Marchand Electronics MB26 User manual

Marchand Electronics Inc.
PO Box 18099, Rochester NY 14618
Tel:[phone] F x:[phone]
info@m rch ndelec.com www.m rch ndelec.com
(c)2006 M rch nd Electronics Inc.
MB26 Push-pull tube amplifier
M rch nd Electronics Inc www.m rch ndelec.com 585 423 0462

P rts List
A section
R1 10K0 1% met l film
R2 1K00 1% met l film
R3 49K9 1% met l film
R4 1M00 1% met l film
R5 49K9 1% met l film
R6 49K9 1% met l film
R7 1M00 1% met l film
R8 1K00 1% met l film
R9 49K9 1% met l film
R10 100K 1% met l film
R11 1K00 1% met l film
R12 200 Ohm 3W
C1 0.047uF,250V film
C2 0.22 F,250V film
C3 0.047uF,250V film
C4 0.47uF,250V film
V1 12AX7WA du l triode
V2 EL84 pentode
B section
R1 10K0 1% met l film
R2 1K00 1% met l film
R3 49K9 1% met l film
R4 1M00 1% met l film
R5 49K9 1% met l film
R6 49K9 1% met l film
R7 1M00 1% met l film
R8 1K00 1% met l film
R9 49K9 1% met l film
R10 100K 1% met l film
R11 1K00 1% met l film
R12 200 Ohm 3W
C1 0.047uF,250V film
C2 0.22uF,250V film
C3 0.047uF,250V film
C4 0.47uF,250V film
V1 12AX7WA du l triode
V2 EL84 pentode
__________________________________________
R13 nu
R14 1K00 1% met l film
R15 19K1 1% met l film
R16 2K21 1% met l film
R17 10K0 1% met l film
R18 2K21 1% met l film
R19 nu
R20 3K92 1% met l film
R21 2K trimmer
R22 180K 1/2 W
CB 0.1uF xi l monolythic
C5 100uF,250V luminum electrolytic
C6 100uF,250V luminum electrolytic
C7 100uF,250V luminum electrolytic
C8 330uF,25V luminum electrolytic
C9 330uF,25V luminum electrolytic
C10 0.001 uF polypropylene
L1 Wire jumper
D1,2,3,4 UF4007 ultr f st 1A diode
D5,6 1N5248 18V zener
D7 UF4007 ultr f st 1A diode
D8 1N5248 18V zener
D9 1N5232 5.6V zener
D10 LED
D11 UF4007 ultr f st 1A diode
IC1 SG2525 DIP16 socket
M rch nd Electronics Inc www.m rch ndelec.com 585 423 0462

Q1 IRFP240 MOSFET
Q2 PN2222A NPN
Q3 IRF540 MOSFET
Q4 IRF540 MOSFET
T1 P3622 2T+2T / 40T 26 AWG
Packing list
Resistors
4 100 Ohm 2W
7 1K00 1% met l film
2 2K21 1% met l film
1 3K92 1% met l film
3 10K0 1% met l film
1 19K1 1% met l film
8 49K9 1% met l film
2 100K 1% met l film
1 180K 2W
4 1M00 1% met l film
1 2K trimmer
C p citors
1 0.001 uF polypropylene
4 0.047uF,250V film
2 0.22 F,250V film
2 0.47uF,250V film
5 0.1uF xi l monolythic
3 100uF,250V luminum electrolytic
2 330uF,25V luminum electrolytic
Semiconductors
6 UF4007 ultr f st 1A diode
3 1N5248 18V zener
1 1N5232 5.6V zener
1 LED
1 SG2525 switchmode converter
1 IRFP240 MOSFET
1 PN2222A NPN
2 IRF540 MOSFET
Tubes
2 12AX7WA du l triode
2 EL84 pentode
1 tr nsformer P3622 w. h rdw re
1 tr nsformer H mmond 1608
1 2-pos. sm ll termin l blocks
1 3-pos. sm ll termin l blocks
2 4-pos. sm ll termin l blocks
4 9-pin tube socket
1 16-pin DIP socket
6 #6 hex st ndoff
6 #6 st r lockw sher
6 6/32 x 1/4" m chine screw,
10 6/32 x 1/4" m chine screw, bl ck buttonhe d
12 6/32 x 1/2" m chine screw, bl ck buttonhe d
1 4/40 x 1/2" m chine screw, bl ck buttonhe d
1 4/40 hex nut
1 MICA insul tor TO247
1 Therm l gre se
1 MB26 circuit bo rd
1 re r p nel
1 top cover
1 bottom cover
4 stick-on rubber bumper
1 Wood B se
1 n mepl te w. screws
1 RCA connector, red, w. h rdw re
1 Binding post, red
1 Binding post, bl ck
1 BInding post guide
1 power connector
2' 22 g uge wire, red
2' 22 g uge wire, bl ck
2' shielded wire, 2 conductor
1 15, 4A univers l power supply
M rch nd Electronics Inc www.m rch ndelec.com 585 423 0462

Top view (component side) of assembled circuit board.
The tube sockets are installed on the other side (solder side) of the board.
M rch nd Electronics Inc www.m rch ndelec.com 585 423 0462

Detail view of power supply.
Note the mounting of the transformer and the 5 leads.
The 3 leads from the primary are soldered into holes ,B and C. The twisted lead goes into hole marked B.
The 2 leads from the secondary are soldered into holes D and E.
The leads are magnet wire with poly insulation; this insulation will melt away with the heat from the soldering iron.
When soldering these leads apply enough heat for enough time until the insulation is gone.
The trimpot R21 will be adjusted for 12.6V filament voltage during initial checkout..
M rch nd Electronics Inc www.m rch ndelec.com 585 423 0462

ssembly instructions for MB26 power amplifier.
ssemble the main cicuit baord using the parts list above.
Do not install the tube sockets at this time.
Do not install Q1 (IRFP240) at this time.
ttach the 2 transistors Q3 and Q4 about 1/2” above the circuit board (do not shorten the leads).
Note the 200 Ohm resistors are constructed by connecting two 100Ohm resistors together.
See pictures above to help with installing the power transformer on the board.
ttach the IRFP240 transistor to the main circuit board using three 2” wires.
Note that the IRFP240 is mounted to the top plate with a mica insulator and heat sink compound on both sides of the mica.
Install the 4 tube sockets on the solder side of the board.
Use the top plate as a guide to make sure the sockets fit correctly.
Mount Q1 to the top plate.
Mount the output transformer to the top plate.
Mount the circuit board to the top plate
ttach the leads of the transformer to the circuit board.
The leads are attached to the terminal blocks as follows:
Red: V++ (near C5)
Blue: P2
Brown: P1
Blue/yellow: not used
Brown/Yellow: not used
Run a wire from terminal block V++ to terminal block S1
Run a wire from terminal block S2 to terminal block S1
ttach wires to the terminal blocks:
Black hookup wire to GND and red hookup wire to V++(near C8). These are for the 15V DC supply.
Twist these two wires togeter.
Black hookup wire to GND and red hookup wire to FB ( on 4-pos terminal block). These are for the feedback from the speaker
terminals.
Twist these two wires togeter.
Shielded wire to IN abd GND (near R10). Connect the shield to GND, center wire to IN.
Mount the top plate assembly to the top of the wood base, with all wires sticking out of the rear opening.
Install all connectors to the rear panel.:RC connector, Power connector, Binding Posts.
The 15VDC wires are connected to the Power connector: red wire is center post.
The feedback wires are connected to the binding posts: black to black, red to red.
The shielded wire is connected to the RC connector.
Now the secondary wires from the transformer are connected to the binding posts.
Use the diagram on the box for 8 Ohm speaker.
Make sure the black wire fromthe transformer goes to the black binding post and the yellow wire to the red binding post.
It is also possible to use the connections for 4 Ohm or 16 Ohm (depending on the loudspeaker)
In any case, the black wire should be connected to the black binding post.
mplifier should be functional now.
Do not install tubes yet.
djust the trimmer potentiometer as follows:
Connect the DC power supply.
!! Warning: high voltage will appear on circuit board. !!
The LED should be on, indicating plate voltage.
Check the filament voltage (between GND and pin H (next to P) on V1.
Should be 12.6V; adjust with trimmer.
Check V++; should be approx 275V.
Now install tubes;
Plate voltage should go down somewhat; like approx 240V.
Filament voltage will be lower also; this is OK if above 12.0V
Install bottom plate and rubber self-stick feet.
Done.
M rch nd Electronics Inc www.m rch ndelec.com 585 423 0462

U11
NH12AX7
R2A
1k
R5A
50K
U1
NH12AX7
R6A
50k
R3A
50k
C1A
47n
R4A
1000k
C3A
47n
R7A
1000k
U2
NH12AX7
R2B
1k
R5B
50K
U3
NH12AX7
R6B
50K
R3B
50k
C1B
47n
R4B
1000k R7B 1000k
C3B
47n
R8A
1k
R9A
50k
R1A
10K R8B
1k
R9B
50k
R16
10K
U5
R12A
200
R10A
100k
C4A
0.47µ
U4
R10B
100k
C4B
0.47µ
R12B
200
C2A
0.22µF
C2B
0.22µF
R14
1k
R15
19.1K
R11A
1k
R11B
1k
L1
20H
L2
20H
L3
80mH
C7
100µF
C6
100µF
C5
100µF
plate1 plate2
vpp
vpp
tp1
input
outputpost
groundpost
Hammond 1608
Output transformer
OUTPUT to SPEAKER
EL84/6BQ5 EL84/6BQ5
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