? I don't see a whole lot of encouragement here regarding the possibility of getting my 3455A working.? Maybe I will just put it aside and wait for a scrap unit to swap out boards or parts.? My 3456A still works so I am grateful for that.
> Bob
>? ? On Wednesday, April 1, 2020, 06:40:17 AM PDT, Chuck Harris <cfharris@...> wrote:
>
>? The 3455A was a dinosaur when it was first released.
>
> The 3455A and 3456A were sold side by side, with the
> 3455A being about twice as expensive as the much more
> capable 3456A.? The 3455A's interesting feature was
> it was supposed to be cheap to calibrate.? All you
> had to do to do a complete calibration was to unplug
> the module in the back panel, and replace it with a
> recently calibrated module.? The idea was you could
> order up a calibration by mail, and return your old
> calibration module as a core... never having to send
> the full meter in for calibration.
>
> Interesting idea, but surely not worth twice the price
> of a 3456A.
>
> I say it was a dinosaur, because it used all small
> scale logic rather than large highly capable hybrid
> circuitry, like the 3456A.? It should be much easier
> to repair, but it should also be much less reliable.
>
> And, that is my experience with the two units.
>
> -Chuck Harris
>
> paul swedberg wrote:
>> With respect to the 3455 and 3456 the difference is night and day. I have
>> numbers of 3456s and was given a seriously troubled 3455. Quite a
>> interesting meter.
>> Replaced at least 11 actually malfunctioning chips on the logic board. The
>> logics simple so easy to verify the chips were bad. No shot gunning
>> involved. Never really did get it working but ended up with a different
>> 3455 that needed help and the AC board and it is in fine shape. With
>> respect to the old 3455 it has both a logic and voltmeter issue. The 3455
>> uses an unusual processor and teh DVM uses the same proc and a masked eprom
>> that is known to go bad. It acts as a state machine.
>> The 3456s are losing there eproms and copies can be found on the net. Thank
>> heavens.
>> Regards
>> Paul
>> WB8TSL
>>
>>
>>
>>
>
>
>
>
>
>
>
>
Re: HP 3455a DVM repair

 

Hi Bob,

I don't see how you can come to that conclusion.

The 3455A is highly reparable, and should be well
within your abilities. Lots of people have fixed
their own successfully.

What you won't be able to do is send its calibration
module out for calibration. You will have to do that
yourself. But, it is not any more difficult to
calibrate than the 3456A.

It is not my meter of choice, as I greatly prefer
the 3456A, but for many, it is a useful addition to
their labs.

-Chuck Harris

Bob Albert via groups.io wrote:

I don't see a whole lot of encouragement here regarding the possibility of getting my 3455A working.? Maybe I will just put it aside and wait for a scrap unit to swap out boards or parts.? My 3456A still works so I am grateful for that.
Bob
On Wednesday, April 1, 2020, 06:40:17 AM PDT, Chuck Harris <cfharris@...> wrote:

The 3455A was a dinosaur when it was first released.

The 3455A and 3456A were sold side by side, with the
3455A being about twice as expensive as the much more
capable 3456A.? The 3455A's interesting feature was
it was supposed to be cheap to calibrate.? All you
had to do to do a complete calibration was to unplug
the module in the back panel, and replace it with a
recently calibrated module.? The idea was you could
order up a calibration by mail, and return your old
calibration module as a core... never having to send
the full meter in for calibration.

Interesting idea, but surely not worth twice the price
of a 3456A.

I say it was a dinosaur, because it used all small
scale logic rather than large highly capable hybrid
circuitry, like the 3456A.? It should be much easier
to repair, but it should also be much less reliable.

And, that is my experience with the two units.

-Chuck Harris

paul swedberg wrote:
With respect to the 3455 and 3456 the difference is night and day. I have
numbers of 3456s and was given a seriously troubled 3455. Quite a
interesting meter.
Replaced at least 11 actually malfunctioning chips on the logic board. The
logics simple so easy to verify the chips were bad. No shot gunning
involved. Never really did get it working but ended up with a different
3455 that needed help and the AC board and it is in fine shape. With
respect to the old 3455 it has both a logic and voltmeter issue. The 3455
uses an unusual processor and teh DVM uses the same proc and a masked eprom
that is known to go bad. It acts as a state machine.
The 3456s are losing there eproms and copies can be found on the net. Thank
heavens.
Regards
Paul
WB8TSL
Re: HP 3455a DVM repair

Bob Albert
 

I don't see a whole lot of encouragement here regarding the possibility of getting my 3455A working.? Maybe I will just put it aside and wait for a scrap unit to swap out boards or parts.? My 3456A still works so I am grateful for that.

Bob

On Wednesday, April 1, 2020, 06:40:17 AM PDT, Chuck Harris <cfharris@...> wrote:


The 3455A was a dinosaur when it was first released.

The 3455A and 3456A were sold side by side, with the
3455A being about twice as expensive as the much more
capable 3456A.? The 3455A's interesting feature was
it was supposed to be cheap to calibrate.? All you
had to do to do a complete calibration was to unplug
the module in the back panel, and replace it with a
recently calibrated module.? The idea was you could
order up a calibration by mail, and return your old
calibration module as a core... never having to send
the full meter in for calibration.

Interesting idea, but surely not worth twice the price
of a 3456A.

I say it was a dinosaur, because it used all small
scale logic rather than large highly capable hybrid
circuitry, like the 3456A.? It should be much easier
to repair, but it should also be much less reliable.

And, that is my experience with the two units.

-Chuck Harris

paul swedberg wrote:
> With respect to the 3455 and 3456 the difference is night and day. I have
> numbers of 3456s and was given a seriously troubled 3455. Quite a
> interesting meter.
> Replaced at least 11 actually malfunctioning chips on the logic board. The
> logics simple so easy to verify the chips were bad. No shot gunning
> involved. Never really did get it working but ended up with a different
> 3455 that needed help and the AC board and it is in fine shape. With
> respect to the old 3455 it has both a logic and voltmeter issue. The 3455
> uses an unusual processor and teh DVM uses the same proc and a masked eprom
> that is known to go bad. It acts as a state machine.
> The 3456s are losing there eproms and copies can be found on the net. Thank
> heavens.
> Regards
> Paul
> WB8TSL
>
>
>
>



Re: Where to connect the efc input on a 10544A?

 

It's up to you. How close do you want to be abl to set it?

A +-5V supply an 10 Turn pot is not too hard to do. Personlly I've used a isolated 12V output DC-DC converter with lots of filtering, a 10V reference IC? a 1:1 resistive divider connected to the EFC common, and a 10k 10 tun pot.

Robert G8RPI
Re: Fixing a sick 4332A LCR meter

 

Hi Joel,

I might have meant R36. All I have to go on right now is the awful manual scan that Keysight hosts. It's very hard to read, and some of the key diagrams are illegible. I suppose I should see if Artek has a scan, or try to find a manual on ebay.

I may contact you as I continue to troubleshoot; thanks for the tips.

Sean


On Wed, Apr 1, 2020 at 06:05 AM, Joel Setton wrote:
Hello,

I also have a 4332A and the manual, too. I looked at the A4 schematic and found that R35 on A4 is a 9.09K resistor, not 100 ohms. I don't see how a 9.09K resistor could burn, you'd need something like 60V or more to burn it. There's no high-voltage source in the 4332A so I don't understand how R35 could overheat.

I would first suggest disconnecting the four input signal leads to A4: the HIGH and LOW leads, and the orange wire and the white-red-green wire. Then you can test the various voltages which are shown on the A4 schematic to look for a failed part.
And please let me know, I'm happy to help. The 4332A is quite a neat instrument !
Joel Setton
Re: HP 3455a DVM repair

 

The 3455A was a dinosaur when it was first released.

The 3455A and 3456A were sold side by side, with the
3455A being about twice as expensive as the much more
capable 3456A. The 3455A's interesting feature was
it was supposed to be cheap to calibrate. All you
had to do to do a complete calibration was to unplug
the module in the back panel, and replace it with a
recently calibrated module. The idea was you could
order up a calibration by mail, and return your old
calibration module as a core... never having to send
the full meter in for calibration.

Interesting idea, but surely not worth twice the price
of a 3456A.

I say it was a dinosaur, because it used all small
scale logic rather than large highly capable hybrid
circuitry, like the 3456A. It should be much easier
to repair, but it should also be much less reliable.

And, that is my experience with the two units.

-Chuck Harris

paul swedberg wrote:

With respect to the 3455 and 3456 the difference is night and day. I have
numbers of 3456s and was given a seriously troubled 3455. Quite a
interesting meter.
Replaced at least 11 actually malfunctioning chips on the logic board. The
logics simple so easy to verify the chips were bad. No shot gunning
involved. Never really did get it working but ended up with a different
3455 that needed help and the AC board and it is in fine shape. With
respect to the old 3455 it has both a logic and voltmeter issue. The 3455
uses an unusual processor and teh DVM uses the same proc and a masked eprom
that is known to go bad. It acts as a state machine.
The 3456s are losing there eproms and copies can be found on the net. Thank
heavens.
Regards
Paul
WB8TSL
Re: HP 3455a DVM repair

 

With respect to the 3455 and 3456 the difference is night and day. I have numbers of 3456s and was given a seriously troubled 3455. Quite a interesting meter.
Replaced at least 11 actually malfunctioning chips on the logic board. The logics simple so easy to verify the chips were bad. No shot gunning involved. Never really did get it working but ended up with a different 3455 that needed help and the AC board?and it is in fine shape. With respect to the old 3455 it has both a logic and voltmeter issue. The 3455 uses an unusual?processor and teh DVM uses the same proc and a masked eprom that is known to go bad. It acts as a state machine.
The 3456s are losing there eproms and copies can be found on the net. Thank heavens.
Regards
Paul
WB8TSL
Re: Fixing a sick 4332A LCR meter

 

Hello,

I also have a 4332A and the manual, too. I looked at the A4 schematic and found that R35 on A4 is a 9.09K resistor, not 100 ohms. I don't see how a 9.09K resistor could burn, you'd need something like 60V or more to burn it. There's no high-voltage source in the 4332A so I don't understand how R35 could overheat.

I would first suggest disconnecting the four input signal leads to A4: the HIGH and LOW leads, and the orange wire and the white-red-green wire. Then you can test the various voltages which are shown on the A4 schematic to look for a failed part.
And please let me know, I'm happy to help. The 4332A is quite a neat instrument !
Joel Setton
Where to connect the efc input on a 10544A?

 

Hi,

So while we are stuck at home and have nothing to do but play with all
the instruments I started a project to build a distribution amplifier
for 10MHz reference. I do have a GPSDO, but that is cumbersome to use
as I don't have a good view of the sky from my room. So Instead I
decided that I build a two-in-one distribution amplifier + OCXO
reference, as I have a spare, well aged 10544A laying around. (I'll
share the design if it ever gets done.) That would be plenty of enough
precision for what I do, the GPSDO could be used to calibrate it once
in a while. That should be plenty of enough for me, as I would be
driving signal and function generators from it, nothing extreme
time-nuttery.
So my question is: Is it worth to connect the EFC input of the OCXO?
The datasheet says it has about 1 Hz range, but then I would need to
provide the -5/+5V supply for it, preferably with some good quality
reference. I know that this input is not connected in the 5335A for
example, only the "coarse" adjustment is used.
I guess it is is good for the 5335A then it should be good for me, but
on the other hand, why not make some overly complicated thing when we
finally have time for it :-)
So basically, my question is would you recommend to simply short the
EFC input and only have the coarse adjustment or should I take the
extra effort to have this fine adjustment? Would it have any drawbacks
if I do?

Thanks.

Szabolcs
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