Why no love for this GE roundie ?

[Findm-Keepm]

Originally Posted by tvcollector

I ran the set probably less than a minute total at full 120v.. Nothing seemed to be burning out.. I started to smell the scent of burning dust, the horizontal output tube was the only thing I removed and also the HV lead with sucksion cup that connects to pic tube so I can remove the chassis.. I tested all the tubes, and there are alot of tubes with grid leakage, shorted, or weak.. I'm not going to power it up anymore until I get the horz osc coil replaced, tubes replaced, coils replaced, and the .047 600v cap replaced. Then I'll do a slow power up with lamp in series with 200watt bulb, and with all HV connected..

I tried the lamp procedure with a 100watt bulb and it didn't seem to work...

Coil and cap on their way - trk# 9400109699939475974899

[tvcollector]

My variac doesn't have an amp meter, nor do I have an extra multimeter to test amps while testing B+, if I would be using my multimeter to measure B+ voltages, if I could find another tool that I can plug into that measures amps etc.. at the same time, that would be great.. Back to B+ subject, Sorry for my lack of knowledge, I'm starting to get the hang of all this, but I don't know where I would connect my multimeter to measure B+ voltages as I crank up the variac.. I'm looking at the Sams LV power supply board and it shows numbers, some with voltages (bottom of board pic), I assume those are voltage check points.. Not sure which meter probe to connect to where.. I've never did voltage checks throughout circuits yet.. Also if I have to connect multimeter on bottom of pc boards to do voltage checks, I think it would be impossible to check while powered up and everything connected, but then again, I think where I see the voltage points on bottom of board image, and I look at the top board image, it looks to show metal stubs coming out a little, enough where alligator clips could clamp on.. Some have an "X" near them looking at the actual board in the TV set... If I'm understanding all this correctly, I assume red lead from tester goes to test point on board and black to metal of chassis? Also number one (390v) on Power supply board I'm assuming is a voltage check point for B+ ? I don't have an HV prob yet, so that would be out of the question at least for now..

I came up with this homemade lamp in series from parts bought at Home Depot.. If I can come up with something like this or buy something that has an amp meter on it that has an outlet that would be great.. Also another option, using this with a socket outlet adapter, and use a second multimeter to test current..


Thanks Findm-Keepm for all your help..

[zeno]

For tube sets clip the negative lead to ground, the
metal chassis.
Sams probably shows the 390 V as #1. That goes to
all the #1's on the schematic. The voltages may not be
exact as the set is not regulated. If its + or- 3% you are
usually OK. There is often a distribution chart that shows
how many places the sources go, that helps when tracking
down a short.
As far as an amp meter goes almost anything will do.
Keep in mind a cold set just coming on will draw a ton
of current & pin the needle for a second on some meters.
Hope that helps.

73 Zeno

[init4fun]

Originally Posted by tvcollector

I tried the lamp procedure with a 100watt bulb and it didn't seem to work...

The bulb likely lit full brightness and the TV set not at all , correct ?

Your TV draws what , 300 to 400 watts , give or take a watt or few ? You will need light bulbs up to around 300 or 400 watts worth for the TV to get enough power to begin to show life . Doing this with bulbs is easy if you get 4 sockets and wire them in parallel , and then wire that parallel bank of sockets in series with the load , as you now have your single bulb . This way , and using an assortment of common 100 , 75 , and even 50 watt bulbs , you can slowly up the current by screwing in more and higher power bulbs till the desired current is reached .

[dtvmcdonald]

150 and 200 watt bulbs are very readily available, still.

I did notice that the Federal budget proposal for next year
continues a ban on funding for enforcing a regulation that
makes it hard to get any size regular tungsten bulb.

[tvcollector]

I bought a cheap multimeter at pepboys and measured amps powering my CTC15 up.. Meter keeps reading between 0.00 and 0.02 and no change as set is powering up and tubes warm up.. Doesn't make any since to me.. I must be doing this wrong.. got probe connected to 10amp, and the other to the Com of meter and meter set to 10amp..

the 100 watt bulb lit full brightness and went down slightly, with nothing coming up on the TV set..
the 200 watt bulb lit full and goes down dim as the tubes come up.

That's the pattern the amp meter should be reading but when I power my CTC15 up, it's giving me numbers that don't make since..

Here's what the settings I have on the multimeter..

[Electronic M]

That DMM only has DC current measuring capability...There is no DC current in normal AC mains power so the readings you are getting are predictably meaningless.

If you have a 5W or more resistor that is say 1 Ohm, then you can connect it in parallel with the meter (and put both of those in series with the line), set the meter to AC volts and read current....This is relying on ohms law: V=IR voltage equals current times resistance. A resistor anywhere between 0.01 and 10 ohms will work, as long as it's power rating is high enough to handle the current the set draws. Also go with 1*10^whole integer number (ie. 0.01, 0.1, 1) to make the math easier...Basically if you do that the AC voltage on the meter will be the AC current only the decimal point may be shifted.

Or you could skip that whole rigamarole and use your other meter if it happens to have an 10A AC current setting...

Good luck.

PS: Power = R(I^2) on that resistor. Power also = VI. So to find a safe resistor power rating divide the TVs rated power by your line voltage to get the designed current draw of the set then multiple that value by 1.2 for 20%-over-current safety margin or as much as 1.5 (for 50% over current) then plug that current and the resistance of the line current sensing resistor into the first equation in this paragraph to get the power rating you want that resistor to have.
The resistor power rating can be as much as 50% lower than that calculated power and still work for maybe 5 minutes before the smoke is released if you don't have a high enough power resistor.

[tvcollector]

Must be this cheap multimeter.. I hooked my klein tools meter up and it reads 2.6 amps with the CTC15 fully powered up..

[tvcollector]

That's it.. You're right.. I didn't realize this.. I even read the package etc.. Pepboys is getting a return..

[Electronic M]

If your other meter is able to measure AC current then you could measure the line with that one, and use the pepboys one to measure DC B+ voltage....Which it should be capable of.

[tvcollector]

Oops.. A little late for that.. Went to return the meter to Pepboys and went next door to Home Depot and spent a little more money on the smaller Klein Tools meter.. Now broke till Saturday..

CTC15 when powered up goes from 3.5 amps drops to around 1.5 amps and slowly goes up to 2.6 amps after warmed up..

[tvcollector]

I installed 2 new interlock coils so far, they are much bigger than the original ones.. I didn't install the cap nor the osc coil yet.. But I did power the set up only to 30 volts or less with the variac, and with the volt meter connected to HV check points, the meter keeps bouncing around to random numbers and keeps going into OL OL OL OL.. And it starts doing that at less than 10volts applied to the set... Not sure if that's because the coil or cap isn't installed yet..

[tvcollector]

Cap, coils, horz osc coil, and tube is all installed.... with the horz and vert output tubes removed.. Meter still bounces around to random numbers, and when it bounces to really high numbers is when it goes into OL, which does it about one time a second.. Set draws only 1.6amp at 115volts..

[tvcollector]

oops I think meter was bouncing around from ac to dc... Had to set to DC mode.. It's around 400vdc at 120v.. Drawing around 1.5 amps..

[tvcollector]

Just powered it up for the first time.. Can't get Horizontal to lock, and doesn't fill in the screen fully.. Focus looks blurry when I raised the screens all the way up.. The Horz Osc Tube is kinda weak, BK 747 tester shows in the middle between good/bad (?).. Not sure if that's the cause.. Here's a video I took.. B+ voltage when fully powered up and amp it draws with everything fully up...

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