B K 707 help needed

[Tom Mills]

On my B&K 707 Dyna-jet tube tester the meter deflects backwards when testing
tubes in the upper section. The lower section is working OK. All the
calibration adjustments seem to adjust correctly. When testing a diode like
a 5Y3 in the upper section it does work OK. It appears to me the problem is
with the mutual conductance, emission circuit working correctly. I was
wondering if someone in the group had experienced the same problem or had
any ideas. I did replace the 83 rectifier with a 80, but it did not make
any difference. All the electrolytic caps have been replaced.

Thanks, Tom.



Inspiration can be found in a pile of junk.
Sometimes, you can put it together with a good imagination and invent
something - Thomas Edison

[Paul P]

I have no direct suggestions but only a thought. It sounds like it may be a
single point failure with the switch. And not in the maze of tube sockets.

http://bama.edebris.com/manuals/b&k/707/ Schematic starts on page 19 of the
viewer.

http://www.tuberadio.it/utils.htm Stand-a-lone viewer for above file.


I'll stare at the schematic a bit to see if I can get a hint and report back
if I do.

Paul P.

Post by Tom Mills
On my B&K 707 Dyna-jet tube tester the meter deflects backwards when
testing tubes in the upper section. The lower section is working OK. All
the calibration adjustments seem to adjust correctly. When testing a diode
like a 5Y3 in the upper section it does work OK. It appears to me the
problem is with the mutual conductance, emission circuit working
correctly. I was wondering if someone in the group had experienced the
same problem or had any ideas. I did replace the 83 rectifier with a 80,
but it did not make any difference. All the electrolytic caps have been
replaced.
Thanks, Tom.
Inspiration can be found in a pile of junk.
Sometimes, you can put it together with a good imagination and invent
something - Thomas Edison

[Paul P]

After looking at the schematics for both the 700 (that is darker and is not
cut off) (I have this one) and the 707 it is my conclusion that you will
have to do some circuit tracing of PB-5 circuits. And there are a lot of
them.

One of the sections is probably not transferring. Minimize the Sensitivity
control to just see the negative deflection to protect the meter from
extreme backwards deflection.

Also print the BAMA 700 pdf schematic. It helps.

Good Luck,

Paul P.

Post by Paul P
I have no direct suggestions but only a thought. It sounds like it may be a
single point failure with the switch. And not in the maze of tube sockets.
http://bama.edebris.com/manuals/b&k/707/ Schematic starts on page 19 of
the viewer.
http://www.tuberadio.it/utils.htm Stand-a-lone viewer for above file.
I'll stare at the schematic a bit to see if I can get a hint and report
back if I do.
Paul P.

Post by Tom Mills
On my B&K 707 Dyna-jet tube tester the meter deflects backwards when
testing tubes in the upper section. The lower section is working OK. All
the calibration adjustments seem to adjust correctly. When testing a
diode like a 5Y3 in the upper section it does work OK. It appears to me
the problem is with the mutual conductance, emission circuit working
correctly. I was wondering if someone in the group had experienced the
same problem or had any ideas. I did replace the 83 rectifier with a 80,
but it did not make any difference. All the electrolytic caps have been
replaced.
Thanks, Tom.
Inspiration can be found in a pile of junk.
Sometimes, you can put it together with a good imagination and invent
something - Thomas Edison

[Tom Mills]

Thanks Paul. I will check the PB5 connections and reply back. Also there
is a much cleaner schematic at the following link.
http://pacifictv.ca/wanted.htm#testequip
--
Inspiration can be found in a pile of junk.
Sometimes, you can put it together with a good imagination and invent
something - Thomas Edison

Post by Paul P
After looking at the schematics for both the 700 (that is darker and is
not cut off) (I have this one) and the 707 it is my conclusion that you
will have to do some circuit tracing of PB-5 circuits. And there are a
lot of them.
One of the sections is probably not transferring. Minimize the
Sensitivity control to just see the negative deflection to protect the
meter from extreme backwards deflection.
Also print the BAMA 700 pdf schematic. It helps.
Good Luck,
Paul P.

Post by Paul P
I have no direct suggestions but only a thought. It sounds like it may be
a single point failure with the switch. And not in the maze of tube
sockets.
http://bama.edebris.com/manuals/b&k/707/ Schematic starts on page 19 of
the viewer.
http://www.tuberadio.it/utils.htm Stand-a-lone viewer for above file.
I'll stare at the schematic a bit to see if I can get a hint and report
back if I do.
Paul P.

Post by Tom Mills
On my B&K 707 Dyna-jet tube tester the meter deflects backwards when
testing tubes in the upper section. The lower section is working OK. All
the calibration adjustments seem to adjust correctly. When testing a
diode like a 5Y3 in the upper section it does work OK. It appears to me
the problem is with the mutual conductance, emission circuit working
correctly. I was wondering if someone in the group had experienced the
same problem or had any ideas. I did replace the 83 rectifier with a
80, but it did not make any difference. All the electrolytic caps have
been replaced.
Thanks, Tom.
Inspiration can be found in a pile of junk.
Sometimes, you can put it together with a good imagination and invent
something - Thomas Edison

[Tom Mills]

Here is the answer to the problem. After all else failed to find the
problem I powered up the oscilloscope and found that the (phase shift
circuit) containing two #55 lamps was the problem. One lamp had been
replaced with a #51. After digging around I found and replaced the 51 with
the 55 and the problem cleared. Understanding how the tube tester works
priceless.
--

Post by Paul P
After looking at the schematics for both the 700 (that is darker and is
not cut off) (I have this one) and the 707 it is my conclusion that you
will have to do some circuit tracing of PB-5 circuits. And there are a
lot of them.
One of the sections is probably not transferring. Minimize the
Sensitivity control to just see the negative deflection to protect the
meter from extreme backwards deflection.
Also print the BAMA 700 pdf schematic. It helps.
Good Luck,
Paul P.

Post by Paul P
I have no direct suggestions but only a thought. It sounds like it may be
a single point failure with the switch. And not in the maze of tube
sockets.
http://bama.edebris.com/manuals/b&k/707/ Schematic starts on page 19 of
the viewer.
http://www.tuberadio.it/utils.htm Stand-a-lone viewer for above file.
I'll stare at the schematic a bit to see if I can get a hint and report
back if I do.
Paul P.

Post by Tom Mills
On my B&K 707 Dyna-jet tube tester the meter deflects backwards when
testing tubes in the upper section. The lower section is working OK.
All the calibration adjustments seem to adjust correctly. When testing
a diode like a 5Y3 in the upper section it does work OK. It appears to
me the problem is with the mutual conductance, emission circuit working
correctly. I was wondering if someone in the group had experienced
the same problem or had any ideas. I did replace the 83 rectifier with
a 80, but it did not make any difference. All the electrolytic caps
have been replaced.
Thanks, Tom.
Inspiration can be found in a pile of junk.
Sometimes, you can put it together with a good imagination and invent
something - Thomas Edison

[Paul P]

Post by Tom Mills
Here is the answer to the problem. After all else failed to find the
problem I powered up the oscilloscope and found that the (phase shift
circuit) containing two #55 lamps was the problem. One lamp had been
replaced with a #51. After digging around I found and replaced the 51
with the 55 and the problem cleared. Understanding how the tube tester
works priceless.

Tom,

Thanks for the follow up. I will print your solution and keep it with my
700 documentation.

Paul P.

[Tom Mills]

Post by Paul P

Post by Tom Mills
Here is the answer to the problem. After all else failed to find the
problem I powered up the oscilloscope and found that the (phase shift
circuit) containing two #55 lamps was the problem. One lamp had been
replaced with a #51. After digging around I found and replaced the 51
with the 55 and the problem cleared. Understanding how the tube tester
works priceless.

Tom,
Thanks for the follow up. I will print your solution and keep it with my
700 documentation.
Paul P.

Paul check out this site. It has some very good info on the 700 and 707.
It even goes over the #55 lamps. Thanks again for your original reply, it
got me back looking for the problem.

http://tubesound.com/2008/03/23/bk-707-tube-tester/

[Paul P]

Post by Tom Mills

Post by Paul P

Post by Tom Mills
Here is the answer to the problem. After all else failed to find the
problem I powered up the oscilloscope and found that the (phase shift
circuit) containing two #55 lamps was the problem. One lamp had been
replaced with a #51. After digging around I found and replaced the 51
with the 55 and the problem cleared. Understanding how the tube tester
works priceless.

Tom,
Thanks for the follow up. I will print your solution and keep it with my
700 documentation.
Paul P.

Paul check out this site. It has some very good info on the 700 and 707.
It even goes over the #55 lamps. Thanks again for your original reply, it
got me back looking for the problem.
http://tubesound.com/2008/03/23/bk-707-tube-tester/

Thank you Tom. I will peruse the web site (again and again). :~)

Paul P.