Wait a minute. Did you say a thermister was bad ?
Did you change it ?
If you did it could be the wrong type. Some go up in ohms when
hot & some go down.
Also does this use a relay for DGS ? Moto was one that did
but I dont remember how they worked. That was the early 70's
that I last changed one !

Zeno:smoke:

Changed the thermistor already exact one for the set moto number and no relay

Would it be a bad idea to jump the thermistor to at least see what the voltages show.the strange thing is first turn it on b+ will show 390v but steady it drops and lands at just making it to 360v.

You are most likely chasing a phantom here.

Remember that no 2 sets are exactly alike, and tubes are VERY forgiving about their bias sources.

If it says "385v" on a SAMS, this does not mean that the MUST BE that voltage there ABSOLUTE, there will always be variance, sometimes +/- 10% and this does not necessarily mean there is a problem, this is in fact normal.

but by all means, check the PWS area, but you will most likely find, there is nothing to worry about there.

:D

If you first get 385V and it drops as the set comes on, then it's possible a tube is
conducting too much current, and dragging down your 385V Source. It can be
ANY Load connected to Any Spurce point, But start with 385V.
As for the starting voltage, The formula for figuring Voltage from a doubler is
approx 2X(V-Peak) - .7V(Diode Forward Conducting Voltage.) From the
Transformer ( 143V X2 ) -.7 = 185.3V

If it's drawing more than 380ma. it is reasonable to believe a circuit may be drawing
more current than it should.

If your transformer secondary is less than 143VAC I would first go forward
and look on the primary side. The 143 V is with the tv on and all stuff
hooked up as in the schematic.

Not a Phantom, He has several PS voltages too low, and one too High.

You better double-Check that Thermister too.....

.

You may cause excessive current to flow. You can check the AC voltage drop
across it.

It might be a good idea to check line voltage, & Compare it to the primary
of the power transformer. I think it should be a small difference maybe
10VAC no more......??

113V at cheater cord, Maybe 108VAC at primary???? I don't know what to
say about that, I have no idea what THAT Thermister's specs are???

The Thermister at 25 Ohms cold, My Guess is it would go close to
Zero when it warms up, So Very little voltage drop across it.
when it's hot....

L46, & L47 appear to be line filters, There appears to be no Degaussing
circuit on the schematic. The Thermister must be to prevent a surge.


.

As for the thermistor I got the same results from the new thermistor as the old one. None of this make any sense to me tracing the 145v to specific tubes and trace back to the power supply and there’s 175v. It still seems to me that something is crossed within the power supply cap network so I’m going to go back to this area and look again because it make no logical sense to have 175v at a 145v spot this voltage is coming from somewhere. Bottom line is I believe something is back feeding another circuit and I need to find it. I would think if something is pulling it down then all the voltages should be bottoming out but there not the circuit has no real amperage to keep voltage up during a short of some kind.

You are jumping too far ahead of yourself, don't focus on the 145v issue yet, for that is load dependent, IE if the 2 loads on it are insufficient, it will drift up, no matter what you do.

Go through the steps that Squirrel boy described, especially the current check at L54 (380ma ).

go through the checks he gave.
AC V@ plug before L46/L47 and after.
AC V@ primary of power xformer (blk-red/black)
AC V@ secondary of power xformer (red/red-green) before & after M7, 143ac
DC V& Ma@ L54 395V 580ma.

145v is sourced via 5.6k resistor (r216) from the 275v rail, and goes to L25 & v9, as mentioned, if things are not right in other parts on the set, the load on the 2 won't be normal, and it will drift up.

The 145v seems to be primarily used for Audio, pin 8 of the audio output, and power to the Audio det/limiter, but it also goes to pin 5 of the tuner power connector to provide 130v B+#2. If the tuner is not connected/ inactive, the load on the branch for 145v won't be enough, and thus read high.

On the choke red wire measures .29 amp yellow wire nothing. Not sure what that comes out to in ma.and the thermistor in place warmed up the ac lost 2 volts ended up at 113 vac so not bad I have an ac running here on the same line so it will be alittle low. I think I’ll run 3 wires out for the 3 voltages 145 190 275 to check with the chassis in all hooked up and take it from there but I do know the b+ was always low hooked up or out on the bench.

.29a = 290mA

very odd, could the DVM have been set for AC amps rather than DC?

My dvm has both ac dc but it showed up on the ac scale not the dc. Is 290 ma not so good thing here.

it needs to be on the DC scale in order to take the correct measurement shown on the SAMS, if set to AC, it can be triggered by the AC ripple and give an inaccurate reading, thus you got .29a on one side of the coil and nothing on the other when set to ac.

My dvm does it digitally no way to set it to dc. Maybe the diodes are leaky at this point I don’t know.I checked my dvm I can switch it , it’s got ac on top dc on bottom micro amps if I switch it it goes to ac micro amps so I had it set right.

Time for a cheap DVM that will.

I have one of these as one of my 3 " throw away" DVMs

https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

If i fry it, no big loss, and I CAN set it to DC amps.

Maybe there’s to much ac here idk. Diodes come to mind.

SI diodes don't normally wear out, this does not mean they can't be damaged or stressed, but if used within specs, they tend to last forever, unlike selenium.

I just find VERY unusual that you can't set your DVM from AC/DC amp measurement modes, if this indeed true, it casts doubt on everything it's telling you, and I do wonder what the heck type that is, cause in all my many years of tech repair, I have never seen that before.
And, it's highly recommended that you get another DVM, like the one I suggested, or any other low to mid range one, and use it as a 2nd opinion.
Don't rely on just the one, especially if it WON'T let you put it into DC amp mode.

Well this dvm never failed me it’s a g2 phoenix it just didn’t pick up dc I don’t know why. it has 2 scales top and bottom ac top dc bottom and when I powered up with the clamp on it initially gave me a quick number on the dc scale but went right to ac. I’m going to put the chassis back in and check the 3 voltages. I have 3 wires coming out to check these voltages.

That explains it...
The inductive clamp sensor can only mesure AC current.
To test DC, you must put the meter in series with the filter.
http://www.instrumart.com/assets/uei...nix-manual.pdf

WARNING

your DVM can only take 2a max.

https://www.youtube.com/watch?v=x2NLYydxbo4

You must put the DVM in line between the output of the diodes and the filter.
The clamp on thing won't work.

Oh ok so much for that lol.

Ok chassis back in hooked up b+ 350 v the 145 v is now 133 v the 190 v 165 v the 275 v is 244v these voltages are more in line now but drastically low and this was at 114 vac. I guess I’m going to pull tubes one by one maybe there’s one that was manufactured wrong even though the heater works all tubes do light up heaters are good. Well I hope it do come to a shorted ceramic disc finding that can be challenging unless a short goes away when a tube in that area is pulled.

Keep in mind, the SAMS had the voltages taken with an input of 117, if you ar running at 114, you will of course see lower voltages, HOW MUCH lower, who knows.

to be 100% sure, you should be on a variac and at 117v AC input at least input, just like the SAMS says.

this 3v may seem like not very much, but once it gets through the doubler + the RMS of everything, who knows.

Maybe so but I still at one point I had 120 v and still had the low voltage.

You still have yet to determine what the Ma load is at the point between the connection of x2/c1 – L54, as mentioned, you will have to put your amp meter in series to see if you have excessive load , more than 580 ma,
and as been mentioned by others, check for voltage drop across circuit breaker M7.
Check for 147vAC on the secondary.
Check for voltage drop across plug & Socket 2 ( 9 – 8 )

And if you STILL find nothing, & current is within normal, your voltage doubler could simply be under preforming with your chosen new caps.
I would still recommend larger ones 180uf @200 647-UCY2D181MHD3 and these diodes 78-SF4007
I have used this combo many times w/o any problems.

I already changed the doubler caps to 250 v 180 uf both the same. I checked ac line in at the thermistor with a loss of only 2 volts. I was thinking of replacing the diodes with 1n4007 if I have to. I also had checked for any resistance with the breaker and I also disconnected the diodes and the secondary has 143 vac just what the sams shows. And I don’t want to burn my dvm but I remember I have a ma meter I used to used for cathode current on the rca clones.

One thing bothers me. Go back to @1975 with this set. It comes in
no snd / no raster. Something finally killed it No mater how many
other problems it has, probably many, one thing should bring it back
to just running.
After a quick check to see if the PS is up & running go to the H sweep, maybe
the H out tube is dead. We did not pull a Sams to be sure the voltages were
within 3%. At that point the jug was evaluated ( by eye) & it went from
there. SO IMHO only get the raster back & not worry so much about the
crazy PS voltages. You only need a few voltages to make the H osc & H out run even with lowish B+. You may have bad width but it will give you a raster.

BTW Never blindly trust Sams or the OEM manual !
BTW #2 A good meter is a lifetime investment. Since the 70's I have
had a Hickock ( bench meter) a Beckman & a few flukes. They all still run
& are very hard to accadently get fried. I also got both my sons Flukes
for xmas.
BTW#3 Never blindly trust a tube or CRT checker we NEVER used a tube
checker but had a TOTL B&K for customers & it was a big profit center !

enuf fer now
Zeno:smoke:
LFOD !

Yes I Agree with Zeno, you need to invest in a good meter. I got me a brand spankin
new Beckman 330 back in the day, Love it, works like a charm. Loved it so much
I got a second a few years ago off ebay for $30. It had calibration stickers on it
from a lab of some kind. Checked it on all scales against my original, & it's Spot On!

The 2V drop across the Thermister is great! At this point you need to partly suspect
your meter on some readings. Also be aware some cheaper meters are not so immune
to AC noise on your DC readings. And DC Amps you have to use probes in series
with what your testing. Clamp is only for AC.

Also be aware that the Horiz Output tubes get a feed from your 385V source, and as
stated above, this could be dragging down your power supply voltages. There are
both Voltage & Current numbers printed on the schematic that can be helpful
in the H Output circuit.

If you have all the stuff in the PS working and have low voltages then you need to look
at excessive current draw somewhere in the set, and that can be dragging down your
voltages.....

This schematic is very smart, Most power supplies will produce it's designed voltage
At some rated Current. Once that current is exceeded the voltage begins to drop.
This is one possibility, and it's for you to find.... That's why there are current readings
at key points on the schematic for this tv......




.

I know there are key points to test but none are listed specifically for ma or amp or what the parameters should be.

I am also in agreement with what the others are saying, better test equipment is needed.
Especially as many have stated, an oscilloscope, or else you are in risk of just going in circles.

For example, my list of stuff includes.
Fluke 77 Series II Multimeter
Fluke 117 multimeter
Tektronix 7934 oscilloscope
The above is the authority and bedrock of most all my testing.
Extra stuff is.
LCD 1999 3 1/2 BM4070 LCR Meter
LCR-T4 Mega328 Digital Multi Tester
Etekcity Digital Multimeter MSR-A600
Proster Digital Multimeter Mini Multi Tester
Crenova MS8233D Auto-Ranging Digital Multimeter.

This stuff is rather cheap and therefore I'm not afraid to damage it in any kind of risky tests, and they have held up well so far, and even though they are what I deem cheap throw away equipment, they still tend to agree with the calibrated Fluke meters over 97% of the time.

What would cause resistance in the circuit breaker it’s just an on off switch , arcing ?

The circuit breaker is a common failure point, it's not just an on off switch, it has a thermal element that reacts to current, and causes the breaker to trip when it goes over set point.

carbon on the contacts is the reason for most fails.
If you are seeing large voltage drop across it, then it's clearly bad, you can temp jumper it to see if the voltage problem goes away.

Ok placed the ma meter plugged in started low around 80 ma but as the tubes heated the needle went up steady and quickly and it pinned my meter at 500ma the meter only goes to 500ma so I have a massive load pulling it down.

SAMS says "580ma" at L54,

So it stands to reason, that once the HV kicks on and the sweeps start up, it will jump over the range of your meter of 500ma, if that's its limit.

My schematic the ma is kind of messed up can’t make out why it says ok so it says 580ma I thought it should be around 380ma. I would think 580 is absolute max

not exactly, it will be different from set to set, tube to tube, don't be surprised by a difference of 10-15%

Well this ma went up very fast and I would have thought as it approached the 500ma it would have slowed down but it didn’t it was fast. My dvm only goes to 400ua so this meter can’t use

Avalanche event, horizontal oscillation starts, HV comes up and so does horizontal sweep, there is now boost for the vertical to start, voltage is now optimal at CRT for raster.
All these events in succession cause a rapid uptake in current, this is normal.

Ok makes sense but now it’s anyones guess what’s going on here. I already put in 2 sets of b+ caps the doubler caps.

Well I pulled one tube at a time voltage went up very little or went down alittle at this point this could be either not enough ac for some reason or a cap ceramic or one of the red caps but as of now at least 70% of the red caps are changed already and every one I took out checked perfect unless there’s one I didn’t change may be the bad one.