Re: HP 5342A blowing fuses on switch on
Jack,
I would check CR1 and CR2 (the bridge rectifiers) 1st. One might be shorted. Assume you have a DVM and know how to do this.
(with the board removed of course)
Mark
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My 5342A freq counter has started blowing fuses on switch on.
I removed the A19 board which just left the filter, fan and oven transformer in circuit. No blown fuse and the fan runs.
Replaced the A19 board and BANG.
?
I am seeing a kit of PSU boards for a 5343 which, by the board numbers, look the same.
Should I just get these 3 and replace then all of does anyone have some insight?
I do not have an isolation transformer and am very hesitant to work on this while it's connected to the mains.
?
Thanks
?
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HP 5342A blowing fuses on switch on
My 5342A freq counter has started blowing fuses on switch on.
I removed the A19 board which just left the filter, fan and oven transformer in circuit. No blown fuse and the fan runs.
Replaced the A19 board and BANG.
?
I am seeing a kit of PSU boards for a 5343 which, by the board numbers, look the same.
Should I just get these 3 and replace then all of does anyone have some insight?
I do not have an isolation transformer and am very hesitant to work on this while it's connected to the mains.
?
Thanks
?
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Re: HP 339A Distortion Test Set repair/refurbish (hamfest find) (long read)
Thanks Dave.
?
I'll look into that next. During my initial testing I did look at the freq. output of the oscillator and I didn't see anything that looked outrageous re: actual vs. setting, but I didn't run the math to see if in spec. I the cases where the input LED was on, sometimes the oscillator freq was spot on and other frequencies where the LED was on freqs. seemed off from spec, but not too far off. I think it may be a little bit of both - notch filter center freq. being off in some cases, oscillator freq. off in others.
?
I looked through the schematic at the section for the monitor output and it's a simple path from the main meter circuitry (which appears to be working) - just a resistor, fuse and then the isolation relay. I hear the relay get activated/deactivated, so once I have the unit open again I will probe that path and see where the signal stops. I am hoping that it's just the 0.062A fuse.?
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I am going to let the unit "bake" for a week or so. After 24 hours the freq. that starts requiring the vernier is now down from 3.5 KHz to 3.3 KHz.
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Did I read somewhere where HP did not include the schematic for the 339A's oscillator itself in the service manual?
?
JB
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Re: 8566B attenuator removal
The sizes I¡¯ve seen for watches weren¡¯t 1/2mm cross section. They were thicker like 0.6mm (1.0 ID/2.2OD or something like that).
The proper size isn¡¯t that hard to come by.
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Hi, O©\rings are 2mm OD and 1mm ?D. Commonly used to seal the stem on wristwatch winders. Just be wary of cheap imports made from inferior materials!
On 8 September 2024 17:45:38 BST, "Jinxie via groups.io" <paul666@...> wrote:
I have now extricated the attenuator from the guts of the analyzer (see picture). Can some kind soul point me to the disassembly instructions for this thing? I've also included a photo of the spare attenuator I have which I may have to cannibalize to repair
the original one. Also, if anyone has a rough idea of the size of the o-rings I might encounter later on, that would be helpful. I have quite a selection of o-rings 'in stock' here.
?
J.
?
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Re: 8566B attenuator removal
If the problem is with the o-rings (likely scenario), you will not be doing anything to the attenuator cards. You will not be removing them unless they have been overloaded. The cards are made of thin film resistors on saphire substrates.They don't deteriorate unless overloaded.
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For o-ring replacement, you will have to carefully unhook the plastic plungers from the leaf springs. You will need some fine tools like tweezers or similar to manipulate the plungers out of the slots in the springs. The o-rings are mounted on these plungers. Then, you will put all that back in. A low power microscope or watchmaker's loupe would help. Before you start the extraction of the plungers, study the layout and understand why the rings are there. Exercise the plungers by hand to see how the mechanism works. If you don't see a ring, it may have cracked and fallen off. Compare to the neighboring section to see where it should be. The most important thing is to not bend the springs past their elastic limit while dealing with the plungers.
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Vladan
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Re: 8566B attenuator removal
Okay, many thanks indeed for all the info and pointers. That lot should set me in good stead for the task ahead, which I'm not really looking forward to as it seems to require a good eye and steady hand - neither of which I'm blessed with!? I really don't want the bench fully occupied with 'stuff' as it currently is until next Sunday, so will attempt this repair by making time during the week and pray for no hitches. I'm just hoping it's nothing terminal. Just out of curiosity, what material are these pads made from? I gather they can be a bit brittle and fragile. Were they like that from new or is it just another aspect of the age of this analyzer?
Anyway, ludicrously late here in my part of the world now so time for some shut-eye, methinks..
?
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Re: 8566B attenuator removal
Jinxie, I made a mistake, the 8566 attenuator has four sections, not three. I may have mixed it up with the 8568 attenuator. A 40dB attenuator card with good return loss to 22GHz is difficult to make, so the 8566 uses two 20dB cards to get 40dB plus another 20dB card to get to 60dB. The remaining card is 10dB. Your numbers show that one of the 20dB stages in your attenuator never bypasses.
?
The 8566 attenuator you have (85660-60121) may possibly also be found under the following part numbers. This is from some old notes I have, verify before buying anything.
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33321YH
5086-7814
5086-6814
33321RF
and possibly 85660-60304
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The reason for all these numbers is that HP sold parts to the outside world, as well internally from division to division. Also, each 8566 (and 8568) attenuator was supplied with a PROM containing calibration data for attenuation for each stage. Don¡¯t worry about that PROM, the corrections are of very limited use. The standard 33321 is the same hardware without the PROM.
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Your 8495K uses either 24 or 5V for switching. It should have a label somewhere on it showing which. Option 024 is 24V and option 011 is 5V. Default is Opt. 024, but you should check what you have.
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The disassembly instructions were referenced in a recent post:
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?
This writeup may also exist in the files section of this forum.
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In a few words, there are two compartments. One consists of the solenoids, the other is a channel with the attenuator cards and leaf springs. You start out by removing the end plate held in place with four socket screws. This is the end plate that is opposite from the one with the control line connector. The screws are often hidden by a decorative cover plate which is lightly glued on. Once you remove the end plate, you can slide off the U-shaped metal cover. Don¡¯t try to pry it off by putting a screwdriver into the seem on the side, that¡¯s not how it was designed to be opened.
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After you remove the solenoid cover but before you open the rf side, check visually that the solenoids are moving by changing attenuation via the front panel keys.
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The RF block is opened by removing the screws you see around and under the label. This is the area where you will be doing most of the work. Keep this area free of lint. Be extremely careful to not deform the leaf springs that act as contacts. They are easily bent and ruined. You will have to stress them a little while unhooking the plungers which have the o-rings on them. Maybe the o-rings are still ok, in which case you don¡¯t have to risk damaging the springs. You can inspect the o-rings without removing the plungers. The o-rings are 0.039" ID x 0.024" hydrogenated nitrile rubber, 80 durometer, shore A.
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Vladan
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Re: 8566B attenuator removal
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Re: 8566B attenuator removal
Hi, O©\rings are 2mm OD and 1mm ?D. Commonly used to seal the stem on wristwatch winders. Just be wary of cheap imports made from inferior materials!
On 8 September 2024 17:45:38 BST, "Jinxie via groups.io" <paul666@...> wrote:
I have now extricated the attenuator from the guts of the analyzer (see picture). Can some kind soul point me to the disassembly instructions for this thing? I've also included a photo of the spare attenuator I have which I may have to cannibalize to repair the original one. Also, if anyone has a rough idea of the size of the o-rings I might encounter later on, that would be helpful. I have quite a selection of o-rings 'in stock' here.
?
J.
?
Attachments:
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Re: HP 339A Distortion Test Set repair/refurbish (hamfest find) (long read)
I had this problem too, ten or so years?ago when I got my 339A.? The notch filter's lock-in range doesn't quite overlap?with the oscillator.? I don't remember exactly what I did but I think I bent the oscillator so it was centered with respect to the filter,
by tacking on caps or resistors on the troubled ranges on the A1 oscillator board.? Looking at the schematics today, I see that the A4 notch filter board has trim-pots for filter center frequency and null.? I don't know if I missed that, or was the filter
okay and the oscillator off?? Anyway, there's a place to start.
HTH,
Dave Wise
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Hello All,
?
As a possible opportunity to upgrade my? test bench's HP 333A, I recently obtained a HP 339A distortion analyzer of unknown heritage, but very late serial number.
?
Physically, not in too bad shape, all things considered:?
- missing bottom feet (not unusual, I suspect - probably was rack mounted) - I would be interested in finding these, if anyone knows of a source (new or used)
- missing end cap for input knob, otherwise all knobs complete (and not broken!)
?
- Cleaned up well, internal inspection didn't reveal any previous obvious "tinkering", looked clean. Powered up and went through basic testing (using internal oscillator), seemed to mostly work but with the following observations:
1) Output monitor completely dead (not too worried about this yet)
2) Using the internal oscillator (1V output), for frequencies below ~3.5 KHz, the Freq. Input LED (counter clockwise) illuminates. I can extinguish the LED by moving the frequency vernier knob off of the "calibrated" detent position. If I do this, then
all of the lower frequencies are reported to be in the notch filter's range and autoset works under this condition, depending on the actual frequency the vernier knob has to be set anywhere from just off the detent to about 2 o'clock max. As frequencies go
lower than 3.5 KHz, the vernier has to be turned more CW. I've tried various voltage output settings (3, 0.1, .03) and the above behavior doesn't change as far as I can determine. Reported distortion values seem reasonably close (if not in,) to spec.
?
What I've done so far:
- carefully deoxit only the metal contacts on all wafer switches (yes this took a while)
- re-seated the one board in a connector
- re-seated all cable and connectors
- loosened, re-tighted all mounting screws
- supplied missing endcap for input knob (my HP8640B parts bin had exactly one knob with the right cap size & color - from the output attenuator's center variable control, I believe)
?
I am going to leave the unit powered up for a couple of days, it seemed like the longer it was on, the lower I could set the frequency and not have to use the un-calibrated vernier setting (capacitors reforming??) and see where it's at.
?
- I have not compared it to my HP 333A yet, but I have hooked up a couple of other sig gens that I have just to see its operation, results seemed reasonable
- Other than the output monitor being dead, it seems like it just might need an alignment/calibration
?
I have some equipment (HP pulse generator, scopes, freq. counters, etc.), but nothing calibrated by a lab, just a semi-serious hobby for me - testing/repairing my own stuff.
I have not looked at the supply rails with a scope yet, I have looked at the output - looks like a nice sine wave.
I will review the schematic for the output monitor, but I am not hopeful if it turns out to be an active device (finding replacement transistors are pretty much unobtanium nowadays, it seems).
?
Suggestions , opinions on where to go next?
?
sorry for the TL;DR
?
Thanks,
Jim
?
I gotta say, I just love seeing the gold PCB traces on this era's equipment - no tin-wiskers here! I smile every time I open up this type of equipment.
?
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Re: 8566B attenuator removal
I have now extricated the attenuator from the guts of the analyzer (see picture). Can some kind soul point me to the disassembly instructions for this thing? I've also included a photo of the spare attenuator I have which I may have to cannibalize to repair the original one. Also, if anyone has a rough idea of the size of the o-rings I might encounter later on, that would be helpful. I have quite a selection of o-rings 'in stock' here.
?
J.
?
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Re: 8566B attenuator removal
Okay, done a bit more testing. As was suggested, I bypassed the internal variable attenuator with a fixed 10dB one and attempted calibration once again. It now calibrates fine.
I thought whilst I had the front panel off but still connected, I'd run a test of the attenuator using a spare spectrum analyzer I have. Methodology was simply to squirt RF in at the input and measure its actual level of attenuation vs its stated level of attenuation for each of the settings 0 through -70dB using the front panel to change the settings each time.
Got some quite interesting results.
?
Setting (dB) ??????????????????????????????????? Actual attenuation (dB)
0????????????????????????????????????????????????????????????? -20
-10????????????????????????????????????????????????????????? -30
-20?????????????? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? -20
-30 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? -30
-40 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? -40
-50 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? -50
-60 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? -70
-70 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? -80! (with massive noise so presumably dirty contacts)
?
Clearly the attenuator needs to be removed and inspected, so that's what I shall now do... ??????????????????
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Re: HP 141T Power Supply Help Needed
No worries Mike.? You guys clearly have more experience.? I've just been doing my best to follow along.? I wanted to make sure I was understanding things correctly.? Seems like your close Bill!
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-Frank
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HP 339A Distortion Test Set repair/refurbish (hamfest find) (long read)
Hello All,
?
As a possible opportunity to upgrade my? test bench's HP 333A, I recently obtained a HP 339A distortion analyzer of unknown heritage, but very late serial number.
?
Physically, not in too bad shape, all things considered:?
- missing bottom feet (not unusual, I suspect - probably was rack mounted) - I would be interested in finding these, if anyone knows of a source (new or used)
- missing end cap for input knob, otherwise all knobs complete (and not broken!)
?
- Cleaned up well, internal inspection didn't reveal any previous obvious "tinkering", looked clean. Powered up and went through basic testing (using internal oscillator), seemed to mostly work but with the following observations:
1) Output monitor completely dead (not too worried about this yet)
2) Using the internal oscillator (1V output), for frequencies below ~3.5 KHz, the Freq. Input LED (counter clockwise) illuminates. I can extinguish the LED by moving the frequency vernier knob off of the "calibrated" detent position. If I do this, then all of the lower frequencies are reported to be in the notch filter's range and autoset works under this condition, depending on the actual frequency the vernier knob has to be set anywhere from just off the detent to about 2 o'clock max. As frequencies go lower than 3.5 KHz, the vernier has to be turned more CW. I've tried various voltage output settings (3, 0.1, .03) and the above behavior doesn't change as far as I can determine. Reported distortion values seem reasonably close (if not in,) to spec.
?
What I've done so far:
- carefully deoxit only the metal contacts on all wafer switches (yes this took a while)
- re-seated the one board in a connector
- re-seated all cable and connectors
- loosened, re-tighted all mounting screws
- supplied missing endcap for input knob (my HP8640B parts bin had exactly one knob with the right cap size & color - from the output attenuator's center variable control, I believe)
?
I am going to leave the unit powered up for a couple of days, it seemed like the longer it was on, the lower I could set the frequency and not have to use the un-calibrated vernier setting (capacitors reforming??) and see where it's at.
?
- I have not compared it to my HP 333A yet, but I have hooked up a couple of other sig gens that I have just to see its operation, results seemed reasonable
- Other than the output monitor being dead, it seems like it just might need an alignment/calibration
?
I have some equipment (HP pulse generator, scopes, freq. counters, etc.), but nothing calibrated by a lab, just a semi-serious hobby for me - testing/repairing my own stuff.
I have not looked at the supply rails with a scope yet, I have looked at the output - looks like a nice sine wave.
I will review the schematic for the output monitor, but I am not hopeful if it turns out to be an active device (finding replacement transistors are pretty much unobtanium nowadays, it seems).
?
Suggestions , opinions on where to go next?
?
sorry for the TL;DR
?
Thanks,
Jim
?
I gotta say, I just love seeing the gold PCB traces on this era's equipment - no tin-wiskers here! I smile every time I open up this type of equipment.
?
|
Re: HP 141T Power Supply Help Needed
Frank, ? I appreciate your calculations.? Bill¡¯s problem is more fundamental than exact calculations would suggest.? It seems that since the voltage at C6 (the bulk capacitor) is so low (<1V) that there must be a wiring problem, or the diodes are bad, or the power transformer has a bad winding (which is very unlikely).? Bill says that he checked the diodes so the only thing left is a broken wire somewhere.? That is the way I see it. ? Mike ?
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From: [email protected] < [email protected]> On Behalf Of Frank Mashockie Sent: Saturday, September 7, 2024 12:29 PM To: [email protected]Subject: Re: [HP-Agilent-Keysight-equipment] HP 141T Power Supply Help Needed ? Wouldn't it be ~27VAC across the winding (11 and 13)? Or ~13.5VAC at both 11 and 12 and 13 and 12?? For a center tapped full wave rectifier Vout = Vp (sec)/2 - diode drop.? Since the center tap is -12.6V and you have 6.0VDC at the output, if we make -12.6V ground, you have Vout = 18.6VDC.? (18.6 + ~0.7)x2 = 38.6Vp.? 38.6 x square root 2 = 27VAC in rms across the winding from pins 11 to 13. Or am I missing something?
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Re: E4438c display problem, controler memory location please
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Re: Leaking alkaline cells
The whole discussion of battery reliability reminds me of another issue a couple of decades ago.?I was on a project that had to store many images in an image library. CDROMs were one option were they reliable?
I found a ?NIST? report on the archival properties of writeable CDROMs. They investigated many different types from many different manufacturers; some were useful for archiving within acceptable limitations, some weren't. From memory, the main parameters were the chemistry of the writeable layer, and the top-surface protective layer. The writeable layers came in a few colours. Some colours were always unusable, some were usable depending on the specific chemistry involved - but you couldn't tell the difference by simple observation. On top of that, each manufacturers tended to sell a variety of chemistries without specifying which you would get.?In essence the brands appeared to be little more than names applied to whatever they could source this month.?
Thus the only way to tell whether a batch of CDROMs was suitable for archival purposes was to test them for that. Not helpful.
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looking for a scan of the HP8901A pull out reference card
I am looking for a pull out reference card for the HP8901A modulation analyser.
Mine used to be rackmounted and lost its card in the mists of time. Now that I have repaired its PSU it is time to stick it into my ham shack.
?
A ?hi-res scan would be great, who can help me please? Sofar drew blanks on Google e.a.
?
Vy73 Wilko
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Re: Leaking alkaline cells
Morris,
I've just checked the pack I bought them in and it says (proudly and in several places) "Made in Germany" so it would seem the ones available in the antipodes are made to an inferior standard under licence - presumably - somewhere else on the planet. I can't ever recall having had an issue with Varta batteries and I use them preferentially in everything I value. Duracell really needs to take a long, hard look at itself.
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Re: Leaking alkaline cells
Forgive me if I missed something but I have not been following this thread very closely.
?
I'm not saying they were wrong, but weren't environmentalists behind the EPA forcing removal of mercury from alkaline cells?? The mercury was present to reduce the tendency to evolve hydrogen gas which swelled the cells or caused them to leak.? 1996 time frame for enactment of the rule/law.? Link:
My memory is that was the beginning of the end for alkaline reliability.? It would appear that as with? Tetraethyllead in fuels, the industries never came up with a a good replacement for the environmental toxin they had to remove.? Some countries may still make cells with traces of mercury, the US pretty much banned it except for button cells.? Considering how many of those have leaked since the ban started I assumed they removed it from them as well.? Button cells almost never leaked, now leaks are common.? I don't know which or if all other countries have banned mercury in batteries.? China only banned it in 2021 (a 2017 law).
?
I have a large number of dead alkaline cells in a jar many of them have leaked since they were removed but quite a few leaked before being fully depleted.? Both Duracell and Energizer batteries are leaking, more the longer they have been depleted.? I have seen leakage in a new cell from a large pack as well.? The variabil;ity is probably due to manufacturing process variations in the seals.? I had one small lot of batteries that all leaked shortly after depletion.? Fortunately I used most of those on my wireless mice and keyboards so they were removed before they leaked but they leaked before I put them in the recycle jar.? It took a couple of years to use them up, but the age didn't seem to matter, just once they were below 1 volt, leakage was imminent.?
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Clay
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Jack
Jinxie
Frank Mashockie