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 Post subject: assistance with a 2407 wavetek sig gen
PostPosted: Aug Tue 21, 2012 5:01 pm 
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Joined: Aug Tue 21, 2012 4:57 pm
Posts: 1
ive got a wavetek sig gen at my shop and its giveing me some problems, power up self test is failing the adc 0v ref and 10v ref. and the sig gen will not output a signal. i was wondering if any knew where i could find a troubleshooting pub or if anyone has ran into this problem before. any input would be helpful


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Nov Sun 29, 2015 9:19 pm 
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Joined: Nov Sun 22, 2015 8:48 pm
Posts: 3
I have a similar problem, and am looking for some help.

I have the 0V Ref failure, but not the 10V Ref failure.

By pressing the + key, I'm able to proceed, and it reports that it's
operational, but I get no RF Output.

I notice that the 15V regulator is running very hot on the control BD, and
suspect there might be something going on with a component supplied by that
rail.

Any assistance would be appreciated.

Thanks,

DE Rick, K1RDM


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Apr Tue 04, 2017 10:53 am 
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Joined: Apr Tue 04, 2017 10:46 am
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Long shot but I've got exactly the same problem (hot ctrl board, -0v ref fail), did you find the root cause??

Cheers,

Paul
VK4PLY


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Apr Tue 04, 2017 8:45 pm 
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Joined: Nov Sun 22, 2015 8:48 pm
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Not yet.I planned to thermocouple up several components to find the hot one, but the project got put on hold.

Maybe we can figure it out together, between the two if us.


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Apr Tue 04, 2017 9:07 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 847
Location: Wayside, NJ Monmouth
If the power supply section or any board has Tantalum caps, check them first. They tend to go bad fast and ether go very low in resistance or short. I use a Non Contact IR Thermometer to check for hot spots.


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Apr Tue 04, 2017 9:52 pm 
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Joined: May Thu 14, 2015 4:15 pm
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Location: Dallas, TX
My experience with Tantalum capacitors is that they are very reliable, except if they become reversed biased, then they turn into low value resistors!

_________________
Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Apr Tue 04, 2017 11:33 pm 
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Joined: Nov Sun 22, 2015 8:48 pm
Posts: 3
With the card plugged in I'm not able to measure it with the infrared thermometer. But I have pulled the card out and zero'd in on the location of the board and sort of isolated section of the schematic in question.

That's when I got sidetracked with another project.


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Apr Wed 05, 2017 12:16 am 
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Joined: Feb Sun 01, 2009 2:56 pm
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Location: Victoria, Australia
I have a guy I went to school with & he ran a Radio & TV servicing business for decades. Prior to going diabetic blind. He did tell me at one point that some of the tantalum caps were not exactly reliable. Definitely do not be deluded into thinking any part is infallible.

Strange things happen assume nothing: E.g. Not for the first time I have a 1947 radio on the bench: Went intermittent & died, not an unusual scenario. It has been repaired several times, not refurbished (there were still dodgy (tested: failed) caps in it). But after all of that, pin 2 of the 6V6, was still not soldered.

Cracked & dry joints still happen. Caps still go short. Thermal induced cracking on printed circuit boards is never unusual.

Marc


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Apr Wed 05, 2017 2:13 pm 
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Joined: Apr Tue 04, 2017 10:46 am
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I suspected the power board, but with no load all voltages were right. I pulled most of the cards and the regulator stopped overheating (current limiting). Placing the boards one by one showed 3 boards (synth/dev mtr/ lo) all had shorted caps on the +18v line. Have replaced most and those boards are back in (no overheating anymore and the fan works, fan not spinning was a symptom).

Not had time to finish the fixes so still not out of the woods and could be something else as well, but caps C619 /C483 and a few others (all 1uF 25v) had shorted.


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Apr Wed 05, 2017 3:05 pm 
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Joined: Feb Sun 01, 2009 2:56 pm
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Location: Victoria, Australia
There are several possibilities why those caps failed: Lack of use (loss of form); Wrong voltage; What vintage is it? In the 90's there was a spate of failures, mainly in computers but I had some elsewhere as well.

These were apparently made using a hacked formula, they normally leaked & oozed a tan coloured electrolyte. Irrespective of that, I would replace every electrolytic in it and not power it until that has happened. Most of the 3 terminal regulators lock up on short.

Marc


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Feb Tue 06, 2018 11:38 pm 
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Joined: Apr Tue 04, 2017 10:46 am
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Hi all, long time dormant, would still love to get this going 'one-day'. Did anyone have any luck/insight?


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 Post subject: Re: assistance with a 2407 wavetek sig gen
PostPosted: Feb Tue 06, 2018 11:54 pm 
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Joined: Feb Sun 01, 2009 2:56 pm
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Location: Victoria, Australia
Based on what has happened with caps already; this may be like my Heathkit OS-1 Oscilloscope. Once I had eliminated the dodgy parts (virtually every cap & resistor in it) it had no more faults.

Marc


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