Marchand Electronics MB26 Assembly Instructions Manual

Brand: Marchand Electronics

Model: MB26

Type: Assembly Instructions Manual

Marchand Electronics Inc.

PO Box 18099, Rochester NY 14618

Tel:(585) 423 0462 Fax:(585) 423 9375

[email protected] www.marchandelec.com

MB26 Push-pull tube amplifier

Marchand Electronics Inc www.marchandelec.com 585 423 0462

Parts List

A section

R1 10K0 1% metal film

R2 1K00 1% metal film

R3 49K9 1% metal film

R4 1M00 1% metal film

R5 49K9 1% metal film

R6 49K9 1% metal film

R7 1M00 1% metal film

R8 1K00 1% metal film

R9 49K9 1% metal film

R10 100K 1% metal film

R11 1K00 1% metal 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 dual triode

V2 EL84 pentode

B section

R1 10K0 1% metal film

R2 1K00 1% metal film

R3 49K9 1% metal film

R4 1M00 1% metal film

R5 49K9 1% metal film

R6 49K9 1% metal film

R7 1M00 1% metal film

R8 1K00 1% metal film

R9 49K9 1% metal film

R10 100K 1% metal film

R11 1K00 1% metal 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 dual triode

V2 EL84 pentode

__________________________________________

R13 nu

R14 1K00 1% metal film

R15 19K1 1% metal film

R16 2K21 1% metal film

R17 10K0 1% metal film

R18 2K21 1% metal film

R19 nu

R20 3K92 1% metal film

R21 2K trimmer

R22 180K 1/2 W

CB 0.1uF axial monolythic

C5 100uF,250V aluminum electrolytic

C6 100uF,250V aluminum electrolytic

C7 100uF,250V aluminum electrolytic

C8 330uF,25V aluminum electrolytic

C9 330uF,25V aluminum electrolytic

C10 0.001 uF polypropylene

L1 Wire jumper

D1,2,3,4 UF4007 ultra fast 1A diode

D5,6 1N5248 18V zener

D7 UF4007 ultra fast 1A diode

D8 1N5248 18V zener

D9 1N5232 5.6V zener

D10 LED

D11 UF4007 ultra fast 1A diode

IC1 SG2525 DIP16 socket

Marchand Electronics Inc www.marchandelec.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% metal film

2 2K21 1% metal film

1 3K92 1% metal film

3 10K0 1% metal film

1 19K1 1% metal film

8 49K9 1% metal film

2 100K 1% metal film

1 180K 2W

4 1M00 1% metal film

1 2K trimmer

Capacitors

1 0.001 uF polypropylene

4 0.047uF,250V film

2 0.22 F,250V film

2 0.47uF,250V film

5 0.1uF axial monolythic

3 100uF,250V aluminum electrolytic

2 330uF,25V aluminum electrolytic

Semiconductors

6 UF4007 ultra fast 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 dual triode

2 EL84 pentode

1 transformer P3622 w. hardware

1 transformer Hammond 1608

1 2-pos. small terminal blocks

1 3-pos. small terminal blocks

2 4-pos. small terminal blocks

4 9-pin tube socket

1 16-pin DIP socket

6 #6 hex standoff

6 #6 star lockwasher

6 6/32 x 1/4" machine screw,

10 6/32 x 1/4" machine screw, black buttonhead

12 6/32 x 1/2" machine screw, black buttonhead

1 4/40 x 1/2" machine screw, black buttonhead

1 4/40 hex nut

1 MICA insulator TO247

1 Thermal grease

1 MB26 circuit board

1 rear panel

1 top cover

1 bottom cover

4 stick-on rubber bumper

1 Wood Base

1 nameplate w. screws

1 RCA connector, red, w. hardware

1 Binding post, red

1 Binding post, black

1 BInding post guide

1 power connector

2' 22 gauge wire, red

2' 22 gauge wire, black

2' shielded wire, 2 conductor

1 15, 4A universal power supply

Marchand Electronics Inc www.marchandelec.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.

Marchand Electronics Inc www.marchandelec.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 A,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..

Marchand Electronics Inc www.marchandelec.com 585 423 0462

Assembly instructions for MB26 power amplifier.

Assemble 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.

Attach 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.

Attach 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

Attach 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

Attach 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.:RCA 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 RCA 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.

Amplifier should be functional now.

Do not install tubes yet.

Adjust 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.

Marchand Electronics Inc www.marchandelec.com 585 423 0462

U11

NH12AX7

R2A

R5A

50K

NH12AX7

R6A

50k

R3A

50k

C1A

47n

R4A

1000k

C3A

47n

R7A

1000k

NH12AX7

R2B

R5B

50K

NH12AX7

R6B

50K

R3B

50k

C1B

47n

R4B

1000k

R7B

1000k

C3B

47n

R8A

R9A

50k

R1A

10K

R8B

R9B

50k

R16

10K

R12A

200

R10A

100k

C4A

0.47µ

R10B

100k

C4B

0.47µ

R12B

200

C2A

0.22µF

C2B

0.22µF

R14

R15

19.1K

R11A

R11B

20H

80mH

100µF

plate1 plate2

vpp

tp1

input

outputpost

groundpost

Hammond 1608

Output transformer

OUTPUT to SPEAKER

EL84/6BQ5

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Marchand Electronics MB26 Assembly Instructions Manual

Brand: Marchand Electronics

Model: MB26

Type: Assembly Instructions Manual

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Marchand Electronics MB26 Assembly Instructions Manual

Marchand Electronics MB26 Assembly Instructions Manual

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