Juggling multiple TVs this weekend that I have right on the edge of working. I'm still trying to get this 7" Motorola to produce a picture. I replaced the 1N34 germanium detector diode that seems to be the culprit in most of these TVs with a diode kindly sent to me by Don S. who has used them successfully in his VT-71s. I thank him so much for sending me 10 of these for no charge. Unfortunately, that didn't solve the issue.

I have a nice and bright raster on the screen. I'm trying to see if I can get a crosshatch pattern from my Sencore VA62 to go through the antenna with a 1KHz audio tone. I get sound OK but still no picture, just the raster. I'm not all that familiar with the 62 functions yet but I have used it as a pattern generator on other sets and it works fine. Any suggestions as to the next step should be? I suppose I should start with injecting a video signal through the video amplifier 6AU6 but I'm not exactly what I should try to put through it from the VA62. I've been told this is a pretty good tool and I suppose I should start to learn how to use it. Thanks all.

C

The camera can't pick it up but there's a bright 4-3 raster on the screen. I'm feeding a crosshatch pattern with a 1KHz audio signal through the antenna leads. Sound is fine...no picture. I've tried a bunch of different RF levels with no change. Should I start by feeding a video signal through the video amp tube and work my way back? Is that a good strategy? All the caps and any out of tolerance resistors have been replaced and all of the tubes test strong or are NOS. Replaced the 1N34 diode with the recommended substitute. It's a shame I can't get an image on this. Very strong 7JP4...an RCA replacement that's almost NOS as well. If I can get this producing a picture, this will be a really nice piece.

Have you verified that the horizontal and vertical sweep frequencies are correct, or at least close to being correct?

jr

No I haven’t. Should that be the first step before I dive into the IF series?

I would check the frequencies when the screen display is messed up...Looks to me like the horizontal frequency is way off. :scratch2:

jr

+1 , looks like horizontal is off.

Greg b

I know with those vt71 sets if the horizontal hold is turned all the way to one side you get lines and looks like a horizontal problem until you turn it the other way try that maybe that’s it. There is also a few mica caps in the horizontal section I had to change because of really bad horizontal issues so look into those. these mica caps look like dominoes. There is a 680,200,900,mmf

Thanks Timmy I’ll try that. I didn’t replace any of the dominoes because it’s pointless for most restorations I’ve been told but I’ve never been comfortable leaving old components in these things. Such a shame this is stuck where it is. Very strong CRT and a beautiful cabinet. Sometimes I just think I’ve got a black cloud over my bench. I guess I’ve seen too many videos where people change a couple of electrolytics and the thing fires right up!

Yes a lot say that the old dominoes mica caps don’t go bad but there’s more that go bad then not. I have 6 of those little Motorolas and iirc 3 of them needed the horizontal micas

I'll give it a shot...not hopeful but I'll try. Thanks.

Careful - those might be 1,000 volt mica caps. I'm assuming by the thread title this is a VT-71 with a TS-4H chassis?

Careful - those might be 1,000 volt mica caps. I'm assuming by the thread title this is a VT-71 with a TS-4H chassis?

That's correct. Most of what I've come across are 500v maximum but I have seen 1 or 2 1000v caps listed in the Sams.

That's correct. Most of what I've come across are 500v maximum but I have seen 1 or 2 1000v caps listed in the Sams.

You can check the micas with a cap checker as I did with mine and the few 1 kv micas I did use 500v and they are in there for years and never had a problem.

It's not like ya can't find 1kv ones if you really need to! :D

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CDV19FF681JO3F?qs=tNDx7qEChkdmHOvQNQEczw%3D%3D

but, they are very tiny next to the original! :O

Generally speaking don't touch micas in the tuner or IF system, but change sweep circuit micas with maximum prejudice...
Typically RF/IF micas have very little DC on them (worst case 200V) and maybe a volt of AC signal... They'll live forever like that.
Sweep stage micas can have 350-1000VDC on them while being whacked by 200-1000VAC pulses.
Logically you can see what is more stressed and thus more prone to failure.

The nice part about this is the sweep can be eyeballed back into adjustment (so no reason not to change sweep micas), where as the tuner and IF take special equipment and a lot of skill and effort.

Another thing to watch out for is I have encountered tin whiskers in Motorola pots in these sets.

I changed the sweep mica caps and checked them. They were all open. I replaced them with the correct size and voltage new mica replacements. The control pots on the back were all cleaned out with CRC contact cleaner but I did it again for good measure. Tubes checked again...all good and I cleaned the tube pin sockets with a mini-wire brush I got. Rechecked the antenna connections and went through all the solder joints and connections in the sweep circuits and IF. No change on the TV. Still no picture getting through. Audio yes but no video. Might be time to put this back up on the shelf for a while.

Did you trace down the cathode on the crt ? What about the contrast knob to much one way picture gone but sound will stay. Is the b+ up where it should be and take an extra look at the video amp.

According to the Motorola vt71 svc_manual, you should be able to see a healthy 1.8v ptp video signal with an oscilloscope on the grid of the video amp U6 (P1 6AU6), if, all is working OK, and the signal is getting to and past the detector, at point D.

I feel like this was discussed on your last thread on this set, but I don't have time to dig for the info (BTW it's kinda moderation policy here to not allow multiple topics on the same TV to avoid this situation) but if you have anything that can generate a test pattern IF signal on the frequency this uses (such as a B&K 1075-1077 family analyst, modified Sencore VA-62, another working old IF band TV tapped for signal just before the detector) signal injection at the IF grids in your Motorola may yield some guidance on where the problem is.

Looking at things closer, V6 has to be working for there to be sound, as the sound pickup is through C35, but perhaps problems with coils L32/L33 or C72, it should be easy enough to trace with a scope, cause you KNOW, it has to be getting as far as the video amp for sound, just need to see where it may be getting lost from pin 5 to CRT point C.

Modest disaster. Ballast tube popped and shattered. I knew this was the weak link. I supposed it got tapped while manipulating the chassis upside down when it was blazing hot. My chassis was missing the steel thermal shield around the tube. All the elements are intact but I can't use it as is. I guess it's rebuild a replacement or try to find a best fit replacement for the glass. In my chassis, the ballast is the rarer 17A4...3030 and almost all of the rebuild plans I've found are for other designs. Part of the adventurous learning curve in this hobby.

I actually have an old Ballast Tube in my collection of weird stuff someplace, no clue as the make or value of it.

Motorola 17A470303 R80 R-80 are quite unobtainium, however... Bandersen has been down this path a few times, and I'm sure can offer guidance if needed. :)

Interesting! This is the first TV I've bought that had one. I did a lot of research looking for replacements in case something like this happened and came to the conclusion it's the rarer of the 2 ballast tubes Motorola used in this TV. Phil has a simple resistor build on his website for the more common one and I suppose I could just modify the values to match the one I'd be substituting for. I have seen the alternate capacitor based, soft start ballast replacement but it's also a replacement for the more common ballast tube so, I don't think I want to mess with trying to adjust that design for my needs. If you come across the ballast, let me know and I can provide the pin values I would need but don't go digging just for me!

Yup had to make several ballasts for my sets just a few resistors and that’s it works fine.

The damage

Oh yeah well check the schematic and the pins of the ballast and just use resistors just make sure the wattage is high enough.

Resistors of sufficient wattage are good.

Capacitance isn't hard. If you know the ballast resistance just Google search capacitance impedance calculator and look for one that lets you plug in the impedance and frequency and get the capacitance...Or plug in the frequency and guess and check the capacitance a few times (8.2uF is a good starting point).
IIRC the heater portion of both Motorola ballasts used in that chassis family is the same so that math shouldn't need to be redone...The non-heater resistors need to be resistors anyway so there isn't much to dealing with them.

If you're concerned about messing it up start it on a variac and measure heater voltage as you crqnk up the line voltage.

It's a bit more tricky than just resistors, :yes:

https://www.youtube.com/watch?v=VEbozz-pVok

As mentioned, He has dealt with this b4! :P

Best I can figure from the schematic pin out below. I think Phil said he used 25 watt resistors:
Pins 3 and 4 200 ohms
Pins 1 and 5 37 ohms
Pins 2 and 5 105 ohms
Pins 5 and 7 105 ohms
Pins 6 and 8 Can't find on schematic. Measures 21 ohms on what's left of the ballast.

So my plan would be to use a piece of aluminum as a heat sink mounted on the chassis and screw these to it with thermal paste. Then I'll make the appropriate connections to either a spare pin socket or directly to the socket contacts on the chassis. I will also look into the capacitor calculations and if that's viable, I'll post the plans here first. Any comments or suggestions?

I'm sure that if you follow his examples in the video, it should be OK, he may even see this thread sooner or later and offer some sagely advice, having done this so many times before. :)

This is what I used on my sets that have this ballast config. The 200 ohm is 20 watt.

This is what I used on my sets that have this ballast config. The 200 ohm is 20 watt.

Wow thank you so much! I'll probably make both the resistor and capacitor version and see how they work.

BTW, I didn't check video signal with the scope but I had continuity between the 6AU6 plate and the CRT so there's no mechanical issue. The coils are good and I changed the capacitor just for good measure. Still no image getting through...just sound and the bright and full screen raster.

What checking with the scope would tell is if the video is getting to the cathode of the CRT at the needed amplitude for a picture, w/o any distortion, if it is, the sync may be SO FAR out of wack that it MIGHT obscure video display ( unlikely, but who knows.) , or the voltages at the CRT are so far off, it just can't let it show video, assuming that it's good enough to in the first place.

What checking with the scope would tell is if the video is getting to the cathode of the CRT at the needed amplitude for a picture, w/o any distortion, if it is, the sync may be SO FAR out of wack that it MIGHT obscure video display ( unlikely, but who knows.) , or the voltages at the CRT are so far off, it just can't let it show video, assuming that it's good enough to in the first place.

Yeah...way to go on this one. On these electrostatic focus tubes, I don't have anything to go on to judge quality other than the brightness of the picture and the fact that it's not the original, it's an RCA 7JP4 and bright. N way to test on my Sencore CRT tester. No matter at this point. I've got a ballast to build. I can check the CRT voltages once that's done...as long as I know what pins are HV.

Wow thank you so much! I'll probably make both the resistor and capacitor version and see how they work.

BTW, I didn't check video signal with the scope but I had continuity between the 6AU6 plate and the CRT so there's no mechanical issue. The coils are good and I changed the capacitor just for good measure. Still no image getting through...just sound and the bright and full screen raster.

Did you check the position of the contrast control ? I didn’t give the wattage for the others all the resistors listed that have the = mean that’s the ohms that I used for that one. The 2-150 ohm 2watt. 22-or 25 ohm 20 watt 37or 50 ohm 10 watt all these are what is in my sets. How about the position of the horizontal hold pot?

A few things. You had a very rare after market glass Amperite ballast :tears: That's only the second 303 glass ballast I've seen in many years of looking.

They do not have a shield around them. They are prized because they actually regulate the current to the tubes. They're filled with hydrogen gas and have finely twisted iron wires. The hydrogen seeps into the iron and affects it's resistance. When the wire get's hot, some of the hydrogen is forced out and the resistance drops. That causes the wire to cool and it absorbs more gas.

That perforated metal tube is the stock ballast. It's just some resistance wire on a mica wafer like a toaster. That metal shield is to keep fingers away.


Here are four types. Left to right.
Clarostat aftermarket replacement.
Stock Motorola ballast.
Amperite glass ballast (this is a more common '459 type)
Homebrew using Capacitors, resistors and thermistor.

https://live.staticflickr.com/3771/9238546544_fd7ebc2b92_c.jpg (https://flic.kr/p/f5nY2f)

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

https://live.staticflickr.com/65535/51682117896_a45e067c42_z.jpg (https://flic.kr/p/2mJYn5d)Andersen[/url], on Flickr

https://live.staticflickr.com/65535/51687817568_e169d3dee1_c.jpg (https://flic.kr/p/2mKtzoq)

Note this is for the 17A435459 ballast. The '303 is very similar but you will need to move one wire. I believe it's moving the connection from pin 6 to pin 5.

http://suzaku.live-evil.org/0222231655.jpg
I knew i had one!

SYLVANIA 40a1 ballast tube.

Not sure what it can be used in. :O

http://suzaku.live-evil.org/0222231655.jpg
I knew i had one!

SYLVANIA 40a1 ballast tube.

Not sure what it can be used in. :O

That one is definitely not for the small Motorolas.

That one is definitely not for the small Motorolas.

https://frank.pocnet.net/sheets/137/4/40A1.pdf

OK, so THIS is what it's used for, :D
no idea where I found it!

http://suzaku.live-evil.org/0222231655.jpg
I knew i had one!

SYLVANIA 40a1 ballast tube.

Not sure what it can be used in. :O

I think it was used in dual power portable radios.

Thanks everyone for their input and especially to Bob and others who took the time to post design drawings and their advice. I think I will give Bob's diode and thermistor design a try first as I have several of the CL-90s and a pack of 1N5408 diodes. I actually lost sleep last night over my clumsiness in losing the very rare 303 glass ballast in my mini-Hindenburg event. Oh the Humanity! Klutz!

Just bought this 459 replacement on eBay. Looks like this company (JFD) did make a replacement for the 303 at one time. I'll either modify it or canabalize it to make Bob's replacement

Just bought this 459 replacement on eBay. Looks like this company (JFD) did make a replacement for the 303 at one time. I'll either modify it or canabalize it to make Bob's replacement

If it's still good I'd leave it alone and add the CL-90 under chassis.

Just bought this 459 replacement on eBay. Looks like this company (JFD) did make a replacement for the 303 at one time. I'll either modify it or canabalize it to make Bob's replacement

Plug it in try it who knows it may work most of those ballast rust up inside and they are just to old and don’t work.

Plug it in try it who knows it may work most of those ballast rust up inside and they are just to old and don’t work.

Can't hurt right? I've done plenty to F&$# up this TV. What more could I possibly do to hurt it?

Plug it in try it who knows it may work most of those ballast rust up inside and they are just to old and don’t work.

Says it's NOS so who knows. In the original box and packaging.

Says it's NOS so who knows. In the original box and packaging.

Is that the ballast for your set because there are 2 different ones.

It isn't, but should work with a minor modification. The '303 has an extra element, but I'm pretty sure the TS-4H doesn't use it.

He will need to move the ac line from pin 5 to pin 6

It isn't, but should work with a minor modification. The '303 has an extra element, but I'm pretty sure the TS-4H doesn't use it.

He will need to move the ac line from pin 5 to pin 6

That’s what I will do.

I noticed when fooling with series string electrostat TVs that the heater would flash on turn on, glow bright, and then subside.
I thought it was due to them not being controlled warm-up heaters in these jugs, including the Pilot 3KP4.
Do I recall correctly?

I believe that's due to the inrush of current. I've always brought this TV and my Pilot up on a Variac.

Yes, it is due to the inrush of current when the filaments are cold. Using controlled warm up version (typically ending with 'A') does not eliminate the inrush current. It simply means it is well defined. Typically taking around 11 seconds for the filaments to warm up.

The series string doubler electrostat should have had a heater transformer on the jug to extend its service life.
Do any restorers do this for working display sets?

The series string doubler electrostat should have had a heater transformer on the jug to extend its service life.
Do any restorers do this for working display sets?

Some, though there's a better option. TVS (transient voltage suppressor) diodes (8.2V IIRC) in parallel with the heater will clip the peaks off the AC voltage clamping true AC RMS voltage at 6.3V. I'm planning on installing them in all my series sets next time I can place a mouser order.
The person that came up with this has a great scientific thread explaining how they work/how he came up with it over on ARF.

I'm building Bob's design. Waiting for the resistors. I think all I need to do is move the AC line from pin 6 to pin 5. I have 10 of the "Littlefuse" in the appropriate size for this TV. Bob's design incorporates a CL-90. Will that be enough to protect the TV from the surge?

I'm building Bob's design. Waiting for the resistors. I think all I need to do is move the AC line from pin 6 to pin 5. I have 10 of the "Littlefuse" in the appropriate size for this TV. Bob's design incorporates a CL-90. Will that be enough to protect the TV from the surge?

CL-90 yup it will.

I built Bob's design for the replacement ballast but the CL-90 hasn't arrived yet so I bypassed it with a jumper and brought the TV up slowly. I'll solder it in once it comes. The image on the picture of the screen is not what it looks like. The bright area in the picture is spread out in a 3-4 configuration across the entire screen face. There's no video signal through the IF as before but there's audio.

My next question is does the electrostatic tube and focus in any way affect the installing of jacks for composite video? I'm not giving up on solving the IF issue but I'd like to know if that's an option.

The thing that makes adding composite video dangerous is if you forget to plug the TV into a power isolation transformer your signal source device will be destroyed...

I built Bob's design for the replacement ballast but the CL-90 hasn't arrived yet so I bypassed it with a jumper and brought the TV up slowly. I'll solder it in once it comes. The image on the picture of the screen is not what it looks like. The bright area in the picture is spread out in a 3-4 configuration across the entire screen face. There's no video signal through the IF as before but there's audio.

My next question is does the electrostatic tube and focus in any way affect the installing of jacks for composite video? I'm not giving up on solving the IF issue but I'd like to know if that's an option.

Hi,
I follow your poor story since a while.:tears:
Do you have any signal tracer?
They make it easy to find trouble sections in radios.
Try one (see safety instructions when working on life chassis) to check the video amp
and IF-section.
Do you have a clean sound from a "TV station", means a DVD or VCR?

Regards,
TV-collector:stupid:

Looking at things closer, V6 has to be working for there to be sound, as the sound pickup is through C35, but perhaps problems with coils L32/L33 or C72, it should be easy enough to trace with a scope, cause you KNOW, it has to be getting as far as the video amp for sound, just need to see where it may be getting lost from pin 5 to CRT point C.

Back to this PIA TV inspired by Bob and his recent "Green CRT" video. I noticed the Sams and the Motorola service differ as to the direction of the 1N34 diode in the video detector. The service data has my chassis, VT-71H in it and the diode direction is the opposite configuration from how I installed it. I switched it around and it made no difference. I tried a different JP4 CRT to see if maybe there is a cathode issue with what I've been using and the "image", a full screen and bright raster with no video information getting to it, is the same. The sound coming off pin 6 of the video amp 6AU6 is clear and buzz free with plenty of volume. There's a new 0.047 uf cap replacement for the 0.05uf C-72. I've checked the 2 coils between the video signal off the plate and the CRT and their continuity and they are fine. Just for grins, I replaced them one at a time with the same coils off a parts chassis that tested fine with no change. Scope is down right now so I can't check signals but if I have audio getting through the detector, everything before it should be fine as far as the video signal correct? The only thing I have not confirmed are working are the 8 and 15 pf caps in the detector but they're the type that are supposed to never go bad. I am at a complete loss with this missing video signal. It's a real mystery. When I get my new, USB oscilloscope, I'll be able to do more accurate tests but until then, I'm totally stumped.

One bad but real possibility is that given the CRT is cathode fed it's video if a heater cathode short occurs it'll swamp out the video.

One bad but real possibility is that given the CRT is cathode fed it's video if a heater cathode short occurs it'll swamp out the video.

I've swapped out the 7JP4 with another good one I have and the picture is the same.

What about the crt plug bad connection at the cathode wire within the plug itself.

What about the crt plug bad connection at the cathode wire within the plug itself.

I have continuity all the way from the output side of the 0.05uf cap (C72 in the Sams) to the tabs in the CRT socket #2

I also replaced C31, the 0.1uf cap that feeds pin 1 of the video amp with a tested new cap and I re-flowed the solder connections at all points.

Well you could take the schematic and start at the video amp and work back from there with double checking all connections and components I’m sure you will come up with something we all make mistakes I have been in the same situation as you are with this set. It’s time consuming but it will be worth it especially if you have sound all that’s left is the video. Even one leg of a resistor placed in the wrong spot can be a headache it’s happened to me and all of us with these sets.

Well you could take the schematic and start at the video amp and work back from there with double checking all connections and components I’m sure you will come up with something we all make mistakes I have been in the same situation as you are with this set. It’s time consuming but it will be worth it especially if you have sound all that’s left is the video. Even one leg of a resistor placed in the wrong spot can be a headache it’s happened to me and all of us with these sets.

OK but I'm confused. All of the information from the RF/IF comes out of the detector at one point. According to another expert in this thread, if I have sound, I should have video. The signal for both audio and video go into the video amp through pin 1. Video comes out of a grid at pin 5 and audio comes out from a grid on pin 6. Audio information then feeds into the limiter, ratio detector, audio amp etc... Video goes to the CRT cathode through a 0.05uf cap that has been replaced with a new 0.047 uf cap. I've only been looking at the video route after pin 5. Should I still go looking backwards?

OK but I'm confused. All of the information from the RF/IF comes out of the detector at one point. According to another expert in this thread, if I have sound, I should have video. The signal for both audio and video go into the video amp through pin 1. Video comes out of a grid at pin 5 and audio comes out from a grid on pin 6. Audio information then feeds into the limiter, ratio detector, audio amp etc... Video goes to the CRT cathode through a 0.05uf cap that has been replaced with a new 0.047 uf cap. I've only been looking at the video route after pin 5. Should I still go looking backwards?

Well yes it’s said that video rides along audio so you can still go backwards but at this point there could be a problem with the alignment coils and still have sound but no audio. Try different channels 3 or 2 or maybe 6 I had one of these sets that had sound but no video blank screen and it was a think ts 4h with the adjusting coils in front so I concentrated on channel 3 and eventually got video. Remember you probably don’t know the history of the set who know who was in it or what may be bad in the IF section.

OK thanks. Expecting a decent oscilloscope to arrive tomorrow and I also purchased a good 100X probe. I'm tired of trying to make this 45 year old analog Textronix work for me.

Have you gone through the Sams resistance chart for the CRT and 6AU6 video amp?

CRT and Video amp resistances are fine but pins 5 and 6 on the 3rd IF amp should be 1.2K and they are at <300 ohms. Both feed into the detector. The rest of the IF strip is fine. I have a parts chassis. I'm wondering if I should just swap out the detector.

No, if you have sound but absolutely no vide, I seriously doubt it's the detector. A scope should give you the answer in a few minutes. Start at the detector and go through each stage to the CRT. At some point the signal will disappear and that will be the problem point. I suspect either something is open or shorted.

Got it. I received my usb/laptop oscilloscope this evening and I’ll trace it out tomorrow night. Thanks Bob

No, if you have sound but absolutely no vide, I seriously doubt it's the detector. A scope should give you the answer in a few minutes. Start at the detector and go through each stage to the CRT. At some point the signal will disappear and that will be the problem point. I suspect either something is open or shorted.

Morning Bob...do you mean move forward in the circuit between the detector and the CRT or check the entire RF/IF string? Timmy has commented it's possible to have sound but no video due to problems prior to the detector but others have commented if there's sound, your video information is getting lost somewhere between the detector and the CRT cathode. There's not much between the detector and the CRT...a couple of coils and capacitors and all have tested good. I have a resistance on the video amp pin 5 that's spot on by the Sams. I've checked physical wiring continuity from the 0.05uf cap to the halfway plugged in CRT pin 2 and that's all there as is continuity through the 2 small coils after the detector. I've tried a different 7JP4 and have the same raster/no video result. Totally stumped but I will look for the actual signal with a scope next.

Between the detector and the CRT.
Check the signal at the grid of the video amp.
Check the signal at the plate of the video amp.
Check the signal at the cathode of the CRT.

Note that the sound is picked off the screen of the 6AU6 video amp while the video comes off the plate. So I'm thinking it's possible that circuit is screwed up in some way that allows the signal off the screen to be OK, but not from the plate.

Understood. Thank you very much!

Keeping in mind, I just got this thing and my skills with it are very, VERY limited, I took pictures of the waveforms of the signals going into the video amp pin1, and out the video amp pin 5. The scope has an auto trigger and an auto adjustment feature that creates the best display parameters. First in pin 1 input from the detector. The second is pin 5 video output. Am I doing this trace correct so far? I've never looked at a video signal on an oscilloscope before. I'm feeding an RF modulated video into it and I have sound but no image information on the CRT...just a raster.

No. Look at the frequency. It's 60Hz. You're just seeing noise from the AC line.
Amplitude is pretty big too. What do you have the ground of your scope connected to?



Get that frequency dialed in to more like 45kHz or higher so you can see the horizontal sync pulses.

It should look something like this.
https://www.electronixandmore.com/projects/tvtoscope/tvscope14.jpg

Ground is connected to the chassis. I thought I was seeing AC when I saw that. The 60Hz pulse is what is going into the amp pin 1 from the detector.

No, the chassis is not ground - it's floating. Connect your scope to B-. Same place the negative leads of your electrolytics caps are going.

and make sure you have the TV running on an isolation transformer!

I don't have one...just a Variac but I ordered one so I'll keep away until it's safe!

Yikes! Remember B- connects directly to one side of the AC plug. If you connect that to ground on your scope - POW!

Yikes! Remember B- connects directly to one side of the AC plug. If you connect that to ground on your scope - POW!

Scope is OK. I did try it (:screwy::screwy::screwy::screwy:), grounding it to B-, but the scope still works ok on my calibration generator. That's my issue with understanding parts of this hobby and being out to lunch with other things. I'm a science guy...a biology professor and researcher, but there are things about electronics where I have no idea what I'm doing. Feel pretty stupid at times working on these things...but I just learned B- connects directly to one side of the AC line!!!!!

You should also check continuity of the ground lead of your scope probe....The positive path can be OK at the same time the ground is open and the probe will still work on the scopes internal calibrator because they share an internal ground, but connect it to a working TV chassis and you'll get hum and weird behavior from the open ground...Ask me how I know!

I used an external frequency generator atom

Tom. Not atom!!!!

I am atomic! Lol. You can edit your posts if you want to there should be an edit button next to quote if you are reading this via a web browser.

It's encouraging that it was an external generator, but you can still get same false reassurance from an external generator if both the generator and scope have 3 prong power cords...Most test equipment that have 3 prong power tie the signal negative/ground to building ground and test equipment plugged into the same outlet can sometimes use that in lieu of the signal cable ground when it goes open.

I am atomic! Lol. You can edit your posts if you want to there should be an edit button next to quote if you are reading this via a web browser.

It's encouraging that it was an external generator, but you can still get same false reassurance from an external generator if both the generator and scope have 3 prong power cords...Most test equipment that have 3 prong power tie the signal negative/ground to building ground and test equipment plugged into the same outlet can sometimes use that in lieu of the signal cable ground when it goes open.

They are both run off USB cables off non-grounded plug in transformer chargers...thank God

So when are we going to see a nice clear picture on that Motorola.

Just got the isolation transformer yesterday so I’m going to start back up again this weekend!

I give up. It's going back on the shelf again. All thumbs with the oscilloscope. Grounded to B- and the TV plugged into an isolation transformer, I get no signal off pin 5 of the video amp despite getting audio off pin 6. I've tried 4 different tubes, all tested good. I clip on the probe and the auto-read function gives me nothing...no signal. Before anyone wastes their time trying to help me go further with this, I'm going to put it up on the shelf and start working on something else. I wish there were some gurus around Philadelphia who would take it on and get it running for me. Tim and Chuck A. are in Northern NJ but I really don't know of anyone else who would be able to fix this and Chuck keeps his contact information very private as he should. I was so impressed with his take on the business of restoration during the February online meeting. Bob A.'s too! Anyway, thanks to everyone who tried to help this clumsy novice through this. Sorry if I frustrated you.

If you ever get back into working on the set, you always have the option of trying to direct feed video into the grid of the 6AU6, far side of point D on the SAMS, making very sure your video source is protected and isolated, ( TV on isolation transformer, video coupled via capacitor), according to the service manual, signal level out of video detector is 1.8v PtP, standard composite video level should be close enough to this to see SOMETHING W/O any amplification.

If you ever get back into working on the set, you always have the option of trying to direct feed video into the grid of the 6AU6, far side of point D on the SAMS, making very sure your video source is protected and isolated, ( TV on isolation transformer, video coupled via capacitor), according to the service manual, signal level out of video detector is 1.8v PtP, standard composite video level should be close enough to this to see SOMETHING W/O any amplification.

Thank you so much...yes I will try that. At the least, it will give me a reference as to what can be ruled out. Also, it will be so wonderful to see an actual picture on this!!! A few questions...what value capacitor...should the ground for the composite input be to the chassis or B- and, I have the variac set to 117 volts plugged into the isolation transformer so the setup is IT-Variac-Television. Is that OK? I know it makes sense to me but I trip over so much stuff in this hobby.

I give up. It's going back on the shelf again. All thumbs with the oscilloscope. Grounded to B- and the TV plugged into an isolation transformer, I get no signal off pin 5 of the video amp despite getting audio off pin 6. I've tried 4 different tubes, all tested good. I clip on the probe and the auto-read function gives me nothing...no signal. Before anyone wastes their time trying to help me go further with this, I'm going to put it up on the shelf and start working on something else. I wish there were some gurus around Philadelphia who would take it on and get it running for me. Tim and Chuck A. are in Northern NJ but I really don't know of anyone else who would be able to fix this and Chuck keeps his contact information very private as he should. I was so impressed with his take on the business of restoration during the February online meeting. Bob A.'s too! Anyway, thanks to everyone who tried to help this clumsy novice through this. Sorry if I frustrated you.
Hey Chris I’m up here in ferndale ny upstate probably 2-3 hours from philly if you give up take a road trip.

Well since C31 is a .1, most likely a film capacitor of the same size will work for coupling, but the value is not super critical, .1,.01 should not matter TOO much.

What's important is taking the same safety measures that were in place when the oscilloscope was used, MY guess would be to use chassis gnd, but someone who has worked on the set, and knows it a bit more may know more info on how it's to be done.

I have 6 of those Motorola sets and had one that had audio but no video had my share of problems with those sets. I can get a picture on your set I’m sure. A lot easier then a color set lol….

Thanks Timmy. My guess is you have a good 7JP4 to use? Unfortunately, you're 3 hours away by car. PM me and let's see if we can work something out!

Thanks Timmy. My guess is you have a good 7JP4 to use? Unfortunately, you're 3 hours away by car. PM me and let's see if we can work something out!

I have a 3fp7 same base as a test tube and a numbers matching with box 7jp4.

Thank you so much...yes I will try that. At the least, it will give me a reference as to what can be ruled out. Also, it will be so wonderful to see an actual picture on this!!! A few questions...what value capacitor...should the ground for the composite input be to the chassis or B- and, I have the variac set to 117 volts plugged into the isolation transformer so the setup is IT-Variac-Television. Is that OK? I know it makes sense to me but I trip over so much stuff in this hobby.

Ground for the composite source connects directly to B-. Anything 0.01 and up for the connection between the composite signal and tube grid as Yamamaya42 said.

So what I'm thinking is that the 6AU6 plate is being shorted to something and the screen is acting as the plate to get a signal for the audio. What voltage do you have on the plate and screen (pins 5 and 6)? How about the 6.8K, 4.7K resistors and 20uF cap?

Good luck!

Ground for the composite source connects directly to B-. Anything 0.01 and up for the connection between the composite signal and tube grid as Yamamaya42 said.

So what I'm thinking is that the 6AU6 plate is being shorted to something and the screen is acting as the plate to get a signal for the audio. What voltage do you have on the plate and screen (pins 5 and 6)? How about the 6.8K, 4.7K resistors and 20uF cap?

Good luck!

Thanks Bob and I will check those values and post later tonight. Do you want to know voltage on the resistors? They have been replaced already with 5% value resistors. I did that after I started troubleshooting issues from the video amp to the CRT, and the originals were spot on anyway. Timmy has graciously offered to get it going and we've worked out a shipping scenario but I'm willing to give it one more shot before bubble wrap, Styrofoam and a corrugated box!

There are other tests you can do! First, get a .01 to .047 uF film cap (greater than 250 volts) and connect the 6.3 volt filament line to pin 2 of the CRT (point C on Sam's) with it. This should generate a substantial hum bar on the screen.

You could also try connecting the 6.3v through that cap to pin 1 of V6 (video amp) as that should product a really strong hum bar.

There are other tests you can do! First, get a .01 to .047 uF film cap (greater than 250 volts) and connect the 6.3 volt filament line to pin 2 of the CRT (point C on Sam's) with it. This should generate a substantial hum bar on the screen.

You could also try connecting the 6.3v through that cap to pin 1 of V6 (video amp) as that should product a really strong hum bar.

enter confused mode---:scratch2:

The heaters are series wired in this set, so which point in it would be a tie reference to give the 6.3v for a hum bar pattern to show on the screen?

Ground for the composite source connects directly to B-. Anything 0.01 and up for the connection between the composite signal and tube grid as Yamamaya42 said.

So what I'm thinking is that the 6AU6 plate is being shorted to something and the screen is acting as the plate to get a signal for the audio. What voltage do you have on the plate and screen (pins 5 and 6)? How about the 6.8K, 4.7K resistors and 20uF cap?

Good luck!

Jesus...I have -0.5V on the plate and 180V on the screen. 180V through the whole circuit all the way to the 20uf electrolytic. I'm grounded to B-

250V going into the detector and nothing coming out

First IF amp, 6AG5, I have no voltage on pins 1 and 2...around 100V on 5 and 6.

so, now you have a fault to track down! Congratulations! :D

First IF amp, 6AG5, I have no voltage on pins 1 and 2...around 100V on 5 and 6.
this seems normal

Like I keep suggesting - do the resistance checks. Should be around 11.5K between pin 6 of the video amp tube and B++ (pin 4 of the ballast tube).

https://www.earlytelevision.org/pdf/motorola_7vt1_7vt2_7vt5_sams_83-6.pdf

Looking at the schematic, the 20mfd electrolytic that goes to the screen grid on the 6AU6 only has three parts that bring plate voltage to the 6AU6. A 6800 ohm resistor, and two coils. I would bet the 6800 is good as on my set it is a two watt. The small coils could have some corrosion where they connect to the leads. Looks like they are wound on resistors.

Timmy has the VT71 but he has questions as to the chassis designation. It does say TS-4H on the chassis but it's hand written. I've looked at a couple of sites for manufacture date and serial number (including VK), and I think it's a TS-4H but I'm wondering if there are sources in this community who could venture a guess. The chassis was manufactured in June 1948 with a SN#38069. Oh and BTW, I think my work is giving Timmy angina!!!!! Thanks all.

Is there a way to differentiate between the ts 4j 4h 4d they all use the same ballast but there are slight changes between them is there any concrete tell tale that would identify any differences.

Hey Chris I believe I found the voltage and resistance chart

Great Tim!!! Thanks for trying to undo my mess!!!

Serial # 38069 would be TS-4H. The TS-4H does not use the same ballast as the TS-4J late. It uses the older '303 type

Serial # 38069 would be TS-4H. The TS-4H does not use the same ballast as the TS-4J late. It uses the older '303 type

Really wow I have 4h 4j and 4d schematics and from what I see it shows r80 for all 3 look the same. Ok great now we know that this set is infact a 4h thanks bob for that info. The 3 ballasts seem to show the same resistances but I think the ts-18 is different with one less resistor.

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

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

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

https://live.staticflickr.com/65535/51682117896_a45e067c42_z.jpg (https://flic.kr/p/2mJYn5d)Andersen[/url], on Flickr

https://live.staticflickr.com/65535/51687817568_e169d3dee1_c.jpg (https://flic.kr/p/2mKtzoq)

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

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.

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

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.

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.

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.

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.

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.

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.

Trying again

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

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

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!

Did that already never had this problem befor.

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.

This is what I made for the ballast. I didn't mount the CL90 at the top like Bob did but it does match his hand drawn schematic

Well I’ll tell ya that sucker gets really hot

I actually considered installing a small fan on the chassis. Maybe I'll do that anyway.

Tim is having issues with posting so he sent me this...one of the coils in the video circuit. There are 2 in the detector and 2 after the video amp tube so I'm not sure which one this is. I checked continuity on the 2 outside the detector can and they ohmed out good but...that's why I shipped it to him!!!

One of the coils in the detector can! That's where video was getting stopped!

You definitely should not be needing to install a fan. The whole TV only consumes 100 watts. The diode ballast should be less warm than one of the 25L6s in the TV.

In other words, if implemented correctly, using the ballast that Bandersen designed in a healthy Moto VT-71, it should NOT be getting volcano level hot unless there is something really wrong?

Got a whole lot going on with this moto. Going over the vertical because it appears the picture is being torn from the side and it’s very unstable looks like it’s fighting against vertical and horizontal.

Or, perhaps there is a bias / power supply problem, that may or may not be directly related to the ballast, IE, if main power was low or unstable, then vertical and horizontal sweep would be at odds with each other for consumption of what little stable power IS available, just a guess.

The schematic shows it should be 300 volts but there is around 280v seems it’s enough or the vertical depending on the problem I guess it could drag it down alittle bit.

Looking at Bobs schematic for the ballast and pictures of what I built I made a single change. The thermistor was installed between pin 5 (due to the pin switch for this chassis) and the intersection solder point at the top for the resistors. I did this because my chassis had the older version of the ballast installed originally and that made the pin setup different… a switch from pin 6 to pin 5 for one side of the AC line. Maybe I made a mistake somewhere? I don’t remember it getting to the realm of too hot to touch but I’ve made so many errors on this tv it’s hard to imagine what state of mind I was in when I did it!

Looking at Bobs schematic for the ballast and pictures of what I built I made a single change. The thermistor was installed between pin 5 (due to the pin switch for this chassis) and the intersection solder point at the top for the resistors. I did this because my chassis had the older version of the ballast installed originally and that made the pin setup different… a switch from pin 6 to pin 5 for one side of the AC line. Maybe I made a mistake somewhere? I don’t remember it getting to the realm of too hot to touch but I’ve made so many errors on this tv it’s hard to imagine what state of mind I was in when I did it!

Even after about 5-7 minutes checking voltages you cannot touch it it’s hot but I feel the voltages are in the right area. If a mistake was made on the ballast then there should be several discrepancies in the voltages. So if later on I find that there is infact a problem with the ballast I’ll just put one together with resistors.

Looking at Bobs schematic for the ballast and pictures of what I built I made a single change. The thermistor was installed between pin 5 (due to the pin switch for this chassis) and the intersection solder point at the top for the resistors. I did this because my chassis had the older version of the ballast installed originally and that made the pin setup different… a switch from pin 6 to pin 5 for one side of the AC line. Maybe I made a mistake somewhere? I don’t remember it getting to the realm of too hot to touch but I’ve made so many errors on this tv it’s hard to imagine what state of mind I was in when I did it!

That's what I have been trying to get at, from the info that Bob gave, it should NOT be getting that hot, if it is, that is a sign of a problem with the ballast itself or related to it, OR something loading way down to the point that there is dirty power from the voltage doubler.

what ever the problem is, you will have to be VERY meticulous and go over every part from the AC plug onward to find what is wrong.

This ts4h is full of surprises while the schematic shows 2 caps on a given tube pin the chassis actually only has 1 maybe this chassis was a production change because 2 other schematics 4d and 4j show the same as the 4h but this chassis is clearly different and these locations were factory never touched and including some capacitors have a different value.

We’ll…maybe I’m starting to feel not too bad about my failed efforts. Just want to publicly thank Tim for taking this on. He has been so generous with his skills and time. I know I have made numerous mistakes working on this piece but it appears it is a challenge and not the 1-2-3 get it going/works fine project. It’s in great hands and being worked on by someone who can actually check, test and problem solve in response to the expert suggestions given here. My most heartfelt thanks to Tim and everyone interested in this project’s success!

've restored a couple TS-4H and took a bunch of reference photos. Which tube and which pin are you referring to?

've restored a couple TS-4H and took a bunch of reference photos. Which tube and which pin are you referring to?

There’s nothing in particular just some areas are not what the schematic shows compared to an area that was not touched, it’s odd.

In other words…strangeness and oddities but not from what Chris did!!!

In other words…strangeness and oddities but not from what Chris did!!!

Strangeness and oddness = referring to yourself in the third person! :D

Are you using the original Motorola service info? It's very accurate.

Strangeness and oddness = referring to yourself in the third person! :D

Who him? I mean who me? I mean…?????

Using the Motorola schematic and the power supply shows b+ 150v and b++ 300v however all that’s there is 276v and 111v so this low b+ could be the reason why the vertical and horizontal seems to be fighting each other at least that’s what it looks like on the screen. The first and second clipper has 2 pins looks like 2&6 that b+ feeds but it’s to low so hot to find out why and it looks like either something in the ballast or a defective power supply cap that feeds the b+.

In other words…strangeness and oddities but not from what Chris did!!!

Motorola shared engineering between divisions, so the average Moto TV is part car radio (look at the UHF presets on a late 60s-mid 70s color set and a period car radio if you doubt me), part mobile communications reciever, part TV in the design approach...

I’m getting schematic fog if someone has a ts-4h I cannot find r80 E on the ballast pins 6&8 omg lol.

I’m getting schematic fog if someone has a ts-4h I cannot find r80 E on the ballast pins 6&8 omg lol.

junction of V7 & V15 at the bottom of the VERY blurry Moto schematic, has a clear arrow for gnd.

I’m getting schematic fog if someone has a ts-4h I cannot find r80 E on the ballast pins 6&8 omg lol.

It is not present. The TS-4H does not use that section of the ballast.

Seems like something is dragging the supply voltage down. Probably why the ballast is hot.

junction of V7 & V15 at the bottom of the VERY blurry Moto schematic, has a clear arrow for gnd.

I can’t find it anywhere.

It is not present. The TS-4H does not use that section of the ballast.

Seems like something is dragging the supply voltage down. Probably why the ballast is hot.

Why would it be shown on the ballast if it’s not in the circuit? I am putting a ballast together with resistors to rule out any trouble with the one in there now. So only 8-6 is not used?

I can see it on the schematic, but Bob just stated that it's not wired into this version. so if you are looking for it in the set, it's not there! :O

There are many revisions shown in the moto service manual, I'm not sure, but the one for this set may be on page 103, all seem to have the same ballast, but page 103 shows that part NOT being used.

I see what's going on here, it states in the table of contents that this moto service manual only covers up to TS-4D, therefore changes made on TS-4H won't be in there.

You will have to be very careful going forward with this.

It is not present. The TS-4H does not use that section of the ballast.

Seems like something is dragging the supply voltage down. Probably why the ballast is hot.

In the ballast I built pins 6 and 8 are unused. The CL-90 is not on pin 6. I put it on pin 5.

Why would it be shown on the ballast if it’s not in the circuit? I am putting a ballast together with resistors to rule out any trouble with the one in there now. So only 8-6 is not used?

Hi Tim. Take the cage off the ballast I built and check it before you go through the trouble of making a new one. I don’t care if it’s torn up getting to the inside. Do what u need to do!

Well I went over the power supply cap wiring and it looks good it’s correct however the b+ is low 111v and the b++ is also low 276v some of these sets are 150 and 300 others list 150 and 250 this ts-4h lists 150 and 300v so this is why I’m thinking of putting a ballast together.

Well I went over the power supply cap wiring and it looks good it’s correct however the b+ is low 111v and the b++ is also low 276v some of these sets are 150 and 300 others list 150 and 250 this ts-4h lists 150 and 300v so this is why I’m thinking of putting a ballast together.

Whatever you decide to do. It’s up to you!

From what I can see, there is no reason that Bob's design for the ballast should not be working, IF, it was made correctly, and there is no fault elsewhere.

You should take a very close look at it and how it was built.

This is my understanding of how it works.
CL-90 thermistor (120 cold 3 hot) = inrush dampening.
1n5408 x2 = dc for filament strings, lowers voltage & current.
39 ohms 7w & 18 ohms 3w = load balance for the 2 filament strings.
22-33 ohms 5w = shock dampening for voltage doubler capacitors / diodes.
200 ohms 5w = part of voltage divider for lower bias area.

If you go over it very carefully, and find no mistake, like something wired wrong, or damaged diode, or whatever, if it is getting too hot, then what part of it is getting hot?
What ever individual component that seems to be getting much hotter than any others, should be some clue of the problem.

Unfortunately I’m having another brain fart the ballast looking at the bottom of the socket under chassis number 1 starts clockwise and counterclockwise if looking down at the socket on top of chassis would that be correct? I know the key marks 1 and 8.

Unfortunately I’m having another brain fart the ballast looking at the bottom of the socket under chassis number 1 starts clockwise and counterclockwise if looking down at the socket on top of chassis would that be correct? I know the key marks 1 and 8.

That's the way I wired the ballast...with the socket being read like a tube socket, numbers read clockwise from the bottom, counterclockwise from the top

Why would it be shown on the ballast if it’s not in the circuit? I am putting a ballast together with resistors to rule out any trouble with the one in there now. So only 8-6 is not used?

It's shown because they all use the same ballast. They just didn't need that section in the TS-4H

That's the way I wired the ballast...with the socket being read like a tube socket, numbers read clockwise from the bottom, counterclockwise from the top

I just wired one up and it don’t work I used the same resistors that I used in my other sets and they work it’s kind of puzzling

I see what's going on here, it states in the table of contents that this moto service manual only covers up to TS-4D, therefore changes made on TS-4H won't be in there.

You will have to be very careful going forward with this.

Sure, it does. TH-4H through TS-4J late are in a pocket.

https://live.staticflickr.com/65535/52849191730_aa1c343225_z.jpg (https://flic.kr/p/2ow6VsS)

Here's the TS-4H schematic: https://www.earlytelevision.org/images/motorola_vt71_ts4h.jpg

I just wired one up and it don’t work I used the same resistors that I used in my other sets and they work it’s kind of puzzling

Did you wire it up so that the AC is going to pin 5 and not 6?

So I wired clockwise looking at the plug pins 200 ohm 4-3 50 ohm 1-5 150 ohm 6-7 150ohm 6-2

Well there's your problem. That's the wrong ballast for this revision. Switch pins 6 and 5

Also 150 ohms is a bit too much. 120 would be better

This is what I did as per Bob’s instructions. These are his photos. The only change I made was switching the CL-90 lead from pin 6 to pin 5.

Well there's your problem. That's the wrong ballast for this revision. Switch pins 6 and 5

Put 5 in 6 position?

Also 150 ohms is a bit too much. 120 would be better

My other motos use the same ohms and they work perfectly so I’ll see lol

This is what I did as per Bob’s instructions. These are his photos. The only change I made was switching the CL-90 lead from pin 6 to pin 5.

so, power comes in from interlock, to pin 6, to CL-90, resistors (3) and onward? :o
things are a bit confused :p

This is getting really bizarre I switched 5-6 tubes light but the b+ having the meter on + - the voltage starts to go up then drops showing I have the polarity wrong on the meter and no b+ the 2 150 ohm resistors get hot but the others stay cold I had checked the supply caps and they look correct for wiring. This is nuts because I believe this may be the problem with the clipper circuit not enough voltage.

Yeah I’m lost as to where we are with this. I think we need to call in Chicago to straighten us out. The way I understood the thread exchange many pages ago, the TS-4H has a slightly different pin arrangement for the ballast. If u look at the picture I posted of Bobs hand drawn schematic, what I understood at the time was for the H chassis a switch of the CL-90 needed to go to pin 5 and not pin 6 as it was drawn. Given all the recent confusion I think we probably need to get back to basics as to what the ballast should look like.

That is the only change required. Move anything from pin 6 to 5. Done

I don’t want to look at the ballast that you made what I’m trying to do is put it as it was original with resistors in the ballast because maybe I’m missing something in the power supply link I don’t know yet. So now the ballast is right and now no b+ and the Polaris showing it’s wrong if so the diodes won’t work.

So now checking the pins how I wired the ballast with 5-6 switched the other resistors can’t be checked according to the pins because one for each resistor was moved except for the heater resistors that’s good I wired the ballast from the schematic 4 resistors in that order.

That is the only change required. Move anything from pin 6 to 5. Done

Bob…what diodes did you use to replace the selenium rectifiers? I would normally do this with 1N4007 diodes but I vaguely recall a suggestion, not necessarily from you, to use something else. When I spoke to Tim he believed the rectifier diodes I i installed were too big to be 007s.

Ok alarms off the ballast worked but I’m getting the same voltage as with the new ballast so Chris your ballast is ok so now there are only 4 places that take b+ 2 for the clipper 1 for the audio trans and 1 for the limiter so I will be looking at the clipper first because of what the screen is showing maybe the clipper tube is full on drawing down the b+ it’s been as low as 107v but the b++ is still around 280v the sound is good almost to say the audio trans is good. Chris the diodes you have here are good 1kv 3 amp. The horizontal is working but there is very limited vertical because the vertical hold don’t work at all I’ll be checking the pot and there are a few caps in the vertical that could be the cause here as I had to replace them in a few of of my sets. If you look at when the pic rolls slow there is a block separating top from bottom that moves as it rolls but it’s stuck just below the center of the screen won’t move with the pot.

I have a parts chassis. I can send the pot to u

I have a parts chassis. I can send the pot to u

I’m going to check the pot tomorrow it’s a 5 meg I have one here if need be. Just got to get to the bottom of these issues and didn’t know of any of these problems until video was present which helps. Originally when video first came on shortly after I heard a hi voltage arc from where i don’t know but that’s when all the vertical issues started.

Bob…what diodes did you use to replace the selenium rectifiers? I would normally do this with 1N4007 diodes but I vaguely recall a suggestion, not necessarily from you, to use something else. When I spoke to Tim he believed the rectifier diodes I i installed were too big to be 007s.

Due the general knowledge that a selenium rectifier is not as efficient as the replacement silicon diode, where the OEM selenium may drop anywhere between 5 and 20 Volts (or more) when new, and slowly increase as the part ages, a silicon diode has a drop of less than .6 Volts, give or take, resulting in substantially higher bias voltages, which need to be often adjusted for with a dropping resistor.
As for what kind of silicon diode to use, there is a large amount of flexibility as long as PIV & current needs are met, so as Timmy mentioned, the 1000v 3a ones used are pretty much bullet proof in such a set that hardly takes 1 amp.

Well oddly if I turn the fine tune alittle bit the picture straightens out and the vertical hold works so I’m wondering now if the signal is overloading , the pic is not perfectly clear but watchable.

I used 1N5408 1,000 volt, 3 Amp diodes. There's no need to add additional resistance. That's already taken care of inside the ballast by the thermistor and surge suppression resistances. I've found the resulting B++ to be around 230 volts in working sets.

Anyone have the schematic for the ts-4h to confirm c158 it’s very blurry looks like a 680

Anyone have the schematic for the ts-4h to confirm c158 it’s very blurry looks like a 680

equivalent part on the SAMS very clear, 680pf. :D

equivalent part on the SAMS very clear, 680pf. :D

Thanks the schematic is blurry that I have.

hmmm, SAMS has that cap and the 900pf near it listed as "fixed trimmer capacitor" whatever that is..

hmmm, SAMS has that cap and the 900pf near it listed as "fixed trimmer capacitor" whatever that is..

It’s a mica

where you can get an exact replacement for the 680 if needed,
https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CDV30FF681JO3F?qs=m78fPdUw%2FC7qszdopvQ9sA%3D%3D

the same is not for the 900pf

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CDV16FF911JO3F?qs=tNDx7qEChkeOg6KcNnbMvA%3D%3D

best you can get is 910 :/

Anyone have the schematic for the ts-4h to confirm c158 it’s very blurry looks like a 680

I agree...680pF on both sources...Sams and the one from the TS-4H schematic in the service manual

where you can get an exact replacement for the 680 if needed,
https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CDV30FF681JO3F?qs=m78fPdUw%2FC7qszdopvQ9sA%3D%3D

the same is not for the 900pf

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CDV16FF911JO3F?qs=tNDx7qEChkeOg6KcNnbMvA%3D%3D

best you can get is 910 :/

Tim, remember keep track of the time spent on this and the price of the parts. I'll compensate you for everything you have done.

where you can get an exact replacement for the 680 if needed,
https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CDV30FF681JO3F?qs=m78fPdUw%2FC7qszdopvQ9sA%3D%3D

the same is not for the 900pf

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CDV16FF911JO3F?qs=tNDx7qEChkeOg6KcNnbMvA%3D%3D

best you can get is 910 :/
I replaced the 680 900 and 100 with micas in my sets things are much more stable

Does anyone have the other parts of the ts4-h schematic to see exactly what voltage b+ And b++ is supposed to be.

Bob stated that in a working set, B++ be around 230 volts, given the ballast and respective loads are correct.

But the b+ is very low and I disconnected b+ and it still has 111v on the wire and in taking that off the tearing of the picture remains the same so maybe the clipper is not running because of the low voltage to that tube. I don’t know at this point how to get that voltage up it’s 39v short if it’s 150v and my ballast with resistors made no difference at all I checked the cap responsible for the b+ it’s good. So if there’s something dragging the voltage down I would say it may be on the b++ that’s at around 276v if 230v is good then the 40v should go to the low b+. Getting lost a bit.

I'm restoring a TS-4J right now and B+ is only 90 volts but the set works fine.
B+ is derived from 6 tubes acting as a voltage divider.

I'm restoring a TS-4J right now and B+ is only 90 volts but the set works fine.
B+ is derived from 6 tubes acting as a voltage divider.
Well I went over ever tube so whatever the reason is for the picture tearing from side to side maybe the problem this is where it’s starting to stump be from a simple TV set. There is a perfect picture that can be seen between the tearing.

I'm restoring a TS-4J right now and B+ is only 90 volts but the set works fine.
B+ is derived from 6 tubes acting as a voltage divider.

Ahh OK, I see! :D

Every tube that has it's cathode tied to B+ is working in tandem to charge up the bias cap and circuit for the B+ area. Sneaky!


EDIT-
I figured out how they did that trick in my Stromberg Carlson TV, where they sourced the secondary 90v from 2 seprate tubes from a larger voltage.

Yeah, that's some next level engineering.
https://live.staticflickr.com/65535/52851915398_a5a700f517_c.jpg (https://flic.kr/p/2owkT7E)

There are I believe capacitors wired to one side of the heaters in the IF strip they are missing and 240pf micas are in place I have no clue if they are right or not or the value that should be there because the schematic don’t show these caps

I'm restoring a TS-4J right now and B+ is only 90 volts but the set works fine.
B+ is derived from 6 tubes acting as a voltage divider.

Well if yours is good on 90v then 111v should be ok as well.

There are four 250 pF caps on the IF tube heaters. They are shown on the schematic in the filament string section. The values are not critical to the TVs operation. They just filter RF noise off the heater supply.

I'm restoring a TS-4J right now and B+ is only 90 volts but the set works fine.
B+ is derived from 6 tubes acting as a voltage divider.

There are four 250 pF caps on the IF tube heaters. They are shown on the schematic in the filament string section. The values are critical to the TVs operation. They just filter RF noise off the heater supply.

There is 240pf mica caps in place should these be ok?

Yes, sorry I meant NOT critical. Mica is overkill for that matter. Any cheapo ceramic disc cap would be fine.

Unless I’m just nuts but the schematic shows there is v10AB v11AB v18AB but where exactly is the clipper shows v10 but both 18 and 11 is being used for audio and oscillator and afc and osc.

I’m just rambling this simple set suddenly is alittle above simple LMAO.

I’m just rambling this simple set suddenly is alittle above simple LMAO.

No wonder this clumsy novice had no luck with it. Most of the vintage sets I’ve restored needed parts replaced rather than intense analysis. When I did need help I found it here and I was often successful but with this Motorola I obviously was in way over my head!

Yes, V10 sections A & B are the clipper. Not sure where the confusion is? There really shouldn't be any need for intense analysis.

I think I’m getting screwed up here because I have a voltage chart that I don’t think is the right one for this ts-4h does anyone have the correct voltages for v10 clipper. I only have the schematic no tube location and most numbers are blurry and can’t make out what is what.

The voltages shown in the SAMS should be rather close in all versions, not sure why so much focus is being drawn to this clip circuit, it's most likely OK, the circuits tied to it (v11) , transformers ETC, almost look like a horizontal blocking oscillator setup, and if there is raster, it must be running.

OK, so I guess the better name for this “clipper” would be sync separator.
But as seen in Bob's YT videos before, the GIGO principal has major impact here, if the received video is not up to par, too high/low or distorted in some way, the sync sep won't have clean info to pass through to the sweep circuits, thus you get unstable video lock.

Vertical is affected and looks like horizontal lines as well it looks like it’s trying to tear but can see a nice clear picture in between the tearing I thought maybe it was overloading at the video level but not sure as yet I have something else I’m going for.

If the video signal is overloading to much for the sync to work then ok possible but from what I understand the slug on the detector was turned maybe this would cause this not sure.

I'm just going on speculation here, never having worked on a electrostatic type set myself yet, but assuming that bias power and video is clean, winch really can't be done with the naked eye from a troubleshooting standpoint, but if so, you would have to go over every inch of the sync separator circuit (or as it's called, clipper here.) from where it's taken off the video amp circuit to where it's processed, and fed to the horizontal / vertical OSCs, making sure that all in between is correct and in tolerance.

Got a perfect picture now however when it warms up the vertical size collapses and gets jittery and lines across mostly the bottom and some on top. I tried the retrace mod and it gets rid of slot of lines but the size problem is still there.

Don’t know if this will help Tim but there might be an issue with the CRT socket at pin 2. When I was troubleshooting the video loss I noticed the full screen raster I had collapsed when I moved the tube in such a way that the wire going to pin 2 got flexed at an angle approaching 90 degrees to the socket. That’s why there’s heat shrink on it to stiffen it up. I’m just throwing that out there in case there’s some issue with that connection when the CRT gets warm. I can’t remember if the vertical collapsed to a horizontal line or the screen went dark when this happened. In any case, there may, emphasis on may, be an issue with the CRT socket at pin 2 connection.

Don’t know if this will help Tim but there might be an issue with the CRT socket at pin 2. When I was troubleshooting the video loss I noticed the full screen raster I had collapsed when I moved the tube in such a way that the wire going to pin 2 got flexed at an angle approaching 90 degrees to the socket. That’s why there’s heat shrink on it to stiffen it up. I’m just throwing that out there in case there’s some issue with that connection when the CRT gets warm. I can’t remember if the vertical collapsed to a horizontal line or the screen went dark when this happened. In any case, there may, emphasis on may, be an issue with the CRT socket at pin 2 connection.
Yes I noticed that but I managed to pinch the pin tighter and it’s been ok. But according to the schematic there is supposed to be a .1 cap at the 6sl7 .05 to .1 to ground but I’m not finding the .1 so idk if this was a run change for this chassis who knows but I’m going to tack one in and see if the vertical size comes back to life.

No, it's not a run change. That cap needs to be there. I suspect you just found the problem.

No, it's not a run change. That cap needs to be there. I suspect you just found the problem.

Yes I found it but I still looking for the reason why if I use vertical size to widen the screen up and down sometimes it goes and other times it don’t but it’s got vertical lines on the bottom and some on top but very unstable it rolls but it does stop with the hold pot this almost seems to be a bad cap or wrong cap I don’t know. The .004 cap was replaced with a .0047 I wouldn’t have put that in since the .004 is available. Oh and I reversed the 1n34 diode and got a perfect picture except for the lines and instability in vertical. I thought I had a decent picture befor I reversed the diode but now it’s perfect now have to figure what’s going on with vertical.

Yes I found it but I still looking for the reason why if I use vertical size to widen the screen up and down sometimes it goes and other times it don’t but it’s got vertical lines on the bottom and some on top but very unstable it rolls but it does stop with the hold pot this almost seems to be a bad cap or wrong cap I don’t know. The .004 cap was replaced with a .0047 I wouldn’t have put that in since the .004 is available. Oh and I reversed the 1n34 diode and got a perfect picture except for the lines and instability in vertical. I thought I had a decent picture befor I reversed the diode but now it’s perfect now have to figure what’s going on with vertical.

The detector diode is a strange trip. In the TS-4H schematic I have it was installed correctly. I had it in the direction you now have it but reversed it when I saw the schematic. The original 1N34 was installed the way u now have the replacement wired so IDK…these TVs have a lot of variability

The detector diode is a strange trip. In the TS-4H schematic I have it was installed correctly. I had it in the direction you now have it but reversed it when I saw the schematic. The original 1N34 was installed the way u now have the replacement wired so IDK…these TVs have a lot of variability

The original was put in the opposite of the way the schematic shows? That’s how I have it now and the b+ voltages came up good.

Just forget it! I even confused myself, when I read what I wrote!

I just got one of these working last night. Maybe this video will inspire? https://youtu.be/WiFyS_SVpeM

I just got one of these working last night. Maybe this video will inspire? https://youtu.be/WiFyS_SVpeM

Nice video I was hoping you may have had a problem with vertical size lol

I just got one of these working last night. Maybe this video will inspire? https://youtu.be/WiFyS_SVpeM

I wish I had ordered the Adapt-a-caps before I did the electrolytic re-cap on this. They look so clean. I'm using them on the Dumont Doghouse RA-103 and they look great, even mounted under the chassis as the TV has cans in some very hard to get to places for top mounting them.

Funny you mention RA103. You'll like my next video

Funny you mention RA103. You'll like my next video

That’ll be great! I got the replacement relay but someone already did some “bodging” to get around it…but that’s for the other thread.

Certain scenes the picture has lines across the top other scenes it disappears I wonder if it’s the 4 caps in the vertical or maybe a .005 cap.

Hi Tim. The “cherry drops” capacitors in there are pretty cheap, Chinese knockoffs I got in a multi-pack kit off Amazon. I tested them before I soldered them in and they were in spec and not leaky but I’m wondering if changing them out would help. The Wima high voltage caps are the standard replacement caps for that area and should be ok. Then there’s the pesky resonance spring around the HV rectifier Bob messed with a video or two ago. I believe it is in the correct place but I’m suggesting whatever I can to help out!

Hi Tim. The “cherry drops” capacitors in there are pretty cheap, Chinese knockoffs I got in a multi-pack kit off Amazon. I tested them before I soldered them in and they were in spec and not leaky but I’m wondering if changing them out would help. The Wima high voltage caps are the standard replacement caps for that area and should be ok. Then there’s the pesky resonance spring around the HV rectifier Bob messed with a video or two ago. I believe it is in the correct place but I’m suggesting whatever I can to help out!

Hey Chris the hv spring is good because the hv is at 6 kv I also checked the hv caps they look good I’m coming away from thinking they might be a problem. I sent you an email give me a ring when you have time.

The hv I lowered to 5kv max is 6kv and 3kv is recommended so it’s at the happy medium.

Does anyone have an idea if this ts-4h has channel 1 or is it just 3-4

Hey Chris I’m done with this moto I have had it playing for about an hour with no issues and I’m probably going to let it play for another hour. And Chris the nut on top of the hv cage now has a period correct nut, LOL.

Hey Chris I’m done with this moto I have had it playing for about an hour with no issues and I’m probably going to let it play for another hour. And Chris the nut on top of the hv cage now has a period correct nut, LOL.

Thanks so much Tim! I bet you’re done with it! I can post video of it running once I have it back. Check your PayPal for my thanks and gratitude for your lengthy efforts!

Does anyone have an idea if this ts-4h has channel 1 or is it just 3-4

2-3
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So what was the final fix?

2-3
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So what was the final fix?

Oh there was lots to be done lots of soldering bad connections I literally went over everything. The final was the vertical size 2 4.7 meg resistors at 6sl7 were new but the actual solder never made a connection it looked ok but it wasn’t and other numerous resistors. L39 was open that’s why there was no video.

Oh there was lots to be done lots of soldering bad connections I literally went over everything. The final was the vertical size 2 4.7 meg resistors at 6sl7 were new but the actual solder never made a connection it looked ok but it wasn’t and other numerous resistors.

I’m so ashamed😩😩😩😩😩

I’m so ashamed😩😩😩😩😩

Lol stop no shame here what’s the big deal after all you said someone else was in there no big deal we all run into odd stuff 😂 Chris I sent you an email.