I just ordered a CM 7000 at
http://www.solidsignal.com/
You type in your coupon's number as you check out on their web page order form pages. Obviously afterwards you have a spent coupon card you get to keep...
On the product guide web page they had specs:
http://www.solidsignal.com/prod_disp...d=CM-7000#MORE
TUNER:
Frequency Range: 54 to 864 MHz
Input Impedance: 75 Ohm
Input Connector: F-Type, Female
Channel Bandwith: 6 MHz
Input Dynamic Range: -83 to -5 dBM / SNR - 15 dB
No other box had specs, so I don't know if the above are exceptional performance specs, or lousy...
Seems that there is an inactive RCA jack for digital audio, and they left out a buffer circuit inside to make the box qualify for the coupon. A handful of transistors and resistors and caps (probably a 75 ohm driver circuit to buffer a chip's output).
From
http://www.avsforum.com/avs-vb/showt...1004274&page=3 post 81
Quote:
Originally Posted by dingo99 View Post
Fry's has the CM-7000 on sale again, so I went and picked one up. See attached for a closeup view of the digital output circuit.
Missing are 4 resistors, 3 capacitors, and 2 transistors. Using a DMM, I measured +1.65V @ RA7, +5V @ RD60, and +5V @ CD28/QD9. Any theories what the missing component values should be?
@drlava, actually it does support anamorphic widescreen. Simply hit the "Wide" button on the remote to select the "Full" picture setting.
Excellent info!
Here's a quick visual analysis:
The 1.65V is the rms voltage of the 3.3V biphase manchester encoded data coming from the chip. This goes to the amp/buffer PNP transistor QD10 whose emitter (and base of QD9) is biased by RD60. QD9 may be a NPN transistor with a buffer cap on its collector (CD28). Its output goes to impedance matching/filter network RD61, 62, and CD29, and is finally AC coupled to the coax output through CD30.
RA7 may be necessary for signal integrity to cut down on ringing, or provide additional pull up or pull down current.
With one of these in hand, I could probably have a working solution in an hour or less.
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This box has S video, so one could split off the luma channel to in turn feed a TV modulator that then feeds a B&W TV set. Like my 1950 Admiral.
