Recapped the Avanti and....

[zeno]

Originally Posted by TinCanAlley

Okay, hang in here with me. I just want to make sure this is as simple as I believe it is. I will take a clip-on lead from the ground point of the canister and then a clip-on lead from one of the 400uf legs of the canister. I will then take the other ends of the leads and clip them to a good cap and turn the set on. Is this correct? Also, if I'm reading the schematics correctly, the second 400uf cap is on the other side of the 16ohm filter that the first 400uf connects to. Should I do parallel both at the same time?

Negative to ground + to the can section. OK ?
The 16 ohm is a choke, common arangement called a pi filter.
Do one cap at a time. Sometimes subbing either side will
improve it, the bad part is the one that shows most improvement.


73 Zeno

[TinCanAlley]

Originally Posted by zeno

Negative to ground + to the can section. OK ?
The 16 ohm is a choke, common arangement called a pi filter.
Do one cap at a time. Sometimes subbing either side will
improve it, the bad part is the one that shows most improvement.


73 Zeno

Oh yeah, should I put the caps on single or should I series them? If I put one on, it will be a 400uf in parallel with what ever value the can still has. If I series them first, then it will add around 200uf to what ever value the can has left.

Thanks

[Eric H]

Originally Posted by TinCanAlley

Oh yeah, should I put the caps on single or should I series them? If I put one on, it will be a 400uf in parallel with what ever value the can still has. If I series them first, then it will add around 200uf to what ever value the can has left.

Thanks

The old caps should be disconnected completely, besides adding capacitance they can still short out if left in the circuit, and they can also be leaky between sections.

Some of us like to gut the old cap and put the new ones inside for appearances sake.

[TinCanAlley]

Originally Posted by Eric H

The old caps should be disconnected completely, besides adding capacitance they can still short out if left in the circuit, and they can also be leaky between sections.

Some of us like to gut the old cap and put the new ones inside for appearances sake.

At this point I'm just trying to see if the jail bars change based on the addition of the paralleled cap. If it's best to disconnect the lead from the canister, then I think I'll just get all the replacement caps needed to clone the canister, install them on the bottom side of the chassis and leave the can in place for show.

[zeno]

Originally Posted by Eric H

The old caps should be disconnected completely, besides adding capacitance they can still short out if left in the circuit, and they can also be leaky between sections.

Some of us like to gut the old cap and put the new ones inside for appearances sake.

100% correct but we are just doing a quick test to see if the
jail bars go away. Dont unhook the old ones. Since the old
caps are probably near OK otherwise you would have servere
symtoms. We always used a 80 or 100mfd for this test.
Whatever was laying on the bench.
Even if you had a totally open say 200mfd it would make a
huge improvement & you could check the set for other problems
before giving an est.

73 Zeno

[TinCanAlley]

Well I paralleled both of the 400uf caps with a 200uf and it had no affect on the jail bars. Now I did those separate of each other as I don't have enough caps to do both at the same time. Should I get another 200uf cap and do both at the same time, or is it time to look elsewhere for the problem?

I didn't do anything with the 500uf caps as those are for the 24V.

[andy]

...

[sampson159]

my chromamcolor II had jailbars too.only on dvd.on satellite,no jailbars.i use an rf converter to operate multiple sets and when i disconnect 5 of the 6,jailbars disappear!

[zenith2134]

If it is source-dependent, there are likely variations in programme luminance content. Sometimes a DVD will flaunt the monitors' tiny errors.
For example, a strong signal with minimal attenuation in the highest of video frequencies(minimal sharpness) will tend to look the best, but wil usually be the most crucifyingly transparent when it comes to any defects.
On a set with power supply issues, in the form of either poor filtering on the supply rails or noise entering the video after the IF strip, It will never perform as new until the issue is eliminated.
Case in point, a 1981 zenith 19" with 9-160 mainobard and direct-entry tuner, hard power switch/vol. I used to use.

[DaveWM]

when you get done with all that, don't forget to check the horz blanking circuit.

[TinCanAlley]

Originally Posted by DaveWM

when you get done with all that, don't forget to check the horz blanking circuit.

I'm still pretty new to all of this and learning. How would I go about check the HBC? I should be able to get my hands on just about any piece of equipment for testing, so that shouldn't be an issue. Just need to know how.

Also, I have the option of purchasing a new 9-57 module (horizontal board). Is it worth it to swap them or is this issue most likely not on the module itself?

Thanks

[DaveWM]

buy a schematic, get s scope, find someone that knows how to use it, check the blanking pulse from the fly back to the video amp, if incorrect apply normal diagnostics to the circuit involved.

[Findm-Keepm]

I found these tips in some old Zenith Tech Topics I have - hope they help in some way - perhaps not now, but in the future.



Cheers,

[zeno]

Originally Posted by TinCanAlley

Also, I have the option of purchasing a new 9-57 module (horizontal board). Is it worth it to swap them or is this issue most likely not on the module itself?

Thanks

I wouldnt bother, the only thing on them was the 330 ohm resistors
like the ones on the 9-90 used in the upright.
IIRC there was a board to fix tearing from VCR's. It was
sold as 9-57VCR or something like that. Had an IC on it &
a hold adj. Ifyou find that buy it There
was a bulletin about it, IIRC even had improvements for 6U10
sets. Way to long ago, maybe someone has a collection of them,
mine long gone................73 Zeno