Magnavox Color Roundie

[tvcollector]

Here's the screen voltages:

Pin 4 340v
Pin 13 360v
Pin 5 345v
Pin 6 around 140-150 should be 200v
Pin 12 the same as pin 6
Pin 2 again same as pin 6 and 12
Pin 7 630v should be 960v
Pin 11 600v should be 980v
Pin 3 597v should be 860v

Voltages are being checked without the convergence board hooked up if that matters.. Please read previous posts as its started another page and I posted other posts..

[DaveWM]

pin 5 is the ref voltage from the voltage divider off the boost.

Clearly the boost is low as it should be in the 800v range (the voltage divider of the 1.5 meg resistors and the HV adj pot sets up the 400v that should be there.

the low voltage on the pin 5 means the shunt is completely cut off, so its doing nothing (the HV adj is prob not having any effect).

I would look at the .068 caps off the eff coil, leakage there could pull down the boost voltage.

check the resistance reading of the yoke as well for the horz windings.

[DaveWM]

with the horz tube out of the socket, read the DC voltage at the plate lead (the one that says "do not measure") again WITH THE HORZ TUBE OUT OF THE SOCKET.

[DaveWM]

the 1k resistor in the cathode of the shunt must have gotten very hot at some point and carbonized to that that low (181 ohms). This means something bad wrong happened in the shunt circuit at some point. could have just been a shorted tube, but hard to say.

Did you ever read the DC voltage to ground of the filaments of the CRT?

[tvcollector]

I checked both caps that are .082 and .068 off the EFF coil and they are good and no leakage according to my cap checker, even checked a new one with one in comparison...

If you mean the ohms in between the two yellow wires and two wires that are blue and red.. I get 00.8 ohms between them.. I don't have the yoke hooked to it...

Which pins are the firmaments to test?

Which pin on the HV output tube to measure I see where it says do not measure but not sure which pin..

The EFF coil was adjusting strange I thought.. it's a position in the middle where it can stay below or around 200ma, if I start adjusting either way, it starts going up..

[DaveWM]

crt pin 1 to ground. what is the DC voltage

the yoke resistance is given in the sams, check where the horz wires plug in.

you need to disconnect the yoke to check the resistance readings, otherwise the yoke should always be attached when running the set with the sweep circuits active.

[tvcollector]

Pin 1 to ground is around 195vdc... Trying to figure out the yoke resistance.. Looking on the sams, and I still can't figure that one out..

Still not sure about the horz output tube.. Shows the lead going to the flyback section where it says to "do not measure", but I don't see any wire going to the fly section from the HV output tube..

I can't have everything hooked up when doing voltage checks, I leave everything in the set, and remove the chassis/tuner/controls/ and set up all that in a different room on a table to work on.. As there is no room.. Yoke stays on pic tube in the set..

I'm following the sams and it says there is a 1240v boost point on the convergence board which is tied into the other higher voltages I listed that are low.. Now I'm measuring without the convergence board hooked up.. Is that why?

Update: I tested voltages with everything hooked up, and I checked pin 7 for voltages and it's even lower.. I noticed the shunt tube filament came up..

[DaveWM]

horz windings of yoke should be around 6.6 ohms per sams (disconnect red and blue leads before checking)

HV readings (currently at 5kv) was that taken with the yoke connected or not connected?

HV will not work if yoke is not connected.

[timmy]

well you may get 5kv with the yoke out, if your lucky. sounds like the headache i had with that silvertone hv problem. BTW its still working great , whites are white, lol..

[tvcollector]

I tried it both ways and HV was the same.. I disconnected the red and blue wires and put the the probes of the meter where the blue and red wires would go and my meter reads 007.5 ohms..

[DaveWM]

No change with the yoke connected and not connected huh, that is odd.

I suggest you do some continuity checks from the yoke leads back to the set, something is not right. I think the yoke is not in the circuit.

what is the ohms of the leads?

[DaveWM]

also check while working the horz pos pot back and forth.

[tvcollector]

00.72 ohms between the blue and red wires.. It does change slightly moving the horz centering pot, if that's the one you are talking about..

[tvcollector]

These long things.. I'm not sure what they are.. I figure they are a resistor of some sort, or a fuse.. The black long thing and the bumble bee colored black/yellow thing.. I measure them with my ohm meter and they measure open.. I get no continuity out of either of them on both continuity beep mode or regular resistance mode....

[DaveWM]

focus rectier (long black), the other is a 66meg resistor, not part of the problem.
Could be the horz osc is WAY out of tune.