Re: Tektronix 2235 preregulator


tom jobe <tomjobe@...>
 

Hi Graeme,
The Tekscopes message archive has lots of information about your 2235
question, including what common component to substitute for what, when you
replace components.
Many of the 22xx's have the same basic power supply (PS), such as 2213A,
2215A, 2224, 2230, 2232, 2236 etc.
There is also a fine 22xx power supply repair document available from our
friend Hakan at:
http://www.hakanh.com/dl/docs/troubleshooting_tips_on_2200_ps.pdf
His method of injecting the 43 volts from an external source works very well
in a case like yours. It is a big help in figuring out what is wrong in a
complex system.
From my own experiences, the least likely thing to fail is the PWM chip
U930, but your testing will often make you think it is the problem when it
actually isn't. Obviously U930 can be bad, however unlikely that might be.
There is no "unobtanium" in the 22xx PS, and there are common substitutes
for the PS's components that are not proprietary such as the transformers.
Even the transformers are available used if you look around.
tom jobe...

----- Original Message -----
From: "zl1gbb" <zl1gbb@...>
To: <TekScopes@...>
Sent: Monday, February 08, 2010 12:40 PM
Subject: [TekScopes] Tektronix 2235 preregulator


Hi
I have a 2235 oscilloscope which appears dead (no lights, no trace). Fuse
is not blowing. I have no voltage on the 43v preregulator line.

Is there any common problems with this model?

tia
Graeme



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