Tek 2230

[Tchotky]

Hi, I've been reading this group for some while now and there seems to
be some good advice given in amongst the bogus posts, spam and flame wars.

Anyway, I have plenty of xp repairing scopes but I just got 2 Tek 2230's
in with the same problem, so I'm wondering if its just me or something I
missed previously.

On slow timebase setting say 2mS with readout on but not storage, I'm
getting interference on the trace, like the alphanumeric data is
strobing the trace. On faster timebase speeds no problem. I was
wondering if anyone out there has a 2230 they could take a look at and
see if this is just a design fault, its odd to get 2 of a kind, in fact
I was thinking its me being daft, and went around turning off the
flourescents in the workshop in case it was just interference strobing,
but no joy. Power rails are all clean. Incoming mains is clean. Nothing
else electrically noisy in the workshop.

So if you have a 2230, put it to single trace, (or dual on Alt), around
2mS timebase, readout on, and tell me do you get interference on the
trace? Like unsynchronised dark spots running through.

Email address is bogus so please reply through the group.

Thanks in advance. JC

 

[Jim Yanik]

Hi, I've been reading this group for some while now and there seems to
be some good advice given in amongst the bogus posts, spam and flame
wars.

Anyway, I have plenty of xp repairing scopes but I just got 2 Tek
2230's in with the same problem, so I'm wondering if its just me or
something I missed previously.

On slow timebase setting say 2mS with readout on but not storage, I'm
getting interference on the trace, like the alphanumeric data is
strobing the trace. On faster timebase speeds no problem. I was
wondering if anyone out there has a 2230 they could take a look at and
see if this is just a design fault, its odd to get 2 of a kind, in
fact I was thinking its me being daft, and went around turning off the
flourescents in the workshop in case it was just interference
strobing, but no joy. Power rails are all clean. Incoming mains is
clean. Nothing else electrically noisy in the workshop.

So if you have a 2230, put it to single trace, (or dual on Alt),
around 2mS timebase, readout on, and tell me do you get interference
on the trace? Like unsynchronised dark spots running through.

Email address is bogus so please reply through the group.

Thanks in advance. JC

the "dark spots" are the readout characters being written.

 

[Tchotky]

the "dark spots" are the readout characters being written.

But should there be this interference with the trace? Its quite
noticeable and would annoy me if I had to use one of these. I suspected
a fault in the blanking circuitry but can't see anything out of spec
which is why I was hoping someone would confirm if this is usual or a
fault. On Philips analog scopes with on screen readout no such effect is
visible, I would have thought Tektronix would be of comparable quality.
I've noticed this on a 4 channel 2245 since,even more noticeable with 4
traces, its starting to bug me. Thanks for your reply anyway. JC

 

[Jim Yanik]

But should there be this interference with the trace?

the RO gets written the same time the trace is scanning across the screen.
The RO circuits interrupt and deflect the beam to where the RO is written.
At some sweep speeds,it becomes noticeable. It may even be a holdoff
setting that makes it 'worse'. That's why you can turn off the RO.

Its quite
noticeable and would annoy me if I had to use one of these. I suspected
a fault in the blanking circuitry but can't see anything out of spec
which is why I was hoping someone would confirm if this is usual or a
fault. On Philips analog scopes with on screen readout no such effect is
visible, I would have thought Tektronix would be of comparable quality.
I've noticed this on a 4 channel 2245 since,even more noticeable with 4
traces, its starting to bug me. Thanks for your reply anyway. JC

I don't know how Philips does their on-screen readout.

 

[Tchotky]

the RO gets written the same time the trace is scanning across the screen.
The RO circuits interrupt and deflect the beam to where the RO is written.
At some sweep speeds,it becomes noticeable. It may even be a holdoff
setting that makes it 'worse'. That's why you can turn off the RO.


I don't know how Philips does their on-screen readout.

well, guess you are correct, I just got a 2246 in and its the same,
beats me how I didn't notice this before. I suppose I don't use the
slower timebase speeds during calibration much. I'll have to take a
closer look at a Philips next time I get hold of one, maybe it does have
the same problem but I've used them a lot in the past and not noticed
anything. Cheers Jim, JC