Philco Safari Problem - raster and weak sound, but no picture - please help!

[goat1981]

Thanks for the replies, guys!

Originally Posted by Electronic M

I have a parts chassis (no cabinet trim no CRT) if you need anything.

Thanks for this as well! I may contact you if I need to purchase a part based on what everyone says.

Here is a link to the schematic (JPEG image on my box account)

https://app.box.com/s/8p6u58ccdusfxwhzi36npmc4t34aawyx

I have already replaced all the electrolytic (polar and non polar) and paper caps, but have left the ceramic caps alone. Still have only raster, scratchy sound and no pic. Changing the channels does nothing to what I see on the screen.

The test points are described in the service manual as follows:

TP1 should be -.35V and is the Horizontal Oscillator Base (reads on spec)
TP2 should be -.35V and is the Horizontal Stability Coil (reads on spec)

Test Points 3 - 5 on the Video/Audio/Sync board are quite off.

TP 3 should be 1.5V and is the Video IF Bias (reads -.2V)
TP 4 should be 10V and is the 1st Video Base (reads 7.4V)
TP 5 should be .05V and is the Sync Sep Base (reads -.05V)

Again, the +/- 11 volt supply reads quite low at around +/- 8.5v.

Thanks again for all your help.

[zeno]

For now measure voltages on all 4 IF & the video out transistors.
Look for something way off. The +11 runs most of the low level stuff
& may be getting loaded down.

73 Zeno

[Zenith26kc20]

Be careful, the transistors ARE germanium. If I remember correctly, Philco developed the surface barrier transistor that made this set possible. These sets usually have dried out electrolytics causing all kinds of symptoms.
I would get a cheap ESR meter to check the electrolytics. Since they are mostly low voltage, the ESR meter can find them easier than the high voltage ones.
Once working these sets are great!

[goat1981]

Originally Posted by Zenith26kc20

Be careful, the transistors ARE germanium. If I remember correctly, Philco developed the surface barrier transistor that made this set possible. These sets usually have dried out electrolytics causing all kinds of symptoms.
I would get a cheap ESR meter to check the electrolytics. Since they are mostly low voltage, the ESR meter can find them easier than the high voltage ones.
Once working these sets are great!

I have already replaced all the paper/electrolytic capacitors, so those shouldn't be an issue.

I'll start checking voltages in the IF stages when I have some time. Any other opinions/suggestions are welcome in the meantime.

Thanks for your help, everyone.

[rca2000]

WELL...a question I asked some months ago...has been ASNWERED !!

The safari DOES use the flyback...for some Low B voltage sources !! NEVER knew this...

SO...I would have to wonder:: Is the voltage TO the flyback--looks like a 5 volt supply--OK? If NOT...ALL outputs will be LOW..

And like others have said...it is possible--you have a heavy load on the 11 volt source...

I ASSUME...the diodes in this set are silicon. If NOT...if they are SELENIUM...CHANGE them--they DO get WEAK--OFTEN.

[goat1981]

Hey guys,

I just got done taking voltage readings of all the IF stage transistors, the Video Amp transistor, and the Video Output transistor and found some interesting results (especially the video out transistor...)

Here are the readings in order of what's specified on SAMS and what I read with my multimeter.

Supply Voltages:
-5v -- reads -4.4v
+11v -- reads +8.2v
-11v -- reads -8.8v

First IF Transistor (X1)
Base -- 1.5v -- reads 0.85v
Collector -- 0v -- reads 0v
Emitter -- 2v -- reads 1.22v

Second IF Transistor (X2)
Base -- 2.0v -- reads 1.27v
Collector -- 0v -- reads 0v
Emitter -- 2.2v -- reads 1.57v

Third IF Transistor (X3)
Base -- 8.5v -- reads 6.62v
Collector -- 0v -- reads 0v
Emitter -- 8.6v -- reads 6.77v

Fourth IF Transistor (X4)
Base -- 8.5v -- reads 6.37v
Collector -- 0v -- reads 0v
Emitter -- 8.6v -- reads 6.58v

Video Amp Transistor (X5)
Base -- 10v -- reads 7.28v
Collector -- 4v -- reads 2.84v
Emitter -- 9v -- reads 7.5v

Video Output Transistor (X6) -- here is where the problem is...
Base -- 9v -- reads 6.65v
Collector -- 9.5v -- reads -8.66v (!)
Emitter -- 0.5v -- reads 8.11v (!)

Could it be a bad Video Output transistor? I haven't replaced any of the diodes, which are the original 1N60A germanium diodes -- these seem pretty common and I can replace them if you think it'll help.

What do you guys think about these readings? If you missed the schematic, I included it in a previous post.

Thanks again for your help!

[goat1981]

An update!

I found broken circuit traces on the Video/Audio/Sync board! This TV must've undergone some kind of trauma in the past. Maybe it was left in the heat or dropped?

I found four traces that lacked continuity. I found this when I was checking voltages and two points on the same trace had different voltages...

https://app.box.com/s/s3yxjeabwn8b6k27act3jygq3k2ou2uv

I soldered in some jumper wires and got a picture and sound!

https://app.box.com/s/pjip2xjvoovx1dz86p9l2ztkmjgziflw

There are still some issues, but this is progress. The focus and linearity aren't that great. Also, I am having trouble getting clear sound. There is a buzz that slowly goes in and out in the sound. I uploaded a video of this behavior on my box account. Link:

https://app.box.com/s/txgqhar3szysgyitb9jta9evc6f6fvua

I am wondering if it's the type of modulator (a cheap one I bought at Walmart) that I'm using, because the same thing happens on a Sony 5-303W that I have. Either that, or both TVs have the same problem (I haven't really worked too much on the Sony yet).

Thoughts? Could it be bad diodes? Again, thanks for all of your help!

P.S. Sorry for the huge pictures. Any way to control that?