Another 819 line TV set. - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Maarten · 25th Jul 2018, 7:35 pm

Quote:

Originally Posted by FERNSEH

Hi Maarten,
I've found the production and date codes of the CRT printed on the aquadag.

NE4
Z3E
234

It will be be possible to find out which Philips works made the tube. Date of manufacture was May 1973.

Correction: the model number of the receiver is 1594-3.

DFWB.

NE4 confirms the 4th version of the A61-120W. 3E is indeed for May 1973. I'm not 100% sure, but the Z is for Philips Monza if the factory letters are shared with receiving tubes.

FERNSEH · 30th Jul 2018, 4:36 pm

Turning my attention to the timebase panel.
The "S" correction capacitors have been identified and the appropriate capacitor for the line standard is selected remotely by those switches attached to the channel sector button unit. The number of line timebase switches has been kept to a minimum, the line oscillator must operate on 15,625Hz or 20,475 Hz. so no doubt there will be wires to the channel sector to carry out that function.
How the characteristics of the vision IF amplifier are altered for system E and L is still a mystery? No problems with the AM sound IF amplifier because it is the same frequency for both systems, that is, 39.2Mhz.
The values of those burnt resistors must be found out, so the actual function of the resistors must be determined. Most likely they in the line output stage stabilising circuits.

DFWB.

FERNSEH · 30th Jul 2018, 5:05 pm

One of the burnt out resistors still has it's colours; yellow, violet and red - 4.7K and it's safe to assume the other resistor has the same value.
Edit: damping resistor across the line linearity coil.

DFWB.

30th Jul 2018, 4:36 pm	#22
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Another 819 line TV set. Turning my attention to the timebase panel. The "S" correction capacitors have been identified and the appropriate capacitor for the line standard is selected remotely by those switches attached to the channel sector button unit. The number of line timebase switches has been kept to a minimum, the line oscillator must operate on 15,625Hz or 20,475 Hz. so no doubt there will be wires to the channel sector to carry out that function. How the characteristics of the vision IF amplifier are altered for system E and L is still a mystery? No problems with the AM sound IF amplifier because it is the same frequency for both systems, that is, 39.2Mhz. The values of those burnt resistors must be found out, so the actual function of the resistors must be determined. Most likely they in the line output stage stabilising circuits. DFWB. Attached Thumbnails

30th Jul 2018, 5:05 pm	#23
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Another 819 line TV set. One of the burnt out resistors still has it's colours; yellow, violet and red - 4.7K and it's safe to assume the other resistor has the same value. Edit: damping resistor across the line linearity coil. DFWB. Attached Thumbnails Last edited by FERNSEH; 30th Jul 2018 at 5:15 pm.