VT-71 Making me crazy!

[Adam]

Thanks for the information on finding those capacitors, for a long while I couldn't order anything because the mail delivery here is awful, and stuff would always go in wrong peoples boxes, get lost, and anything that wouldn't fit in the box just got returned to the sender. But I finally went and got a PO box, so I don't have to deal with that mail delivery awfulness anymore, so now I can order something and actually expect to get it.

"They may also have the high wattage resistors you need to make a ballast replacement. I used Dale type resistors on a little copper board. You can read more about that project at:http://antiqueradio.org/motvt73.htm"

I enjoyed reading that, I had been debating how to place the ballast resistors, and I liked that piece of metal ontop of the chassis, and then plug them into the ballast tube socket idea you had. The last one I fixed was unsuccessfully converted to filament transformers by a previous owner, rather than stripping the rather extensive modifications out, I managed to finally get them working as I think they were intended to, but it was a real mess to sort out and I don't want to go through that again. Also that arcing crt socket made me think that that 1 crt I have might not be arcing inside the tube, but maybe inside the base, I know it's not the socket, because it doesn't do it with the other 7JP4s.

All 3 of my TS-4J chassis are 1948, the one I fixed previously with the filament trans. is not copper plated, the other 2 are copper plated. I think there must be alot more of these 7" motorolas out there than there are good 7JP4s left.

[Phil Nelson]

You guys probably know this, but there were something like eight chassis variations for this TV. Different ballasts, you name it. I haven't looked at it in a year or two, but I believe the Riders manual runs to 80 - 100 pages. Make sure you're looking at the right schematic for whatever chassis you're working on.

The devil's in the details :-)

Have fun.

[7"estatdef]

The manual I got from the radiio guy which is a copy of the original Motorola manual is great. It's about 130 pages. But it doesn't have much info on the J just the diagram. Sam's has the info for the J but the diagram is harder to read because it doesn't show the split power supply very well. Both use different numbers for the componets so you have to keep all the numbers staight.
Maybe us VT-71/3 owners should write up a supplement of service notes and burn it to a cd with the manuals?
Terry

[7"estatdef]

Well after about five days of troubleshooting It turned out to be L-43 the limiter grid coil was open!! Was causing the grid to be at -9v when it should be +95v (split power supply) The limiter tube was hauling down 40ma of plate current ouch!
Terry

Phil you are so right

The devil's in the details