Summary of Contents for Musical Concepts PA-7
- Page 1 Musical Concepts PA-7 ALL MODELS INCLUDING ULTRA Kit Modification for Hafler amplifiers DH-200, DH-220, DH-500, XL-280 and XL-600...
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Page 3: Circuit Description
This modification is designed for the Hafler DH-200/220/500 and XL-280/600 power amplifiers. Dedicated constructors with consider- able experience can use the PA-7 to drive a MOSFET output stage using from 2 to 12 lateral power MOSFETS in complementary source follower mode. Such projects should be undertaken only by the most self sufficient types, since Musical Concepts cannot offer assistance for custom installations. -
Page 4: Installation Instructions
3.( ) The input wires from the RCA jacks at eyelets 1 and 2 are at the ‘top’ of DH-200/220, XL-280 PCB, but the ‘rear’ of the DH-500/XL-600 PCBs. You may re-use these wires to connect the PA-7 or replace them with supplied wiring. There may be a length... - Page 5 Tighten securely(Hardware is 12 MM)! Both channels are done the same way. The shoulder washer must fit inside of the hole to be electrically isolated. These will be wired to eyelets E1 and E2 of the PA-7 in a later step.
- Page 6 17.( )[DH-500/XL-600 only] These amps route the output signal through a relay which provides DC protection. If you wish to remove it from the signal path simply wire around it, i.e. wire the output posts either directly to the PA-7 (eyelet 8) or via the speaker fuse holders.
- Page 7 XL-280/600 and 3 thru 14 on DH-200. With all wires removed, the board can be removed from the amp. 20.( ) Refer to Figure C for this step Before installing the PA-7 board to the heatsink, it is necessary to make some changes to the MOSFET support circuits.
- Page 8 Look to Fig. A, B and C and this table to connect your PA-7 boards. Final version of XL-280 varies - look to Fig. A, B and C Purpose of connections to PA-7 compared to original Hafler circuit boards PA-7...
- Page 9 Reconnect it according to your notes and with reference to the table, plus Fig. A, B and C. Connect the input jack wiring to the PA-7 . Remember eyelet E1 on PA-7 is for the hot wire of the input signal, i.e. connect to the center pin of the RCA jack, while eyelet E2 is for the ground part of the input jack.
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Page 10: Performance Options
And don't even think about using "audiophile grade" solder unless you are very sure of what you are doing. Some of it we've tested is not pleasant sounding. One advantage of the PA-7 is it's 12 ga. wire eyelets that are provided where... - Page 11 Figure A. PA-7 Ground connection 'Hot' input connection from input pair, i.e. to from input pair, i.e. to ground tab of RCA jack center pin of RCA jack Grayed out circuit tracks shown are on the bottom / solder layer. Top...
- Page 12 PA-XX, Figure B IMPORTANT NOTE: If you have purchased one of our PS series power supplies the connection instruc- tions in those kits supercede the above diagrams.
- Page 13 PA-XX, Figure C DH-500, XL-600 N-CH P-CH DH-200/220, XL-280 N-CH P-CH N-CH...
- Page 14 PA-7 voltage pictorial Approx. 0.6VDC -58VDC (DH200)* -88VDC (DH500)* -30VDC +58VDC (DH200)* +88VDC (DH500)* +60VDC (DH200)* 0V(Set with DC offset pot) -60VDC (DH200)* +90VDC (DH500)* -90VDC (DH500)* APPROX. 1.4VDC eyelet to eyelet This pictorial may be useful for verification of operating points and/or repairs. It is provided as a tool in the event of malfunction so that a local competent technician might assist you with repair services.
- Page 15 YOUR TECHNICAL NOTES:...
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