MTS2000 Jedi - removing mic/speaker flex cable

[g8tzl2004]

Any hints on removing the mic/speaker flex cable?

How do you remove the mic part? Is the mic insert soldered to the flex? There is some form of "enclosure" around the mic insert..I'm not sure how to get into this?

Is the flex soldered to the front case "DTMF" PCB. There is a bank of 2 rows of solder points - is this where the flex is soldered to the PCB or is it some kind of plug assembly which pushes into the PCB?

Thanks

[g8tzl2004]

Any ideas?

[WB6DGN]

"Any hints on removing the mic/speaker flex cable?"
Remove the piece of capton tape over the contacts on the flex where they're soldered to the board. Then carefully use a vacuum desoldering tool to clean as much solder off of the contacts as possible. If necessary, use a soldering iron set at 550 to 600 degrees, starting from a corner and "tap" any contacts that are still adhered to the board OR use a hot air handpiece set at about 450 degrees and keep SLIGHT tension on the flex until it lifts off.

"How do you remove the mic part? Is the mic insert soldered to the flex? There is some form of "enclosure" around the mic insert..I'm not sure how to get into this?"
The mic. element is soldered directly to the flex. Again, the vacuum desoldering tool works well here. The mic. element is "encased" in a split rubber(?) casing. When you lift it out of its "receptacle" in the case, that "casing" will fold open to remove the element.

"Is the flex soldered to the front case "DTMF" PCB." YES "There is a bank of 2 rows of solder points - is this where the flex is soldered to the PCB or is it some kind of plug assembly which pushes into the PCB?" Wishful thinking! No plug. Desolder as above.

Whole thing is harder to explain than it is to do. Good luck,
Tom

[g8tzl2004]

Many thanks Tom - very helpful.

I'm looking to find a chip capacitor which I think is soldered on the flex between the mic and speaker. It could be on the underside of the flex so if I remove the mic from the rubber casing I might be able to see the underside of the flex. The chip cap is used to suppress any RF.

Do you know where the chip cap is located on the flex. I'm getting a terrible loud tone on the TX audio (monitored on another radio..its 100x louder than any CTCSS tone) which is due, I think, to RF getting into the audio. The hopeful fix is to resolder the chip cap on the flex. When I use an external speaker mic, the TX audio is perfect.

Thanks

[N4KVE]

Just change the whole spkr/mike/flex assy. With a small screwdriver pop off the metal retainer that holds in the speaker. Where the mike attaches just slides up & out. The flex comes out by pulling up on the retainer that holds it in. These complete assy's are cheap & easy to find. No soldering, & 5 minutes to re install. GARY

[g8tzl2004]

I'm hoping its just a dry joint on the chip cap...so easy to resolder...but its just a matter of finding its location!!!

My MTS2000 is also a front display version with the full keypad - so you would need to resolder any replacement flex to the keypad PCB

[WB6DGN]

Do you know where the chip cap is located on the flex.

Doesn't sound familiar. Maybe I just never noticed it. Think I've still got some used flexes around here. If so, I'll take a look tomorrow and see if I can find it. I think there is a chip cap. across the mic. terminals. Could that be what you're referring to? When you described the sound, I thought of a bad mic. element. Perhaps that cap. keeps RF out of the mic. element? Anyhow, I'll see if I can find a used flex or two and look for that cap. If I find anything I'll get back to you.
Tom

[g8tzl2004]

Tom - yes, I guess it could be the chip cap across the mic terminals.

When I use an external speaker mic the TX audio is perfect - but when I use the internal mic, all I get is a very very loud warbling tone (when listening to the signal on another radio). Also when I place my finger on the front of the MTS2000 just over the mic "hole", I also get a hum induced onto the warbling tone. When I speak into the internal mic, I can just hear my audio but its mainly a 99% loud warbling tone.

I previously read that a possible fix was to resolder the chip cap on the flex between the mic and speaker which is used to stop RF getting into the audio...so I guess the cap could actually be directly across the mic terminals. As you say, it might also be a bad mic element.

[WB6DGN]

Sorry it took so long for me to reply; those flexes were pretty well hidden among my stuff. The only chip cap I see, and, I'm sure, the one you're referring to is on the flex pigtail that goes from the vicinity of the speaker left side (facing back of spkr) down to the mic. element. On the bottom side of the flex there is a small chip that goes from the audio common trace (the wide one) to the mic. high line. You noted that it went from the speaker to the mic., probably actually the audio common which also goes to the speaker and to the mic. So, as you noted, it could be either that cap. defective or the mic. element, or, elsewhere for that matter. If it were me, I think I'd start with the mic. element. Those were troublesome in some radios though I can't remember the symptoms, been too long.
Hope this helps,
Tom

[g8tzl2004]

Tom - many thanks indeed. I really appreciate your help in locating the chip cap.

Hopefully it might just be a dry joint - but as you say it might need replacing or could be a faulty mic element or something else.

At least I now know where to start looking!!!

Thanks again.

[WB6DGN]

Please let us know what you find. Handy to have in the "memory banks" for future use.
Tom