B&k 467

MikeyDee

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I just acquired a B&K 467 CRT tester.

For the most part it seems to work fine, except that the heater voltage control will cut out and then not work until the unit is off for a short time.

The heater pot is sort of crunchy when I turn it. All the other pots are very smooth.

Also, I cannot calibrate the heater voltage with R16 (as noted in the manual). R16 is working (resistance changes when turned) , but no change is made to the heater voltage when I turn it.

I'm assuming that this heater voltage pot is bad. I've never seen a pot that fails when heated up and then works when cool. So maybe it's something else.

Any suggestions on what to check or replace. Also, what would be a suitable replacement for the bad pot?


Thanks,
 
rejuvinator

You might need to resolder the the circuit board in side the unit.

I found that on one of my B&K's that the solder joints all went cold, do to being bounced around all these years.

Throw some contact cleaner on the pots and the rotary switches. Check the pins on the connector.

RJ
 
I just acquired a B&K 467 CRT tester.

For the most part it seems to work fine, except that the heater voltage control will cut out and then not work until the unit is off for a short time.

The heater pot is sort of crunchy when I turn it. All the other pots are very smooth.
Does the resistance across the pot adjust smoothly despite the "crunchiness"? As stated above, try cleaning it up and look for cold solder joints while inside the case.


Also, I cannot calibrate the heater voltage with R16 (as noted in the manual). R16 is working (resistance changes when turned) , but no change is made to the heater voltage when I turn it.

I'm assuming that this heater voltage pot is bad. I've never seen a pot that fails when heated up and then works when cool. So maybe it's something else.


R16 adjusts the gage needle in order to synchronize it with the actual heater output. You need to watch the needle and adjust R16 to the correct level.
 
I also have a flaky 467. Is there any other common problems to look for while it's open?
 
What do you mean by flaky? Cold solder joints can cause inconsistent operation. I have also seen some problems with the old electrolytic caps drying out, so I suggest replacing them while in there.
 
Is it a wirewound pot? If so, those will feel a bit funny when you turn them.
 
The heater voltage pot does vary the resistence (when working).

Since the pot drops out completely, it does sound like cold solder joints. I'll go over them.

The R16 pot does nothing to the needle when I try to calibrate.
 
Unfortunately, there isn't a manual w/schematics on the B&K website.

http://www.bkprecision.com/products/docs/manuals/467_manual.pdf

This file only has setup instructions and not the wiring diagrams.

I fixed a 470 before. It would power up but when you went to zap the tube it would blow the fuse. It was interesting to try to track down the problem as it didn't have any shorts that were easy to find. It had a leaky diode.
 
Many problems with the 467 are due to cold solder joints on it's main pc board. In particular, pay attention to the soldering at all the connector header pins on the circuit board. Same thing for the soldering of the main rotary switch. Years of rotating that switch and bouncing the tester around takes a toll on the solder joints.

Also, there's a couple of electrolytic capacitors on the 467's circuit board that ought to be replaced since this model is over 30 years old.

467 Service Manual:

http://home.comcast.net/~mtpacifico/_kenskorner/files/BK467 Service Manual.pdf

467 owner's manual:

http://home.comcast.net/~mtpacifico/_kenskorner/files/BK467 Manual.pdf

The owner's manual lost some resolution (particularly of the schematic diagram) when it got converted from .max file to pdf format. I have the original manual scans (including schematic) still in the original Paperport (.max file) format if you need better resolution.
 
Thanks for the info and links. I have the original manual that came with the unit. I've never seen the Service manual before. Thanks.

The fact that the heater voltage pot just drops completely out (dead) after it warms up sounds like bad solder joints. I'll go over it when I get some free time (in a couple of weeks :mad: ). I'll also replace the electrolytic caps while I'm in there.
 
I found some suspect solder joints around the Heater voltage pot. After re-flowing them, the unit works great.

The Heater voltage pot is different from all of the others. It is really big and the "crunchy" feel might just be due to how it is made and supposed to work. I've seen funky volume pots that feel rougher to turn because of how they are made.


Thanks for the help. It's working great now!
 
The Heater voltage pot is different from all of the others. It is really big and the "crunchy" feel might just be due to how it is made and supposed to work. I've seen funky volume pots that feel rougher to turn because of how they are made.

Yup... if it's a wire wound pot it'll have a "zipper" kind of feel to it when you turn the knob.
 
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