Re: Type 503 Oscilloscope Issues

Dave Casey

One last thing - you might go ahead and verify that the black stuff on the
yellow wire is actually stuff that used to be yellow and has burned as
opposed to something else that has landed on that wire (does is scrape off
and reveal undamaged yellow insulation below?). This black stuff was
present in the video you posted the other day. It may have been there the
whole time you've had the scope and have nothing to do with the burning

I'm also wondering if the problems I thought I saw with V620 and V659 are
misinterpretations of the video. The red color inside V620 may just be a
reflection of the trace rotation knob, and the "flickering" of V659 now
looks more like a result of the changing camera angle. (V692 definitely
shouldn't be doing what it's doing though!)


On Thu, Apr 6, 2017 at 12:02 AM, enchanter464@... [TekScopes] <
TekScopes@...> wrote:

Hello all,

I feel bad that it has been several days since my last posting.
Unfortunately, my work is at a standstill right now. Over the past weekend
I had focused most of my work on restoring a vintage volt meter (Triplett
630-A), which is now working (and supports up to 6000 V, although I lack
the HV leads, so no -3000 V testing yet). As such, I only now have gotten
time to focus on the scope.

However, when I connected the leads to the ground (chassis) and -100 V
test point, plugged in the scope, and after the brief burning smell,
nothing happened (no lights for the scope, no CRT turning on, no tubes
activating). I discovered that the fuse had blown during my attempt to get
the voltages, but after no luck in going through my fuse stock, I ended up
having to order a set of new ones to come in, so that won't be until next
week earliest.

For the scope, I was still able to check the non-voltage components on the
power circuit. The diodes still check out, with D652 (and others) giving
readings of ~0.65-0.65 on my multimeter. However, only diode D672 gave a
reading of 0.041 on two different multimeters, so I suspect this one is
bad. This one is connected to the +12.6 V circuit.

As for resistors, some also seem to have issues, with R692 (going to V692)
being at 1.4-1.5 ohm, but it is supposed to be 4.3 ohm. I admit I am having
a bit of difficulty in locating R659, so I was unable to confirm if that
one is okay.

Once the fuses come in, I'll let you know how the voltages read out.
However, as for the burning, think it may be coming from the wires leading
to the T601 (see the photo:

- Evan

[Non-text portions of this message have been removed]

Join to automatically receive all group messages.