THE PREAMPLIFIER DH-110 INSTRUCTIONS for ASSEMBLY and OPERATION LM132 $3.00 Please refer to this serial number in all communications regarding this equipment.
SPECIFICATIONS The numbers in parentheses refer to the paragraph in the IHF specifications manual which defines the test procedure. PHONO PREAMP SECTION Rated Output: 3 Wms, 8 Hz-105 kHz Maximum Output (3.5): 12 Vrms, 20 Hz-20 kHz at recording output Total Harmonic Distortion: Less than 0.0006% @ 1 kHz, 3 Vrms Frequency Response (3.13): +0, -0.25 dB, 20 Hz-20 kHz RIAA Equalization Accuracy: +0, -0.1 dB, 30 Hz-15 kHz Full Power Bandwidth: -6 dB, 4 Hz-210 kHz Sensitivity (3.7): 12.
INTRODUCTION Your preamplifier is the control center of your music system, acting as an interface between the sound sources-record players, tape recorders, FM and Video tuners-and the power amplifier which drives the loudspeakers. As the focal point of your system, it should be attractive and easy to use, versatile and yet functionally unobtrusive.
The DH-110 is provided with accessory Rack Mount end caps in addition to the standard end caps installed on the unit. These accessory caps extend the width of the front panel to that of a standard 19” rack, with appropriate mounting holes. Installation instructions are detailed later in this manual under Additional Information. POWER CONNECTIONS As assembled, units are normally wired for 120 VAC, 50-60 Hz, as in the USA, unless they are specially identified on the carton.
fects that can result from unpowered electronic circuits in the tape decks when they are connected to the Recording Outputs, it is recommended that tape recorders be switched on when the preamplifier is in use. This is a commonly overlooked cause of less-than-ideal preamplifier performance. Signals at these outputs are at line input level (phono signals are first amplified and equalized). These outputs are unaffected by external processing circuits, or by the DH-110’s Mono, Filter, Tone or Volume controls.
The following controls affect all signals which are heard through speakers or headphones. They have no effect on the signals to the recording outputs. MONO SWITCH When this button is IN, left and right channel information is combined, and the composite signal is fed to both left and right outputs. In this mode the sound image should appear to be centrally located between the loudspeakers.
There are three basic rules for success in electronic kit building: 1: Read the instructions carefully, and follow them in order. 2. Make secure solder connections which are bright and smooth. 3. Check your work carefully after each step.
Excess solder may be removed from a connection by heating it and allowing the solder to flow onto the iron, which is then wiped on the sponge. ALL SOLDER USED MUST BE ROSIN CORE Never use acid core solder or any separate flux in electronic work. Silver solder is also not suitable. If in doubt about unmarked solder, always obtain a fresh supply of rosin core solder. We recommend 60/40 for easiest use. Do not confuse it with 40/60, which is harder to melt.
BUILDING THE KIT Partial mechanical assembly of the kit provides protection for major components during shipment. Most of the hardware thus used is included in the quantities listed in the parts list. The exception is that used to install the rear mounting bracket on the PC-14, as this is considered an integral assembly. Only the two screws securing the bracket to the side pieces need be removed, along with the hardware securing the front sub-panel. Dismount the power transformer and remove the side pieces.
each socket, the board is marked to indicate the side of the hole on which the center mounting tab should be positioned, so that it will be soldered to the widest part of the circuitry on the back side. Leave the phono plug in the socket while bending and soldering is completed. If you do not bend the center tab quite flat against the board, it is easier for solder to flow under the tab for a good connection.
23 [7 Select the 6 black 5/8" screws, the 6 spacers, and 6 small nuts. Insert the screws from the outside of the back panel at the locations nearer the center of the panel (not in the end holes marked “Grounds”). Install a spacer on each screw and tighten them. Place the PC-12 assembly in position so that its two screws pass through the end holes. Install the nuts on the black screws, and tighten them. 24 0 Select the 2 small nuts and the 2 knurled thumb nuts.
IGHT i 13 1.
HT LINE- - LEFT LINE - aa “;T Fl v 0 I E 1 No 0109 E 0 n -r 0107 (J Ql- c21 - -D5k 012 011 @oE v Cl9 -D7k --R66-R65- I 1 I 1 +D6- 0 -R62- 8 llll 6 g 3 K(TUK III1 ,- 0 C36 h 8 I iD12--R59- - --R45- Do EO -R64- 0 C32 --R56- Ic38) --R57- VOLUME L -R44R --R144- 527 (0 - M l - 0 c34 izJ 141- Q-&xo T co “0 “0 R26 ‘0 “6
wire to hole Q, which is between the center lugs of Jll and 512. (S). The wire should not protrude significantly beyond the front surface of the board to avoid coming in contact with a connector. To assure a good solder connection, bare wire should be visible on the circuit side of the board. Connect the green wire to hole P in like manner. (S). 44 0 At the rear of the phone jack, connect the black wire from the first group (lugs 2 and 3) to PC14 eyelet G3. (S).
IF A PROBLEM ARISES If neither LED lights when you first turn on the power switch, turn the unit off immediately. Check the fuse. Check the polarity of the LEDs. Check the power transformer wiring for proper connections for your line voltage. Look for a short caused by a stray strand of wire, or for a solder splash on the circuit board. A print of the circuit pattern in this manual enables you to check out a doubtful connection which might include a solder bridge.
ADDITIONAL INFORMATION RACK MOUNT END CAP INSTALLATION Every DH-110 is supplied with front panel accessory end caps which adapt it to a standard 19” rack panel, and with a 5/32” Allen wrench which fits the mounting screws. Remove all power and signal connections from the DH110. On a protected surface such as a towel, remove the two cover screws on each side of the bottom, and slide the cover back. Remove the screws in each corner of the front panel. Exchange the end caps-they slide outward.
MINIMIZING NOISE IN THE SYSTEM Your choice of separate components is the right way to secure the best performance from a music system, but the wide-band characteristics and complexity of the best systems may also not conceal the introduction of ground loops and noise pickup-especially RFI (radio frequency interference). With exceedingly high quality equipment we may become conscious of distractions that would be ignored on a lesser level.
Tape 2 TONE law 1 FILTER CD/Video Phono 1 EPL PHONO 1 B v C Phono 2 2 C Tuner 0 v, 0 R LINE OUTPUTI To Right Channel Record Out EPL Send EPL Roturn FUNCTIONAL BLOCK DIAGRAM 18 Treble Bass SAL V O L 1 r-K Switched E Direct
COMPONENT VALUES COMPONENT VALUES Rii channel corresponding values have designations above 100. All resistors are 1/4 watt I% Metal Film unless otherwise noted. RI R2 R3 R4 R.5 R6 R7 R8 R9 RIO RI1 RI2 RI3 RI4 Rl5 R16 RI7 RI8 RI9 R20 R2l R22 R23 R24 R25 R26 R27 E R30 R3l R32 R33 R34 R35 R36 R37 R38 R39 R40 R41 R42 R43 R44 R45 R46 R47 R48 R49 R50 R5l R52 R53 R54 R55 R56 E8’ R59 R60 R6l R62 R63 R64 R65 ii: R68 R69 :: s3 s4 S5 s6 93,lOOohms 93,1OO ohms 1,100 ohms 22,100 ohms 22,100 ohms 147.
CABLE PIN NUMBERS PC12a TUNER @j----o N ISELECTOR] ” TAPE 1 R24 I E P L S E N D (0)“’ JlO e ,T m-c I I I ‘I I I DIRECT OUTPUT -U+ OUTPUT VIA PHONE JACK PHONO 1 PHONO 2 GROUND pos1.s 6 ,a PHONE JACK I3 I4 I 0 513 rbd I - L 07 08 00 010 e,, 012 1 I L l0g000 R QQJ 7 527 pm*” Cl8 8 _ 67 ‘R b 1 00 50 4 0 3 0 2 0 10 L 1 Twisted Wlms black b .
LINE AMPLIFIER CABLE PIN ASSIGNMENTS PC13 lYONOl Fcml R J22 TO J23:A PIN IB*LINCE] 4 1 AUX L 2 TUNER L 3 RECORD L 4 LINE GND L 5 SHIELD GND 6 AUX R 7 RECORD R 8 TUNER R S LINE GND R 10 PHDN02R 11 WON0 GNDR 12 PHDND2L 13 PHOND 1 R 14 PHOND GND L 15PHONOlL 520 9 l75y7q C29 C30 J24 T O J25;B PIN I5 L SYMBOLS I3 POWER SUPPLY GROUND m SHIELD GROUND MUTING + m LEFT , 6 > CHANNEL SIGNAL GROUND m RIGHT 1 o+ 1 o- ; POWER SUPPLY 1 GUT LINE L 2 SH IELD 3 WT LINE R 4 SHIELD 5 EPLSENDR 6 EPL RE
KIT PARTS LIST KIT PARTS LIST Minor variations may sometimes be encountered in value or appearance. These will not affect performance. Some items may have been used to package the kit for shipment.
SERVICE POLICY AND LIMITED WARRANTY Your DH-110 Preamplifier has been carefully engineered to provide many years of use without maintenance or service. Factory assembled units undergo many physical and electrical tests before shipment. The circuit board in kits is similarly tested to meet all primary specifications before it is packed. Nevertheless, shipping damage can occur, or human error may intervene to make service necessary.
Printed in USA
