Motorola vt-71 restoration
 

I am finally starting the restoration of a Motorola vt-71 that I got from Sean when I was in Missouri. It has the late ts-47 chassis and a replacement mask already (thanks Sean). I just ordered the caps and resistors I need. Does anyone know where i can get new paper labels for the back or replacements?

http://img.tapatalk.com/d/13/01/07/era6eqep.jpghttp://img.tapatalk.com/d/13/01/07/agujanem.jpghttp://img.tapatalk.com/d/13/01/07/ety4usyg.jpghttp://img.tapatalk.com/d/13/01/07/qahyresy.jpg
I have the knobs sitting on my desk

So far I have replaced mOst if the caps in the set except for the filter caps and there are no hv caps installed at all and there are 5 papers eating on just radios.
Would it be ok to test it for a short amount of time? I plugged it in a little while agao and got good clear audio but only a white dot on the screen ( don't worry I turned down the brightness do it would not burn in) I would like to show it to my parents do they can see the progress

With no HV caps installed you will get no vertical or horizontal deflection which is why you got just a white dot on the screen. I would not test it like this as you can very quickly burn a dot onto the picture tube phosphors. Wait until you get the high voltage caps replaced in the deflection circuits and the high voltage power supply then test it. After that, you will probably have a useable picture with which you can continue the restoration. Don't expect it to work reliably until all paper caps and electrolytics have been replaced.

With the brightness and contrast turned all the way down there is no dot would it be ok to run it for a few minutes like this or would it damage the high voltage transformer?

I noticed an empty tube socket on the back. That is where a ballast tube goes, and unless it has been replaced with resistors under the chassis, there is no way the whole set will work without it.

I used the schematic I found on here to rebuld the old one with capacitors and resistors. Those pictures are from when I first got it.
I would post some pictures but my iPhone wolnt let me upload them for some reason.

Be careful using plain wirewound resistors to replace the legs of the ballast that the CRT is on. I did just that, and now, every time I turn it on, the CRT lights up bright white until the other tubes in series get warmed up. Must be a few with "controlled heater warm-up time" in the string (of which the CRT is NOT). I'm still looking for a toaster-wire-type ballast substitute for mine as well.

I used the schematic in this thread
http://www.videokarma.org/showthread.php?t=249434

If you are looking for a ballest I have heard good things about the amperite ballests sold apparently they last allot longer than the orgionals and provide some sort of current regulation.

I currently have an Amperite ballast tube in my Motorola replacing the original metal one that burned out and it works great.

Got the hv caps and all but 4 paper caps and I am rewarded with this! At first it wouldn't come in at all but then I realized the set wasn't plugged in:p
Any ideas miswired socked or misplaced hv caps?

http://img.tapatalk.com/d/13/01/23/je3yzuba.jpgy It's a very crisp cross hatch pattern in person

I know the CRT needs to be turned.

Looks promising :) Does adjusting the horizontal and vertical controls on the back help any ?

Yes it did help some could a weak or gassy 6sl7 cause this?

http://img.tapatalk.com/d/13/01/23/3a5ypuzu.jpg
The lines move side to side but those vertical lines are not there in person

.
Never mind

Doubt it's just the 6SL7 tube causing your troubles. Waves could be some hum in the power supply. Do you have something like a B&K 1077 to inject signals into the video IF stages ?

No I don't have any signal generator.
Is it ok if I used electrolytics in place of the film caps in the ballest?

Are they non-polarized ? Ideally I think motor run caps should be used because they're designed to handle continuous AC current.

I havent replaced the filters yet (probably should have done that first... DUH

about the ballest I had the set on for a few minutes (longer than I have ever had it on) and I noticed the electrolytics were getting very hot and begenning to vent. Motor run caps would probably work good but arnt they in big sardine cans filled with toxic preservatives like PCB I know the old ones were not shure about the newer ones.

Yikes! Yes, you need to use non-polarized caps. They stopped using PCBs in caps a few decades ago so no worries there unless you dig up some ancient ones.

I used a plastic film motor run cap like this in my Predicta Holiday. I've used regular film caps too, but I'm not sure how well they'll hold up under extended use.

http://www.digikey.com/product-detai...9401-ND/207387

http://media.digikey.com/Photos/Pana...SERIES_sml.jpg

I will probably buy those soon since I plan to watch this tv nightly after i get it working!

Be sure to check the dimensions before you do. They're too big to fit inside an original mesh metal ballast tube.

I could probably stick em under the chassis if they don't fit.
Is there a way I could inject a signal in the if stages without a signal generator?

bump...
I haven't been able to work on the set lately had a ton of school work but I did get the ballast fixed but it still does the same thing. anyone any ideas? even remote possibilities?

Did you replace the filter and all the paper caps ? Are the ballast caps still getting hot ?

no I replaced the capacitors in the ballast with film ones so it does not get hot anymore I got all the paper caps replaced except for one .004 at 600 volt cap and I have not replaced any of the filters yet bu I will probably get to that on Monday since I don't have school.

That pattern looks like audio to me. Those tightly packed vertical lines would be the 4.5mHz FM audio subcarrier. Do the lines go away with no input signal? If so, I would be pretty sure of it.