Akai-MPC1000-mpc-sup 电路图 维修手册.pdf
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1、 ENGINEERING CHANGE NOTICE ECN #: PRODUCT(S): DATE: ASSEMBLY(S): CHANGE TO BE MADE REASON FOR CHANGE: Microcontroller cannot properly detect pad version when the user power cycles too rapidly. SPECIAL INSTRUCTIONS: Number of pages attached: _ This modification must be performed on all PCBs prior to
2、rev K until the new revision that incorporates this fix is released. MATERIAL DISPOSITION: Mark “X” on all that apply. USE AS IS APPLY CHANGE(S) SCRAP ON ORDER X WIP X STOCK X RETURNS X PROJECT ENGINEER: BOM UPDATED: _/_/_ _Shultz_Wang_ UPDATED BY: MANF. ENGINEER: / DIRECTORS INITS. WORK ORDER UPDAT
3、ED: _/_/_ _/_ COORDINATOR: AH19701 July 16, 2007 AC1A 9-79-0456-A Change resistor R3 from 330k to 390k. Add a 1N4004 or 1N4148 diode across resistor R3, with the cathode on VDD and anode on the point between R3 and C3. 1 RadioFans.CN 收音机爱 好者资料库 AC1A Pad Version Detect Fix Procedure: Note: The follow
4、ing modification is to be performed on the rev A Operation PCB connected to the pads (AL9-40-0456-A). 1. Remove resistor R3 (330k). 2. Solder 390k resistor into location R3. 3. Solder 1N4004 or 1N4148 diode across resistor R3, with cathode (line) on VDD (the end of resistor R3 further away from chip
5、 U2), and anode on the point between R3 and C3. RadioFans.CN 收音机爱 好者资料库 Jul 11, 07 ? ac1apda01j.sch ? 9-79-0456-j-1 ? 9-40-0456-j ? SHSW ? PC(#)Operation - Pad ? Akai ? SIZE: ? FILENAME: ? ASSY NUMBER: ? PART NUMBER: ? TITLE: ? DRAWN: ? C ? B ? A ? C ? D ? 6 ? 5 ? 4 ? 3 ? 2 ? 1 ? D ? B ? A ? RELEASE
6、D: ? DATED: ? DATED: ? SHEET: OF ? SCALE: ? COMPANY: ? B ? 1 ? 1 ? NC ? NC ? NC ? NC ? NC ? NC ? Theory of operation: ? Requirements: ? A circuit is to be added such that the microcontroller ? can determine that the current board is of a later rev ? than the original board. This must be done with ch
7、anging ? only the PAD PCB and without changing the connectors to ? the main board. ? An RSFF is set by an RC and cleared by PS0. This turns ? on and off tristate buffers and analog muxes. An RSFF ? circuit has 4 states: ? Inputs Outputs ? 00 11 ? 01 10 ? 10 01 ? 11 Hold previous state ? One input to
8、 the RSFF is an RC, chosen such that its ? its time constant is slower than the time needed for ? the microcontroller to pull PS0 low. When PS0 is pulled ? low, and the RC has not charged up, the inputs are 01 ? from top to bottom, thus outputting 10. This inhibits the ? analog muxes, tristating the
9、 outputs, and turns on the ? tristate buffers. The output 10 will be held even when the ? RC charges up, since that will put the RSFF into the hold ? state. ? Once the microcontroller pulls PS0 low, it may then send ? any bitstream through PS2, and it will appear on the lines ? PAD1-8 and PAD9-16. I
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