The readout problem is straightforward although it may not be easy to
find the specific fault and access may be limited. I am sure it is
not related to the intensity problem unless Tektronix did something
really weird.
On Mon, 9 Jul 2012 20:30:20 -0400, David Holland
<david.w.holland@...> wrote:
Yeah, I've a 7B85 down in the basement. I'll plug things in and
fiddle with them (probably tomorrow) and see what shows up. (Or
doesn't.)
Before running to far down the rabbit hole, I should probably describe
the readout symptoms.
AFACT, the readout doesn't display units. I get a number in the
correct locations, that will change depending on the settings of the
plugins, but there's no units associated with them.
Perhaps its related, perhaps not.
Anyways, thank you for the pointers.
David
On Mon, Jul 9, 2012 at 1:08 PM, David <davidwhess@...> wrote:
Do you have a dual time base, a 7B87, or a 7B80/7B85 (or equivalent)
which you could use to check if the A intensified by B display is
correct?
I wonder if your readout troubles are related. The stored trace
intensify command could be controlled through the readout or from the
same place the readout is controlled from. Verifying it should be as
simple as disabling that function by pulling a transistor but I did a
cursory search of the service manual and did not find out it.
You might try fiddling with the contrast adjustment on the front of
the oscilloscope to see if that affects anything. I know mine has
trouble with the intensified display when using some dual time bases.
On Mon, 9 Jul 2012 12:36:13 -0400, David Holland
<david.w.holland@...> wrote:
Yup. Blanking looks good to me...
I'll double check the pot, and make certain its smooth. It looks
like I have some reading to do in the manual....(this is certainly
going to be umm.. interesting)
David
On Mon, Jul 9, 2012 at 11:32 AM, <larrys@...> wrote:
Are the parts that are supposed to be blanked getting blanked?
-ls-
David Holland <david.w.holland@...> wrote:
Hello all,
I'm kind of getting around to poking at my 7854 scope.
The stored trace brightness is excessive, and the adjustment won't go
down any further. I'm reasonably certain the pot is good, since
it'll smoothy vary over what range it does have. (From "too bright",
to "cr*p, I'd better turn that down before the CRT gets burnt").
Normal display, and readout's are of a more reasonable intensity, and
have goodly range. (Readout isn't working correctly, but that's
not the problem I want to concentrate first on.)
Before I crack the covers, any suggestions of which parts of the
service manual would be most relevant to read...
thanks in advance...
David
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