[Coco] Re: Re: New CoCo 3 - RF Out problem

[chadbh74]

   I have a scope and a ESR tester.  Also got the service manual.  Will
   have to check what I can as time permits.  The exterior and interior of
   the case have good color and no signs of corrosion.   The rubber feet
   are all missing and the bottom of the case is cracked near one foot.
   However, there appears to be no damage to the PCB.

   -Chad

   https://sites.google.com/site/cbhlab101/

   Sent from my Galaxy S4

   --------- Original Message ---------
   From: Zippster
   To: CoCoList for Color Computer Enthusiasts
   Date: Sun Oct 25 19:40:51 CDT 2015
   Subject: Re: [Coco]A Re: New CoCo 3 - RF Out problem
   Hi Chad,
   As Rogelio was saying, check the 8v supply to the RF.
   The fact that composite out is working tells me that the Q3 EF circuit
   is working.
   The output is split off right after that to both the RF box and another
   EF to the
   composite out jack.
   The output from Q3 is AC coupled via C67 into the RF box. I'd check to
   make sure
   that cap (an electrolytic) is good, and that the video signal is making
   it into the box.
   The only things I see in the modulator that might have gone bad are a
   couple of small
   electrolytics, and a couple of transistors(less likely).
   Do you have a scope? Definitely entering territory where one would help
   here.
   - Ed
   > On Oct 25, 2015, at 6:46 PM, chadbh74 <chadbh74 at hotmail.com> wrote:
   >
   > It's a 26-3334
   >
   > -Chad
   >
   > https://sites.google.com/site/cbhlab101/
   >
   > Sent from my Galaxy S4
   >
   > --------- Original Message ---------
   > From: Al Hartman
   > To: CoCoList for Color Computer Enthusiasts
   > Date: Sun Oct 25 18:26:52 CDT 2015
   > Subject: Re: [Coco] New CoCo 3 - RF Out problem
   > What's the catalog number on the unit?
   > Could it be a PAL Coco 3?
   > -[ Al ]-
   > -----Original Message-----
   > From: Chad H
   > Sent: Sunday, October 25, 2015 6:23 PM
   > To: 'CoCoList for Color Computer Enthusiasts'
   > Subject: [Coco] New CoCo 3 - RF Out problem
   > I FINALLY acquired a CoCo 3 that was in uncertain condition. He said
   > the
   > last time it was used years ago it worked fine though. It was still
   > sealed
   > appears to be the base 128K setup. The first thing I did was switch
   my
   > RF
   > cable from my CoCo 2 to the CoCo 3 and power up...click but nothing
   > else. I
   > pressed the RESET button and could hear the relay click, but snowy
   > picture
   > on the old TV. Switched the RF 3/4 switch a few times and nothing.
   Put
   > the
   > cable back to the CoCo 2 and its perfect image again.
   > I then took the unit to another TV that had a front hookup for RCA
   Line
   > IN
   > and hooked it up that way. The expected startup message comes right
   up,
   > nice and clean.
   > Anyone have idea what could be going on here? Simple fix I hope. I
   > could
   > still use it in Line IN mode but I would rather have the CoCo FULLY
   > functional if possible.
   > - Chad H
   > http://sites.google.com/site/cbhlab101/
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