Tektronix 2465A Channel 1 problem

[[email protected]]

Hello,

I have the following problem on my 2465A.
When I am connect ch1 and ch2 to the calibrator, ch2 displays a
rectangular signal and ch1 displays something that becomes a
triangular signal when I increase the frequency.
I have put pictures on:

http://scalbert.dyndns.org/IMG_0004.JPG
http://scalbert.dyndns.org/IMG_0005.JPG
http://scalbert.dyndns.org/IMG_0006.JPG
http://scalbert.dyndns.org/IMG_0008.JPG

Sorry, pictures are not very good.

Any ideas ?

Thanks in advance,
Olivier

 

[[email protected]]

In fact it is like I have a capacitor in parallel on the ch1 entry.

 

[Charles Schuler]

In fact it is like I have a capacitor in parallel on the ch1 entry.

Yes, that would explain the integration (square to triangle).

Obviously, you have switched the probes?

 

[Jim Yanik]

Hello,

I have the following problem on my 2465A.
When I am connect ch1 and ch2 to the calibrator, ch2 displays a
rectangular signal and ch1 displays something that becomes a
triangular signal when I increase the frequency.
I have put pictures on:

http://scalbert.dyndns.org/IMG_0004.JPG
http://scalbert.dyndns.org/IMG_0005.JPG
http://scalbert.dyndns.org/IMG_0006.JPG
http://scalbert.dyndns.org/IMG_0008.JPG

Sorry, pictures are not very good.

Any ideas ?

Thanks in advance,
Olivier

you can remove the CH.1 attenuator,take it apart carefully(a plastic frame
retains the relays),and use an eraser to LIGHTLY clean the switch pads on
the ceramic substrate.
*Don't remove the gold plate.*
**Don't crack the substrate.**

the attenuators are succeptable to outgassing from plastics coating the
contact pads. The other part of the switches are the relays,I would not
attempt to clean those contacts,maybe spray with a zero-residue/zero lube
contact cleaner.

you have to remove the front plastic edge trim to access the screws to pull
the front panel,to access the screws to remove the attenuator.
there's a procedure in the service manual for atten removal.

New attenuators are no longer available;TEK does NOT support this product
series anymore.

 

[[email protected]]

Thanks

Obviously, you have switched the probes?

Yes, I have changed them and also changed the Volts/Div

 

[[email protected]]

Thank Jim.

I will have a look this wee-end.
I have not the schematic of the scope. Do you think I can exchange
some parts of Ch1 and Ch2 to locate where is the problem ?

Olivier

 

[JW]

Thank Jim.

I will have a look this wee-end.
I have not the schematic of the scope. Do you think I can exchange
some parts of Ch1 and Ch2 to locate where is the problem ?

Olivier

You can download a service manual here if you need one:
ftp://bama.sbc.edu/downloads/tek/2465a_2467/

 

[Jim Yanik]

Thank Jim.

I will have a look this wee-end.
I have not the schematic of the scope. Do you think I can exchange
some parts of Ch1 and Ch2 to locate where is the problem ?

Olivier

Ch.1 and Ch.2 preamps can be swapped.
That and the attens are the whole Channel 1 and 2.

IIRC,the BAMA site has the service manual for download.