Found a Sylvania SS/Tube hybrid - Page 8 - Videokarma.org TV - Video

MRX37 · #**106** 10-07-2015, 08:17 PM

Yeah i'll worry about the delay line, and the thermistor, and everything else after I see if the CRT still has life in it... That image I posted was with the drive controls, brightness and contrast at max...

Oh and correction about the focus control. It does help, but that's the best I can get the image.

EDIT: Something else I should mention. Since bypassing the delay line, the brightness control is now working in reverse. as in the image gets brighter the lower I set it.

MRX37 · #**107** 10-08-2015, 08:52 AM

I decided to make a new video showing what the TV is doing now.
http://www.youtube.com/watch?v=7qnAr...ature=youtu.be

The screen controls still do nothing, but I have a good hint that the CRT is okay. Setting the color drive controls to minimum still produces a visible image, now that the delay line has been bypassed.

However the image is still very dim. I'd like to solve this issue first before moving onto focus. I think I should go back to the 12HL7 and measure the voltages again. I'll do that after lunch unless you guys have any other suggestions.

EDIT: okay, new 12HL7 voltage readings taken using the same clockwise measurement as last time. Screen and color drive controls are set to about mid point.
Pins 1,4,5,6 and 7 have negligable mV readings.
Pin 2 starts off at 350, then drops to 146 volts
Pin 3 starts at 355 volts, dropping to 250
Pin 8 is the biggest change. It started at 0.5 volts, went up to 2 volts, then dropped to around -200 mV
And pin 9 started at 0 mV, slowly climbed up to 200 mV before dropping back to 0 and starting over.

Also I think that 12HL7 tube is running hotter now.

zeno · #**108** 10-09-2015, 04:22 PM

First the 12HL7 shows it is cut off IMHO which gives a
high plate V so high CRT cathode so dark pix.
The 12HL7 is a 12 V tube BUT the filament is tapped so you can
run it at 6VAC in a series set.
You should get apx 6 VAC at pins 4 & 5 to ground.
Pin 6 must go to GND. Its the tap.
Next change the 12HL7 its fast & easy & eliminates it.

BTW looking at my Sams under better light I see tiny
check marks around the drives & other plate components.
Someone may have been chasing the same problem. They
DID NOT do what they should have, write down the sympton
& cure, ass hole............
Gotta put the feed bag on, more later.

73 Zeno

MRX37 · #**109** 10-09-2015, 05:56 PM

Quote:

Originally Posted by zeno

Next change the 12HL7 its fast & easy & eliminates it.

I need a spare 12HL7. I can order one on eBay, they're cheap enough. However before I do that, should I check to see if anything else might be open?

zeno · #**110** 10-10-2015, 08:28 AM

While waiting for 12HL7 check from Q4 & Q5 over
to the 12HL7.
Also R147 & 153 at 6LR6 grid 1.
I would also price a 40 KV HV probe, you may need one
for the focus problem. Can discharge CRT with it also.

73 Zeno

andy · #**111** 10-10-2015, 09:41 AM

...

MRX37 · #**112** 10-10-2015, 02:38 PM

Quote:

Originally Posted by zeno

While waiting for 12HL7 check from Q4 & Q5 over
to the 12HL7.
Also R147 & 153 at 6LR6 grid 1.
I would also price a 40 KV HV probe, you may need one
for the focus problem. Can discharge CRT with it also.

73 Zeno

Little confused by this. Check what from Q4 and Q5? Voltage to ground? Continuity?

I'll hunt down R147 and 153 when I have some time, probably Monday. Depending on whether or not they're good, I'll see about acquiring a 12HL7

zeno · #**113** 10-10-2015, 04:59 PM

Check voltages. Also especially any high ohm resistors over
say 50 K ohm. Test coils, IIRC there are 2 of them. Test the transistors also.

Also as stated early Sams gave things there own designations. Parts
on a PCB may not line up with the Sams numbers. Also a factory ( FSM)
service manual may have different numbers. This changed it latter
years but dont remember when. Just gotta live with that.

Quote:

Originally Posted by MRX37

Little confused by this. Check what from Q4 and Q5? Voltage to ground? Continuity?

I'll hunt down R147 and 153 when I have some time, probably Monday. Depending on whether or not they're good, I'll see about acquiring a 12HL7

MRX37 · #**114** 10-12-2015, 12:20 PM

Okay, I believe Q4 and Q5 are supposed to be the transistors for 1st and 2nd video amp. I had a few minutes to do some testing so i tested the voltages for the 2nd video amp transistor: (the one closest to the delay line)

Emitter: 9.6 volts, raising to 10, then dropping to 9.8 upon warm up.
Base: 14 volts, going to 15, then dropping to 14.5
Collector:14.9, going to 15.7, dropping to 15.1

If need be I'll get voltages for the 1st video amp transistor later.

DavGoodlin · #**115** 10-13-2015, 03:52 PM

Remove and test those transistors with your DMM on the "diode function".
I recall GE sets of this vintage (KE chassis) with similar symptoms from shorted video driver transistors.

The emitter and base voltages should not be more than 0.6 volts difference.
It may be shorted by the look of those voltages unless you have E and C mixed up.

MRX37 · #**116** 10-13-2015, 04:30 PM

Quote:

Originally Posted by DavGoodlin

It may be shorted by the look of those voltages unless you have E and C mixed up.

I obtained the voltages by testing one pin at a time, using chassis ground for the DMM's negative lead. The transistors has EBC labeled for the pins. I doubt I messed up the order.

Pulled the transistor and tested it using the diode function:

Collector to base: voltage going one way but not the other.
Emitter to base, same reading. Voltage one way but not the other.
Emitter to collector, no reading either way.

Edit: transistor for the 1st video amp tests the same way.

I have a new 12HL7 coming in the mail. Should have it by Monday. See if popping that in makes a difference.

MRX37 · #**117** 10-19-2015, 11:12 AM

Okay I received the new 12HL7 in the mail today. Popped it in. No change.

Brightness control still operates in reverse. Picture is still dim and unfocused.

The only thing I can think to do from here is pull the neck socket again and test the voltages there.

MRX37 · #**118** 10-24-2015, 05:54 PM

There's been a new development!

I am now the owner of an EMC 213 tube tester! So I've been testing the tubes in this TV, well at least the ones listed in the user guide. This tester was made in 1964, this TV is a bit newer then that so I couldn't test some of tubes. However I discovered something odd.

The HV rectifier tube that's in this set is a 3A3B.

The TV's schematic calls for a 3CU3.

Could this be a contributing factor in why the image is dim and/or blurry?

Can't test the 3A3B unfortunately. It's not listed in the tube chart for this tester.

Captainclock · #**119** 10-24-2015, 06:28 PM

Quote:

Originally Posted by MRX37

There's been a new development!

I am now the owner of an EMC 213 tube tester! So I've been testing the tubes in this TV, well at least the ones listed in the user guide. This tester was made in 1964, this TV is a bit newer then that so I couldn't test some of tubes. However I discovered something odd.

The HV rectifier tube that's in this set is a 3A3B.

The TV's schematic calls for a 3CU3.

Could this be a contributing factor in why the image is dim and/or blurry?

Can't test the 3A3B unfortunately. It's not listed in the tube chart for this tester.

I actually have the 3A3 tube and also the 3CU3 tube as well I believe and I'm surprised the tester I sent you can't test the 3A3 tube...

Scratch that, Just took a look at the chart and the tube tester I sent you CAN test a 3A3 tube, generally tube tester charts don't put the letter suffixes after the tube designation because they're all the same tube just different heater warmup times.

MRX37 · #**120** 10-24-2015, 06:58 PM

Need to find out of that tube is a proper substitute for the 3CU3 that should be in there.