65 maggie - Page 10 - Videokarma.org TV - Video

timmy · #**136** 02-12-2015, 07:16 PM

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.

timmy · #**137** 02-13-2015, 07:04 AM

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

DaveWM · #**138** 02-13-2015, 08:31 AM

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

timmy · #**139** 02-13-2015, 09:14 AM

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

timmy · #**140** 02-13-2015, 10:11 AM

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 ?

DaveWM · #**141** 02-13-2015, 10:51 AM

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

timmy · #**142** 02-13-2015, 10:59 AM

i did that already and nothing changed.

timmy · #**143** 02-13-2015, 11:09 AM

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.

Bill R · #**144** 02-13-2015, 05:42 PM

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?

timmy · #**145** 02-14-2015, 06:53 AM

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.

stusnyder · #**146** 02-14-2015, 07:21 AM

Quote:

Originally Posted by timmy

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.

Bill R · #**147** 02-14-2015, 09:59 AM

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.

timmy · #**148** 02-14-2015, 10:13 AM

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.

timmy · #**149** 02-15-2015, 11:22 AM

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.

timmy · #**150** 02-16-2015, 03:51 PM

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.