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.

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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


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