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TEK 465 Scope - Power Supply Voltages

G

Guest

Jan 1, 1970
0
I left my 465 on for a few days and now there is no trace. All voltages are
correct except 2KV, 95V and 32V Unreg. The 32V blows the .25 amp fuse. Any
suggestions?
Thank you,
Dale
 
D

DaveM

Jan 1, 1970
0
I left my 465 on for a few days and now there is no trace. All voltages are
correct except 2KV, 95V and 32V Unreg. The 32V blows the .25 amp fuse. Any
suggestions?
Thank you,
Dale


I'm looking at the 465 and the 465B manual, and I don't see any of these low
voltage supplies. The only unregulated outputs are +120V and the unregulated
source for the +55V regulated output (actually +78V) and +15V unregulated. .
There is a +110 regulated output, but no 95V output.
Which version of the 465 do you have? (465/465A/465B)
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Some days you're the dog, some days the hydrant.
 
J

Jim Yanik

Jan 1, 1970
0
I'm looking at the 465 and the 465B manual, and I don't see any of
these low voltage supplies. The only unregulated outputs are +120V
and the unregulated source for the +55V regulated output (actually
+78V) and +15V unregulated. . There is a +110 regulated output, but
no 95V output. Which version of the 465 do you have? (465/465A/465B)

It's a 465M,not truly a *465*. It's more like a 455A2B2 with wider BW.

The 32V-unreg runs the HV,he probably has a bad multiplier or CRT.
 
G

Guest

Jan 1, 1970
0
Jim,
What do you suggest for the next trouble shooting step? Unplug the CRT? or?
Thanks,
Dale
 
J

Jamie

Jan 1, 1970
0
Jim,
What do you suggest for the next trouble shooting step? Unplug the CRT? or?
Thanks,

If you have a HV-Probe, stick it on the Anode lead.
I don't know what the HV is suppose to be on that unit
how ever, the last one i looked at was aprox 12k.
I had to replace a trippler in old MIll Spec scope
made by Dumont years ago. i still have the scope at
it works nicely.. 60 Mhz..
I ended up making a new trippler using the old
case that was in there. because i too, left the
scope on for a couple of days and came back to
find the fuse blown out.
I used a dermal tool to remove all the old contents.
used some common HV diodes and got some caps together.
soldered them together on a predilled board with no
foil. laid it in the case, and used HV putty layers
at a time with a heat gun to fill the majority of it.
then top it off using silicone.
It works perfect..

What i did to test it, i disconnected the HV coil
lead going to the trippler. did a HV ac test from there.
 
J

Jim Yanik

Jan 1, 1970
0
Jim,
What do you suggest for the next trouble shooting step? Unplug the
CRT? or?
Thanks,
Dale

disconnect the HV drive to the multiplier.The 95V should come up and the
32Vunreg fuse should not blow.

Do you have a 465M service manual?
 
G

Guest

Jan 1, 1970
0
Jim,
I disconnected the HV drive at pin 10 of the transformer where it is
connected to the HV multiplier. Fuse still blows. What next?
Dale
 
S

Sam Goldwasser

Jan 1, 1970
0
Jim,
I disconnected the HV drive at pin 10 of the transformer where it is
connected to the HV multiplier. Fuse still blows. What next?

This isn't the usual shorted tantalum cap problem? :)

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
 
J

Jim Yanik

Jan 1, 1970
0
Was that the wire from a post on the side of the multiplier to a separate
post on the xfmr?
This isn't the usual shorted tantalum cap problem? :)

then the HV osc xstr is probably failed.

time to troubleshoot.

BTW,there's an excellent circuit description in the service manual that
tells how the circuits work,I always referred back to them,I consider them
invaluable.I hope they included it on your CDROM.
 
D

dale

Jan 1, 1970
0
Jim,
Yes, the lead I disconnected was from a post on the multiplier to a separate
post on the xfmr. Sam mentions a tantalum cap. Is there a certain one that I
should check? If the osc transistor failed would it load down the supplies?
I'll be on travel for a few days and unable to do any more testing until
Thursday pm. Can I write you at kua.net?
Thanks,
Dale
 
J

Jim Yanik

Jan 1, 1970
0
dale said:
Jim,
Yes, the lead I disconnected was from a post on the multiplier to a
separate post on the xfmr. Sam mentions a tantalum cap. Is there a
certain one that I should check? If the osc transistor failed would it
load down the supplies?

Don't you think a shorted xstr would blow the 32Vunreg fuse?
I'll be on travel for a few days and unable to
do any more testing until Thursday pm. Can I write you at kua.net?

FIRST,I suggest you READ THE CIRCUIT DESCRIPTION for the HV oscillator.
Then you should know how to troubleshoot it. I'm not going to tell you
"check this,then this ,then this".....ad infinitum.

I also do not have any TEK manuals to reference,I work from memory.
 
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