# Help please with Tek 465 problem

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#### Yzordderex

Jan 1, 1970
0
I recently bought a Tek 465. It was working fine, but now scope
traces aren't sweeping across. Just a pair of dots where channels are
supposed to be. I'm not too familiar with this type scope and was
wondering if it's possible that I accidently moved a control and lost
the sweep. I've pretty much tried everything in the way of fiddling
with controls. But maybe secret button somewhere I don't know of.

Ok, so assuming it's a problem inside scope, what am I looking at in
the way of circuits? Obviously there's a sweep oscillator generating
I would guess a sawtooth. Is there some kind of integrated circuit
with a Tek part number on it that's not going to be easy to get hold
of? Or am I likely to find run of the mill parts that I probably have
kicking around.

I guess what I'm asking for is for someone to take a peek at schematic
and give me thumbs up or down. I have another scope and my
troubleshooting skills are good, just don't have schematic in front of
me. If job is no-brainer I'll get hold of a schematic and go for it.
Otherwise have to ship it back to guy I bought from and pay him to fix
and ship back $$. Thanks guys. Regards, Bob S #### Stewart Jan 1, 1970 0 I recently bought a Tek 465. It was working fine, but now scope traces aren't sweeping across. Just a pair of dots where channels are supposed to be. I'm not too familiar with this type scope and was wondering if it's possible that I accidently moved a control and lost the sweep. I've pretty much tried everything in the way of fiddling with controls. But maybe secret button somewhere I don't know of. Ok, so assuming it's a problem inside scope, what am I looking at in the way of circuits? Obviously there's a sweep oscillator generating I would guess a sawtooth. Is there some kind of integrated circuit with a Tek part number on it that's not going to be easy to get hold of? Or am I likely to find run of the mill parts that I probably have kicking around. I guess what I'm asking for is for someone to take a peek at schematic and give me thumbs up or down. I have another scope and my troubleshooting skills are good, just don't have schematic in front of me. If job is no-brainer I'll get hold of a schematic and go for it. Otherwise have to ship it back to guy I bought from and pay him to fix and ship back$$$. I seem to remember a similar querk when first bought my 465 secondhand several years ago. Did you set the multi turn delay pot to Zero? Sorry no Schemmatic J #### John Duffus Jan 1, 1970 0 Yzordderex said: I recently bought a Tek 465. It was working fine, but now scope traces aren't sweeping across. Just a pair of dots where channels are supposed to be. I'm not too familiar with this type scope and was wondering if it's possible that I accidently moved a control and lost the sweep. I've pretty much tried everything in the way of fiddling with controls. But maybe secret button somewhere I don't know of. Ok, so assuming it's a problem inside scope, what am I looking at in the way of circuits? Obviously there's a sweep oscillator generating I would guess a sawtooth. Is there some kind of integrated circuit with a Tek part number on it that's not going to be easy to get hold of? Or am I likely to find run of the mill parts that I probably have kicking around. I guess what I'm asking for is for someone to take a peek at schematic and give me thumbs up or down. I have another scope and my troubleshooting skills are good, just don't have schematic in front of me. If job is no-brainer I'll get hold of a schematic and go for it. Otherwise have to ship it back to guy I bought from and pay him to fix and ship back$.

Thanks guys.

Regards,
Bob
Hi Bob,
Funny, I have the exact same problem with a 2235. (I'm waiting for a basic
low bandwith PC based scope so I can troubleshoot it.)
Since you have another scope I would get the manual and go for it. Good to
have the manual in any case. Haven't been inside a 465 but if it is anything
like a 2235 most of the electronic parts are shelf items.
I got a TEK manual on Ebay for about \$20. Complete schematics, component
layouts, test points and waveforms, circuit description, troubleshooting
guide etc.
One thing you could try when you come to localize the problem is set it to
X-Y mode (on the sweep control on a 2235) and see if you get horizontal
drive with X input (ch 1 on the 2235).
You said you just got dots but I assume you got a vertical deflection with
input to one of the channels. If not it is probably a power supply problem.
Regards,
John Duffus

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#### Dave Moore

Jan 1, 1970
0
Q652 or Q650 in the trigger circuit bad can cuase this.

I just recently posted some info on this in
sci.electronics.repair , try a Google search there.

Or feel free to email.

Also, the bridge rectifiers in the power supplies have been
know to take a dive.

Good Luck
=^^= DM

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#### Yzordderex

Jan 1, 1970
0
Thanks guys.

I tried everything and still broke. Local guy I bought scope from is
good to deal with and is going to swap out for another unit no charge.

regards,
Bob

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