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Don't be concerned about the primary and secondary winding resistance. The failure mode of the transformer is leakage between primary and secondary.
Try taking in the replacement transformer. Other than that, something is causing the oscillator to run fast. I do not think it is a resistor as they tend to drift upward in value. Capacitor leakage can. Check to ensure all the paper dielectric capacitors at oscillator grid including the integrator are replaced. |
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I'm assuming by "confirmed bad" you mean that the vertical windings check shorted. I'm not familiar with the Eico tester, but other yoke and flyback testers will read "bad" if one forgets to open the resistor paralleling the winding. The 730 uses a 560 ohms across each vertical winding. |
I had thought of that. I wasn't certain if there was or not. I'll pull the yoke and confirm, thanks for clarifying :)
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You have vertical deflection......... Full screen even..... I can't see it being the yoke....
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the picture is too big vert. too.... . |
Right, but then I ran into this:
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Well, Ok, you have more than one problem... You need to do some troubleshooting.
First turn it on and hit it a few times..... figure out if it's got an intermitant.... Bad solder joints... If you get a nice stable set while hitting it, then it's a part.... Look at what you don't have and look in the part of the set that most likely lost it.... Raster no other stuff.... ?? Get out the block diagram and figure out where the problem might be..... Or at least a place to start... Hitting it... Use a wood dowel, 12" long, 1/2" dia. Bounce it off the chassis in different spots. Gently hit the tubes, hit the coils, etc. You're just looking for a bad connection. . |
Well, before I do anything, I'm gonna set the chassis on the bench and do some voltage checks to see exactly what is amiss. I'll have to be a little creative in suspending the picture tube, but it'll be pretty easy.
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Got the chassis on the bench. Found at least part of the problem. V1, the 6J6 RF amp, has only 88.2 VDC on pin 1 and 84.8 on pin 2. Should be 145 VDC on both.
V2, the 6J6 mixer, voltages are right where they should be. V3, the 6J6 oscillator, pins 1 and 2 are high. Should be 75, I'm getting 98. Problem has to be in those small white mmf caps that I didn't change. Are they anything special, composition wise? |
Those are ceramic caps that seldom fail. Generally OK to replace with mica caps.
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If the rf amp plate voltages are low, try adjusting the contrast (picture) control to minimum. There is no agc on this set and it may be the grid bias. I do not think the caps are bad and they are best left alone because of alignment.
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I was just working on an Admiral 30A1 and was thinking of THOSE caps. This set doesn't have ceramic caps. Oye. Working on too many sets at once....
Anyway, I discharged the HV and flipped the chassis over. Removed the screws on the lower tuner cover, and of course I can't see anything under the 6J6 because the tuner's in the way. Still poking around in here..... |
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Just to recap (har har), I have no raster on this set at this point but audio is fine, adequate HV (neon bulb test). Had a nice bright picture briefly, but doesn't now as outlined in the previous posts.
Usually at this point I'd start by measuring voltages working from the RF amplifier forward or going to the first video IF and working backward. Since I've got weird voltages right at the RF amp I'm kinda puzzled as to where to go from here. |
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