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  #1  
Old 10-27-2014, 04:08 PM
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63 silvertone

ok im back again with the same set it is a 63 silvertone ctc12 clone. i have a few issues and to this day i cant seem to solve. on the schematic there is a section of the 6bk4 and it has 2 lines coming together with a circle on each end and this is where to check regulator current but it shows a jumper that goes across it so is this jumper always across these 2 lines and then removed to put a meter in between and then put back or is it left separated. because i removed this jumper and now have no control of the hv 30kv is high, not right. the other problem is like on modern tvs there is a screen control on the flyback and if adjusted to high then there is lines across the screen until its lowered and this is what i have on this silvertone it as though the bias is to high but it is counterclockwise all the way down and these lines are each one is red, green, blue, and no mater what i do adjusting, subbing tubes nothing gets rid of them i am thinking there may be a resistor or a shorted cap in the chroma board , i just dont know at this point. i have since replaced the flyback when i discovered the 1v2 was wired wrong and i had focus issues now i dont just the lines. so i dont know if its a bias issue or a color drive issue. hopefully someone can shed some light on this never ending sega with this set. so what ever is going on here still is affecting the hv if that jumper stays in place when not checking reg current then ok but i then have to have the hv at max to get decent hv and if something is being driven to hard will have an affect on the hv and this is what it seems like thats going on here. the 1.5meg resistors are good and the high watt resistors around the drives as well check good.
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Old 10-27-2014, 05:57 PM
DaveWM DaveWM is offline
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You need to replace the jumper, its only removed for testing with a current meter.

The diag lines you see I suspect are due to trying to drive the CRT too brightly.

You need to follow this order

1) set the HV up with a HV meter on the CRT anode and the current meter for checking shunt current on the 6bk4, follow the sams procedure, please don't jump around. This wil include not only the shunt current but the cathode current of the horz out tube, again all of this is in the Sams.

2) setup up the drives using the setup switch and again following the procedure, this will include the correct setting of the bias pot or switch (which ever is used).

3) check the grey scale and adjust the bias pots for no tint in the high lights again part of the setup covered.

My "guess" is you are simply driving the CRT too hard (maybe its getting soft).

If for some reason the 1st 3 steps do not work then you may have a circuit problem that should be addressed. Good HV regulation is a must, trying to get a good pic with out it is a waste of time. You also need a good grey scale setup, if the set can not produce a good BW pic then no need to try for a color until that is resolved.

Last edited by DaveWM; 10-27-2014 at 06:04 PM. Reason: grammer critique sounded harsh sorry
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Old 10-27-2014, 06:20 PM
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ok well i have done this except the reg current on the 6bk4 and the bias IS DOWN ALL THE WAY AND THE 3 COLORS RED, GREEN, BLUE drives are completely down, off and still have lots of color and with the b@w pic there is still visible lines but bearly. how else could i be trying to drive the crt to bright i took away all that brightens the crt and still have the lines. this problem has gotten worse each time i would run it for alittle while and now its at the point im trying to get to the bottom of it,lol, its making me crazy. this gave me the idea that something on the chroma board may be bad, i have done so many grey scale setups. the reg current is in milli amp or micro amp or is this the same,lol...

Last edited by timmy; 10-27-2014 at 06:24 PM.
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Old 10-27-2014, 06:24 PM
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with the G2 drives all the way down and the bias all the way down you should not be able to get the setup lines and the crt should be dark.

You have a problem with the voltages going to the CRT pins. You need to get out the VTVM and start checking the K, G1 and G2, to narrow it down to what is the problem, then you need to see if the pots that control them are indeed working.
but 1st you need to make sure the HV is correct.

If you do not already own it I HIGHLY suggest you get the TAB book vol 1 RCA service manual by Carl Babcoke. He does a great job explaining all aspects of early RCA color sets, and goes into great detail regarding trouble shooting.

Last edited by DaveWM; 10-27-2014 at 06:31 PM.
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Old 10-27-2014, 06:38 PM
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yes the crt is dark but still see the drive lines and i already checked the pots and they are in range. when i put the jumper back i will be able to adjust the hv but what is going on it struggles to regulate yet i can get it adjusted to 25kv but with the hv pot maxed. so ill have to check the voltages at the crt and hopefully ill get somewhere there.
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Old 10-27-2014, 06:40 PM
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Could your control pots be going open, or the supplies driving them be feeding the wrong voltages?

EDIT: Should have refreshed the page before replying.
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Old 10-27-2014, 06:49 PM
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problem is i dont have any books of sort to give me any guidelines as to what voltages should be at a given place or anything to compare. so im working in the dark,lol,lol.....
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Old 10-27-2014, 06:50 PM
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you must have the jumper in that's a given.

You should have good HV regulation. If not then you need do the HV setup which includes current checks of the 6bk4 and the 6JE6.

the next step on what to check will be dependent on the outcome of those checks. Stop worrying about the lines until the HV is working correctly.

I am not going to list the possible problems as its just a lot of speculation with out knowing the current in the regulation and horz out tubes. I don't believe in random attempts to solve a problem. there is a methodically approach diagnostics. You MUST have good HV regulation, after that you can move on to the next issue.
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Old 10-27-2014, 06:51 PM
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Quote:
Originally Posted by timmy View Post
problem is i dont have any books of sort to give me any guidelines as to what voltages should be at a given place or anything to compare. so im working in the dark,lol,lol.....

the book I referenced is on ebay all the time.
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Old 10-27-2014, 07:11 PM
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The Sam's should list voltages at important points on the schematic. Once you have your HV right (As Dave said do that first) if the lines persist check that the voltages going to the pins of the CRT are in the correct range, and verify that control adjustments change them in the expected manner.
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Old 10-27-2014, 07:28 PM
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Ya know..... screwin around like that and letting the hv go up to 30kv is gunna
let out a buncha those little x-rays.... and they gunnaroastyernads.....

just sayin..... be crarful...... mostly cause ya can't see em comin.....

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Old 10-27-2014, 08:28 PM
DaveWM DaveWM is offline
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ok I am going to go ahead and take a leap of faith here with Timmy and GUESS what we are talking about.

I am currently uploading a video of a set that exhibits what I think Timmy is talking about ( I don't recall seeing any pictures or video). it will be done in a few..
One thing for sure if I reduce the brigthness control I can eliminate them.

IF its what I think it MAY be some kind of vertical retrace issue. Note the issue I see does not seem related to the color lever setting on the front of the set. It does seem related to the brightness and contrast settings. This would point to the luma signal from the video out where the vert retrace pulse is fed for vertical blanking during the retrace interval.

a wild guess could be assuming the level and duration of the pulse is correct, would be maybe an issue with the video out tube (poor gain)? I have no 1st hand experience with this being a cause but I have noticed it before, generally shows up on tube that are not it the best shape, hence I just assumed it was related to the condition of the picture tube. Perhaps a cut off issue. I do know that at least in the CTC-17 there was a transistor inserted into the vert blanking. I have never tried to increase the amplitude or duration of the pulse to see if this was indeed the issue.

Now that I have reversed myself and gone ahead and speculated, I will see if that video is done and will link it here.
I just checked the schematic, the vert blanking pulse is fed in at the plate of the video out (cathode of the CRT) so guess the gain of the vert out tube is not an issue, that leaves either not enough of a pulse or not enough cut off control of the CRT.


Timmy get that HV fixed.

Last edited by DaveWM; 10-27-2014 at 08:49 PM. Reason: looked at the vert retrace on the schematic
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Old 10-27-2014, 08:40 PM
DaveWM DaveWM is offline
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here you go Timmy, don't leave me hangin'

I did notice that on the CTC-35 the vert pulse was fed into the grid of the second video amp (wrong phase for video out grid). Maybe that would be a more effective blanking, assuming its just that a weak CRT could use the help.

new link

https://www.youtube.com/watch?v=39Dl...CVtyRrqXVtll-g

Last edited by DaveWM; 10-28-2014 at 02:59 PM.
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Old 10-28-2014, 03:52 AM
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Last edited by Tubejunke; 10-28-2014 at 03:55 AM. Reason: Couldn't get link to work
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  #15  
Old 10-28-2014, 10:33 AM
DaveWM DaveWM is offline
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come on Timmy don't go dark on me.
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