[channelf] Fixing an ITT Tele-match

  • From: Fredric QJ Blåholtz <e5frog@xxxxxxxxx>
  • To: channel_f_and_videobrain@xxxxxxxxxxxxxxx, channelf@xxxxxxxxxxxxx
  • Date: Sat, 15 Jun 2013 23:08:50 +0200

I bought an ITT Tele-match from eBay, pretty cheap for something called
fully functional (17 Euro). Shipping was a bit more than the auction price
though.

Received it, poorly packed, a newspaper page in the bottom, flat, console
with no bag around it or other protection and then broken off parts of
styrofoam on top of that, loose little white pearls all over and inside the
console...

Anyway, it took some time before I got to try it but I did today and the
LED lit up fine but I couldn't get any picture at all. As I was trying it
on a recently aquired TV that I had just been tuning the service menu on I
thought I may have messed something up (although the Luxor had a perfect
picture on a different frequency).

Tried it on another TV, nothing, third one, really old with eight channels
and manual tuning... no remote, but nothing...

So, after complaining through eBay I opened her up and took a peek. No 12V
at all, transformer humming, to the 12V regulator there was only 13.2V -
should be something like 18.
As I have had this problem before I pulled the RF modulator box from the
motherboard (it's in a socket) and I got the proper voltages...
Even saw some G? floating faintly on the TV screen in reverse luminance.

So, desoldered the sides of the RF box and desoldered the red little
suspect - it was shorted alright, 0.2-1.3 Ohms depending on direction.
Tantalum capacitor, don't know if they fail from age or what goes wrong.

I replaced it with what I had, a plain electrolytic cap 25V instead of 16
and checked it with ESR meter and multimeter before soldering it in - all
good.
Problem solved... but sound was awful and didn't get normal until I had
tuned the TV so much that the color disappeared and I got distortion - so I
had to tune the sound frequency pot as well and then it was good. Someone
had been at this before apparently and didn't quite manage to find or solve
the problem. Rusted fingerprints on the RF box metal and also on the VSLI
circuit metal chip cover. The bottom sticker was also broken to get to the
channel tuner.

Then when trying it out I noticed the controllers felt fine but all
directions weren't working. I was worried I had damaged a chip when
cleaning the black silver oxide from the pins but after moving the knob
around a bit it started working so I guess it was just
dirt/styrofoam/oxide... I'll probably open and check sometime.

So fully working now, can't possibly have been that when it was sold.

I took some pictures while working:
http://s17.postimg.org/n87h85isv/IMG_2691.jpg
http://s17.postimg.org/cqhfcehyn/IMG_2694.jpg
http://s17.postimg.org/otrcdpien/IMG_2695.jpg
http://s17.postimg.org/hf20lbwj3/IMG_2696.jpg
http://s17.postimg.org/x1t9ypab3/IMG_2698.jpg
http://s17.postimg.org/xsm04hcof/IMG_2701.jpg
http://s17.postimg.org/7mur1xw8f/IMG_2702.jpg
http://s17.postimg.org/fr2v6oinj/IMG_2704.jpg
http://s17.postimg.org/5jfqgj71r/IMG_2705.jpg

/ Fredric
-- 
__________________________________
* Fairchild Channel F collector extraordinaire *
http://channelf.se - The Gallery of Channel F

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  • » [channelf] Fixing an ITT Tele-match - Fredric QJ Blåholtz