Re: HP 8594E PSU repair/debug safety checklist
Don't get too enamored with tracing out and debugging your power supply, 9 times out of 10, the problem will be simply a case of bad electrolytic capacitors. I am not being casual with my statistics, this is hard won personal experience. The quickest way to "get'er'done", is to get an ESR meter, and check each electrolytic capacitor. Look exclusively for those that have ESR much greater than 1 ohm. When you find one, remove it, and measure its capacitance. Most of the time, it be low in an inverse relation to how high the ESR is. When you find a bad cap, replace ALL identical caps in the supply. Temperamental supplies are that way often because the electrolytic capacitors get worse when they are cold. For instance, a becoming very bad 100uf cap may be 25uf when hot, but only 2uf when cold. 25uf isn't great, but it may be enough to keep running, but 2uf isn't enough to start the supply (and warm up the cap). I do virtually all of my power supply debugging and repair with the power off, and no schematics. -Chuck Harris On Tue, 26 Nov 2024 06:53:47 -0800 "Ke-Fong Lin via groups.io" <anotherlin@...> wrote: Hi everyone,
My HP8594E has a temperamental PSU, sometimes everything just works
fine otherwise the SA just doesn't turn on. Something is obviously
wrong and needs to be debugged.
I've not opened the case yet. I've just searched a bit the internet (
). (
) ) HP
doesn't provide schematics but people have already attempted repair.
I may have to work on the "mains connected" (120VAC US or 220VAC
Europe) side. So I just want to be sure that I would be safe with a
differential probe, and if I use a diff probe, an isolation
transformer wouldn't be needed.
Seems that "curious marc" is using a variac as some form of isolation
transformer:
In general, do you guys have some links or checklists for safety when
working on these kind of switch mode power supply. Thanks!
Best regards,
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Re: VNA Resonance Methodology
Note that the 6cm diameter loop antenna ideally needs to form a closed loop, so one end of the loop connects to the centre pin of the coaxial connector and the other end of the loop connects to the outer (ground) of the coaxial connector.
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Re: VNA Resonance Methodology
If it helps, I dug out one of my test solenoids and put a 390pF ATC 800B cap across it and used the loop antenna method to find the resonance with the VNA set to s11. See the image below where the resonance was at 1.945 MHz. If you use a modern synthesised VNA like this (even a nanovna), the proximity of the test resonator will not pull the frequency of the VNA. This is unlike a typical old school GDO where the GDO will lose its frequency calibration if you bring anything too close to the GDO's external coil as it will cause the GDO to change frequency.?
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In the example case below I could bring the loop antenna really close to the solenoid and the dip frequency did not change. Because the resonator capacitor is huge at 390pF it dominates any stray capacitance from the loop antenna. It's even possible to touch the solenoid and the loop antenna together and the dip stubbornly stays at the same frequency. But you can see that this isn't necessary as I got a decent dip with the setup in the image below.
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If I had fitted a variable capacitor it would be possible to watch the resonant frequency change in real time as the capacitance was changed. You can't do that with a GDO :)
There is no calibration performed on the VNA, it is running uncalibrated as it is only necessary to look for a dip with this method. You do have to set the VNA to 1dB/div or less. If using something like a nanovna I'd recommend using 0.2dB/div.
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You can see the loop antenna is just a loop of tinned copper wire with about a 6cm diameter. This is big enough to pass over the test coil with a good clearance. This method won't work so well for physically smaller solenoids and a different type of pickup loop may be required. It may even require a different test method. However, you are making a large air cored solenoid so this method should work really well :)
?
?
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Re: Troubleshooting a 8591e with opt 130
Marco, ? For A1-A5 and G1 to G3: +0.019V/ 1=+4.8V For G4 to G6:? -7.4V / +14.28V With my 8595E, A5 -16dB is activated with CORR=ON, and OFF when CORR=OFF. This would mean that I would probably have a similar problem if my A5 attenuator was not working, I would have a signal at -5dBm instead of -20dBm. ? I don't have the behavior you have, going from -9dBm to -10dBm. ? Yves
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Pulling CT2 Demodulator (opt 110) from HP8594E
I have a 8595E that I want to remove the CT2 Demodulator (option 110) card from.
Now I am wondering if any rewiring is required? I tried to find the option 110 installation
instructions, but sofar no luck.
?
Any ideas?
?
Wilko
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Re: Troubleshooting a 8591e with opt 130
Yves,?
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I finally had some time to solder and to the measurements, sorry for the hold up.
Below are the results
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Next I checked all the lines to see if they would ever change by changing the ref level and log/lin setting. It looks like we are onto something there.
| ? |
low |
high |
| A1 |
0,003 |
5,15 |
| A2 |
0,003 |
5,15 |
| A3 |
0,003 |
5,15 |
| A4 |
0,003 |
5,15 |
| A5 |
0,003 |
0,004 |
| G1 |
0,004 |
5,15 |
| G2 |
0,004 |
5,15 |
| G3 |
0,004 |
5,15 |
| ? |
low |
high |
| G4 |
14,238 |
-5,5 |
| G5 |
14,238 |
-5,755 |
| G6 |
14,238 |
-3,075 |
?
A5 seems broken, G6 looks somewhat suspicious. The level being about 15dB off also fits the A5 16dB attenuator not working. I'll take out the A7 Analog board to directly solder a wire to U111 pins 8 and 9 to see if the output of the 74HC374 has failed or that the IOB12 is faulty.?
Perhaps the function of IOB12 is identifiable because IOB12 also switches several other signals like A7 U201 Pins 2 and 3 (10dB Section in or out), A7 U11 pin 19 (ATP1), d4 of A7 U104 (Bw control Dac), A7 U107 pin 9 (IFG5). Since IFG5 seems to work I suspect IOB12 must be working.?
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Then some other strange behavior caught my eye. Ofcourse we can expect some additional noise since both the LogAmp and the Amp control have quite some gain, they mis the top of the enclosure and they have several antennas running off the board to measure the levels, but a big difference was observed in noisefloor between two ref levels.?
Note the 2 plots below. The only difference is Ref level -9 and -10. The -9dB ref has upward spikes jumping around, the -10dB has downward spikes but a ~15dB higher noisefloor.
I guess this might have to do with the 16dB attenuator not kicking in.
?
Are G4/G5/G6 at the same levels on your analyzer??
?
Marco
?
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Re: Sticky ink of schematics
Greetings,
?
I asked a longtime friend who spent his career in the printing and photo lithography industry.
?
He suggested reaching out to the ¡°American Academy of Forensic Sciences¡± located in Colorado Springs, CO.
?
FWIW I hope this helps.
?
Regards,
?
Ken
?
toggle quoted message
Show quoted text
On Mon, Nov 25, 2024 at 08:01 PM, Lexter Negron wrote:
found thru searching "toner"
I read in your links to the threads...that ISO...which I paraphrase here... they think "if there is transfer, and sticking, it is likely toner."
AFAIK, that... if I have articulated their claim correctly... is untrue.
There are several kinds/types of 'imaging materials.'
"ink' and "toner" are two of them; but, 'ink' is? not the same as 'toner'
Oil based inks, used on offset printing... can and do... stick pages together... and transfer, as well.
I'm not sure it ultimately matters; but, you can sometimes determine what printing technology was used by examining the print, and the paper.
Sometimes... particularly in older monographs... and some manuals... you can find information about how the documented was printed, in the document's colophon.
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Re: HP 8341B 1992 firmware version
Hi saevar,
I saw them but these are labeled as for 8340B not 8341B. Do you know whether firmware for 8340B and 8341B is exactly the same?
Regards
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Re: VNA Resonance Methodology
On Tue, Nov 26, 2024 at 04:30 PM, Jinxie wrote:
On Mon, Nov 25, 2024 at 10:12 PM, jmr wrote:
"The other alternative would be to use a ferrite core based inductor. It should be possible to get a Q of about 400 at 1.45 MHz with a small ferrite core inductor with about 50uH inductance. But this won't be suitable for large signal operation."
Due to core saturation?
?
Yes, and also the ferrite can introduce non-linear artefacts at levels below saturation. This type of distortion can happen if you use the ferrite in a narrow bandpass filter for example.
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Note that you can mimic a GDO with a VNA if you set it to s11 and set the scale to 1dB/div or less. Then connect a simple small loop of wire across the far end of your test coax. A wire loop about about 6cm diameter should be fine when looking for resonant tanks below 30MHz or so.? You don't have to calibrate anything on the VNA. Just hold the test loop near the inductor under test assuming it has been resonated with a parallel capacitor. It's best to experiment with the orientation of the test loop with respect to the inductor under test.
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At the resonant frequency of the tank you should be able to see a tiny downwards blip in the s11 trace. It might only be at about -0.2dB to start with but you can move the loop closer if you don't see a blip initially.
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For your application, this approach will outperform any GDO assuming you have a VNA with a good display and a reasonably fast sweep rate. Unlike a GDO, there's nothing to adjust, you just hold the loop near the inductor and look for the frequency where the resonant tank absorbs energy from the VNA. Then use the marker to tell you the resonant frequency if you need a bit more accuracy.
?
?
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Re: Sticky ink of schematics
On Mon, Nov 25, 2024 at 08:01 PM, Lexter Negron wrote:
found thru searching "toner"
I read in your links to the threads...that ISO...which I paraphrase here... they think "if there is transfer, and sticking, it is likely toner."
AFAIK, that... if I have articulated their claim correctly... is untrue.
?
There are several kinds/types of 'imaging materials.'
"ink' and "toner" are two of them; but, 'ink' is? not the same as 'toner'
?
Oil based inks, used on offset printing... can and do... stick pages together... and transfer, as well.
?
I'm not sure it ultimately matters; but, you can sometimes determine what printing technology was used by examining the print, and the paper.
?
Sometimes... particularly in older monographs... and some manuals... you can find information about how the documented was printed, in the document's colophon.
?
?
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Re: VNA Resonance Methodology
Check the double tuned LC network theory.
As you change the coupling between two tuned ckts, they interact, and the usual resonant peak becomes split.
In a GDO your exciting the LC DUT with the GDO oscillator.
The closer they are coupled the less sharp the peak and grid dip.
We just move the search coils away as we tune the GDO.
About ferrite or other cored inductor, the GDO is most sensitive to slugs or open magnetic path geometry.
Boontoon LF version coils are indeed ferrite for 20-100 kHz, perhaps half of a pot core.
Your solid state GDO should give similar results
Finally one can try capacitive coupling instead of inductive, just a wire gimmick between the LC and GDO.
Notice that the LC MUST be parallel and not directly connected to the GDO circuit.
Suggest you read the app notes, manuals for GDO and look up ARRL / QST articles on GDO useage.
Have an absolutely fantastic day
Jon
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Re: Sticky ink of schematics
On Mon, Nov 25, 2024 at 08:01 PM, Lexter Negron wrote:
I suspect heating from many summers in a warehouse did this.
?
If they were stacked...heat, pressure, and time.
?
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Re: HP 8594E PSU repair/debug safety checklist
On Tuesday 26 November 2024 09:53:47 am Ke-Fong Lin via groups.io wrote: I may have to work on the "mains connected" (120VAC US or 220VAC Europe) side.
So I just want to be sure that I would be safe with a differential probe, and if I use a diff probe, an isolation transformer wouldn't be needed. An isolation transformer is always a good idea when working on mains-connected circuits. If nothing else, a couple of regular transformers connected in cascade with the second "primary" being the mains source for what you're working on will do. Seems that "curious marc" is using a variac as some form of isolation transformer:
I haven't looked at the link, but a variac is NOT an isolation transformer. -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin
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Re: VNA Resonance Methodology
On Tuesday 26 November 2024 09:22:35 am Jinxie via groups.io wrote: Sorry, Froggie, I can't help you on the Honymooners; never seen it. Wikipedia provides the answer. The name was "Trixie", not Jinxie... :-) -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin
|
Re: VNA Resonance Methodology
On Mon, Nov 25, 2024 at 10:12 PM, jmr wrote:
"The other alternative would be to use a ferrite core based inductor. It should be possible to get a Q of about 400 at 1.45 MHz with a small ferrite core inductor with about 50uH inductance. But this won't be suitable for large signal operation."
Due to core saturation?
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Re: VNA Resonance Methodology
You say the GDO must be loosely coupled, which does make sense I can see now. However, that's another aspect of my method which was wrong, then. I was inserting the probe coil actually inside the test coil. I'm not even sure what kind of coupling that arrangement would provide! The tendency is to go for closer and closer coupling when you can't find a dip whereas in reality that might just make things worse!
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Re: HP 8594E PSU repair/debug safety checklist
Differential probe isn't going to keep *you* safe...... The isolation transformer might. (And most variac's are NOT isolation transformers) On Tue, Nov 26, 2024 at 9:53?AM Ke-Fong Lin via groups.io <anotherlin@...> wrote:
Hi everyone,
My HP8594E has a temperamental PSU, sometimes everything just works fine otherwise the SA just doesn't turn on.
Something is obviously wrong and needs to be debugged.
I've not opened the case yet. I've just searched a bit the internet ().
HP doesn't provide schematics but people have already attempted repair.
I may have to work on the "mains connected" (120VAC US or 220VAC Europe) side.
So I just want to be sure that I would be safe with a differential probe, and if I use a diff probe, an isolation transformer wouldn't be needed.
Seems that "curious marc" is using a variac as some form of isolation transformer:
In general, do you guys have some links or checklists for safety when working on these kind of switch mode power supply.
Thanks!
Best regards,
|
Paint colour for 5300 / 34740 packages
Hello everyone,
?
Would anyone have a RAL paint colour number for the top and bottom case halves of the 5300 and 34740 series ?
Thanks !
?
Joel Setton
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Re: VNA Resonance Methodology
Jinxie, the Megacycle meters are perfect for the application.
No variac needed, just a 240:120 step down trsf.
I have many including the rare UHF and LF heads and coils.
Much wider range than most VNA.
Bonsoir
Jon
PS Joyce Randolph played Trixie ( not Jinxie) in the 1955 TV weekly
I was close .....
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HP 8594E PSU repair/debug safety checklist
Hi everyone,
?
My HP8594E has a temperamental PSU, sometimes everything just works fine otherwise the SA just doesn't turn on.
Something is obviously wrong and needs to be debugged.
?
I've not opened the case yet. I've just searched a bit the internet (
HP doesn't provide schematics but people have already attempted repair.
?
I may have to work on the "mains connected" (120VAC US or 220VAC Europe) side.
So I just want to be sure that I would be safe with a differential probe, and if I use a diff probe, an isolation transformer wouldn't be needed.
?
Seems that "curious marc" is using a variac as some form of isolation transformer:?
?
In general, do you guys have some links or checklists for safety when working on these kind of switch mode power supply.
Thanks!
?
?
Best regards,?
|
Froggie the Gremlin
Jinxie