Repair of Tektronix DPO/MSO4000/B O'scope

[mikehank]

Hey Guys,

I have lots of experience working on these scope.  If you need help and/or advice ask here and we will try to help.

[OYAZI]

Hello,
Do you have any idea to repair front panel intermittent (chattering??) encoder?
(VOLT SCALE,  POSITION etc.)
I tried to cleaning the contact.
 (Ethanol,  Electrical contact cleaner), Cotact grease...
The good result was not obtained.

[OYAZI]

I forgot to write.
A model name is DPO/MSO4000 series.

[mikehank]

Hi OYAZI,

The way I have fixed encoders jumping around is to exercise  them.   Get a electric screwdriver or drill and spin fast in one direction for around a minute then another minute in the other direction.  This will fix I would say 75% of the issues.  If this doesn't work the encoder will need to be replaced.

Thanks.

[OYAZI]

Hello,
Thank you for your reply.
I will Try....

[analogRF]

Hey Guys,

I have lots of experience working on these scope.  If you need help and/or advice ask here and we will try to help.

Hi
Can somebody confirm whether in DPO4034B the +1.5V rail (in the row of power supply test points) is up and running after turning on the scope?

I have a DPO4034B stuck at splash screen and the remedies mentioned in this thread didnt help. However, I noticed that all power supplies
are ok except that +1.5V which reads ZERO
I have spent a couple of hours trying to trace that rail to where it is generated and/or where it is used with no luck
I am beginning to think that maybe it just does not exist on 4034B and only exists on MSO or 4104B or on MDOs?
I do not see it being used anywhere on the board except by an uninstalled chip.

Still I could be totally wrong and have not seen its origin.

[mikehank]

The 1.5V rail is used for the MSO-Band MDO(non B) scopes.  I believe its used for the digital threshold compariter used with the 16 digital inputs.  The DPO's will not have this chip.  If you can post the boot script it would be very helpful in reparing this scope.  Also look at the on off let on the front panel.  Should be orange when plugged in but off.  Green during operation and boot if all is good.

[mikehank]

Also check each of the test points to ground.  I cant remember the correct resistances but none should be anyware close to short.