Re: Tek 2230 power supply strange


Don Black <donald_black@...>
 

Well, at least if it ever turns up for sale and a member here gets it, we'll know whose it is (unless this becomes a standard mod with dozens of examples).

Don Black.

On 28-Apr-13 11:14 AM, Bert Haskins wrote:
 

Disclaimer:
If you are one of the list members who believes that all Tek scope
should be maintained as close to factory stock as possible,
please just skip all that follows.


// trim

Measuring the current ramp via resistor R907 will show if the
transformer inductance is low. The current ramp should be linear
without any curvature which would indicate that T906 is saturating.

This brings up an interesting possibility. If the transformer
inductance was low because of damage, then the cycle-by-cycle current
limiting implemented via pin 16 of the TL594 could cause what looks
like unstable operation and Q9070 or CR907 could run hot and fail
because of high peak current.

//

Several years ago I found myself with a couple of total basket cases.

A 2213 with that ~!!@# current limiter and T906 both gone and a Epson
printer with a bricked print head.
It dawned ( literally at dawn after one of my normal sleepless nights ) on me that
both happened to have a 42 volt SMPSs.
I really had nothing to lose so I tried patching the Epson supply to the 42 volt section of
the 2213, set my electronic circuit breaker to two amps and hit the start button.

The scope returned to the land of the living.

I then cobbled er.., a.., installed the Epson PS into the scope and it went back out into
"hell on earth"  otherwise known as machine shop floor and field service calls.

It was doing fine at least up until it was stolen from a job site several months later.

At the very least it gave my 465B and 465M scopes a little bit of rest.

   Bert



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