Re: Tek 310 and Looking for Advice

Stan & Patricia Griffiths <w7ni@...>

HI Stan,

I still think the problem you see now is in the power supplies themselves.

The first question I have for you is this:

Are the power supplies "regulating"? That is, do the voltages remain the
same as the line voltage is varied from 105 to 125 VAC? If you don't have a
metered variable line voltage source, now is the time to get one.

Second question:

How much "ripple" is on each supply? Is is about the amount stated in the
manual calibration procedure? (10 millivolts)

Third question:

As you try to set the -150 volt power supply on -150, can you vary it at all
with the adjustment control or is it just at -140 all the time?

Fourth question:

Have you checked the output from the 5651 reference tube? It should be
about 85 volts. Measure this between pins 1 and 7 on V613.

Since all of the power supplies are referenced to the -150, it has to be
accurate for the rest of the supplies to be accurate. Also, the -150
depends on a working +300 to work properly, which means you have a problem
in either the -150 or the +300 or both.


----- Original Message -----
From: "stan mcintosh" <>
Cc: <>
Sent: Sunday, November 02, 2003 6:22 PM
Subject: [TekScopes] Tek 310 and Looking for Advice

Last week, I got the last of the finishing touches complete on the power
supply section. All voltages from the rectifiers, dropping resistors, and
caps are within 3% of spec. The Black Beauties and old electrolytics are
also gone. However, this is a good news/bad news situation.

The good news is that I now feel confident that the selenium rectifiers,
Black Beauties, and old electrolytics are not causing trouble. The bad news
is that the voltages are still pretty far off, in the same manner as before
I started. the -150 is now around -140, +100 is about +60, and +300 is
around +260.

What do the sages advise? Should I disconnect and load-test the regulated
supplies to see if they are possibly just being overloaded by a faulty
circuit? If so, what current would the sages recommend? Or, should I go
through disconnecting and reconnecting circuits until I find the one that is
throwing the system off-balance? What do the sages say?

I know that this is not a high-performance scope, but it has character,
and I would like to make it part of my bench.



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