Here Ron, this is what is in the PDF.
1. Created meter model to allow consistent and unified physical placement of LEDs associated with each meter. Added silkscreen tick mark to allow accurate centering of the LED assembly jig.
2. Added notch below each meter round to provide extra clearance for some of the earlier meter types that had larger rounds.
3. Added slotted meter mounting holes in 4 places to allow for slight side to side dimensional tolerance in the mounting of the meters which is quite common with the PL400 meter mounting method.
4. Added full wave rectifier circuit to the meter drive circuit to provide more accurate reflection the music output in the resulting meter current
5. Changed rectifiers to Schottky rectifier types (BAT46) to minimize dead spot due to diode forward voltage at lower amplifier output levels. The Schottky diodes exhibit ~0.1V forward voltage drop vs 0.65V for the standard silicon diodes.
6. Added user jumper option on each meter to provide for classic half wave rectification meter operation or full wave rectification modes.
7. Full wave rectification provides a 6dB meter sensitivity increase. Provides more responsive meter movements at lower listening levels. Similar to the -20dB switch on the PL700B amplifier.
8. With shunt in jumper positions 1-2, the meters work in full wave rectification mode. Meter sensitivity is 6dB higher (2x) than stock PL400. Boards are shipped in this jumper position.
9. With shunt in jumper positions 2-3, the meters work in classic half wave rectification mode. Meter sensitivity = stock PL400.
10. Added high frequency boost circuit option to allow greater sensitivity to higher frequency signals. Recommended (and installed) values are 3.3K in series with 0.047uF. The 3dB point of this meter boost circuit is ~1KHz. These values can be tailored by the user, it is a preference item. With the recommended values, a boost of approximately 12dB is provide for signals with frequencies of 2KHz and above. To disable this boost circuit, simply remove R10 and R13 (the only vertically oriented resistors on the board).
11. Added plus and minus symbols on the silkscreen artwork for each meter lead connection.
12. Added red and black test points (V+ and Ground respectively) for the rectified and filtered DC voltage that supplies the LED power.
13. Normalized the pads that connect to the amplifier in EXACT same order as the stock PL400 PL18A light board. The L and R meter connections are reversed from the Revision A board. Re-ordered the pad numbering to PAD 1-5 from lower left to upper right to make wiring more intuitive.
14. Overall, improved upon the already high quality of the RevA board in the creation of the RevB artwork by making small moves of components to improve assembly clearances, shorten and widen traces, increase trace clearances, improve signal integrity and minimize vias.
15. Wiring from amplifier to Light Board RevB is as follows:
a. PAD1 = RED, right channel output
b. PAD2 = WHITE, left channel output
c. PAD3 = BLACK, amplifier star point ground
d. PAD4 = GRAY, AC1 from the main transformer (sometimes these leads are green or some other color)
e. PAD5 = GRAY, AC2 from the main transformer (sometimes these leads are green or some other color)
f. The last 2 AC wires are interchangeable, no polarity involved.
, The one eyed bastard and #2. #2 is with Bill the tech right now. One eye got its name because it has a broken meter. Meter was broken off when my old man took ownership in the 80's.
