Have no manual and can not unloch the channels

Well ican give you answer for second question i dont hav manual but you can unlock th channel

Either tune your TV to channel 2 or 3 or (on some TV's) to 91.
Then, connect the COAX-output from the set-top-box to the COAX-input on your TV, or connect the "output" Red/White/Yellow RCA-jacks on the set-top-box to the Red/White/Yellow "input" RCA-jacks on your TV.

want to plug in a set top box but don,t have button for av channel on remote

How are you connecting the set-top box?

COAX CABLE -> SPLITTER -> TV
and
COAX CABLE -> SPLITTER -> Set-Top Box -> AV-out -> AV-in-on-TV

or

COAX CABLE -> Set-Top-Box -> COAX CABLE -> COAX-in-on TV?

In the latter case, just leave the TV on Channel 3.
All the channel-tuning will be done by the Set-Top-Box,
i.e., no need for 'A/V' button on the TV's remote.

f you are connecting COAX-output from the Set Top Box
to the COAX-input on your TV,
then, with the Set Top Box turned on,
access the TV's "menu" and run the "auto-program" ("auto-channel-scan") function.

Your TV should detect just *ONE* channel (namely '2' or '3'),
because the Set Top Box always outputs _only_ to one channel.

Hi,
Try this link:

http://www.smpcshop.com/WD-52525-WD-52725-WD-52825-WD-62525-WD-62725-WD-62825-p-2910.html

It will cost $4.95 though.

I wish there were an archive (for free) of most service/users manuals out there

Please intimate exact model number and brand of your TV to provide solution.
Without model and brand info how can we realize what kind of TV you have.
Thanks.

May I know the exact model number of your projection television? Or even the brand will do.

Thanks