hi all, i am certainly not looking to run up another thread like the last one, but this 65 maggie roundie had a new crt in it but i since traded with another set but the problem i have is the screen is very dark with the new crt and the one i put in. the bias is a switch and if in the min position no screen at all if in the middle i can start to see the screen bearly but with the switch up i have a screen but its very dark. the thing here is the crt thats in it now seems to have a problem with the green gun heater not heating up sometimes and if i tap the neck the blue sparks happen and then its good but i would like to maybe correct whats happening with the lack of brightness and can only get just that with the bias maxed out. i changed the boost diode that was bad, and checked all the high wattage resistors. the voltage at the hot is around 172 volts i dont think it should be that high but then again i dont have a schematic that gives voltages. i was told the chassis was a 16 clone by moyers as i had bought a new fly for a spare and it is correct for the chassis but the rca schematic dont show voltages. maybe this is a simple fix, dont know but at least the chassis will be ok if the crt takes a final dump and if i come across another crt then ill be all set to go. the crt now does work but how long the heater will last i dont know. i feel bad asking for any help since the last thread, lol,lol im sure everyone wants me to fade away, lol...; :smoke:

check HV should be 23-25kv, check focus voltage should be 4-5kv
check crt voltages should be about 280v on the cathodes, 180v on the G1 and 700v on the G2. From there you know where to look.

hv is up where it should be so ill check those crt voltages. "from there i know where to look" lol,lol ok ill see what i can confuse myself with,lol lol... thanks dave.

Timmy, PM me with you email and Ill scan a schematic for you. Does the mag chassis sticker say its a U43 or U45?
I have the Tab Magnavox Color TV service manual by Stan Prentiss, and it helped alot on the 64-70 Mags I ve seen over the years.
I recall having issues in the Video amp stage.

Timmy, PM me with you email and Ill scan a schematic for you. Does the mag chassis sticker say its a U43 or U45?
I have the Tab Magnavox Color TV service manual by Stan Prentiss, and it helped alot on the 64-70 Mags I ve seen over the years.
I recall having issues in the Video amp stage. ok ill get the back off and see what it says, this is a combo so ill have like 25 screws,lol. :yes:

ok all there is on the chassis is 10- 65 g date, and stamped in black ink is , 5 45 5 thats it unless there was more to the tag but its gone. and the model says on the cabinet 20t567k

If it has automatic degausing it will be a 45 series chassis. Thats whats in my 65 combo.

yes it has auto degausing and instant on but i dont use that.

well im not sure if the problem here is in the blanker circuit but the g1 is 159v bright up and bias ccw. otherwise the voltages are close depending where the rgb drives are. but i cant set it up unless the bias is maxed, thats not right, so im looking...

thats a bit on the low side, but you need to find out what the cathodes are, those are directly coupled to the video out tube. You want approx 100v difference in the cathodes to G1 voltage (cathode should be higher).
the greater the difference the more cut off the tube will be (darker). It does not take a lot of change to go from dark to bright.

well it turns out that the g1 159 v is the red the others are 165v the g2 900-1000v and the cathodes 305-318v

well it turns out that the g1 159v the cathodes 305-318v

well there is the problem cut off due to bias of CRT well over 100v

i tested these with the crt cap off because its difficult to test with it on , hope it dont matter. and this was again bright up bias ccw.

I would start by trying a new video out to see if you can drop the cathodes down. if a known good tube does not help then you are back to checking voltages.

The g1 seem a little low as well. so checking the difference amps voltages would be in order, does the CRT bias have any effect?

the crt bias does raise the voltages on the g1.

is this a U45 or an RCA clone?

U45 crt bias pot adjusts the G1 where the RCA adjust the cathodes.

the only way to get a picture or anything on the screen is with the bias maxed and still dark. bias ccw nothing on screen..

in that case I would try a new video out tube for starters.

i dont know if its the 45, 5 -45 -5 is stamped on the chassis its a gold color chassis if thats any give away.

it may be a clone because the rca 16 and 16x chassis uses a 12by7 but this one uses 12gn7

if that does not help trace from the bias pot to a 220 resistor and a .22 cap. the resistor should be isolated so you should be able to check in circuit. You will need to lift a leg of the cap and test with an old school cap tester for leakage.

Its not a clone if the bias pot wiring is as described (bias adj the cathodes of the diff amps, thereby the G1's) close but not a clone

oh and check the 27k power resistors in the plate circuit of the diff amps, should have 410v on one side.

g1 , solid colors the bias adjusts the voltage. and the bias pot is mounted on a board and there are resistors on that board and i checked all of them so it may be under the chassis, wish i had a schematic...

just look for a 220 resistor off the bias pot.

look for a 3.3 meg resistor that goes to one side of the user brightness control

there is one 27k high watt resistor 405 one one side and 244 on the other, and tests perfect. that 220, ohm or k.

the 220 ohm resistor on one end of the bias pot is fine. the .22 cap near the diff amps checks lower in capacitance then another good one i have but its good. it will be very difficlut to reach the bright pot to see if it has a resistor on it. well there is no resistor on the bright pot and without a schematic it will take for ever to find because this thing is a combo and all controls are on one side and has long wires with no plugs to detach from the chassis, omg...

there is one 27k high watt resistor 405 one one side and 244 on the other, and tests perfect. that 220, ohm or k.

lets stick with this for a bit, the 244 should be fed thru a 100k ohm to the G1, and should not be dropping to the 160ish you mentioned before, find the 100k resistors that have one end on the G1 and the other to the 405. Something not right, the 244 should be at G1 as well, there should not be any loss across the 100k resistors in the G1 circuit.

looking from the rear of the set
chroma board
left side
back of board
look between the tube in the corner and a exposed coil for the resistor.

ok there was 3- 27k resistors and they are all ok and there is a 100k resistor at each g1 wire and they too are good. and also one other 100k also good.

ok what is the voltages on both sides of the 100k?

my last post i said there was an additional 100k but it was a 180k, also good. there are no other 100k resistors on the chroma board except each one at the g1 wires.

the 180k has 405 one side and 179 on the other if this matters. if i let it warm it goes to 185 v

I am trying to figure out the G1 voltage, IIRC you had about 160v, but if the 100k resistors have 185 then it should be 185v, which is in the normal range for the G1. Note this is highly dependent on the CRT bias so maybe you adjusted it at some point and got the differing voltage being reported now.

this voltage is from the 180k that i thought was another 100k, was my mistake but the voltages on the g1 are 100v probably because i have the chassis hanging out of the cabinet. but still they are low and this 100v is at each 100k resistor , g1.

ok lets start over again

CRT
G1 voltages
cathode voltages

ok im going to do this with no yoke or crt plugged in, is this ok ?

ok with these things no plugged the cathodes are 340v and the g1 99v i guess lower from befor because the crt and yoke are not plugged and the bias is still ccw.

well you should test them with everthing installed, that being said those voltages are wack.
the 99v does not make since, if the 100k resistors have 180 one the low side, then the G1 should be the same.

no the 100k resistors dont have 180v the single 180k resistor i mentioned has that on one side.

Timmy,
Check your email at 1:20 pm. I scanned a Magnavox "series 45" schematic (CTC16 variant) which you have. The only thing is, there are no voltages on the tubes, only sources like 405 volt supply, etc.
I am ALSO sending a series 41 (similar to CTC12) schematic which HAS VOLTAGES on all the tubes.
On a 41, the blanker feeds into demod tubes' cathodes and the CRT bias sets the bias on the CRT via the B&G drive controls.
Also the 41 schematic shows you CRT voltages:
cathodes =322 volts
G1s = 195 volts
G2s = 700-735 volts

The 12GN7 should measure about 250+ volts on plate pin 7 if too low, pix is bright, too high and pix is dark.
Dont forget that 100 mf @ 25 v cap across the contrast control, jump in a new one

Whatcha got for volts on CRT pins?

ok well 100v on the G1 is clearly the problem, so now you need to check all the pin voltages on the 6GU7's these are the difference amps. I am still a bit lost since I thought you said you had over 200v on one side of the 27K power resistors. If that is the case you should have the same voltage (200v) on the G1's.

the g1 166v-171 cathodes 305v -310v all plugged in . the contrast i touch a cap at the contrast pot and gets nice bright only for a second. g2 anywhere between 546v and 1046v depending where the drives are. the 27k resistor i was talking about was the gig single 27k high wattage resistor , had 405 on one side and i think it was 244 on the other.

the brightness increase is due to the momentary short of the cap on the cathode of the video out. changes the bias of the tube, causes it to conduct hard, drops the plate voltage thru the load resistor, direct coupling to cathodes result in lower cathode (momentary) at the CRT, changes the bias to more conduction (less difference in G1 to K) so more eletron flow in the CRT.

I would start with the assumption that the problem is in the video out, so try a new video out tube. check voltages of that tube as well.

You should also try a new blanker tube since it is part of the crt bias circuit (unlike the CTC-12 this set uses G1 voltage adjustment to set CRT bias not the K's).

if the capacitor i use to jump in on the contrast control has a charge in it the screen gets really nice and bright but for a second. it almost seems as if there is a source to the contrast thats missing.

12gn7 pins- 1 6.15 v 2 4.30 v 7 255 v 8 122 v 9 0 v

Does the contrast control work?

deleted I was wrong about a pin

those all look pretty good, if anything its driving too hard.

the contrast one way with the dark pic is one thing but the other way its so dark not worth trying to see.

power off, pin 1 to ground video out resistance reading? leave it connected for a min to stablize.

196.1 ohms pin 1 to ground after a moment connected.

zero ohms with tube out.

try a new blanker, and check the pin 7 (grid) of one of the diff amps (6Gu7) voltage. blank raster. check voltage with max and min CRT bias

dont know if this is of any help but when this set was always first turned on it was missing a color until about 30 seconds of being on so i thought it may have been one of the diff tubes taking longer to heat or conduct.

zero ohms with tube out.

should have no effect.

6gu7 pin 7 bias down 1.325v bias up -3.53v no diff bright up or down.

if new video out and blanker tubes do not help. I would focus on the crt bias circuit.

the only thing I can see in there is a pot that goes to a .22 uf cap (chroma board up front on right viewed from back) and a 220ohm resistor.

outside of that I am stumped.

ok the 220ohm checks 194ohms so thats good and the .22 i checked with my mfd dvom checker and it came in lower then the cap i have that is good. i dont know if the little difference in capacitance will make a difference but i can change it.

i thought if you pull the blanker tube out the screen is supposed to black out. well it dont its all green and bright

that tube is also one of the difference amps.

i thought if you pull the blanker tube out the screen is supposed to black out. well it dont its all green and bright

The blanker 6GU7 is also the G-Y demod amp, so that makes sense. what happens when you pull the other 6GU7? Bright magenta, right?

6gu7 pin 7 bias down 1.325v bias up -3.53v no diff bright up or down.

pin 8 voltage? crt bias up crt bias down?

pin 8 bias down 6gu7 7.35v bias up 5.95v

what if i was able to get pin 7 voltage of the 12gn7 down to maybe 185v instead of 255v. the lower this voltage the brighter it should be, maybe. but then again how would i do this anyhow.

the silvertone at full brightness is around 145v at pin 7 of the 12by7 if this is where the problem is in this maggie, video output, then maybe it would work ? i checked all the resistors around the 12gn7 tube and found not a thing.

again, you need to try a different tube. a weak video out tube will allow the plate voltage to be excessive

i did

Try a new audio output tube.

audio output , lol,???????

:scratch2:i thought about adding more big vintage speakers too but realized that wouldnt work...

a 1 meg ohm 1 watt resistor from pin 7 to ground should drop it some......... :smoke:

this set uses a stacked B+ from the audio out to supply the screen voltage of the video out (as well as other tubes). It also supplies the hot side of the brightness control. You should be able to locate that 3.3 meg now, it has the 135 (or what ever is the output from the stacked B+) on one side the other goes to the brightness control.

Sams shows pin 7 of the 12gn7 to be 300V. Pin 8 should be 135 volts, which comes also from the cathode of the audio out tube.

so if i have 122 volts at pin 8 would this suggest that the 3.3 meg resistor went up in value ? would this resistor be on the audio board or the chroma ?

the only 3.3 meg resistor i found in the chroma board near the video output tube has 124.4 volts on one side and is the same as pin 8 of the video tube. the other side of that resistor is 4.48 volts. i didnt pull it to check yet but the voltage is the same as pin 8 where its supposed to be 135 volts.

Since brightness is the issue, I would focus on the brightness circuit.

you tried a new video out tube (weak would reduce brightness)
so next look at the brightness control which sets the bias of the video out tube.
this is done via a voltage divider of 3.3meg and 330k with a source voltage of 135v

The next logical things to check would be:

135 source (stacked B+ supplied by the audio out tube acting as a voltage divider). that's a little low but prob not enough to cause a problem. A sub of the audio out tube may increase the 135v source.

The 3.3meg/330k voltage divider is where I would look. Since its unlikely the 330k has dropped (which would need to be the case for it to cause the low brightness) I would test the 3.3 meg (OUT OF CIRCUIT). If it has drifted high significantly that would reduce the voltage available to the high side of the brightness circuit.

The trouble with going strictly with the sams for voltages is there are a lot of variables so they can only be a guide. After that you need to understand how things work and use reasoning to try and narrow down the problem. Like if brightness is low look in the brightness circuit.

the 3.3meg i found in the chroma board is probably the one you are talking about so ill lift a leg and check it but this resistor is the one with 125v on one side. the audio out tube in this set is not called that its a A F output i think thats the one your refering to. the onthers are sound IF and sound demod. this resistor dont have high voltage on both so shouldnt it have 135v on one side already if that voltage was there ?

ok another audio tube did nothing so ill move to lift a leg of the 3.3 meg and check it.

6GC5 the big tube on the audio board.

The 3.3meg resistor has one side to the 135v source (provided by the 6GC5 acting as a voltage divider in a stacked B+ supply).

The other side of the 3.3 meg connects to the 330k resistor to ground.

the brightness control gets it voltage from the junction of these two resistors (a 10/1 voltage divider). If the 3.3meg drifts high the junction of the two (330k/3.3meg) will have a lower voltage for the brightness control to max out at, resulting in a dimmer pic. If the 330k drifts high the reverse is true the junction will have a higher voltage, brighter pic. if the 330k goes low, the junction voltage will be lower, if the 3.3 goes low the junction voltage goes higher. Look up voltage divider for how this works if the above is not clear.

a quick test to make sure you have the right resistor, jump another 3.3 meg in P with the existing one, that should brighten it up a lot. if it does then you know you are on the right resistor.

take it out of circuit and check.

ok so if there is only 125v one the one side of the resistor and it should be 135v then the resistor regardless if it went up in value should still show 135v if its there.

the 135v is from the stacked b+ from the audio tube. if you try another audio tube it will prob be different.

the audio tube supply's the 135v to the rest of the set.

it is determined by the voltage drop in the tube from the plate to the cathode, this is largely determined by the bias of that tube (the 6GC5).

there is grid bias set by a two resistors, again as voltage dividers, a 1.2 and a 1.0 meg resistor pair. The mid point of those two supply the grid bias.

my question is this 3.3 resistor what voltage should be present at one side of it ?

one side should be what ever the 135v source is, this is determined by the audio out tube.

The other side I don't know, it depends on a lot of things. If the brightness control was not hooked up it would be what ever the ratio of the voltage divider is (1/10th if all was correct) but since the brightness control is in the circuit its not easy to determine.

ok so there is a problem in that loop since there is only 125v on one side of that resistor when there should be 135v and im sure that is the correct resistor since its near the video output tube. so being another video tube changed nothing then its safe to say either the 135v source coming from the audio tube could very well be the bias setting resistors at or near that tube or maybe what i read in that magnavox trouble shootlng guide that the 140 source is low because of a resistor in the power supply and its listed as low brightness.

there is no 140v supply from the power supply, there is no 135v supply from the power supply.

ok , what supplys the audio board.

the 280v supply

just curious but where on the schematic is Y B where the 3.3 gets its source shows it goes to because im looking at this one here and the 140v and the 280v dont show a YB connection. not important just wondering

the 135v source is from the cathode of the audio out.

i tried to somewhat weld that green gun filiment wire on this crt and i went as high as 10 volts and it refused to arc when being tapped. i think the blue arc i seen was when the hv was present when i tapped the neck because now that i think of it and now i know where the filiment wire is that was not making contact, the blue arc was coming from further down in the neck, dont really know why unless there is close to a short in there that didnt show up yet. had nothing to lose.but it still works ok .

well ok im just about done with this set, the 3.3meg is good tested out of circuit the 330k tested .740m close i also checked the 1meg and the 1.2 meg at the audio tube all test good. 126v at one side of the 3.3 and also tried paralling the 3.3 just touching made it alittle darker.

this dark screen is with both the new crt and the older one i put in.

A 330K should not test 740K that is way out of range.....
At worst 20% toll. 330K X .2 (+ -) 66K = 393k to 264K would be
an acceptable range if it's a 20% resistor..... 4th band = toll.
no band =20% silver = 10% gold = 5%. yours is 200%+ off.....

Timmy, Don't mess with the filaments on the picture tube... Parallel filaments you will
not weld back because the current is always being drawn off by the other working
ones, over power the working ones and soon you'll have a completely dead tube....

The arcing you see is most likely something down the tube, mostly because that one
gun has no electron flow.... you're gunna have to let it alone till some good idea comes
along...

.

A 330K should not test 740K that is way out of range.....
At worst 20% toll. 330K X .2 (+ -) 66K = 393k to 264K would be
an acceptable range if it's a 20% resistor..... 4th band = toll.
no band =20% silver = 10% gold = 5%. yours is 200%+ off.....

Timmy, Don't mess with the filaments on the picture tube... Parallel filaments you will
not weld back because the current is always being drawn off by the other working
ones, over power the working ones and soon you'll have a completely dead tube....

The arcing you see is most likely something down the tube, mostly because that one
gun has no electron flow.... you're gunna have to let it alone till some good idea comes
along...

.

the 330k tested .740 meg

the 330k tested .740 meg

.740meg=740k=way out of spec for a 330k = replace it!

740K = .740meg. They are the same value....
Your auto-ranging meter just uses that display type....
Best is to use a meter without auto-range and learn it,
rely on yer brain, not a $20. meter to interpret it the right way....

330K Ohm = Orange-Orange-Yellow.
http://www.petervis.com/electronics/Standard_Resistor_Values/330K.html

.

740K = .740meg. They are the same value....
Your auto-ranging meter just uses that display type....
Best is to use a meter without auto-range and learn it,
rely on yer brain, not a $20. meter to interpret it the right way....



That and a few other things are the reason I still like my Simpson analog meter. I get ribbed a lot by techs who find some superiority of their technical skill-set by using devices that think for them to a large degree. I couldn't even get them to use analog when we were testing some potentiometers for bad spots. In short, they didn't want to admit that they couldn't interpret multipliers or read scales. No doubt at all that in the testing of pots that the analog meter is far, far superior; yet perhaps not as accurate in other measurements. Digital and auto-range can be nice as well, but you absolutely must pay attention to detail or really bad results can be the result.

ok was my mistake the resistor 330k tested 339 meg so its ok . so i am at a loss this time now with this set because everything like the silvertone checks ok but the silvertone had a problem and the problem was found but it dont look like this will be found any time soon unless its something so small and easily overlooked like the silvertone it will take time, i guess. maybe its not in the brightness but rather something that affects the brightness.

330K is not equal to 339 meg. Not on this planet....

I like my digital meters, but while they are more precise for some things,
they are not necessarily more accurate. And for things like a quick
cap check, analog wins, bad wiper on a pot, analog wins. And unless
they are specifically rated, I don't trust them on AC other than 60hz,
or RMS voltage.

.

for some reason my dvom sometimes measures in k or meg and i will sometimes check another of the same value to make sure. a 500k would read .500 meg or so ? ?
well the only thing i have is this fluke and its been reliable so far and that .339 i left the point out in the last post. if it came up just 339 then i would think its bad.

Timmy, you need to be precise when you write about stuff here as well....
500K and .500 meg are the same thing, but 500 meg is not equal to 500K.

When you write a number here all we can assume is that that number is exactly
what you mean.... That is often why when someone here asks you what some
reading is, we need a numerical answer, not "it's ok". Things here are often read
by 20 people, and some may get a different idea on the cause of a problem if
a number is given, and each has a reference like a schematic, tube pins, etc.

If people can't easily follow you it will be hard to come up with a solution
to these problems....

.

maybe i dont have a brightness problem i say this because if i were able to set up the R G B drives without having to raise up the bias to just about max then it may be bright enough because these drives do determine brightness to a degree and with the bias down or even half way up i dont get anything, cant see the R G B lines to setup the right way. so maybe there is an issue with these drives because the green is the brightest blue is second and red is the last so if i were able to set the drives higher then i think this would cure the problem but i already checked every resistor related to those drives along with all the power supply resistors, all the high wattage resistors and a few carbon resistors. the voltage at the HOT i think is alittle high although i dont have a spec of what it should be its at around 175 volts if i remember correctly but i did write it down. if i compare to other sets it seems high. most times i found that green always comes up stronger but with this set i dont see it until the bias is just about maxed. so maybe something related to those drives.

replace the .22 cap.

did you check pin 8 to ground of V20, 270 ohms

i will double check the ohms on pin 8 to ground, the video out tube ? the .22 cap where is this located ?

looking from rear of tv, chroma board, front right.

pin 8 6Gu7 common cathode of the difference amps.

ok thanks dave.

the pin 8 to ground measures 278 ohms, so thats good, ill move on to changing that .22 cap.

ok i changed the .22 cap had no effect so now i am really trying to understand what is happening or not happening here with this set. i took vlotages again with the bias at min and the g1 164v 163v 164v g2 1145v 1142v 831v cathodes 338v 310v 338v and these i guess would vary depending on where the pots are. the green drive with bias at min comes right up the way all 3 colors should but there is no blue or red that comes up unless the bias is at almost max and this is with 2 different crts.. these voltages look to be somewhat where they should be with the bias at min so the question is what is preventing the screen from being brighter then it is and or what is preventing the red and blue from coming up the way the green does with the bias down . the crt bias, this works with the blanker circuit so maybe there is other issues within that circuit and would it affect the drives ability to show lines needed for setup and ultimately help in the brightness area via the drives. however i do lack some understanding in some areas of this type of electronics but i do try.

did you try:

known good 6Gu7's (both) and a known good Audio out tube?

did you replace any out of spec resistors in the brightness circuit (3.3 meg/330k)

i tried 3 pairs of 6gu7s, an audio tube , video out tube, and did not replace any out of spec resistors. the 3.3 and the 330k i pulled from circuit and checked again and they are good. i went over every high wattage resistors both in the power supply and where the RGB drives are on that panel.

the problem looks to be a bias issue for the CRT assuming the CRT test ok.

the G1 to cathode voltages have a lot to do with the cut off of the electron flow from the electron gun, the G2s look ok, not sure about why one was a lot lower, I presume that was the green.

The CRT cathodes are high, indicating a weak video out tube or a bias issue (brightness circuit applies a bias voltage, the more neg the control grid of the video out, the less current flow and the less of a drop on the plate load resistor, the less drop (higher plate voltage) the higher the directly coupled cathodes of the CRT. Since the voltages there seem high in relation to the G1 voltages you need to determine the cause (video out tube/bias too low/screen voltage too low/emissions too low all reducing the current flow of the tube resulting in plate voltage too high).

if the tube is ok, and the bias voltage on the control grid is ok, then about the only thing left is the screen grid of the video out. this is supplied by the 140v supply which comes from a stacked b+ derived by the voltage drop across the audio out tube.

The other possibility is the CRT G1 is too low. this comes from the plates of the 6Gu7 difference amps. again you need to look into bad tubes but this time it would not be weak but rather gassy or grid emission problems upsetting the tubes and causing too much conduction dropping the plate voltage (the opposite prob of the video out tube), and direct coupling to the G1 of the CRT too low a voltage (160ish)

what was the contro grid voltage of each of the difference amps?
I have never seen it, BUT if the coupling caps were leaky that could cause a problem in the diff amp bias.

I was a bit concerned by the screen voltage of the video out tube. Has this set been recapped, specifically the caps around the 140v source? there is a 20uf and a 100uf cap in that circuit. you would not want to have leakage there.

check the voltages of the 6GC5 again.

I was a bit concerned by the screen voltage of the video out tube. Has this set been recapped, specifically the caps around the 140v source? there is a 20uf and a 100uf cap in that circuit. you would not want to have leakage there.

check the voltages of the 6GC5 again. yes it was recapped by me but then again i could have put an unknow bad cap in. i notice that the +270v source to the audio board is only 249v and the voltage at the video tube that is supposed to be 135v is not, it is low and the last time i checked it it was around 125v and now im getting 121v . the non blanker tube voltages are, pin 1 167v 2 2.350v 3 7.50v 4 0v 5 0v 6 165v 7 2.150v 8 7.50v 9 0v
the blanker tube pin 1 243v 2 75.7v 3 4.67v 4 0v 5 0v 6 172v 7 1.582v 8 7.50v 9 0v

confrim your line voltage and all the B+ from the power transformer starting with 415v from the output of X2 at 117vac line voltage

yes it was recapped by me but then again i could have put an unknow bad cap in. i notice that the +270v source to the audio board is only 249v and the voltage at the video tube that is supposed to be 135v is not, it is low and the last time i checked it it was around 125v and now im getting 121v . the non blanker tube voltages are, pin 1 167v 2 2.350v 3 7.50v 4 0v 5 0v 6 165v 7 2.150v 8 7.50v 9 0v
the blanker tube pin 1 243v 2 75.7v 3 4.67v 4 0v 5 0v 6 172v 7 1.582v 8 7.50v 9 0v

are these with no signal?

are you using a VTVM?

do you have a cap tester that can test for leakage at rated voltages?

ok looking at the maggie schematic here it shows 140v 200v 270v 390v 405v plus for all voltages can i check these with the chassis out? because its nearly impossible to do this with this type of setup with a stero and tuner that has no plugs.

these voltages were with no signal and i only have a dvom and i do have a cap checker and it measures NF and MF.

if anything voltages should be higher since my line voltage is 122.9 v

try replacing one of the .01 grid coupling caps for the difference amps, see if that changes the voltage reading on the grid of the 6GU7 diff amp tubes.
there are 3 of course, but you may as well only do 1 (say the blue) and see if there is a change. check to voltage before and after the change of the cap.
think you said you were getting around +2v there, I show -2v should be there with no signal.

if you can reach it, do a quick test, check each side of the 6Gu7 .01 diff amp grid coupling cap to ground. report back voltages

on is behind one of the 6Gu7's the others are near the front of the board.

Normally I would just test for leakage, but since you do not have the correct tester you need to replace or rig something up.

ok looking at the maggie schematic here it shows 140v 200v 270v 390v 405v plus for all voltages can i check these with the chassis out? because its nearly impossible to do this with this type of setup with a stero and tuner that has no plugs.

what model number is that for?

this is what you need to get. they are on ebay all the time.

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

i noticed every +140v source is at 121v , not good.

confrim your line voltage and all the B+ from the power transformer starting with 415v from the output of X2 at 117vac line voltage

if its a U45 you should be starting with 415v

send me what you are looking at for a schematic

i found a carbon resistor in the power supply that is a 3.3 k but tested at 40.5 k so i changed it dont know if it will make much difference. the +140 is low and the +270 is at 258v the difference between 258v and 270v is 12v and if that 12v is put to what i have on the +140 line at most its been was 120-125v seems to make up the loss on the +140. so is this 270v source used to boost up the +140 because the 270v comes in and goes threw a resistor just at the audio tube along with the +140v. what im not getting here is both 41 and 45 series schematics have the same setup in the power supply, resistors, so from the output of what looks like x2 it goes to a 1250 ohm 18watt resistor and pulls it down to what looks like supposed to be 270v but i only have 258v so this would suggest that 18 watt is bad so ill have to lift a leg and check. but checking it in the circuit its up around 1330 ohms. would this little bit pull it down to 258v from 270v ?

ok it looks like it is the 41 series and there is some difference in the 2 power supplys. so i lifted one leg of the 1250 ohm resistor and its 1398 ohms.

dave im having problems here getting you the schematic i had got from davgoodlin

is it at all possible to paralle a resistor with the 1250 ohm resistor to raise the voltage to see if this is the problem with the +140v and +270v being the 270v is fed right off the 1250 ohm resistor and it tests at 1398 ohms maybe the rise in ohms was enough to lower this source by 12v and if this 270v source is used together in the audio circuit with the stacked b+ to give +140v then this may be the fix. then there is what value resistor to try as the voltage cannot be that high but its for test purposes and if this does it ill get a new 1250 ohm resistor.

odd, I thought it was a U45 all this time. if its not then everything I have been saying could be wrong.

well i am confused at this point because i looked at both schematics and the power supplys look the same but one the 41 dont have a 140v source but the 45 does so it might just be the 41. but i looked at whats left of the tag on the chassis and there is a u45 in the corner bearly able to see it. and you had said there is no 140v source it comes from the audio circuit.

well the 41 series uses 6cg7 and the 45 uses 6gu7 and thats what i have so it is infact a 45 series.

regarding the B+, did you replace the doubler caps? weak caps there can reduce the B+.

yes i did replace those casps. i have 425v off the diode so there is plenty there to go around.

i dont know for sure but it really seems as if the +140v at the audio tube is dependant on a +270v source but i only have 258v and the only thing im seeing here is that the 1250 ohm is at 1398 ohms and i really dont know if this little bit of rise in this resistor would starve the +270v source of +12v to make up the +270v. what do you think dave ?

try a different audio tube and see what effect it has on both the plate and the cathode voltages

i did that already and nothing changed.

what i did was i took the 270v source away from the audio board and the 140v was gone, well the 125v including up to the cap that is on the 140v was dead, 0 volts. so if just a few volts can mean alot when it comes to a bias issue on a tube then the loss of the voltage on the 270v would have an affect in several places being there are several points that get the 270v source including the audio board and it could very well be that resistor. moyers has a 1.2k 25 watt this may be to big to fit somewhere in the chassis the one in the chassis is not 2and a half inches long , this is what he has.

Ok, I am totally confused. Do you have a 41 series, or a 45 series? Are you sure? The 45 series does not use a 1250 ohm 18 watt resistor, but the 41 does. The 45 series uses a 1100 ohm 18 watt resistor. I have checked two different schematics. The 45 does use 6gu7 tubes, and the 41 uses 6fq7/6cg7 tubes. Do you have a 41 series with the wrong tubes? The 45 series was the first with automatic degausing. If you do not have built in degausing coils it is a 41 series chassis. Just trying to get on the right page here. Also confused about the CRT you are using is it a good one, or the one with the dead green gun filiment?

well i am confused as well i do see that the 45 uses an 1100 ohm resistor but it looks like a factory 1250 ohm in this set and was never touched since 1965 and the hv cage shows 6gu7 tubes so i dont know where else to go to know for sure. but i did notice there is a u45 on the corner of the tag bearly visable that i didnt see before. this maggie has the degauss coil around the crt and the green gun issue is ok the crt is fine at the moment the filiment has not been a problem. so i do believe i have a series 45 but with a different resistor for some reason or maybe a type o on the part of the schematic ? is it possible that this chassis did use 6cg7 tubes because of a last minute production change back in the day? and would it do harm in trying the 6cg7 tubes. for all anyone knows maybe the set was built with the wrong resistor from day one and with everything new at that time it worked acceptable and was never noticed because it dont explain how that one got in there because it was for sure factory based on how it looks.

well i am confused as well i do see that the 45 uses an 1100 ohm resistor but it looks like a factory 1250 ohm in this set and was never touched since 1965 and the hv cage shows 6gu7 tubes so i dont know where else to go to know for sure. but i did notice there is a u45 on the corner of the tag bearly visable that i didnt see before. this maggie has the degauss coil around the crt and the green gun issue is ok the crt is fine at the moment the filiment has not been a problem. so i do believe i have a series 45 but with a different resistor for some reason or maybe a type o on the part of the schematic ? is it possible that this chassis did use 6cg7 tubes because of a last minute production change back in the day? and would it do harm in trying the 6cg7 tubes.

Sounds like you got a 45 then... clip in a 1100 ohm and see what changes. Then try a new 1250 ohm and compare notes.

Sounds like a 45. It should be just like the one in my 65 combo. Cant really explain the resistor though. I thought typo but it is a typo on 2 different schematics if it is. Could have been a production run change. Since you voltage is low you could try an 1100. I dont have the chassis out of mine right now or I could look.

i have a new 1250 ohm coming i located but at the same time im looking around for several power resistors to make up 1100 ohms to see what i get but not having much luck as all i came up with is around 700 ohms, not enough. so if the 1250 ohm resistor is right then i cannot explain why the voltage is low unless the 270v tie points i will eliminate each one as maybe something in a given circuit possibly pulling it down for whatever reason.

ok im going to have to figure what resistance to use in the place of the 1250 ohm im sure they will both work but the 1100ohm will get a better result because i add a 5.6k resistor to the 1250 that went up to 1398 in paralle and it brings the resistance down of the 1398 to 1122 ohms and the voltage is 277v for the +270 and the + 140v that was 125v comes up to 135v so i will try the 1250 when i get it and if the voltages come up near to what they should be then ill leave the 1250 in if not ill get a 1100 ohm that states should be in this chassis. i only did this to see if the voltages would come up to where they should be with the proper resistance and it did. originally i had 258v on the +270 source and 125v on the +140v from the audio tube so the difference showed right away with the resistance change in that power resistor.

ok heres what i did, i placed a 5.6 k 5 watt resistor in paralle with the 1250 ohm that went up to 1398 ohms and it gave me around 1122 ohms. brightness is perfect along with the crt bias, the red and green come up without the bias but the blue needed alittle bias the 258 i had on the +270 source is now between 274-278 v and the +140 from the audio tube that was 125v is now 136v and i changed one .01 cap at the blanker tube being i was getting a meg ohm reading that would not go into infinity. so i could at anytime get the right 1100 ohm resistor and put it in. i decided not to go with what was in there 1250 ohms because maybe it was a mistake or put in many years earlier maybe the 1100 they did not have and subbed the 1250. either way if the 1250 was put in when new the set would have worked nice because everything was new. so im sure i would not have got a result like i got now had i put the 1250 in. here are a few pics, quality of the pics are not that great.

Looks pretty good !

.

you can put that one in the done stack.

Great progress.. Would love to see some fine pics of the whole set...

you can put that one in the done stack.

lol,lol, you can say that again... :banana:

Great progress.. Would love to see some fine pics of the whole set...

ill get some other better pics and post them , of the whole set. :smoke:

Great progress.. Would love to see some fine pics of the whole set...

ok heres a few pics of this monster,lol lol....

It does put off a great pic...