Ham International MM2 problem

[Ron Fouler]

Here's what happened. Got this radio from EBay and it worked fine. Suddenly, a couple of days ago, it stopped TXing on certain channels. Could the chan selector switch be FUBAR'd, or could it just be a dry joint? It makes a difference if I go up or down to the channels, but I have nothing between 1 - 16, and intermittent on 17, then nothing til 31 (going up) or 27 (going down), after which it's "normal".
Help, please!

[Rick]

You need to check the VCO voltage at the test point while changing channel, the voltage should change about 0.02 volt per channel if it does not it is probably the PLL chip, as the PLL is known to fail in the cybernet radios.

Rick

[Ron Fouler]

It's very intermittent. Some channels work sometimes if I jiggle my knob a bit (oooh err, obviously), some work anyway, some have recieve, some have nothing. I've tried contact cleaner and that's helped a bit, but it looks like it may be a buggered switch because it's the same on all bands and in all modes. Anyone else have any input?
TiA

[Rick]

If it is the Channel switch why not just take it apart and give it a clean out, Ask Dave Zodiac he lovers the job, I my self I would just put a new one in.

Rick

[zodiac]

Thanks Rick, does that mean you have NEW channel switches for Cybernet SSB radios.
Dave.

[Ron Fouler]

Thanks Rick, does that mean you have NEW channel switches for Cybernet SSB radios.
Dave.

I was gonna ask about that
OK, Zody, how should I go about cleaning my channel switch ?

[zodiac]

To clean the switch you have to remove it from the radio, so before you do make sure it is the switch that's faulty. I would desolder the pins that go to the PLL as they sometimes brake at the solder joint, by doing this it may show a broken track up. If you find there is no track broken then desolder the other side of the switch and ease the board from the pins. Do not try to remove the switch from the main board at this point. You will have to remove the front of the radio and remove the nut holding the switch to it, then remove the screw and the long brass spacer screw that holds the LED board to the front of the radio. Once you've done that you should be able to remove the channel switch from the main board and the LED board. Mark everything as you go along, if you dont you'll end up with a switch that doesn't work correct like LED's with odd looking numbers. The switch has three discs inside three segments, two of the segments pins face one way and the other faces the opposite way this is the segment which gives the channel codes. To pull the switch apart bend the 4 bits of bent metal that go through the slots in the back plate straight to line them up with the slots in the plate. Now slide each segment off the shaft one at a time and open it up without braking the pins. Make sure you've marked the plastic segments so you dont mix them up or put them in the wrong way round, you can't mark the discs so take note of the way they are when you first open each segment. Now clean the disc and the contacts and hope you remembered which way it goes back together again. Or you could just buy a new clean one from Rick.
Dave.

[zodiac]

Ron,
Forgot to mention there is a black spacer between the switch and the front of the radio, you'll see it when you remove the plastic front, well you see two holes with the plastic poking through them, touch the plastic with your soldering iron to keep it in place and stop it falling out before you remove the switch.
Dave.

[Ron Fouler]

Err.... I think I'll leave it to someone that knows how to do it.... anyone know a reliable, trustworthy, fast and inexpensive rig-doctor in my area (Hertfordshire, England)?

[Chevin]

have a look on www.open-channel.co.uk

[Ron Fouler]

Rick, I see you in there: Where in Beds are you? Would it be feasable to send the rig to you and collect it in person when it's done?