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563buzz [2007/05/20 20:43] (current)
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 +====== Omni VI Power Up Buzz ======
 +**From the Ten-Tec Reflector January 25, 2004**
  
 +Woke up this morning to a problem with my OmniVI Opt/1 and 962.  On startup there is a buzz (brrrrrr) for a few seconds form the rear center to left of the radio and the display comes up a half brightness.  I then tried feeding the radio with 12v from a astron supply and while I don't hear the buzz the display was still at low brightness.
 +
 +........Stuff Deleted........
 +
 +Jeff\\ 
 +KT2K
 +
 +----
 +**January 28, 2004**
 +
 +I had a problem with an OMNI VI+ (964) and 962 combo this past CQWW CW contest.  The buzzing had been happening at power up from time to time for a year or so.  But, after the second or two of buzzing, things always worked ok, even with 48hour duty cycle.  So, I ignored it.  Well, right at the beginning of the contest, every time I tried to transmit, the rig would go bonkers (technical term), the power supply would buzz, rig lights would dim, etc.  This happened for at least 15 minutes.  I couldn't figure out an easy answer, so I powered down and used the other OMNI VI for the remainder of the contest.    
 +
 +After the contest I called TT service and asked some questions.  I thought my trusty rig had given up the ghost.  But, no, it was the
 +power supply!  To demonstrate this, I used an analog voltmeter on the accessory +12v at the back of the supply.  With just the power
 +supply on, it reads a solid 13.8v.  But, when the on/off switch on the 964 was turned on, the buzzing from the rig was accompanied by the voltmeter shown a large overshoot in voltage, past 16v!  So, the rig was doing it's thing and protecting against overvoltage from
 +the power supply.  TT service indicated that some, but not all, 962s have this problem.  The fix is to put a few components on the PC
 +board on the back panel of the PS.  This is not recommended for home repair.  Apparently the regulation circuitry in the negative
 +lead has some instability potential.
 +
 +I swapped the 962 PS with the 961 PS on the other rig.  Both appear to be happy now.  I can't get the buzzing to show up at all.  But, if (when) the problem reappears, I know to swap out power supplies. Round trip shipping and repair doesn't make economic sense to me.
 +
 +Terry Zivney, N4TZ/9