Trio TS120V only zeros on display when turned-on - UK Vintage Radio Repair and Restoration Discussion Forum

Skylark UK · 5th Dec 2022, 12:43 pm

I have a Trio TS120V which I've owned since the 1980s. It doesn't get a lot of use but it's enjoyable when it does.

When I power it up, the digital display reads "band.000.0" for example "14.000.0 or 7.000.0"

The set is otherwise working, the VFO will sweep and the S meter responds to signals, just that the display appears not to have built a head of steam.

After a couple of minutes, the display will show the correct frequency, eg, "14.142.7 or 7.142.7" and so on throughout its frequency range.

Is anyone intimately familiar with these rigs and could point me in the right direction, please?

Although I've held a license since 1982 I'm more of a mechanical engineer than electrical. I also respect the radio Hippocratic oath "first, do not harm"

Many thanks for any input.

Techman · 5th Dec 2022, 2:05 pm

I'm not familiar with this set whatsoever, but some years ago someone asked me to look at a set that had a similar problem from what I remember. I found that there was a small rechargeable backup battery soldered onto the board that was failing and not holding its charge during periods of disuse. Once the battery had taken a charge after the set had been on for a while, everything was normal again - the set always defaulted to 14MHz LSB when the battery was flat...perhaps not the same fault as you've got, but just a thought.

Radio Wrangler · 5th Dec 2022, 3:00 pm

There may be a loss of signal in the path from the VFO to the counter. The counter then properly counts zero cycles.

David

Jon_G4MDC · 5th Dec 2022, 3:45 pm

There is a mixer for the 5.5 - 6MHz of the VFO with 5MHz down to 0.5-1MHz before counting.

The MHz digits are from diode matrix, the kHz and Hz digits come from the counter. It says it blanks if the count is out of range.
I don't think yours is doing that. I assume blank means digit off.

5th Dec 2022, 12:43 pm	#1
Skylark UK Triode Join Date: Nov 2020 Location: Altrincham, Greater Manchester, UK. Posts: 28	Trio TS120V only zeros on display when turned-on I have a Trio TS120V which I've owned since the 1980s. It doesn't get a lot of use but it's enjoyable when it does. When I power it up, the digital display reads "band.000.0" for example "14.000.0 or 7.000.0" The set is otherwise working, the VFO will sweep and the S meter responds to signals, just that the display appears not to have built a head of steam. After a couple of minutes, the display will show the correct frequency, eg, "14.142.7 or 7.142.7" and so on throughout its frequency range. Is anyone intimately familiar with these rigs and could point me in the right direction, please? Although I've held a license since 1982 I'm more of a mechanical engineer than electrical. I also respect the radio Hippocratic oath "first, do not harm" Many thanks for any input.

5th Dec 2022, 2:05 pm	#2
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Trio TS120V only zeros on display when turned-on I'm not familiar with this set whatsoever, but some years ago someone asked me to look at a set that had a similar problem from what I remember. I found that there was a small rechargeable backup battery soldered onto the board that was failing and not holding its charge during periods of disuse. Once the battery had taken a charge after the set had been on for a while, everything was normal again - the set always defaulted to 14MHz LSB when the battery was flat...perhaps not the same fault as you've got, but just a thought.

5th Dec 2022, 3:00 pm	#3
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Trio TS120V only zeros on display when turned-on There may be a loss of signal in the path from the VFO to the counter. The counter then properly counts zero cycles. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

5th Dec 2022, 3:45 pm	#4
Jon_G4MDC Nonode Join Date: Nov 2015 Location: Welwyn Garden City, Hertfordshire, UK. Posts: 2,015	Re: Trio TS120V only zeros on display when turned-on There is a mixer for the 5.5 - 6MHz of the VFO with 5MHz down to 0.5-1MHz before counting. The MHz digits are from diode matrix, the kHz and Hz digits come from the counter. It says it blanks if the count is out of range. I don't think yours is doing that. I assume blank means digit off.