On Aug 27, 10:04 am, Jim Yanik wrote:
gabeschine wrote groups.com:



I just got a used Tek 465m. It worked perfectly when I tested it, and
then a couple more times after that. It would then intermittently not
turn on (although the screen illum would still work). Now, it
consistently won't turn on (still screen illum, tho).

I have opened it up and tested the +5/-5/+32 leads in a couple places
on the board, and none show what they should:

+5 = -0.11 V
-5 = -0.05 V
+32 = -0.04 V

there is some, but very little, variance in the above numbers over
time/tests.

i'm a beginner repairing electronics, but i have the feeling this is a
simple repair -- the thing worked perfectly until a couple days ago...
could it be something as simple as a busted cap? i have the owners/
maintenance manual with lots of diagrams in it (although, it seems,
none of the power supply circuits). could anyone point me in the right
direction to solve this problem? any help would be appreciated!
thanks,

gabe schine

well,first check to see if any internal fuses are open,the 32 unreg has a
fuse.
it could be bad electrolytics;they dry out with age or their ESR rises and
the raw,unregulated supplies are not high enough for the regulators to
work.

TEK PS supplies all reference to one supply,and use pullups so if one
supply dies,they all go out.

HV multipliers are prone to fail,too;that's the black box with a heavy red
lead that goes to the front of the CRT.

Google for BAMA and download a service manual for the scope so you will
have schematics to work from.

Thanks - got the schematics. Tested all the fuses I could find (4 of
them) and they all check out.

Your ref to the PS - does this mean that if the PS dies, I would see
anything from the Scale Illum. feature? That's the only part of the
scope that still works when power is on.

Now I need to go and learn what everything you said means . Thanks
again