Re: Advice on how to use an SA for test point troubleshooting
"Bruce" <bruce@...> writes: If you can find ont, I recommend attaching an HP FET probe to your SA.
If you don't have one, it is a good idea to start looking for one.
I find them a valuable resource for trouble shooting.
Note: the passive probe is unlikely to work. While a FET probe is nice, a suitable high-frequency passive probe (like the PML series) can absolutely work up to 500 MHz and beyond. In fact, you can make them work up to several GHz with proper design. See the Andrew Zonenberg probes, for instance (). Of course, the passive probe approach mandates some sort of voltage division, otherwise this won't work. Sticking some coax between your test point and the oscope will just load down the circuit with a bunch of parallel capacitance. A typical 10:1 or 1:1 oscope probe designed for high input impedance scope termination won't work though. Don't confuse passive probes designed for 1M scope input impedance with those designed for 50ohm scope input impedance. You probably know this, but if you do use a scope and not the SA, make sure the reference point can be connected to earth ground. If not you'll need something to isolate it. The typical approach would be to use a differential probe. Matt
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Re: strange issue on Agilent 54641D MSO
Does it do that if you try moving the input with a non conductive tool? Or just your fingers??
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On Feb 19, 2023, at 1:26 PM, Wilko Bulte <wkb@...> wrote:
?I have an interesting phenomenon on my Agilent 54641D MSO. Upon cold powerup the trace of channel 1 is "all wiggly". The wiggliness is highly sensitive to mechanical movement of the BNC socket of channel 1. See photo below. After (say) 10 minutes the problem goes away, stressing the BNC no longer has a visible effect. The scope works just fine once warm. Channel 2 has none of this nonsense :-) Any ideas? I am toying with the assumption that the socket contacts of the channel 1 hybrid are dirty/temperature sensitive. But that is more like a wild guess. Wilko <0EF0777B-AE21-4A52-B69E-1F1378F81A6C.jpeg>
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strange issue on Agilent 54641D MSO
I have an interesting phenomenon on my Agilent 54641D MSO. Upon cold powerup the trace of channel 1 is "all wiggly". The wiggliness is highly sensitive to mechanical movement of the BNC socket of channel 1. See photo below. After (say) 10 minutes the problem goes away, stressing the BNC no longer has a visible effect. The scope works just fine once warm. Channel 2 has none of this nonsense :-) Any ideas? I am toying with the assumption that the socket contacts of the channel 1 hybrid are dirty/temperature sensitive. But that is more like a wild guess. Wilko 
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Re: 5086-7337 *Yig Oscillator issue*
Ok, let¡¯s do a test set up for current measurements. My plan: separate the oscillator board and make jumpers between both with wire to open them and put the ammeter.
Bruce - I¡¯m measuring rf output directly from the YO, as you can see in the image.
8660 still waiting for pll alignment¡ coming soon
Askild - I will do heater, main coil and FET measurements. I need to be sure before tosh the YO¡
Yesterday I got a little frustrated after seeing that there was no rf signal. So I replaced the YIG oscillator with a sweep signal from my 8341A. This way it proves that the ALC, amps, mixer and multiplier work reasonably well. It's hard to match the SYTM and the 8341A, but after doing a lot of free run sweeps and recording the maximums in the 8566B, I was able to observe a flat and stable amplitude response in all four freq bands of the 83592A. So I can say that the ¡®frankenstein¡¯ plugin seems to work except for YO. At least a good new for me to continue the project ;)
Regards,
Ruben
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Re: Advice on how to use an SA for test point troubleshooting
If you can find ont, I recommend attaching an HP FET probe to your SA. If you don't have one, it is a good idea to start looking for one. I find them a valuable resource for trouble shooting.
Note: the passive probe is unlikely to work.
Cheers!
Bruce
Quoting Matt Huszagh <huszaghmatt@...>:
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"Tony" <tonycox01@...> writes:
I am troubleshooting a signal generator and the service manual says to check TP1 for 500MHz at +2-3dBm.
TP1 appears to be just a probe location on a trace (see attached image).
My question is what sort of probe should I attach to my spectrum analyser (8566B) to check the test point on the trace? Can I use a oscilloscope probe? If so, do I attach the probe ground lead?
I¡¯m used to using straight BNC-based input so this has me a bit unsure how to proceed.
I don¡¯t want to get an incorrect reading or worse, damage my SA! If you have it, I'd probably use a high-frequency passive probe for
this. For example, the PMK PML series:
I think Keysight and others just rebrand this for their high-frequency
passive probes.
The 50ohm-input terminated 10:1 and 100:1 versions will get you up to
1.5 GHz. If you use this with a scope you'll have to use it's 50ohm
input or add a 50ohm pass-through termination. Of course, your SA is
already 50ohm input so nothing additional needed there. If you use 100:1
division, the resulting signal will be on the weak side for an oscope,
but your SA will see it fine.
Of course you can also use a suitable active probe if you have that, but
check it's damage levels first and make sure the signal is within those
before using it (that actually goes for the 10:1 passive probe too,
which can only handle 12V peak).
In the likely scenario you don't have these, I'd just use something you
do have (as others have suggested), such as a normal 10x probe and
realize the attenuation at 500 MHz will be significant. You can solder
in a coax cable too, but realize that you'll be loading down the circuit
pretty badly. The capacitance of the cable will also present a
significant load to the circuit. You might be able to solder a resistor
in series to decrease the loading, but I don't know how easy it will be
to get high-frequency performance doing this.
As for damaging the SA, put a good DC block in series with the
input. That should prevent damage in the case of DC voltages being
present. I actually just leave DC blocks on my 8566's at all times and
take them off if I ever need to see below the 10 MHz cutoff. If you're
still worried, you can probe the signal first with other means (eg an
oscope) to check for large DC voltages or even large AC swings, but this
all seems unlikely to me.
Matt
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Re: 5086-7337 *Yig Oscillator issue*
Rubin -
Two things to do:
1) Check ALL voltages to YIG sub assembly and check cable connections
2) Measure the YIG main coil current - you can ignore the FM coil - there will be a resistor used to sense the current somewhere in the circuit - measure the voltage across this resistor. Be sure the current is within expected values.
If no output, look for broken coac or measure output directly from the YIG
How is your 8660 coming ??
Cheers!
Bruce
Quoting RubenRubio <rubenrb2019@...>:
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Hello everyone!
Although this topic belongs to my 8350B restoration thread I did almost a year ago, I want to imprint some relevance. Shortly, my 8350B mainframe doesn¡¯t have main transformer. Instead of that I feed it with three external sources.
These days I managed to get a 83592A plugin in two separated parts sets. I have put them together and after some power supply issues (classic shorted tantalum), there¡¯s no errors displayed. *But no RF coming out.* Unleveled LED lits in the front panel.?Also no RF at the rear aux output, nor at the exit of YO itself (God shake! it¡¯s tricky to access microcircuits!).
Following the signal path and troubleshooting notes on the manual, I check that the +5, +20, -40 supplies for the YO are present. Also the ON -10 volt signal and the M composite signal on scope. At first glance, G bias signal (which should be -2 volt) was almost 0. I check the associated components and after turning a pot, -2 volt come back.
Still no signal at the output of the oscillator :(
Is there any other way to check the YO before officially declaring it dead?
Regards,
Ruben
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Re: Advice on how to use an SA for test point troubleshooting
Tony
In years past I made probes from two resistors and a length of coax. The probe was made of a series
5100 ohm resistor that connected to the center of the coax cable. A 51 ohm resistor was placed across
the junction of the coax and the 5100 ohm resistor to ground. If you want to have a more precise
probe use two paralleled 10 K resistors for the series resistor and two paralleled 100 Ohm resistors
for the shunt 51 ohm. Using the resistors with the spectrum analyzer, you should have a fairly wide
bandwidth probe up to a GHz with -40 dB gain loss. So for a 0 dBm signal, your spectrum analyzer
will display -40 dBm. The error using this arrangement will be less than 0.1 dB and 5 K plus of resistance
shunting your transmission line on the board will have negligible effect.
Regards
Chuck
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Re: HP 212A pulse generator - asbestos inside!
Asbestos can be removed quite safely if you soak it with water before disturbing it. It will become a soft gooey mess which can be bagged and disposed of in an approved disposal facility.
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Re: HP 212A pulse generator - asbestos inside!
Chuck-
you are not the only one having the same info, I had the same. before that growing up in the 60's we did our own brake work ( no air blowing) , wrapped pipes with disgarded asbestos sleeves, used sheets for fire prevention and siding, etc....We made our own metal heat treating furnace with blocks of the stuff.
the key then and still I believe now...Do not go overboard as many do today but do be respectful of the potential dangers.
If you find it ( asbestos) leave it alone, it is there for a purpose.( do make a note for the next person) . If it has been there for any length of time the worst is ( probably) already long gone ( unless brakes/clutches). If you must move it then treat it like smoke/ashes and just be careful, do not breath the dust ( you may need a mask). pre and post operations clean-up is wet rags to collect/prevent dust and if reasonable (depending on application) paint over it for a seal.
¸é±ð²Ô¨¦±ð
on 2/19/23 7:55 AM, Chuck Harris wrote:
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One thing that doesn't get mentioned much is the small particles
of asbestos don't survive exposure to moderately high heat and to
sunlight.
Or, so said the engineering course I took on air pollution during
the 1970's. The professor was a rabid environmentalist, so I doubt
he would have just made up the information...
It maybe interesting for some to note that back when I was in college,
everyone was worried about the coming ice age... It was well known
that the Sun's activity cycles caused ice ages, and one was long
overdue... thousands of years overdue.
-Chuck Harris
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You might also perform troubleshooting test 15 for BD9 as described in
vol 2 of the manual.
Matt
"Dave Miller" <ve7hr@...> writes:
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Matt,
That may well be the issue.
Do you happen to recall what the your LED¡¯s looked like. I am trying to determine if no keys are pressed are all the LED¡¯s on solid on the keyboard decode on the front left of
the unit with the cover off.
I have 2 8662A and one 8663A so I will eventually figure out how they work.
Thanks for your suggestion.
Dave
On Feb 18, 2023, at 9:41 PM, Matt Huszagh <huszaghmatt@...> wrote:
?I also had a non-responsive keyboard on my 8663. It turns out the metal leaf contact under one of the Bill West keys had come loose and was in a perpetual depressed
position. This was constantly interrupting the processor and preventing it from being interrupted by other key presses. I don¡¯t know if this is your issue but it could be
worth looking into.
Matt
On Sat, Feb 18, 2023 at 7:15 PM Dave Miller <ve7hr@...> wrote:
I am working through my latest score of signal generators. Back is sore. Working on the light ones first.
I am puzzled with this 8662A. I am hoping someone who has been down this path before might give me some
pointers.
Powers up with no errors.
No Smoke :-)
100.0000 MHz -30 dBm On display. Spectrum Analyzer confirms it is as advertised. Yay!!!
It does not respond to any keypresses.
Pressing and holding select does not give you any codes.
Popped the top cover and all LED¡¯s on the key decoder board are on. Pressing all the keys in turn show a different code. I have not checked them against the key
tables yet.
Is all LED¡¯s on with no keys pressed correct? I have not found that in the OSM yet.
Any suggestions?
Thanks
Dave
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"Dave Miller" <ve7hr@...> writes: That may well be the issue.
Do you happen to recall what the your LED¡¯s looked like. I am trying to determine if no keys are pressed are all the LED¡¯s on solid on the keyboard decode on the front left of
the unit with the cover off. I'm sorry, I don't recall, but I want to say that's correct. Since you have other units, I'd check the behavior against those. If those aren't accessible I can probably check mine for you. I haven't put it back in the rack yet, but I'd have to shuffle around a few things to get to it. Matt
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What¡¯s the serial number of your unit? HP got rid of the ROM/RAM board in put all the necessary ROM/RAM on an existing board after some revision.
Is your unit working? If so, your unit is almost certainly complete. Even if not, my guess is it¡¯s still probably complete.
Matt
On Sun, Feb 19, 2023 at 5:10 AM colingoode2000 via <colingoode2000= [email protected]> wrote: I have an 8662a oscillator which has a missing board may be two My question is what should be fitted in the right hand A2 slots coloured Green Blue Purple Grey and White I am missing a Rom Ram board but I have found two types available one for the White Slot and one for the Purple slot Do I need both or just one  ?
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Does an HP Transformer Specification Document exist ?
Did HP have a Transformer Specification Document ?
?
similar to the Tek version:
??
?
Trying to find a close replacement for a small? hp?? HV?? xfmr? ? ?
... hoped? to see if HP had anything close...
thank you,
rick
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Re: Advice on how to use an SA for test point troubleshooting
"Tony" <tonycox01@...> writes: I am troubleshooting a signal generator and the service manual says to check TP1 for 500MHz at +2-3dBm.
TP1 appears to be just a probe location on a trace (see attached image).
My question is what sort of probe should I attach to my spectrum analyser (8566B) to check the test point on the trace? Can I use a oscilloscope probe? If so, do I attach the probe ground lead?
I¡¯m used to using straight BNC-based input so this has me a bit unsure how to proceed.
I don¡¯t want to get an incorrect reading or worse, damage my SA! If you have it, I'd probably use a high-frequency passive probe for this. For example, the PMK PML series: I think Keysight and others just rebrand this for their high-frequency passive probes. The 50ohm-input terminated 10:1 and 100:1 versions will get you up to 1.5 GHz. If you use this with a scope you'll have to use it's 50ohm input or add a 50ohm pass-through termination. Of course, your SA is already 50ohm input so nothing additional needed there. If you use 100:1 division, the resulting signal will be on the weak side for an oscope, but your SA will see it fine. Of course you can also use a suitable active probe if you have that, but check it's damage levels first and make sure the signal is within those before using it (that actually goes for the 10:1 passive probe too, which can only handle 12V peak). In the likely scenario you don't have these, I'd just use something you do have (as others have suggested), such as a normal 10x probe and realize the attenuation at 500 MHz will be significant. You can solder in a coax cable too, but realize that you'll be loading down the circuit pretty badly. The capacitance of the cable will also present a significant load to the circuit. You might be able to solder a resistor in series to decrease the loading, but I don't know how easy it will be to get high-frequency performance doing this. As for damaging the SA, put a good DC block in series with the input. That should prevent damage in the case of DC voltages being present. I actually just leave DC blocks on my 8566's at all times and take them off if I ever need to see below the 10 MHz cutoff. If you're still worried, you can probe the signal first with other means (eg an oscope) to check for large DC voltages or even large AC swings, but this all seems unlikely to me. Matt
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Re: Advice on how to use an SA for test point troubleshooting
A x10 scope probe won't work well with a SA because the probe is made up of a 9M series resistance that works with the 'scopes 1M input resistance to make x10. The SA has a 50R input resistance, so instead of x10 you get x 180000.
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No, I would not use tuner cleaner or any of its descendants. 91% IPA, sprayed liberally (eg. soak it!) does everything that is required. Use a spray bottle, like is used for ordinary window cleaner. Do not add lubricant! It will only make the springs sticky. Plain old 91% IPA as comes from the drugstore. -Chuck Harris On Sun, 19 Feb 2023 00:37:55 -0800 "tom_iphi via groups.io" <iphi@...> wrote: Many thanks for your thoughts and insights!
There are a few commercial sprays for solving contact/corrosion
problems. Here in Europe there are available e.g.
-Contact spray, which removes corrosion, but also contains some kind
of lubricant. So not a good idea? -Tuner spray, which was used in the
old days to clean TV tuners, evaporates without leaving residues. Any
experiences?
Tom DG8SAQ
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Re: HP 212A pulse generator - asbestos inside!
One thing that doesn't get mentioned much is the small particles of asbestos don't survive exposure to moderately high heat and to sunlight. Or, so said the engineering course I took on air pollution during the 1970's. The professor was a rabid environmentalist, so I doubt he would have just made up the information... It maybe interesting for some to note that back when I was in college, everyone was worried about the coming ice age... It was well known that the Sun's activity cycles caused ice ages, and one was long overdue... thousands of years overdue. -Chuck Harris On Sun, 19 Feb 2023 10:59:37 +0000 "Dave_G0WBX via groups.io" <g8kbvdave@...> wrote: Hi.
You left out one of the most common past applications for Asbestos...
It was a significant component material (among others) used in
vehicle brake linings (and clutch assemblies, where used.)
Contaminated dust was released (not just Asbestos particles) each
time you used the brakes... Cylinder head, and exhaust manifold
gaskets pre WW2 also contained it.
There is in an archive somewhere, an advertising film made by the
Asbestos industry, showing how important Asbestos is in such uses,
and what happens if you leave it out.? I haven't found that one yet,
but if you just search YouTube for "Asbestos", there are archival
movies that will make you shudder now!
Is close to what I recall, from about 3:30 min's.
How many modern H&S violations can you spot?
Where does all the dust from the cutting, drilling and grinding go?
Just makes you wonder...
Regards.
Dave G8KBV
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Hi Askild, I have the Artech manuals on the 866A that are wonderful scans. ?I will grab the 8663A set once I am about to work on the 8663A. The 2 8662A are enough of a handful.? They are apparently difficult twins. One is sitting in the corner pouting and ignoring me. The other one is not paying attention all the time.? Thanks for the reminder on other manual sources. I will grab them and compare.?
Dave
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On Feb 19, 2023, at 2:47 AM, Askild <megafluffy@...> wrote:
? Hi Dave,
One place you will find manuals for the 8662 and 8663 is at KO4BB
Regards, Askild
On Sun, Feb 19, 2023 at 6:57 AM Dave Miller < ve7hr@...> wrote: Matt, That may well be the issue.? Do you happen to recall what the your LED¡¯s looked like.? I am trying to determine if no keys are pressed are all the LED¡¯s on solid on the keyboard decode on the front left of the unit with the cover off. ?
I have 2 8662A and one 8663A so I will eventually figure out how they work.?
Thanks for your suggestion.?
Dave ? I also had a non-responsive keyboard on my 8663. It turns out the metal leaf contact under one of the Bill West keys had come loose and was in a perpetual depressed position. This was constantly interrupting the processor and preventing it from being interrupted by other key presses. I don¡¯t know if this is your issue but it could be worth looking into.
Matt On Sat, Feb 18, 2023 at 7:15 PM Dave Miller < ve7hr@...> wrote: I am working through my latest score of signal generators. Back is sore. Working on the light ones first. ?
I am puzzled with this 8662A. I am hoping someone who has been down this path before might give me some
pointers.?
Powers up with no errors.
No Smoke ?:-)
100.0000 MHz ?-30 dBm ? On display. ? Spectrum Analyzer confirms it is as advertised. Yay!!!?
It does not respond to any keypresses.
Pressing and holding select does not give you any codes.
Popped the top cover and all LED¡¯s on the key decoder board are on. Pressing all the keys in turn ?show a different ?code.? I have not checked them against the key tables yet.?
Is all LED¡¯s on with no keys pressed correct? ? I have not found that in the OSM yet. ?
Any suggestions?
Thanks
Dave
?
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Hi Paul, I probably did not explain properly. ? I am referring to the diagnostic LED¡¯s on the front most card on the left side of the card cage.? That one shows using 7 LED¡¯s which key has been pressed. From what I can deduce?
After looking at my 2 8662A¡¯s ( one that almost works and does respond to most of the keys properly) is that those 7 LED¡¯s are on 111 1111 there is no keys pressed. Any key pressed and one or more of the LED¡¯s goes out and the resultant code should match the key code in the schematic in the manual on sheet 2 and 3 I recall. ?
On both units the keys seem to match the manual.? On the unresponsive unit it appears the key codes are correct but the unit is not processing this information. Thus it¡¯s always stuck at 100.00 MHz and -30 dBm.?
On the almost working unit it seems to be processing most of the keys properly and adjust the output ? OST of the time properly but not always display proper information on display. ?Certain frequencies are not displayed properly but output on generator is correct. ?Some segment like the + on the dBm are always on. ? The almost working one is promising as I can control the frequency, output and sweep in most cases. ?
So to summarize from what I have seen all 7 Diagnostic LED¡¯s on key code board should be on with no key pressed. If they are not this would hint that there is a stuck key. Does this make sense. ? Dave
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On Feb 19, 2023, at 7:20 AM, paulswed <paulswedb@...> wrote:
? Oh my 8662 and 8663s are indeed heavy no more than one on the bench at a time... At least my bench. If all the displays are on thats like a power start up and then suspect the unit hangs. Definitely?seems like a cpu issue. Or a always on interrupt?as suggested above. If one of those spring leafs fall out, save it you can fix the switch it came from usually. Good luck Paul WB8TSL
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Re: Advice on how to use an SA for test point troubleshooting
Do you have a scope? If so try that first. Even if the BW is lower than 500MHz you should be able to see some signal and it will give you DC levels. That should let you determine if there are SA damaging voltages present. Given the power levels you suggest that should be ok for the SA. HP had some special cable assay¡¯s that would plug into the two ¡°sockets¡± shown. A 10X probe should be OK, AFTER checking for DC voltages and I would ground the probe. ?From the picture I¡¯d suspect that the other pin is a ground connection. Not knowing what the schematic says on that little circuit it¡¯s hard to guess. ?I think it looks like the black diode might be a PIN switch with the ¡°on¡± bias supplied through the glass diode. ?Another question would be where does the fat trace leading to the left of the black diode go? ?It is also DC blocked, so that could mean the PIN diode idea is OK. If that trace goes to an off board connector you could try sampling after the DC blocking cap or if it¡¯s a connector just pull that connector and see what¡¯s there. ?
Hope this helps a bit. ?Just make sure there are no DC voltages anywhere you try to monitor with the SA.?
Steve
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KB2LMN
RubenRubio
