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Screwy Channel Master front panel channel buttons

post #1 of 10
Thread Starter 
I have two CM-7000 boxes where the front panel channel buttons (fpcb) don't do the same thing as the remote channel buttons. The remote cycles through all channels just fine, but the fpcb skip over some in a way I haven't yet figured out.

At first I thought the fpcb was only cycling through the favorite channels, so I set all channels as favorites... no luck. Then I thought the fpcb was only showing high signal strength channels... nope. The fpcb will even show one of the subchannels and skip another on the same station.

I guess it's possible that I got TWO defective CM-7000 boxes, but this could just be a design defect.

Can anyone else confirm the behavior of the fpcb on their CM-7000?
post #2 of 10
Same situation here. The front panel buttons are too sensitive to accurately tune one channel up or down consistently. Even trying to tap them gently to try for a single channel change often results in jumping two or more channels (or subchannels). It doesn't seem to matter whether there are multiple subchannels or just main channels in the area where you're trying to tune.

If you hold down the buttons, it does appear that the box does run through all mapped channels, although at that scan speed it's hard to see.
post #3 of 10
Personally I notice the same thing on the remote. It's like the repeat delay is Waayyy to short for me. When I push the scan buttons on the remote I have to deliberately push them much shorter than I would otherwise. The units front buttons are even worse as you've found out.
post #4 of 10
I doubt its the switches themselves. It looks like channel master needs to program a better switch debounce algorithm into their firmware.
post #5 of 10
Thread Starter 
What a shame. There are so few boxes with channel buttons and these are pretty much useless. I wonder what their tech support people have to say about this.
post #6 of 10
Anybody actually reported the problem to Channel Master and gotten a response?
post #7 of 10
Thread Starter 
I've sent in an e-mail about it to their tech support but haven't yet had a response.

Quote:
Originally Posted by zqxthree View Post

Anybody actually reported the problem to Channel Master and gotten a response?
post #8 of 10
Thread Starter 
Here's the response from Channel Master tech support. I don't quite follow what Ron means by "carefully using" the buttons though.

Quote:


I have noticed this myself. The front panel buttons are very
sensitive and can sometimes skip a station. However, by carefully using
the UP/DOWN buttons you can tune to the skipped station. We have passed
this information on to our engineers but at the current time, there is no
modification for this.

Regards,

Ron Morgan
Technical Analyst

Tel + 919-938-5707 or 866-430-1307 Ext 207
Fax + 919-934-2809
post #9 of 10
Thread Starter 
I found the cause of the front panel button channel skipping. The plastic button assembly is chattering when a button is pressed. By removing the front panel you'll see that the buttons don't skip at all when pressed with your finger. My theory is that the button assembly chatters when the microswitch clicks, causing a second button press without again clicking the switch. I guess there's a long enough delay to sneak past any software debouncing.

The fix is easy. Cut a strip of electrical tape and stick it to the finger tips of the plastic button assembly. That's enough damping to have the buttons work without skipping.

While you're in there, put some black electrical tape over the clear plastic LED light pipe to reduce the night-light effect. A piece of grey tape stuck to the end of that light pipe will also dim the night-light to your preference.
post #10 of 10
Well as long as I have to return one of my CMs I figured it wouldn't hurt to experiment with trying to eliminate the channel jumping problem. The one I have to return has issues with breaking up signal and also the channel skip problem.
First I removed the cover of the unit and next the front of the unit. That part was a little tricky since one needs to hold basically 3 tabs at near the same time while sliding one side and then the next of the front. Reassembly was easy.
Going off 2 tips I've read here at AVS, one in this thread and another in the main CM thread I tried both, one on the channel up and one on the channel down.
Note I don't know how a person could really do either easily without first removing both the unit cover and also the front of the unit.

First I noted that neither button skipped channels when I pushed directly on the little micro switches with the front of the unit off, that was good. Next on the channel up I used TooLittleTimeZZZs tip of using a piece of black tape between the button and plunger piece that's attached to the front panel button. To keep the tape from falling off later I stuck it to the top of the switch and draped it over the front of the switch. The switch itself was only a couple mm dia. so I didn't think just sticking it to that would hold up for long.
Next I went of a tip from 3elementsmissing but instead of using spray lube I used a small dab of axle grease on the little plunger.
I put the front cover back on the unit and WALA, neither button now skips
So take your pick, axle grease or a small piece of tape, or don't use the front panel buttons all options work. Thanks to the above posters for the tips.
P.S. I'll be posting this in both this and the main CM thread since this topic seems to be active in both.
BTW I also had NOT removed the plastic film on the front of the unit, but in my case anyway removing it did not help the channel skip problem.
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