Already swapped tubes no difference at all and every component within the horizontal oscillator circuit was either changed or checked but ceramic disc caps certain ones I cannot check. Discs are reliable but do go bad.

How much hv should be present at the anode without crt and yoke in circuit.

No telling what the answer is without the yoke in circuit. It is a vital part of generating the high voltage.

So if I plug in the yoke for hv testing but not the crt it should generate the proper hv long as all is good I know the crt acts like a capacitor but will it generate full hv without the capacitance of the crt. Chassis on the bench and these motorolas are different and I don’t have the pin out for testing on top of chassis at lots of test points.

Exactly!

It's all part of the tuned circuit mentioned before, a big feedback loop, I kinda think they made it that way to protect the CRT if something were to fail, if the horz sweep was not right, the HV would shut down and protect the face of the tube from burn.

Does set still have 2 hoz out tubes ?
It would be interesting to see if they are drawing the same cathode current.
OK on discs. Almost all I changed were burning or cracking open or dead
shorted. BUT ?? If you try them I would nip one end then hang in.
Maybe someone still sells an assortment, I would go with 1KV ones.
BTW its getting long so what is the voltage on the G-1's of the
hoz outs ?

Zeno

Ok here’s the kicker the voltages we’re pretty close after checking yet more resistors still finding not a thing wrong switching tubes checking hv pot 6bk4 cap off still lousy hv until I have a light above the chassis I turned off to make sure the heaters were all lit and what do I find but one of the HO tubes top glowing blue lucky I had a good used one put it in reg tube cap off and a massive hiss and lots of corona and I did plug in the yoke on the bench. These 2 tubes were brand new but yet one was bad so I’m sure it’s going to be ok now I’ll find out Monday when I get 2 6eh7 tubes for the IF again new but we’re bad.

When you get NOS tubes beware that many came off a shops shelf
& may be damaged ESPECIALLY hoz outs & big audio outs.
Best to stick with RCA, GE, & Sylvania. Tubes from set mfrs like
Zenith Moto, Maggy etc are a safe bet, most are made by the big 3.
Lots to NOT by, Lyndal & IEC are two junker tube lines.
Well done, progress made !

Zeno:smoke:

One thing to check for is that your CRT G2/screens aren't set too high...I have an industrial Setchell Carlson monitor that for more than a year I couldn't figure out why focus was terrible and HV was very low, but it was fairly bright....The CRT was good and strong and someone had one of the G2s set near max and it was literally making the gun conduct so HEAVILY that the CRT was literally overloading and lugging down the HV. I turned down the G2 and suddenly it was working really good and HV and focus were where they should be...It's not a common issue but it's something to be aware of.

Yes Tom early on I lowered the drives and the g2 pots.

Well at it again got perfect hv now but now I have good sound but no picture no video just a blank screen little fuzz checked tubes again even the tuner tubes. There is the 1n60 diode I don’t know if that affects video and sound or just video other then that any ideas from here maybe something obvious that again I’m missing.

Again, this is a situation where having an oscilloscope would be extremely helpful.
If sound is good, then tuner & IF up to #3 are most likely OK, as the sound is taken off the 3rd video IF V3. So the problem should be after that in L6 and after, the video detector may be faulty, or any one of those peaking coils between L6 & V4 P7.
If you did have a oscilloscope, the method would be to check for the 5v PTP video, starting from the anode of x6, and trace it down to V4 P7 to check it has a clear path.

But w/o one, it's much harder, check everything starting with x6 → V4 P7.

Can a 1n34 be used in place of the 1n60. P7 ?

As far as I can tell, the 1n34 is also a Germanium that's often used for TV video detectors, and as far as I know, they really are not that picky as long as you stick with the general type of diode.

Thanks but what’s the p7 you refer to

I'm looking at the SAMS for the set, P7 = pin7 of V4 video amp 6AW8A, should have a 5v PtP video there.

The voltages are somewhat low because the chassis is out and no tuner plugged in. I had picked up lindal tubes and they say they are no good so I have 2 more coming so maybe these tubes are no good since I had 2 others that didn’t move the needle on the tester and yet I had sound. X6 is almost impossible to reach but I did a test these Germanium diodes are so sensitive that testing each end causes the numbers on the meter to jump back and forth and that’s what the diode in the set did exactly with the diode I have in hand did the same so I’m assuming it’s good and from one end of the diode to pin 7 has continuity. Voltages on 6w8a are there but 7 I think was not 5 volts more like 12 volts but no tuner plugged in.the other part to this is channel 3 may be way off as far as tuned don’t know the history so took out the tuner and the slug for channel 3 was all the way in I don’t know if it’s usually in or out more then in so I ran it out and sprayed the gears the grease gummed up wasn’t really working now it is so I’ll find out tomorrow what happens.

One thing you can do as a diagnostic is to inject composite video at the output of the video detector if you get video on screen then the problem is between the tuner and detector, if not then the problem is in the video amp...This is a good way of eliminating half the video path from suspicion.

If you have tuner/IF issues and you another set with a modern 44MHz IF or a Blonder Tongue AM series agile modulator with an IF out port you could connect either of those in place of the sets original tuner and check if you get picture...If you do then troubleshoot the tuner in the set, if you don't troubleshoot the IF and AGC systems.

Well I’m putting my hopes on the tuner channel 3 is way out of where it should be to get a picture I do have sound but it was fading in and out.

if you are getting sound trough, you should be seeing SOMETHING on the screen, some kind of noise pattern, herringbone pattern, something getting through, as mentioned, the signal is getting as far as 3rd IF, even if it's distorted, you should se something on the screen.

and Electronic M has a valid idea, but be sure to put it through a isolation cap, like a .01 or something like that, so you don't fry your video source.

it needs 5v PtP, but you should see a faint image with standard composite 1v

You have 2 places to try to inject video as EM suggested, it may help you a lot to try it.
http://suzaku.live-evil.org/injection-points.jpg

But as shown on the SAMS, it expects 5v pk-pk at that amp, and composite is only just about 1v, but you should see something.

There is also that 13v potential to deal with, so be sure to feed through an appropriate film cap .01 (guess).

I have done this myself many times with good results.

I do get alittle snow and some lines on top of the screen but to inject a signal would be kind of Impossible hectic access these Motorolas have test points on top of the chassis but the sams don’t show what they are for testing what.

I literally soldered on a lead of a cap to pin 7 of the first video amp on my RCA CTC-16XL when I was working on it to feed in video.

When a point is hard to reach with the chassis installed I pull the chassis enough to reach it, hook an alligator clip lead up to it to bring it out to an easy to reach point and use that.

If you happen to have a working TV test pattern generator with variable output most of those were designed to give 5V or more output to give a nice contrasty output.

Test point B is quite easy to reach from the top of the chassis, and clearly pointed out in the SAMS, you can clip there for video input.

Where on the schematic is test point B on top of chassis would that be to pin 7 of 6aw8

pint b is here

http://suzaku.live-evil.org/poin-b.jpg

its between l10 and l11

http://suzaku.live-evil.org/injection-points.jpg

i have be using this, which i assume is correct?

https://www.earlytelevision.org/pdf/...sams_739-3.pdf

Oh obviously I’m missing that page that shows point B. Yes you have the correct schematic.

Ok so on channel 4 I can almost tune in a picture but can’t make anything out of it and it looks like the horizontal hold needs to be adjusted i tried but won’t clear up so I don’t know if the sync section can keep a picture from displaying along with the h hold not being able to adjust out. I ran the slug all the way in to all the way out.it’s clearly trying to tune in since I got the tuner working properly but just won’t tune in and sometimes on 3 the sound fades like it’s out of tune so the video is getting to where it should. Just when I think the pic is going tune in it don’t it’s that close.

This of course points right back to the low HV area problem.
For some reason, the circuit is not able to synchronize to the incoming video input, this could be for many reasons.

SYNC SEP, SYNC AMP, HORZ AFC, HORZ OSC , & all associated circuits are suspect.


I hate to keep repeating it, but it's the way it is, w/o an oscilloscope to check that you are getting the right signals at the right points in the circuits, you are making this exponentially harder for yourself than it needs to be.

Well yes I know a scope would be a big help and yes it’s frustrating seeking problems without it but as for the hv as I mentioned in an earlier post the problem was a bad ho tube and I even checked ohms on the horizontal hold coil which checked out perfect. And those circuits you mention all new caps and endless resistors checked perfect. This set is beginning to give me a headache lol. Even tubes keep checking them. Those metal shield’s in the IF section is it important to replace 3 solder connections to ground even though there are screw’s holding the shield in place to ground.

So is it safe to say that if you have sound then the video is there as well. I know audio goes one way and video goes in another direction I’m trying to rule out the tuner the slugs do move, I since got those gears to move freely.

Video and sound typically stay combined until the output of the video detector. If you have sound the tuner and IF are not dead...God only knows if fine tuning, IF and audio alignment are correct, or if your video amplifier works at all.

Without a scope or a means of/will to do signal injection such as the procedure I discussed earlier you're basically flying blind without instruments.

There comes a time where the value of the time you waste trying to make do with insufficient test gear is worth so many times the cost of a working used $50 1970s or newer scope, B&K analyst, etc that NOT buying one is costing you much more than buying one.

Watch “that auction site”. You can find even a recent Tektronix for cheap, and that’s all the scope you need to get up and running in scope land. When you see what a scope can do for you, you wonder why you didn’t get one sooner….

Well I have been in the video amp but I didn’t check the video output maybe something there would cause this video issue. How about the blanking circuit ?

Ok well low voltages can give all kinds of problems things won’t work so at 113 volts ac b+ is 360v and the source voltages are 275 is 251 v 190 is 131 v 145 is 175 v and if the 2 voltages were swapped they would be functional and my problems would probably be solved and yet I went over my work with the power supply caps and appears right so this does look like I have 2 power supply caps reversed. I did this with chassis out horizontal tube caps off no hv but these source voltages I would think should be up to par without hv because it’s a source voltage.

Hi Timmy, I believe you have a Power Supply Problem.
You may even have multiple problems, but you need to
focus on the power supply if the below voltages are
actually what you are reading. Check this stuff
in this order.

385V Source - Your reading 360V - too low.
275V Source - Your reading 251V - Too Low.
190V Source - Your reading 131V - Too Low.
145V Source - Your reading 175V - Too High.

So lets figure out what's going on with the 385V. source. First off I assume you
already changed all the power supply caps, So be sure they are the correct values,
and correct voltage ratings, and in the correct spots.

If you do not have 395V at Doide X2 you should then check for 143V AC at the output
of the power transformer that feeds the Voltage Doubler circuit. If it's LOW
than you need to check the Thermister R211 to be sure it's ok.
You can check the other do-dads on that side too, be sure nothing
has an excessive voltage drop across it, Switch too.
Be sure the circuit breaker does not have high resistance across it.
L54 should be around 12 ohms. Be sure to check that W, Z Stuff at the
lower winding on the power thansformer. That 275V source goes through
a few caps & goes to those HV Reg Filiments. You remember having
a Short in that circuit on another tv you worked on with Low HV.

If Ok;

At L4 the choke in the power supply, there is a current reading there of 380ma.
You should use your current meter to be sure this is at 380, if high there is a
excessive current draw. If low you have something open possibly.
Be sure to cut, or remove the input line to the choke, put your current meter
in series with the choke & Diode, use a high current scale, Like 10A, because
the resistance of the current meter will be very low, like 1/10 Ohm, and will
not cause a voltage drop across it.

The 385V source flows through a 550 Ohm resistor R214 and becomes the 275V
Source, you should check this resistor.

Also check R 215.

Finally, Your 145V source is too high...... Please check R 216. And be sure to check all
your wiring in this step.

For your 145V Source to be too high, there is either a wiring mistake, or a possible
shorted capacitor between two voltage sources that can possibly be bringing some
higher voltage to the 145V source. This can be anywhere in the tv.

Next step is - you can see below the power supply is a small box that tells you
exactly how many connection points each source goes to, You will need to start
checking these.

The box is called B+ Distribution

If you read more that 380ma. then you need to disconnect each of the 9 - 385V
sources and try and see if one has a high current draw. Disconnect one, turn the set
on and check 385V source. If it goes up, that point can have a problem.

You need to do this stuff with everything hooked up & ready to work as usual.
You can't do Power supply stuff with parts of the tv turned off, or disconnected.

Good Luck I Won't be around much this week......

..

.

Yes most of what you mention I already checked the choke 11 ohms a new thermistor all the power supply caps even checked them parallel them I even checked the sams for where the 275 190 and 145 voltages go and traced them back to what I did in the power supply, checks fine. At the diodes it’s the same 360v the doubler caps have 180v on each cap diodes clipped there is 143v ac present thermistor is new the 550ohm resistor checks perfect all the ps caps are exact or higher in capacitance. I’m going to check line voltage going to the primary of the power transformer tomorrow and hopefully rule out a thermistor problem or transformer primary problem. And also the 15k and 5.6k both are perfect. All this is with 114v or so line voltage.

Be sure also to double check the polarity of C1 & C2, See how they are hooked
up in the circuit. The 2 160Mfg Caps in the Doubler Circuit.
And check the 380ma current.


.

Polarity is good I went over that several times along with everything else double checking. My digital meter can check amps not sure of ma or if I can get it on the wire. C1 don’t go to ground iirc. Well maybe I’ll pull tubes one by one maybe one is defective in such a way that it would cause a drop in voltage.