Channel Master CM-7000 Digital to Analog Converter - Page 49

Just out of curiosity, what would such an esd/surge protection circuit feature?

I use an RCL meter to check the caps. This provides both the capacitance and the impedance values.

This is typically a TVS (transient voltage suppressor) diode array to clamp the ethernet transceiver pins to an acceptable range. Here is a link to a page about ethernet ESD protection from one of many manufacturers.

Thanks for the update - I had no idea 10/100 and GigE would require different solutions.

Excellent, the drummer from Rush is here!

Craigslist:

http://dallas.craigslist.org/ndf/ele/3048437006.html

That's more like it!

^^^if I lived near that CM I know where I'd be going tonight

Bon Scott and Bob Crane both post on this forum, too, and I thought they were dead.

Hehehe to all of ya!

A $10 RCA still NIB popped up today, same region (Lewisville, TX). Seeing more Zeniths and such but $30-ish range.

I have two of the Channel Master CM-7000 units that have the red light problem. They were purchased under the coupon program in, I believe, 2009, but not plugged in until 2010. They were then run continually. The first one died about 6 months ago, and the second one died today.

I just took the second unit apart and measured the voltage with the power supply hooked up to the logic board (under load). I am getting 13.90V, 5.43V, and 3.27V. I have no way to measure the AC ripple. I will attempt a capacitor replacement and report back. The first unit is in a closet somewhere - if I can find it, I will measure and attempt a repair on it also. Since I have to mail order the caps, I can save on shipping if I do them both at the same time.

If anyone is keeping track of this stuff, the CM-7000 that died today is S/N 70002122090610.

I have repaired about twenty of them. From what I have seen there is no pattern to the serial numbers of the units that are failing. All have had the same revision power supply and logic board. I have seen two different die revisions of the processor IC, two different revisions of software and three different build dates.

Make sure you get good quality low ESR caps. Besides the power supply caps, you will need to replace E5 and E6 (both 33uf 35v) on the logic board. These are difficult to remove and replace because of the inner ground plane that makes a very good heat sink.

I'm moving discussion from another thread into here.

I've had a CM-7000 for a few years but I haven't used it much. Recently I tested it again, thinking I might cancel my cable subscription. The CM seems to work well at first, but it loses a number of stations after it's been on for a while, beginning with KTVU. After about 30 minutes, the picture starts to pixellate and the sound drops out. Eventually, it completely loses the signal.

If I turn the CM off for a while, it will get the station again, but as the signal fluctuates (as displayed via INFO) it trends downward until it hits the 30s and finally loses the signal completely again.

A couple folks on the other thread suggested I swap the CM with a DigitalStream I have connected to another TV & antenna; I did so, and the symptoms followed the box. Then I tried Floydage's suggestion of cutting power while the unit was on, which he says does a hard reset. My channels were still there afterward, and I waited more than 10 seconds before plugging back in, so I'm not sure what was reset, but it didn't help. I also tried a factory reset as described in the manual. This also had no effect.

I've tried the diagnostic screen mentioned in this thread. The unit passed all the tests most of the time, but it did fail the RAM test once.

KTVU isn't the only channel affected. After KTVU goes, a number of the others do, too, but KPIX and KMTP, for example are still going strong long after KTVU has disappeared.

Does this sound like it could be the early symptoms of the capacitor failure that's been discussed on this thread? Whitebar, if you're reading this, are you still offering to do cap replacements?

I'm mainly interested in keeping the CM around to use with my Panasonic Showstopper--it's been a while since I was researching this, but I remember it was one of the better boxes for that purpose. If there's something else these days that's better...or better yet, a modern DVR with built-in digital tuner and no subscription fee, I'm open to suggestions.

@WhiteBar. I recently sent two of the cm7000 units to you for repair. Big Thanks to you. They are working great.

Yes that sounds like the caps on the logic board. And yes I am still doing cap replacements. Send me a PM for additional information.

Could you please post pinout of the connector (J5) ?

jvvh5897 hasn't posted on AVS in almost a year and a half, unless he's has subscribed to this thread I doubt he'll see your question

Forgot that I even joined here.

As I recall the pinout of the connector was marked on the board. I just followed the silkscreen info. Haven't done anymore work on the dump since last post or so.

Hi,

Does anyone have more specifics that would help to order the 33uf capacitors, like Digikey part numbers?

Thanks

Digikey # P14434-ND Panasonic # EEU-FR1V330 CAP ALUM 33UF 35V 20% RADIAL
Mouser will also have this part.