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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" |
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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 >> >> >> >> > > > > > > > > |
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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 >> >> >> >> > > > > > > > > |
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Re: HP 3455a DVM repair
Hi Bob,
toggle quoted message
Show quoted text
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. |
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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 > > > > |
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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. |
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Re: Fixing a sick 4332A LCR meter
Hi Joel,
toggle quoted message
Show quoted text
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, |
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Re: HP 3455a DVM repair
The 3455A was a dinosaur when it was first released.
toggle quoted message
Show quoted text
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 |
|
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 |
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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 |
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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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Re: HP 3325A - with a short in board A14 negative 15V supply
This issue is almost always a shorted tantalum capacitor on the A14 board. Other suspects include the -15V zener diode or the Opto-couplers (4-pin DIPs) on the A14.
This can be an issue with the A3, A14 of A21 boards. You can verify that the A14 is the issue by temporarily disconnecting the ribbon cable supplying the A14. If the unit boots (with errors), then something on the A14 is shorted. Perform a visual inspection of the A14 tantalums. The bad part is usually discolored from heat damage. It's best to use a thermal IR camera to see which part is glowing, but lacking such, you can de-solder and lift one end of each tantalum capacitors along the -15V rail on the A14, then measure the resistance on the lifted diode, and on the -15V rail. The shorted part will eventually show itself using this method. Hope that helps! Joe, KN5U |
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Re: HP 3325A/B Option 002 HV output kit - who wants one?
¿ªÔÆÌåÓý
I would like two boards, please.
Tom Dawson On 3/27/2020 11:19 AM, Jared Cabot via
Groups.Io wrote:
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Re: HP 3325A - with a short in board A14 negative 15V supply
Hi,
toggle quoted message
Show quoted text
I doubt it's the PSU, I would still suspect one of th the caps on the A14. FOr a very simple check, you can measure resistance on the -15V input of the board, if there is a dead short, that would show up. Or you can supply the power from external source and see if that help and that would also enable you to measure current. Szabolcs Maurice Smulders <Maurice.Smulders@...> ezt ¨ªrta (id?pont: 2020. ¨¢pr. 1., Sze, 7:40):
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HP 3325A - with a short in board A14 negative 15V supply
Is there a known issue where there is a problem either in the PSU or Board A14.
Once A14 is connected (ALL other connectors are disconnected) the unit doesn't turn on (No LEDs) No caps look to be bad - haven't had time to dig in deep... What currents should the PSU be able to supply on +/- 15V and +5V, so i can test it with a resistor to see if the PSU is bad? -Maurice |
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Fixing a sick 4332A LCR meter
Hi all,
I recently purchased a very nice looking 4332A LCR meter. It's in great shape cosmetically, but does not work properly. Power rails are in spec, voltage and ripple in or well within tolerance. Inside is clean, except on the A4 amplifier board. R35 (a 100 ohm 1/8W metal film) was cremated and reading well over 1K. No other components are visibly damaged. I replaced it with a 100 ohm 1/4W metal film resistor I had on hand, which did little. The new resistor is not getting hot at all, so perhaps someone overloaded it? In any case, the signals that the service manual says should be present on the various test points are either not present or of much smaller amplitude than the service notes call for. I'm at a loss for what to try next. It seems to me someone cooked that amplifier setup pretty good. Anyone familiar with these little units? I'd like to get it working again but I have a feeling if any of the multilegged semiconductors used in the amplifier circuits are damaged, they are unobtainable. Thanks, |
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hp83592A
Hi gang,
??????????? Still trying to fix my 83592A plug in with uncontrolled rf output power, Biggest problem is trying to isolate what the actual problem is. Initially thought it was just an ALC (A4) problem but then found that i had multiple output peaks between? 10mhz and 2 ghz but they disappeared after that up to 20ghz. more checking revealed that the same problem appeared on the auxillary output on the rear of the plug in, where the nominal 0dbm output is only -10dbm and as far as i am aware the rear output is the output of the yig in the 3 to 6 ghz range and? should be 0 dbm. another observation is that the yig output varies considerably as it sweeps the 3-6 ghz range. So i am beginning to think the yig or it's controller may be faulty. Any suggestions? Ken VK2TKE |
Harold Foster
Maurice Smulders
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