MCS2000 "BONK" on keyup

[cleb]

I recently purchased a MCS2000 VHF 110w. When I first got the unit, it had a handful of conventional channels programmed into it. When I would key the radio, I would hear a short, momentary BONK on keyup, and it would TX fine. No MDC setup on any of the channels, and it would do it on all of the channels programmed into the unit. I deleted all of the conventional personalities, and added my personalities in using the latest CPS. After writing the radio, I did not hear the BONK until yesterday. I was out on a call, and all of the sudden it Bonk'd at keyup on every transmission. I changed nothing with regards to the radio, its mounting, or configuration. I read, and re-wrote the radio today, and it still does it. Only way to turn it off is to disable alert tones, which I don't like. Any way to diagnose whats going on? The radio transmits fine, even with the bonk. No noticeable degradation of signal. No MDC setup on the conventional personalities, and I think I even disabled MDC PTT sidetone just to be sure. But, MDC shouldn't be a bonk anyways... I'm out of ideas.

Thanks,

c

[DPL]

Does the radio show anything on the display when it bonks? My first thought is the VCO is momentarily going out of lock. I believe it will show FAIL001 or something similar on the screen when it does this, but I'm not sure because I don't have much experience with the MCS2000. I would ask if you're running any out-of-band frequencies, but IIRC the bandsplit on that radio is 136-174 so probably not.

[cleb]

Nothing changes on the display when I hear the bonk. The frequency range is 146-174, and the frequencies I am running are 153-155. Strange indeed.

[maxkelley_kc2spy]

I would get bonks randomly on my 900mhz MCS... I eventually disassembled it, made sure the regulators were firmly mounted to the board, and I think that did it... I know I solved the issue, I just can't remember if that's exactly how I solved it or not...

[cleb]

I would get bonks randomly on my 900mhz MCS... I eventually disassembled it, made sure the regulators were firmly mounted to the board, and I think that did it... I know I solved the issue, I just can't remember if that's exactly how I solved it or not...

Thanks for the info. Could you provide more detail on where these regulators are, and how you ensured they were firmly mounted? Sounds like something worth investigating.

c

[Pj]

I don't know if the MCS has it as an option, but if its secure equipped, "clear TX tones" might be selected. This will cause a beep on TX alerting the user that secure is not selected. MCS2000 are secure capable, so you should check the secure setup screens for that.

[cleb]

Pj: I just checked that screen. Secure was disabled (I don't think it has the module) and Clear TX tones was checked. I enabled secure, unchecked the Clear TX Tones box, and disabled secure. Still getting the short Bonk on keyup.

[Pj]

I'm with DPL on this one, or there is an obscure MDC/audio/option setting checked off somewhere that isn't all that obvious.

[resqguy911]

Tx inhibit on busy? Smart PTT enabled?

[cleb]

I went back through the codeplug again and confirmed that no MDC/Smart PTT/Encryption settings were causing the radio to bonk. Starting to look like a hardware issue. Anyone else have any info on the regulators maxkelley_kc2spy mentioned?

Thanks,

c

[maxkelley_kc2spy]

Sorry I disappeared... You've got to take the radio apart, and facing the front of the radio (as you normally would), there's the audio PA IC and two regulators on the underside of the main board, on the left side closest to you. Reflow these with fresh solder and see if that makes a difference. There's metal clips that clamp them to the chassis of the radio to heatsink them. Try reflowing the regulators, then before putting the clips back on and the radio back together, try the radio out to see if it still bonks.
I guess the issue with these is that the little metal clips would push the ICs against the chassis for heatsinking, which is good, but at the same time they would stress the solder joints, causing intermittent problems.

[cleb]

Earlier this week the radio started more strange behavior. When I would hang up the mic, the radio would start transmitting. Taking the mic off the hang up would stop the TX. I would then key the radio, and it would reboot the radio (Display would go blank, then the self test would start. I took the drawer and control head apart, and re-flowed the regulators. So far it seems to be behaving, but time will tell. Anyone seen this behavior from a MCS before?

c

[HLA]

is the mic cable frayed or did anything get in the mic connector?

[cleb]

HLA: Negative to both counts. Mic is in good condition, and the Mic connector on the control head is intact.

[WB6DGN]

Where is primary power connected; directly at the battery? Are contacts clean and is the fuse and its contacts clean and tight? Might also try swapping fuse with a new one and cleaning all contacts even if they look clean and bright. Some radios "Bonk" when pri. voltage drops too low. Just a shot in the dark.
Tom