Q about Tektronix 2220

[Peter Andersen]

Hi

I have a Tektronix 2220 with some startup problems. The power supply is not
able to get the scope up and running, but if i disconnect +5V and +8,6V it
works and after startup I can connect +5V and +8,6V and get the storage to
work.
I have checked and replaced a lot of capacitors but I'm not able to locate
the fault.

Can somebody tell me how much current the different voltage lines draws in
the unit?
+8,6
-8,6
+5
-5
30
100

Thanx!

Peter

 

[John E.]

Peter Andersen sez:

I have a Tektronix 2220 with some startup problems.

There is a Google Group dedicated to Tek scopes and their repair.

E-mail the owner:
TekScopes-owner at Yahoo or
Go to Yahoo Groups and search for "TekScopes" and join that way.

The group has lots of experience and will probably be able to help you with
the problem.

Good luck,
--
John English

 

[Andreas Tekman]

On 2 Mrz., 22:11, "Peter Andersen" <peterander...@mespilus.dk> wrote:

Hi

I have a Tektronix 2220 with some startup problems. The power supply is not
able to get the scope up and running, but if i disconnect +5V and +8,6V it
works and after startup I can connect +5V and +8,6V and get the storage to
work.
I have checked and replaced a lot of capacitors but I'm not able to locate
the fault.

Can somebody tell me how much current the different voltage lines draws in
the unit?
+8,6
-8,6
+5
-5
30
100

Thanx!

Peter

The service manual for the scope has a procedure how to check the LV
supply. AFAIR there is info about the resistance you can measure at
the varios voltage labeld testpoint on the printed circuit board. of
course, scope is power of during these.
The fault you describe I had in two similar Tek scopes, cure was both
times to change the inverter transistors in the LV switchmode supply
(beta was too low, as far as I remember).


hth,
Andreas