In my previously message I told that I have problems with manual mode do not nulling, but I fixed this adjusting bias at A3 PCI card.
Hi Bsst, to explain a little bit more, I ran tests with voltimeter and set level functions and all of them work very well. Now the malfunction is only at automatic mode which puts level meter at overload. Power supply is at +25.15V and -25.52V with almost no ripple.
I misunderstood. I thought you could not null in manual mode either. So I agree that problem most likely in A5. I'll study circuitry so I can ask better questions. Sounds like you've made great progress. You may have it fixed while I'm still studying. 😀
HI,
No, You don't misunderstood, I really was with this problem, but making adjusts at bias on A3 Board I fixed it!
If I interpret correctly, you've made it successfully into section 5-40 and have arrived at 5-44 where you begin to find trouble. I suggest working through section 5-44 and noting any trouble spots where observation doesn't resemble the waveforms in the manual.
There's a similar procedure you have to follow to examine the phase-control loop; it's not explicitly detailed, so HP wants you to sort it out on your own.
Of course both amplitude and phase loops have to perform correctly to get a deep null. If you're lucky, at least one of the loops will be working and will narrow the repair.
Of particular interest is the first sentence in 5-44-d. Seeing -0.5V is a necessary condition for the first sentence of 5-44-c. Finding about 16V on A5-pin 17 is indication that the amplitude lamp and its driver transistor are operable. The corresponding test procedure for the phase loop should find about 16V on A5-pin 10.
Once you've entered Automatic mode, also note the voltages on A5-pins 17 and 10 even though they may be stuck in overload. These will be additional clues about the failure.
I suggest exploring these steps before venturing into photocell adjustment.
Let me know what you observe. Good luck!
Steve
There's a similar procedure you have to follow to examine the phase-control loop; it's not explicitly detailed, so HP wants you to sort it out on your own.
Of course both amplitude and phase loops have to perform correctly to get a deep null. If you're lucky, at least one of the loops will be working and will narrow the repair.
Of particular interest is the first sentence in 5-44-d. Seeing -0.5V is a necessary condition for the first sentence of 5-44-c. Finding about 16V on A5-pin 17 is indication that the amplitude lamp and its driver transistor are operable. The corresponding test procedure for the phase loop should find about 16V on A5-pin 10.
Once you've entered Automatic mode, also note the voltages on A5-pins 17 and 10 even though they may be stuck in overload. These will be additional clues about the failure.
I suggest exploring these steps before venturing into photocell adjustment.
Let me know what you observe. Good luck!
Steve
Highly recommended for help with the 334A - a lot of the engineers who actually designed HP's test equipment are on this board (although maybe not for something as old as the 334A.): https://groups.io/g/HP-Agilent-Keysight-equipment/
Also a good source of help is the "Test Equipment and Tools Discussions" forum at www.antiqueradios.com
Hal
Also a good source of help is the "Test Equipment and Tools Discussions" forum at www.antiqueradios.com
Hal
Hi Steve,
One doubt I had was the set lamp-ldr because I read in several blogs that this unit gave problem there I tested all the photensors according to 5-47 and were all within the tolerance +/- 20%. Now I'm going to move on to section 5-44 and follow the steps.. I think problem just might be there.
Thank you,
Regards and Have a Nice weekend.
Hi Hal,
Thanks a lot for information I'm going to register on that forums.
Regards,
Jorge