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Restoration of a digital to analog converter box
wa2ise
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Posts: 77
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Joined: Nov 2010
City: Oradell, NJ
#1

03-18-2020, 04:41 PM
This is about fixing a bad set top converter box, for your Philco TV set. 

I had a dead Channel Master CM7000 HDTV to NTSC analog converter box.  Its red pilot light, usually an indicator that lights during a boot-up after plugging this box to the powerline, never went to green or orange (indicating it is ready for the user)

As is usual with electronics made recently, it had bad leaded electrolytic caps.  Googled "dead CM7000" and found this thread: https://www.avsforum.com/forum/27-replay...st59384596

I already tested the power supply by using it to power the "logic" board in another CM7000, and it worked.  So the problem is in the dead box's "logic" board.  I got joy   Icon_smile after changing caps E5 and E6 (as marked on the circuit board).  These caps are filters on switching DC-DC voltage converters, going from 5V (or is it 12V) to 3.3V and a second circuit 1.2V.
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morzh
Odobenus rosmarus
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Posts: 15,817
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City: Jackson, NJ
#2

03-18-2020, 05:00 PM
Who made the caps and what kind?
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
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wa2ise
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Posts: 77
Threads: 24
Joined: Nov 2010
City: Oradell, NJ
#3

03-19-2020, 03:07 PM
I tossed them in the trash, I took a look to see if I could find them, but couldn't find them.  They were some no-name brand of aluminum leaded electrolytic cap made of Chineseium...
(This post was last modified: 03-19-2020, 03:08 PM by wa2ise.)
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  1. The PHILCO Phorum
  2. Philco Radio Discussions
  3. Philco Electronic Restoration