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Yamamaya42 11-11-2022 11:26 AM

Quote:

Originally Posted by timmy (Post 3246438)
I can see how it would affect the sound which I’m not worried about sound and how is that it would kill the third IF it should just kill the audio. And there is supposed to be a .4v source coming from the tuner and it’s .13v that’s not right

.4v, normal operating conditions.

no video is not "normal operating conditions", so until there is normal operation of the RF-IF to video input, and the AGC feedback loop is normal, the .4v will always be abnormal.

The sound det is taken from the plate 3rd If, via C43, if V7 is not in the right state, it can clamp down on it.

timmy 11-11-2022 11:31 AM

Quote:

Originally Posted by Yamamaya42 (Post 3246437)
Take a look at the power plug for the tuner, namely pin 5, B+ source 2, this is sourced from 145v which also powers the V7 Sound Det, you have already seen how a faulty Sound Det can overload the 3rd IF and kill video, it is likely that this circuit is dependent on the tuner being connected for it to have the right load to have the correct voltage at the end of the string, w/o the tuner, the 130v goes too high and the Sound Det kills the 3rd IF, unhooking the tuner AGC line may also have an effect as well.

Quote:

Originally Posted by Yamamaya42 (Post 3246439)
.4v, normal operating conditions.

no video is not "normal operating conditions", so until there is normal operation of the RF-IF to video input, and the AGC feedback loop is normal, the .4v will always be abnormal.

The sound det is taken from the plate 3rd If, via C43, if V7 is not in the right state, it can clamp down on it.

Ok that does make sense because the sound as the tubes heat up would sometimes fade in and out alittle and be alittle static. The sound can be clear and loud but about 30 seconds after being on that’s when the sound gets funny. There is something coming down the IF strip being there is audio there

timmy 11-11-2022 11:42 AM

As electronic m had said if you have sound the video is with it so I guess what I’m saying is that could there be something in the sound that could knock out the video at the 3rd IF because test point b says all is ok from there but before that is v3 and sound.

Yamamaya42 11-11-2022 11:55 AM

It all has to do with response curves, it's all a delicate balance that has to factor in many things, including temperature, resistors, capacitors, coils, even tubes fit into this, which is why one never tries to align with old tubes, always new ones, and it's a long exhausting process, you change one thing one one end, it will change something on the other, so you keep going around and around, over and over until you get it as best as you can.
IF alignment is very frustrating.

dtvmcdonald 11-12-2022 08:26 AM

And, as already said, the alignment shape changes with AGC (and hence signal) level.
It behooves us now, who use modulators and coax, to align so that its spot on
at the signal level we expect to actually have.

I disagree that its always hard. Its hard for sets that don't have shielded coils and
really good bypassing, like the Pilot 3" sets and the Hallicrafters 7" electrostatics, both of which seem to oscillate if I follow instructions.

Also as I've said before: I've seen exactly two tube TVs that got to me with even
mildly passable alignment: A TT5 and a TRK12.

timmy 11-12-2022 09:16 AM

A good .001 measures 1.00 when is a cap like this no longer usable. I would think that a measurement of a .001 being 1.55 and 1.44 wouldn’t be good to use especially in an IF area.

timmy 11-14-2022 01:42 PM

I have to wonder if there are chassis that are really sensitive to tubes particularly in the IF now I have a zenith in v1 and a sylvania in v2 I have 5 lindal 6eh7 tubes only one of which I had tried but found that the zenith actually gave more then the lindal so I’m not sure if I may have all lousy tubes wish I could rule it out and not just believe the tube tester. I know lindal tubes they say are not good but I didn’t try the other 4 of them either.

Yamamaya42 11-14-2022 02:01 PM

Are the all NOS tubes?

timmy 11-14-2022 02:30 PM

Quote:

Originally Posted by Yamamaya42 (Post 3246517)
Are the all NOS tubes?

Yes not used

timmy 11-14-2022 02:32 PM

Just how clean does the pins have to be shiny which I have never had to do.

timmy 11-14-2022 02:58 PM

The reason why I ask is I tried the rf cable from the tv tuner and tried it on v2 and I was surprised that there was a picture present with not much contrast but it was very stable no vertical or horizontal issues so I’m looking into dirty tube socket or pin’s.

timmy 11-15-2022 09:40 AM

Why is it that some capacitors listed in sams don’t show voltage how do you know what voltage to put in.

Yamamaya42 11-15-2022 10:24 AM

Take a look at the voltages in the general area that it's hooked to in the schematic, add 100v, as a general rule.

timmy 11-15-2022 11:19 AM

1kv would be ok as well ?

Yamamaya42 11-15-2022 11:24 AM

As long as it can still fit in the same space the old one came from, and the farad rating is the same as the old, larger voltage really can't hurt.


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