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Looking into a 465 S/N B260137 and trying to determine what seems to be causing the additional trace in background of triggered wave forms. Power supplies all look good for voltage and ripple.

Thanks in advance. The squished horizontal is due to low voltage on the 8.6V--in fact all the DC voltages are low by about 15%. (I have read all the 2235 power supply problems and got the schematics

Hi everyone, Yesterday, while working with my Tektronix 2465, I suddenly heard a strange noise from inside, followed by a very unpleasant smell. There was no smoke, and the trace was still visible on

You could... and some designs do.. but they use a series string of them to reduce the voltage across each one. The current is common to all... and the power dissipation of each resistor should be

Mark So the HV board that is in the scope now is not the original but rather a "new" board from QService. I had hoped this would be a known good board. Perhaps that is not the case. The original

does anyone make, or sell 10% resistors? 1% resistors are cheap. (like 0.10USD per @ 1/4 watt) They are used a lot. -- Roy Thistle

I was going to recommend soldering test wires onto the solder tails of the sockets on the bottom of the board, assuming they were through-hole.? Glad you got it fixed. BTW, thanks for mentioning

A very interesting read! But I was hoping he would explain a mechanism behind the variation. Also, he describes using pulsed measurements in order to minimize heat buildup and therefore the

One should always pay attention to resistor VCR specs when using resistors in high voltage circuits. Can be significant even at 2 kV. This App note explains: Or just search on resistor

mail.com@groups.io> wrote: If the scope is dropping into the diagnostic monitor due to a power on self test (POST) failure, the 2465A should leave a front panel LED lit. The LEDs flashing on the

:) :) :) In Italy it was "Vita da Strega"

<Giovanni.becattini@...> wrote: Main character in a 60's TV series called Bewitched. She was the witch wife played by Elizabeth

Thanks again, your help is valuable. I understand the suggestion regarding the resistors. Provided I check the value, could I use normal resistors even if they are not specific for high voltage?

Just a quick one which might help anyone whose scope boots fine but then has no display.. Obviously there are several reasons this might happen, however whilst working on one of these last week,

Hi all, I have a 2465A scope here which fails to boot. It briefly flashes some LED's before going to sleep. No beam finder, no scale illumination etc. The PSU had the Rifa's replaced and the

My experience is that measuring voltages in a high resistance circuit is hardly as trivial as it seems first sight. And I've even seen intermittent changes of values of "precision" resistors randomly.

I no longer need advice for this issue as the 7B92A has been repaired. Turns out Q938 was the issue. Funny thing is I tested all the transistors on my 5CT1N and they all tested fine at the

Ha ha! Excellent Brenda! Try it Gianni. What have you to lose? What you don't know how to do it? I don't either, ask your wife. Renaud

Hello people of TekScopes, I have a Tektronix 7B92A that needs repairing. It has a very severe horizontal deflection off to the right of the display, but the sweep is also jittery and not