Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Oct Thu 22, 2020 1:23 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 44 posts ]  Go to page Previous  1, 2, 3  Next
Author Message
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Jul Mon 29, 2019 9:53 pm 
Member

Joined: Sep Sat 13, 2014 7:05 pm
Posts: 58
google turns up the below

5961-00-412-0953 - | WBParts
https://www.wbparts.com/rfq/5961-00-412-0953.html
1854-0351, 28480, HEWLETT-PACKARD COMPANY DBA ... 2N3904, C0187, MOTOROLA GMBH GESCHAEFTSBEREICHHALBLEITER. 2N3904A, C7191 ...


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Jul Mon 29, 2019 10:01 pm 
Member

Joined: Sep Tue 30, 2014 6:08 am
Posts: 5930
Location: Norfolk, VA
xxx2fan wrote:
google turns up the below

5961-00-412-0953 - | WBParts
https://www.wbparts.com/rfq/5961-00-412-0953.html
1854-0351, 28480, HEWLETT-PACKARD COMPANY DBA ... 2N3904, C0187, MOTOROLA GMBH GESCHAEFTSBEREICHHALBLEITER. 2N3904A, C7191 ...


....all pulled by Web API from WEBFLIS. WEBFLIS gives a bit more data needed only by DoD Logistics folks, but once again, the data is there - free and without much searching.

_________________
Brian
"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Jul Mon 29, 2019 10:28 pm 
Member

Joined: Sep Sat 13, 2014 7:05 pm
Posts: 58
here is a couple links HP cross reference
https://www.sphere.bc.ca/download/hp_xref-free.pdf

http://jvgavila.com/doc_test/HP/HP_CROS ... istors.pdf

https://www.precisionroller.com/hp/cross-reference.html


hope this helps someone
xxx2fan


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Jul Mon 29, 2019 10:38 pm 
Member

Joined: Sep Tue 30, 2014 6:08 am
Posts: 5930
Location: Norfolk, VA
xxx2fan wrote:


Don't forget HP Bench Briefs, with many cross reference lists - transistors/diodes, ICs, and Batteries:

http://hparchive.com/bench_briefs

_________________
Brian
"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Oct Fri 11, 2019 9:51 pm 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 8205
Location: Sunbury, Ohio 43074
Old threads never really die ..... I'm working on either the exact generator from the OP way back in the wayback machine, or one that had the same problem or similar. Same area of the circuit has smoked.

It came with the pile from Alan Douglas, so it may in fact be the same one. While no longer smoking (someone did a fairly expert job of replacing burned parts) it's not working too well. If anyone's interested, I'll update the post as I work through it. There is considerable burning of a few areas of the PCB so I may lift a few leads and "air solder" them to other parts to avoid the burned area. I'll post a few photos once my "exceeded data limit" jail time is over for my cell phone, probably tomorrow. Or maybe I'll use the <gasp> Nikon camera instead lol. Stay tuned....

There were two of these generators, one of which is working fine and on my bench at the shop. This one is for my home shop..... BUT ... I am not going to open the good one up to "cheat" ... gonna try this old-school first lol. Yes, glutton for punishment, I know.

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Oct Tue 15, 2019 3:55 pm 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 8205
Location: Sunbury, Ohio 43074
Here's a photo of the crispy area. I've removed the 4 transistors and a few resistors so I can cut out the carbonized section, or cut some traces loose from it. Transistors tested OK with the 'ohmmeter' test ... I may pause here and fix up one of the Sencore transistor testers I have, or just replace all 4 of the outputs (on the right) again.

Schematic of the output stage is shown as well. Diodes test OK so far. I'll update the photos as I proceed with the repair. Q 504, 6, 507, 8, 9, 11 is the afflicted area. I had good signal at the input side of the 47K resistors feeding the output stage so hopefully everything up till that point is OK.

Stay tuned
Attachment:
fullsizeoutput_8ed.jpeg
fullsizeoutput_8ed.jpeg [ 543.08 KiB | Viewed 889 times ]
Attachment:
fullsizeoutput_8e6.jpeg
fullsizeoutput_8e6.jpeg [ 359.74 KiB | Viewed 889 times ]

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Oct Wed 16, 2019 3:29 am 
Member

Joined: Aug Thu 27, 2009 7:47 am
Posts: 2689
Location: Seattle 98125
Any possibility some of those electrolytic caps are leaking and keeping the transistors drawing more current than they're designed for? C506/C507 and their pair on the other side?

I see one is replaced already in that photo.


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Oct Wed 16, 2019 12:03 pm 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 8205
Location: Sunbury, Ohio 43074
It's possible although a quick check says they are OK. I replaced that one because it was physically damaged when the adjacent resistor flamed out.

Haven't had time to get back to this one yet... but soon. It's consuming most of my bench.

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Oct Wed 16, 2019 2:51 pm 
Member

Joined: Sep Tue 30, 2014 6:08 am
Posts: 5930
Location: Norfolk, VA
One thing I've learned about replacing parts in complementary power output circuits - FOLLOW THE DC PATH. For Audio Power Amps, blown outputs usually mean blown bias resistors and diodes, as well as any bias adjust pots. For servo amps, the same applies - but I usually go one stage further back beyond just replacing any part that is in the DC path - those directly coupled to semiconductors in the output.

All those diodes? Any one of them, when leaky under a load, could possibly cause runaway conduction and the blowing of the newly replaced outputs.

RCA included some nice troubleshooting with Audio Output Transistors and Hybrid Power Amps.

Verbatim, from a sticker included with an Output Transistor:

IF USED AS A REPLACEMENT:

Determine and cure the cause of previous failure. Check the following:

A) Are all bias voltages present?
B) Are all bias resistors the correct value (i.e. not open or increased in value)?
C) Are all protection circuits functioning properly?
D) Are all power supply voltages present - both positive and negative supplies?
E) Are all coupling capacitors and directly-coupled semiconductors (driver transistors and ICs) operating properly?
F) Are all speaker or dummy load connections the proper ohm rating and not shorted/of too low an impedance?



Thomson Consumer Electronics
Distributor and Special Products Division

_________________
Brian
"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Oct Wed 16, 2019 3:28 pm 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 8205
Location: Sunbury, Ohio 43074
Thanks Brian. I'm all too aware of the various annoyances and potential smoke-releasing paths in DC coupled stages such as these. It makes for rather difficult troubleshooting, since nothing works unless everything works.

Reminds me a bit of broadcast videotape deck servo systems... you end up chasing your tail for a while. Everything has an effect on everything else.

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Sat 09, 2019 2:41 am 
New Member

Joined: Nov Sat 09, 2019 2:24 am
Posts: 3
Hi Barry, I am working on a similar problem, (Low output) and I plan to change q507 and q508 with a 2n3904 3906 pair. You seem to be working from a paper copy of the manual. If you could post a few pictures of the A1 board schematic and board layout, that would be great. I am working off of the fuzzy pdf from the Agilent site and it is almost impossible to identify components by number. If anyone knows of a better pdf, that would work as well. Thank you, Chris


Attachments:
3312a.jpg
3312a.jpg [ 2.25 MiB | Viewed 802 times ]
Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Sat 09, 2019 5:23 am 
Member

Joined: Jan Tue 10, 2012 8:39 am
Posts: 1662
That's very similar to the output stages in many stereo amplifiers. I have repaired dozens or even hundreds of them over the years.

The idea is to replace all bad parts - they are generally toast and not marginal - and then bring up the power gradually with a variac. Measure the output stage idling current and if it starts to rise more than it should, back down the power and look for more bad parts. The diodes are supposed to track the Vbe of the power transistors, close enough to avoid excessive idling current.

If you can raise the voltage to normal without excessive current, it's probably fixed. At that point you can make sure the output is at zero volts and is should pass a signal, first with no load and then wirh full load.

There is no idling current adjustment, unfortunately. So it may require diode selection to control it. I don't see the dc feedback path in the snippet but that must be there to hold the output voltage close to zero.

Perhaps I have stated the obvious here, but these circuits, when they fail, fail expensively. Usually several dead parts. Also make sure the heat sinking is effective.


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Sat 09, 2019 8:33 am 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 8205
Location: Sunbury, Ohio 43074
Sure thing, Chris. Yes I do have the original HP manual and will scan the sections you need. Maybe I'll feel inspired to get back to this. I set it aside a few weeks ago since I was about to see if I could make it fly.... and I had some other things to fix anyway. HP house part numbers make me dizzy. .... same with Tektronix really. :-(

I'll try and post the scans up here. If you need better, PM me your real Email and I'll just send you the PDF's.

Barry

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Sat 09, 2019 12:40 pm 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 8205
Location: Sunbury, Ohio 43074
Here are photos of the board. Note that this is 'revision c' .... my particular unit is 'rev E' ... but they all look to be pretty similar at least in the output stages.

Attachment:
fullsizeoutput_954.jpeg
fullsizeoutput_954.jpeg [ 696.3 KiB | Viewed 797 times ]
Attachment:
fullsizeoutput_952.jpeg
fullsizeoutput_952.jpeg [ 367.58 KiB | Viewed 797 times ]
Attachment:
fullsizeoutput_961.jpeg
fullsizeoutput_961.jpeg [ 290.76 KiB | Viewed 789 times ]
Attachment:
fullsizeoutput_958.jpeg
fullsizeoutput_958.jpeg [ 817.36 KiB | Viewed 789 times ]

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Last edited by Barry H Bennett on Nov Sat 09, 2019 5:11 pm, edited 2 times in total.

Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Sat 09, 2019 4:50 pm 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 8205
Location: Sunbury, Ohio 43074
FIXED!!!!!!!! Update and history of troubleshooting 101

Finally, after many dead ends and false starts, it's working like a champ. To not keep y'all in suspense, in the end it was nothing more than a broken trace at a resistor in the "cooked" area of the PCB .. .but I was misled by visual inspection of the previous owner's repairs being excellent in quality and technique, and the fact that it was quite invisible under my 10x magnifier.

In a nutshell, I pulled the 6 transistors in the output stage, lifted one end of each Tantalum cap and excruciatingly tested all of them, and the resistors (fortunately none needed to be removed as all tested well within spec). So with all the parts individually tested, I put them back in, one stage at a time. Scope indicated signal flow, but massive distortion as I put each stage back in one by one .... but I kept going since ultimately there is a feedback loop from the final to the input. And the reward was.... since nothing smoked along the way, putting the outputs back in gave me a functioning function generator.

I know more about this instrument than I'll ever want, or even try, to remember, although I do have two of them....one at the shop and one on the home bench. I resisted the urge to open up the working one and compare things, which probably would have shaved days off the project. But I was determined to go 'old school' and pretend the second unit didn't exist. Probably won't do that again ;-)

Anyway, it's a nice little generator. I'm going to align it completely and see just how clean the output sine wave is .... stay tuned on that one.

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Sat 09, 2019 5:00 pm 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 8205
Location: Sunbury, Ohio 43074
Chris, if it's just low output, might want to check the resistors in the attenuator first. If there is distortion as well as low output, more likely in the output amp somewhere. I"ll upload a photo of the attenuator shortly

EDIT: See my post above with the photos of the board layout. I added a close up of the output stages area, and the attenuator schematic

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Sat 09, 2019 5:12 pm 
Member

Joined: Sep Tue 30, 2014 6:08 am
Posts: 5930
Location: Norfolk, VA
Barry H Bennett wrote:
FIXED!!!!!!!! Update and history of troubleshooting 101

Finally, after many dead ends and false starts, it's working like a champ. To not keep y'all in suspense, in the end it was nothing more than a broken trace at a resistor in the "cooked" area of the PCB .. .but I was misled by visual inspection of the previous owner's repairs being excellent in quality and technique, and the fact that it was quite invisible under my 10x magnifier.

In a nutshell, I pulled the 6 transistors in the output stage, lifted one end of each Tantalum cap and excruciatingly tested all of them, and the resistors (fortunately none needed to be removed as all tested well within spec). So with all the parts individually tested, I put them back in, one stage at a time. Scope indicated signal flow, but massive distortion as I put each stage back in one by one .... but I kept going since ultimately there is a feedback loop from the final to the input. And the reward was.... since nothing smoked along the way, putting the outputs back in gave me a functioning function generator.

I know more about this instrument than I'll ever want, or even try, to remember, although I do have two of them....one at the shop and one on the home bench. I resisted the urge to open up the working one and compare things, which probably would have shaved days off the project. But I was determined to go 'old school' and pretend the second unit didn't exist. Probably won't do that again ;-)

Anyway, it's a nice little generator. I'm going to align it completely and see just how clean the output sine wave is .... stay tuned on that one.


Dontcha just love it when you tough one out to success? :P Congrats - here's to many happy years-a-producin' little waves......

_________________
Brian
"Capacitor Cosmetologist since 1979"
USN Retired 1984-2006 (Avionics/Cal)


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Sat 09, 2019 5:19 pm 
Member

Joined: Jan Tue 10, 2012 8:39 am
Posts: 1662
For a while I used my HP audio oscillator, what's it called anyway, the one that goes from 10 Hz to 10 MHz 651A? Its distortion never was low enough for me but it is what it is. Maybe very marginal at 1% or a bit less distortion.

Then I acquired an HP function generator. Its distortion is considerably less so the 651A is in the for sale pile and I am happy with the function generator. Even though I have lost the nice calibrated output.

Along the same line, the distortion analyzer has become surplus because I have a nice digital scope with FFT. The voltmeter section of the 331A is missed but I have other instruments to measure signals.

Many years ago I had a boat anchor 650A that was excellent, with distortion of around 0.05%. Modern instruments have a tough time equalling that.

I would be interested in learning what amount of distortion you guys measure in your various audio generators. My old EICO was pretty good I think although I sold it years ago.

I have also looked at close-in spectra of rf generators and can see the hum components, 60 Hz and harmonics spaced from the carrier. They run about 40 dB or more down but I am unsure if that's a good reading or maybe my spectrum analyzer is adding some stuff.

A sanity check seems appropriate here. Yes I know this is just a hobby but still I want to know what I have.


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Sun 10, 2019 2:06 pm 
Member

Joined: Nov Wed 30, 2016 7:35 pm
Posts: 8205
Location: Sunbury, Ohio 43074
Update on Distortion ... after adjustments, I measured an amazing distortion level of -44dB, much better than the minimum spec of -35dB. While I am willing to accept some error in the old HP 334A distortion analyzer, impedance mismatch in my hand selected 50 ohm termination resistor, and my own skill, it's still a pretty amazingly low distortion generator, considering it's age and the fact that it's a function generator.

Plenty clean enough for anything I'm likely to need. All the other adjustments fell right in line ... modulation symmetry, distortion, carrier balance... right on down the line.

They sure knew how to build them back in the day ...

_________________
Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


Top
 Profile  
 
 Post subject: Re: HP 3312A generator - replacement parts
PostPosted: Nov Thu 14, 2019 10:18 pm 
New Member

Joined: Nov Sat 09, 2019 2:24 am
Posts: 3
Hi Barry, Thank you for posting the pictures of the schematic. A PDF would probably print better, so I will PM you for a PDF copy if that is ok. (I find it easier to work with a paper copy) . I hope to get the transistors next week and see if they help the situation. The original transistors seem to get hot, almost to hot to touch, so I will start there. I did have a look at the attenuator but it seemed ok, but it is sort of hard to get at so I may have a closer look if things don't work out. Thanks again, Chris.


Top
 Profile  
 
Post New Topic Post Reply  [ 44 posts ]  Go to page Previous  1, 2, 3  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: DCW, Jim Mueller, SHenion and 16 guests



Search for:
Jump to:  


































-->


Privacy Policy :: Powered by phpBB