Italian 1962 TV B&W

[Sparky]

That 1nF would be more in line with the proper value. I am curious what is the the signal looking like (P-P) on the plate of the 15TP7 and the cathode of the CRT? Also, could you post a clearer picture of the video section as I cannot read the fine print. One area in question is the left section of the 16TP8. Does it say blanking driver?

Originally Posted by lucvic

Hi,
in last week end no time to work on this,
but this evening I found two things:

1) R557 increased from 5.6Meg to 27Meg ( tomorrow I will change)
2) someone in the past changed C549 (cathode of final video amplifier)
from 470pF to 100uF. I don't have one, I put a 1nF but the contrast in the
screen is very reduced compared to the 100uF.

In attach the pic of the signals at grid of video amplifier (TP5)
and node between F902 and K112.

I hope tomorrow I will get more news.

bye

[lucvic]

I hope this pic will be clearer...
if your question is
regarding the 16tp8 text "canc or" ==> "horizontal blanking"

[Sparky]

The text is still not readable but that's OK, I understand now what it says. That was the question.
Have you been able to take some measurements with a scope on the plate and cathode yet?

Originally Posted by lucvic

I hope this pic will be clearer...
if your question is
regarding the 16tp8 text "canc or" ==> "horizontal blanking"

[lucvic]

In these days I don't hve my camera,
I hope tomorrow yes, plate of 15tp7 and cathode of
CRT correct?

[lucvic]

Hi guys,

last evening I tried to make a photo of the signals requested
but I found a new issue.
The signal at the videodetector was suddenly disappeared.
Seemed a bad contact but in 2 hours I didn't fix this.
After various simple checks I was very sad of this but the
signal magically re appear. Can this be a problem on high frequency
down converter or oscillator?
This set have two inputs VHF and UHF and two different tuners.
Since starting on this project I have used a VHF signal I didn't try to switch on the UHF signal.
I will try again to fix the issue tonight.

thank you

[lucvic]

here I am,
today I had some time to work on this TV.
I found some differences in voltages at electrolytic caps
(anodes of the tubes).
This difference was because I substituted the the diodes (2 PY82) with one 1n4007 with a resistor 82 ohm in series. This was a mistake because the 82 ohm is the resistance of one tube but the PY82 are connected in parallel.
Now the vertical sync is more stable but the sound have some troubles yet.
ASAP I will post some images.

thank you for your help

[lucvic]

Hi dear all,
some work on this project in these days,
I found some docs on this set,
various vawes are shown and the first I see is the amplitude
at grid of output video amplifier.
The value I have i 2.5V pk to pk.
This value in doc is between 2.5 to 8 V pk to pk.
So I figure there are troubles in tuner or IF, or a overload of these two
sections.
AGC seems to work propely because bias of IF tube increases if I slightly disconnect the antenna.

Any suggestion on verify I can do?

many thanks