moin, i'm from germany, so sorry for my bad old school english 😉
i' ve got a new toy, also known as boat anchor on my little bench.
a hp339a. i think it's in a good condition - except two knobs - but i think thats more than normal 😉
at first i try to understand how to work with it and i lost my time ...
i recognized that the analyzer don't work under 30mv (rtfm)😀
so i decided to read something more in the manual (are there only manuals in the www with the bad quality in chapter 5 ?)
i start with 3-44 operational verification checks - found out bad osc level reading - opening the 339 measure the voltages in the power supply (ok) - desoxy on all swichtches (like in my old heathkits 😉 and all plugs.
so i found a cable with an open end - a little search and the osc level shows now the right level.
in my opinion the results of the checks are as they should be with an old vernier poti (new bourns are on the road)
the only thing that isn't right i think -
the right indicators lit everytime in the distortion function
osc level switch input range to no lights
switch function to distortion and right led lights up -and no switches the led of 😱
the 339 measure with the burning light - i test my heathkit ig-72 and the ig-1271 the results of this two are just a little bit under the written specs
whith the internal oscillator i got as an example 3v 40khz 0.003% if i read the scale and knobs correct 😕
i hope you understand my question right - is it ok with the brurnig led (i don't think so) and where is the way to find the error
thanx a lot
sun is shining in the low mountain range in the middle of germany
i' ve got a new toy, also known as boat anchor on my little bench.
a hp339a. i think it's in a good condition - except two knobs - but i think thats more than normal 😉
at first i try to understand how to work with it and i lost my time ...
i recognized that the analyzer don't work under 30mv (rtfm)😀
so i decided to read something more in the manual (are there only manuals in the www with the bad quality in chapter 5 ?)
i start with 3-44 operational verification checks - found out bad osc level reading - opening the 339 measure the voltages in the power supply (ok) - desoxy on all swichtches (like in my old heathkits 😉 and all plugs.
so i found a cable with an open end - a little search and the osc level shows now the right level.
in my opinion the results of the checks are as they should be with an old vernier poti (new bourns are on the road)
the only thing that isn't right i think -
the right indicators lit everytime in the distortion function
osc level switch input range to no lights
switch function to distortion and right led lights up -and no switches the led of 😱
the 339 measure with the burning light - i test my heathkit ig-72 and the ig-1271 the results of this two are just a little bit under the written specs
whith the internal oscillator i got as an example 3v 40khz 0.003% if i read the scale and knobs correct 😕
i hope you understand my question right - is it ok with the brurnig led (i don't think so) and where is the way to find the error
thanx a lot
sun is shining in the low mountain range in the middle of germany
Hi jbuk,
Your English is far better than my German!
As you suggest, the LED behavior isn’t correct. The schematic of Figure 8-16 is a good starting point for diagnosis. Two opamp implements a “window comparator” function that drives the level LEDs. Annotations in the schematic indicate the nominal bias voltages at the opamp input pins. Poking around this circuit should distinguish between a failed opamp (U8A or U9) versus an input voltage that is outside the “window." If the input voltage (J203) is outside the nominal window, please let me what voltage you observe and we’ll explore from there.
Your English is far better than my German!
As you suggest, the LED behavior isn’t correct. The schematic of Figure 8-16 is a good starting point for diagnosis. Two opamp implements a “window comparator” function that drives the level LEDs. Annotations in the schematic indicate the nominal bias voltages at the opamp input pins. Poking around this circuit should distinguish between a failed opamp (U8A or U9) versus an input voltage that is outside the “window." If the input voltage (J203) is outside the nominal window, please let me what voltage you observe and we’ll explore from there.
Hi Steve,
Damn you are good at this stuff. If you get bored or looking for another challenge,
feel free to stop by the R&S UPD: #2 Troubleshooting...thread.
I'm always game to learn something new while trying to recall what
I learned just a few years ago. There is so much more I need to learn.
Cheers
Damn you are good at this stuff. If you get bored or looking for another challenge,
feel free to stop by the R&S UPD: #2 Troubleshooting...thread.
I'm always game to learn something new while trying to recall what
I learned just a few years ago. There is so much more I need to learn.
Cheers
You're very kind, Sync.
You're suggesting yet another excuse for procrastination! Just what I need---
😱
You're suggesting yet another excuse for procrastination! Just what I need---
😱
now shines the moon ...
my english might be not so bad - because of watching yutubies in english an reading manuals 😉
i just have a short look in the 339a after i printed the schematic on a a3 sheet.
i'm not an electronic technician just since 2 two years i poking in smaller electronis - with a little bit more than a multimeter.
so it might be a little bit funny 😀
i poked in my short time today:
the voltage an the on j202 ist in specs -15,3 +15,3
than i found j203 (nice a slot) u9 und u8 no A on board
before the phone rings - i just got time to measure on t6 and t7 there is no difference, if the function set to osc or distortion.
with my little knowledge i think the next point to measure is the 5 on j203 or ?
my english might be not so bad - because of watching yutubies in english an reading manuals 😉
i just have a short look in the 339a after i printed the schematic on a a3 sheet.
i'm not an electronic technician just since 2 two years i poking in smaller electronis - with a little bit more than a multimeter.
so it might be a little bit funny 😀
i poked in my short time today:
the voltage an the on j202 ist in specs -15,3 +15,3
than i found j203 (nice a slot) u9 und u8 no A on board
before the phone rings - i just got time to measure on t6 and t7 there is no difference, if the function set to osc or distortion.
with my little knowledge i think the next point to measure is the 5 on j203 or ?
U8A is a reference to the "A" section of opamp U8--- i.e. the opamp with pins 1, 2, 3.
If I understand your comment, yes TP6 and TP7 are fixed and don't vary with changes in function switch position.
An easy experiment: if you adjust oscillator amplitude to produce 50% meter deflection, you should see about 0.5V on J203, U8 pin 3, and U9 pin 2. U8 pin 2 should be about 1V, U9 pin 3 should be about 0.28V If the opamps are functioning correctly, both U8 pin 1 and U9 pin 6 should be near the negative rail. But I'm guessing U8 is not near -15V? If my guess is correct, U8 is probably failed. If U8 has failed, it's possible bias voltages on its input pins could also be displaced from nominal.
If I understand your comment, yes TP6 and TP7 are fixed and don't vary with changes in function switch position.
An easy experiment: if you adjust oscillator amplitude to produce 50% meter deflection, you should see about 0.5V on J203, U8 pin 3, and U9 pin 2. U8 pin 2 should be about 1V, U9 pin 3 should be about 0.28V If the opamps are functioning correctly, both U8 pin 1 and U9 pin 6 should be near the negative rail. But I'm guessing U8 is not near -15V? If my guess is correct, U8 is probably failed. If U8 has failed, it's possible bias voltages on its input pins could also be displaced from nominal.
Now that I review your original post more carefully, perhaps the LED is stuck "on" only in Distortion mode? If yes, my failure to read--- not your English!
What is actual voltage on J203?
What is actual voltage on J203?
i just jumped out of my bed...
yes directly after switching in the distortion function
0,5v is the reading on j203
and in the osc level function on the opamps U9 pin 2 and U8 pin 3
after switching to distortion function : U9 pin 2 got 14,7 and U8 pin 3 the same
yes directly after switching in the distortion function
0,5v is the reading on j203
and in the osc level function on the opamps U9 pin 2 and U8 pin 3
after switching to distortion function : U9 pin 2 got 14,7 and U8 pin 3 the same
I thought I should review where I believe we are so that you can correct me if I’ve misunderstood.
The Level LEDs respond to input amplitude correctly, except when the function is Distortion and then voltage observed at J203 is over 14V. All correct?
In Distortion mode, the J203 signal is generated at U8 pin 8, which in turn is set by TP1. Would you investigate TP1 behavior and determine if it responds properly to changing input amplitude? Results at TP1 should point to either to U1 or its input or to U8C and nearby components.
Good luck!
The Level LEDs respond to input amplitude correctly, except when the function is Distortion and then voltage observed at J203 is over 14V. All correct?
In Distortion mode, the J203 signal is generated at U8 pin 8, which in turn is set by TP1. Would you investigate TP1 behavior and determine if it responds properly to changing input amplitude? Results at TP1 should point to either to U1 or its input or to U8C and nearby components.
Good luck!
i hope so
the led respondig in function osc level works correctly switch to distortion function lights up the right led an the voltage is on j203 (5) is over 14.
osc function, oscilator level about 2v, range in 3v tp1 shows 1,8v after switch to distortion function there are 1,8v, too.
if i set the osc level about 1v i got on tp1 0,9v
is this what you want to know ?
the led respondig in function osc level works correctly switch to distortion function lights up the right led an the voltage is on j203 (5) is over 14.
osc function, oscilator level about 2v, range in 3v tp1 shows 1,8v after switch to distortion function there are 1,8v, too.
if i set the osc level about 1v i got on tp1 0,9v
is this what you want to know ?
So is this your present situation:
Function set to Distortion
TP1 is about 0.9V
But Level LED is lit and J203 is about 14V ???
If yes, then something is wrong at U8C; with TP1 = 0.9V, the expected voltage at U8 pin 10 should be 0.285V. Then the voltage at U8 pin 8 should also be the same 0.285V since U8C has unity gain. If this is what you observe, then U8 has failed.
Function set to Distortion
TP1 is about 0.9V
But Level LED is lit and J203 is about 14V ???
If yes, then something is wrong at U8C; with TP1 = 0.9V, the expected voltage at U8 pin 10 should be 0.285V. Then the voltage at U8 pin 8 should also be the same 0.285V since U8C has unity gain. If this is what you observe, then U8 has failed.
the present situation is like you wrote
now at tp1 0,96V i measure at U8 pin 10 0,3V and at pin 8/9 14 V...
at the other end of the two opamps are the two diodes and my thought was the led light by a (big enough) differnce between U8A pin 1 and U9 pin 6
in the function osc level i measure about -13 on both and in level distortion on U8A +11,2V and on U9 -12,5V...
now at tp1 0,96V i measure at U8 pin 10 0,3V and at pin 8/9 14 V...
at the other end of the two opamps are the two diodes and my thought was the led light by a (big enough) differnce between U8A pin 1 and U9 pin 6
in the function osc level i measure about -13 on both and in level distortion on U8A +11,2V and on U9 -12,5V...
It certainly appears that U8C portion of the IC has failed. Since this section is configured as a unity gain amp, all three pins (+ - out) ought have equal voltages. Replace this IC and this problem should be resolved. With any luck, no further problems will emerge.
It's probably a good idea to go through the performance checks to the extent your available equipment allows.
Good luck!
It's probably a good idea to go through the performance checks to the extent your available equipment allows.
Good luck!
so i ordered one -
i'll solder it in and give a feedback when the 339a will be in function
again.
thanx a lot so far
i'll solder it in and give a feedback when the 339a will be in function
again.
thanx a lot so far
one was enough - it came today and i soldered it in - reasmble the 339a than power power on and connecting with the osc
switch to the distortion level and the led just stay dark.
yes - thank you very much for your help
are you as good in the 334a ?
... but before i'll have to change the potis - ups from digikey wasn't coming today so i'll have to open the 339a another time.
switch to the distortion level and the led just stay dark.
yes - thank you very much for your help
are you as good in the 334a ?
... but before i'll have to change the potis - ups from digikey wasn't coming today so i'll have to open the 339a another time.
Congrats on your repair!
I've never used the 334A but how different can it be? 😉
As you can probably guess, I enjoy troubleshooting. I presume I'd find service docs on the Keysight website?
I've never used the 334A but how different can it be? 😉
As you can probably guess, I enjoy troubleshooting. I presume I'd find service docs on the Keysight website?
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very differnt - i think there are no opamps 😉
service docs are on keysight and all over the web, but ithink it will take a few days
there are a lot of troublebringers near the bench - at first the desoldering iron (why things go bad if they not in use ? )
than the spares fore the 339 and my brandnew heathkit ig-112...variable capacitor lost his balls by the first test
by the way going to work, eat and drink something and repair my cars and so on
service docs are on keysight and all over the web, but ithink it will take a few days
there are a lot of troublebringers near the bench - at first the desoldering iron (why things go bad if they not in use ? )
than the spares fore the 339 and my brandnew heathkit ig-112...variable capacitor lost his balls by the first test
by the way going to work, eat and drink something and repair my cars and so on
I took a quick look at the manual on the Keysight website--- I'm not intimidated; but I don't have to do the hard work, so it's easy for me. I'm game if you are. 😉
I steer clear of offering car advice. 😀
I steer clear of offering car advice. 😀
I have some experience with the 331-334 series, and the 330 before it. However all a long time ago. The design dates from the early 1960's and they were all built in Palo Alto. Two distinguishing features- the RF detector and the auto-null. The 334 has both I think. The circuitry is pretty simple. The distortion residual is not that low- .01% I think. It does tune to 500 KHz and measure to 5 MHz, unlike any current analyzer.
Good luck.
Good luck.