Back to the VT-71H

[Chris K]

Originally Posted by timmy

Hey Chris the ballast you made is that design for this ts-4h ?

Yes...If you look back in the thread, I made it as per a discussion with Bob A. It's the same construction as the other ballast found in these sets but required a change in pin to work correctly. I'm pretty confident it was built correctly as I had many exchanges with Bob and other members in the thread.

Thanks
Chris

[Chris K]

Originally Posted by bandersen

This is my current design using diodes. Compact enough to fit in the original metal tube.

Andersen[/url], on Flickr

This is the start of that part of the thread on page 3

[bandersen]

All TS-4 versions prior to TS-4J use the 17A470303 ballast. It has an extra resistor only used in the very early revisions (prior to the TS-4H).

The other difference the is that the AC line in goes to pin 5.

It is connected to pin 6 in the later version of the ballast which is what you created.

So, you need to move the wore from pin 5 to pin 6 on the ballast tube socket. OR modify the ballast so the CL-90 goes to pin 5 instead of 6.

[timmy]

Ok just checking didn’t want to have to chase another problem. Then ballast ruled out, good, lol

[Chris K]

Originally Posted by timmy

Ok just checking didn’t want to have to chase another problem. Then ballast ruled out, good, lol

The cage for the ballast can be easily removed just by prying it up a bit...if you want to check the work. It doesn't matter to me.

[timmy]

No I won’t check the work on the ballast but I’ll tell you that ballast gets HOT when running for alittle while to the point of not able to touch it. I thought this design is supposed to run cool.

[bandersen]

Hot and cool are relative terms. It should be much cooler than the original, but it does generate heat. A thermistor has to get warm to work properly. That's why I put it on top.
Total dissipation for the unit is something like 8W versus 25W for the original.

[bandersen]

Has anyone made this measurement yet? "Should be around 11.5K between pin 6 of the video amp tube and B++ (pin 4 of the ballast tube)"

There are just two resistors between B++ and the video amp plate. If there's no voltage on the plate, problem has to be here.

[timmy]

Ok here’s where I’m at got video but it appears that vertical is collapsing when I got video the vertical didn’t last long a heard a snap but Don’t know where it came from then trying to adjust will give me a horizontal line but adjusting back down it will stay so there’s something going on in vertical and it looks like whatever is going on it’s creating noise on the video signal.

[timmy]

I’m trying to post pictures but it’s not letting me saying the pics are to large and resized them smaller and still won’t pos pics.

[timmy]

Trying again

[Chris K]

Tim will part the Red Sea...and I understand he has located Jimmy Hoffa's remains!

[timmy]

I don’t know what’s going on with this site now I can’t click on a post let alone post a pic.

[Chris K]

Originally Posted by timmy

I don’t know what’s going on with this site now I can’t click on a post let alone post a pic.

All I can suggest are the usual computer glasses of cold water in the face solutions with ramping up the size of the cup! Close out site...close browser...or reboot!

[timmy]

Did that already never had this problem befor.