Videokarma.org TV - Video - Vintage Television & Radio Forums

Page 2 of 2

Show 40 post(s) from this thread on one page

Videokarma.org TV - Video - Vintage Television & Radio Forums (http://www.videokarma.org/index.php)

- Early B&W and Projection TV (http://www.videokarma.org/forumdisplay.php?f=19)

- - Horizontal Sweep Adjustment? (http://www.videokarma.org/showthread.php?t=264093)

Magnavox300

07-14-2015 10:06 PM

Quote:

Originally Posted by DaveWM (Post 3138264)

just check the coil with ohm meter, should be 45 per sams 1 and 3 I assume 2 and 4 are not used. You can test in circuit. You can check voltages as well, its the plate supply so if its open you would have zero.

Try not to replace any more parts until you cover the easy stuff, like voltage checks and resistance checks (see the sams for pin resistance readings).

The biggest mistake that can be made is LOTS of parts getting replaced in a shot gun manner as a method of repair. It can make for a real tough dog.

Did you go back and double check all the values of the replaced parts looking for a 10x change? did you spray any cleaning agents (specifically near that trimmer cap)?

Measured the coil at 1 and 3, and it measured 47ohms...
I will do voltage checks and resistance checks, but I still have to get the right schematic, and it doesn't look like I can find one.... My chassis varies alot in values and placements of capacitors from the schematic I have... Tubes are all the same though!

DaveWM

07-14-2015 10:12 PM

so the parts you replace, they were the same as the orig regardless of what the sams says?

did you read my post about cleaner and trimmer pots? never get near a trimmer pot with spray cleaner.

Magnavox300

07-14-2015 11:24 PM

1 Attachment(s)

Quote:

Originally Posted by DaveWM (Post 3138268)

so the parts you replace, they were the same as the orig regardless of what the sams says?

did you read my post about cleaner and trimmer pots? never get near a trimmer pot with spray cleaner.

Yes, I only replaced the parts by what was already in the circuit... The sams was different...
and yes, I will always remember not to ever get near trimmer pots with spray cleaner! I don't believe any ran down that far after spraying the Hold pot, but it could have been close!

After lot's of searching, I found a write up of my tv model in some old newspaper clippings, it is a Emerson model 2005, or maybe a 2002 or 3... The reason I couldn't find the right schematic, was I needed the letter "C" in front of it. All I had was the number.
Now I can order it and have the right one... hard to work blindly!

zeno	07-15-2015 10:51 AM

Be careful where you get Sams. You may get a photo copy
or PDF & they both suck to work with. Lots of dealers that
can supply an ORIGIONAL for +- $10. Do a WTB here first,
you may even get a free one !

73 Zeno:smoke:

Magnavox300

07-22-2015 01:14 PM

2 Attachment(s)

Quote:

Originally Posted by DaveWM (Post 3138264)

Try not to replace any more parts until you cover the easy stuff, like voltage checks and resistance checks (see the sams for pin resistance readings).

I finally got the correct schematic...
Okay, I just did resistance checks of the 6CG7 vert. Oscil. tube:
All pins measured pretty close to where they should be,
but PIN 7 did not read at all, it's supposed to read 2.3 MEG.
Should I investigate the caps & resistors coming off pin 7?

old_coot88

07-22-2015 02:04 PM

Quote:

Originally Posted by Magnavox300 (Post 3138961)

I finally got the correct schematic...
Okay, I just did resistance checks of the 6CG7 vert. Oscil. tube:
All pins measured pretty close to where they should be,
but PIN 7 did not read at all, it's supposed to read 2.3 MEG.
Should I investigate the caps & resistors coming off pin 7?

Don't you mean horiz. oscillator?
Definitely check the 1 meg resistor R73. If that sucker's gone high value or open, it would sure mess with your H.sync. Also check the foil traces either side of it, all the way from the dual-diode to pin 7 of the tube.
BTW, which range of your ohmmeter are your using? I.e., when checking foil, use the lowest range. Use a higher range when checking megohm values.

Magnavox300

07-22-2015 09:07 PM

Quote:

Originally Posted by old_coot88 (Post 3138970)

Your right, I meant Horiz. Oscillator;
I used the 20meg setting to test pin 7.
I actually just replaced that 1meg R73 resistor, and double checked the foil traces.
I checked the C55 82pf capacitor, and it doesn't test right, so I'll try replacing that, though I don't know if that would make a difference of the PIN 7 reading.

Magnavox300

07-23-2015 03:57 PM

I should be getting a 2.3MEG reading from PIN 7, but still no reading at all.
I'm not sure, but would any bad component connected directly with PIN 7 cause the meter not to read, or is it just a problem from PIN 7 to the dual Diode?

There's only one component that goes between PIN 7 and the #3 anode of the Dual Diode;
(R73) the 1MEG resistor, and I double checked it... it's new, and checks correctly.

Gregb

07-23-2015 04:03 PM

Its possible you have a bad tube socket, check it with your meter.

Gregb

teevee

08-01-2015 05:50 PM

Few things, "Shorting out the stabilizer coil" is the typical first step in setting up a "Synchroguide" horizontal section, the schematic is not for that type.. Usually to trouble shoot this kind of problem, divide and conquer. Short 6CG7 pin 7 to ground, (Eliminates the synch section) and see if the horizontal can be adjusted to make a correct pic. No synch, so it will be wobbly). If so, then the horiz osc is capable of running on the correct freq. Then, remove the short. Your res reading from pin 7 to ground (open) is suspect, follow that back through the three 1M resistors..

All times are GMT -5. The time now is 07:27 PM.

Page 2 of 2

Show 40 post(s) from this thread on one page