LowB+ in a CBS Ch 817-6

[Doug66]

Yes, with the red disconnected, I actually have 375V on the blue and at the top of C3 and R100.

Let me throw this at you. I replaced the vertical output transformer 1st thing with a Stancor replacement. According to the Sams, you have to change a couple of leads. I thought I did that correctly, but if I made a mistake there, could THAT be dragging my B+ down? Now I just disconnected all 4 of the vert output transformer leads, but the B+ was still too low, so I reconnected them.

[Kevin Kuehn]

I don't have a full schematic so I'm a little in the dark trying to see the big picture.

[EdKozk2]

Originally Posted by Kevin Kuehn

I don't have a full schematic so I'm a little in the dark trying to see the big picture.

Kevin,
The Sam's is 214 folder 2, if you have it.

Doug,
The Sam's notes mention you only need the 10 mmf 2500v cap (C85) for the horizontal feedback. You don't need the 5 mmf cap (C84) that is shown in series with C85. You also don't need C90 the 20kv 500mmf filter cap on chassis 817.

[Kevin Kuehn]

Unfortunately my Sams have a hole from 153 to about 250. Right where all the fun early 50's sets are.

Reading back through the replies it almost sounds like your red and blue yoke wires are reversed, but I'm not able to see if or how that's possibly loading down the B+. What would happen if you pull both the horizontal and vertical output tubes so you can measure only the dc voltage drops across the yoke windings? Have you verified those two windings are not shorting to each other?

[Doug66]

Hey Guys,
Sorry to be so long on getting back with me response.
Kevin, I just checked the replacement yoke I put in against the original yoke (which was good) and it is hooked up right.

I'm somewhat confused on what you mean be checking across the woke windings. I unplugged the vert and horiz output tubes. On each yoke lead I got about 340V. Putting the meter leads directly across the yoke leads reads nothing.

I finally got a pic of the screen with a signal applied. Compressed on left and wavy, and vert lacks height. Brightness is at max. Also can't get a good lock on vertical. Assume this is all due to the B+ being too low.

[Kevin Kuehn]

Originally Posted by Doug66

I'm somewhat confused on what you mean be checking across the woke windings. I unplugged the vert and horiz output tubes. On each yoke lead I got about 340V. Putting the meter leads directly across the yoke leads reads nothing.

I thought if there was any DC voltage drop across one of those that it might lead to where the short was, giving some sense of direction. The picture looks like horizontal ringing, like the damper is not doing it's job, or possibly the horizontal output being overdrive.

[Doug66]

Would the horizontal ringing also cause the reduced vertical. I'm still wondering if I hooked up the replacement vertical output transformer right. The Sams gives instructions in the parts list and they are confusing.
It says: Connect blue lead to transformer plate.
Connect green lead of transformer and Boosted B+ to brown lead of
yoke.
remove green lead from yoke from it's present terminal and connect
to red lead of transformer.
It doesn't say anything about where the yellow lead goes. I assume it still goes to the 340V.
Those instructions are confusing. Here are two parts of the schematic showing where all leads of the original transformer went and also where the brown wire off the yoke went.
The original green lead went to the brown lead of the yoke. The new instructions say do that as well as put the boosted B+ to this lead. If I read the schematic right, the original red lead is the boosted B+. That lead goes thru R76, R77, then thru a 2.2 med (R80) and onto pin 10 of CRT at 525V.

If I've got this transformer wired in wrong, could that be pulling down my B+? However if I disconnect all leads of the vert transformer, B+ is still pulled down.

[Doug66]

I've been doing some more checking in the damper circuit. Pin 3 has 418V. The Sams does not give a voltage for this pin. It goes to a .1 which should have the 340 B+ on the other side.
Pin 5 should have 330V. My VOM showed a small arc when I touched the lead to it but would read nothing. I got out my VTVM which only goes to 300V DC. I figured 30V wouldn't overload it too much. It pegged the left side of the scale meaning a negative voltage was present. I switched it to DC- , then the needle pegged the right side of the scale.

I then reversed the leads on my VOM to read negative, and it shoved an overload.

Pin 5 goes to pin 4 of the flyback.

[EdKozk2]

Hi Doug66,
Did you replace the vertical output transformer with a 4-wire type or a 3-wire type ? If you changed to a 3-wire type ( Stancor A-8141 autoformer) then your connections would follow note #10 instructions in the Sams. If you have a 4-wire type then follow the schematic as shown. The original vertical output has a 1700 ohm primary and 6 ohm secondary.
As for pin 3 of the damper that is the boosted B+.
Ed

[EdKozk2]

Doug 66,
Is that a speaker leaning against the picture tube? Make sure your HV cage is installed before tracing yoke/damper ringing problems.

[Doug66]

Ed. Now we're getting somewhere on the vertical. I did get a Stancor A-8141 from Playthings of the Past, but the unit in the box was a 4 wire, so I hooked it up like the original.

Yes, the speaker is resting on the chassis and touching the CRT strap. Currently, I do not have the HV cage cover on the HV cage, but I will put it back on.