**This procedure worked for us; however,
you undertake modifications on your Jukebox at your own risk. Jumping
Cholla Enterprises, Inc. is not liable for any damages caused by the
opening and/or modification of your Jukebox.
PLEASE NOTE: Your warranty is voided by modifying your Jukebox.
Recommended Tools (added by Tom):
- Needle tweezers
- Flux
- Microscope(*)
- Soldering iron and tools
(*) Optional, but makes
it much easier
Increasing headset volume:
Okay- I could stand it no longer. After seeing how easy it was to take
apart the NJB. I dug in to see what I could do about the headphone volume
situation. Below is the circuit, its pretty simple. The fix involves
pulling out two tiny resistors and replacing them with larger values but
same size physically. This increases the gain of the audio amp about 7.5x
or about 17 dB. I experimented with a 6 dB fix first that I explain here
later but I didn't do it. I listen to this thing on airplanes and it
needed to be a lot louder. With this fix, a volume setting of 15 is quite
loud, 20 is undistorted still but extremely loud.
The "fix" increases the gain of this circuit from -1 to -7.5 by increasing
RB39 and RB38 to 150Kohm from their 20 Kohm value. RB31 and RB38 are 20K
and the gain is the ratio of the feedback R to the input R like an op-amp.
Remove and replace the two R's and you've got it.
RESISTORS:
Order Info (added by Tom):
Mauser Electronics, Inc.
1000 N. Main Street
Mansfield, TX 76063-1514
Phone : 800-346-6873
( www.mouser.com )
Part # : 71-CRCW0603-150k (per piece 10c)
- John Wettroth
