Author Topic: HP 33120A problems  (Read 3827 times)

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Offline vaualbusTopic starter

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HP 33120A problems
« on: August 16, 2014, 12:07:31 am »
I'm still try to repair my HP33120 Arbitrary function generator but after changing the main dac I have three problems.
      - First I broke the vacum displa so I can't see nothing on the screen. Anybody know or have a display to sell to me?
        (I found a seeler on ebay that sell the display only in US, unfortuannlly I'm in Italy, fuc......).
       
      - The output amplifier is gone. Initially after replacing the main dac I saw I strange signal at the output, I did some check and found a burn    resisitor, change it with a new one but after turning on the device it burn with smoke and now, after replacing it again, I see no signal at the output.

      - The last problem is a little bit trick. When I power up the instrument I can change the frequency and I have a sine like the manual said.(I have the signal at the +AMP_IN and -AMP_IN on the board) but If I select for example a square wave I can't select back the sine wave. I heard the bip but I can't change the waveform. I have the same problem with the Freq button, so If I press the amp button I can't come back to the freq selection.
Of course If I had a display it would easier to know what is happening.
The two buttons are in the same column but If it was a column  problem, on the display board, why the instrument beep when I press a button? 

Wish someone can help me.
Best regards, Alberto.
 

Offline free_electron

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Re: HP 33120A problems
« Reply #1 on: August 16, 2014, 10:59:37 am »
Ouch ... That is going to be a tough cookie.
Replace all transistors in the endstage.

The glass. Buy from agilent or look for another donor, but you may be better off repairing the other donor.
Professional Electron Wrangler.
Any comments, or points of view expressed, are my own and not endorsed , induced or compensated by my employer(s).
 

Offline vaualbusTopic starter

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Re: HP 33120A problems
« Reply #2 on: August 16, 2014, 12:42:42 pm »
ya I will replacing all the output transitor.
But first I want to solve the buttons problems.
Any idea what can cause the buttons problem?
 

Offline vaualbusTopic starter

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Re: HP 33120A problems
« Reply #3 on: August 16, 2014, 01:30:25 pm »
And, of course, the entire front panel assembly is no more avaible from agilent/keysight.
The part number is 33120-66502 but it said obsolate.
 

Offline pinkman

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Re: HP 33120A problems
« Reply #4 on: August 21, 2014, 12:32:01 am »
Alberto,
Where are you in Italy?  I'm from the US and I'll be in Milan/Torin for a day, at the end of next month.  If you're near one of those cities, I could bring the display with me and meet you somewhere.  I won't have a car so meeting near milan or turin airport would be best.  I looked on eBay for the display but didn't find it, you would have to send me a link.  Let me know.
 

Offline vaualbusTopic starter

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Re: HP 33120A problems
« Reply #5 on: August 24, 2014, 03:00:34 pm »
Thany you but unfortunally the item has been sell on ebay. See I'm so unlucky for this stupid display.
By the way I'm from Turin
« Last Edit: August 24, 2014, 03:07:27 pm by vaualbus »
 

Offline pinkman

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Re: HP 33120A problems
« Reply #6 on: August 25, 2014, 05:45:58 pm »
Alberto,
Let me know if you find another for sale in the US, I would be happy to bring it.  I know how frustrating it can be when you can't find repair parts!
 


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