Also known as the Mullard 510 and Mullard 5-10.

See also my notes on a Mullard three-three rebuild.

    Construction guides for similar amplifiers - from http://www.one-electron.com/Misc_Docs.html

RESISTORS

RV1 - Variable, carbon, 1 M (log. law).
R2 - Fixed, carbon (high stability) , 180 k (10% - 1 W).
R3 - Fixed, carbon, 1 M (10% -  1/4 W).
R4 - Fixed, carbon, 1.8 k (10% -  1/4 W).
R5 - Fixed, carbon, 100 (10% -  1/4 W).
R6 - Fixed, carbon,  100 k (10% -  1/4 W).
R7 - Fixed, carbon, 68 k (10% -  1 W).
R8 - Fixed, carbon, 1 M (10% -  1/4 W).
R9 - Fixed, carbon, 100 k (10% -  1/2 W).
R10 - Fixed, carbon, 100 k (10% -  1/2 W).
R11 - Fixed, carbon, 33 k (10% -  1/4 W).
R12 - Fixed, carbon, 820 k (10% -  1/4 W).
R13 - Fixed, carbon, 820 k (10% -  1/4 W).
R14 - Fixed, carbon, 4.7 k (10% -  1/4 W).
R15 - Fixed, carbon, 4.7 k (10% -  1/4 W).
R16,R17 - Fixed, carbon:
  Normal loading 270 (5% -  3 W).
  Low loading 390+47 (5% - 3 W).
R18 - Fixed, carbon, 1.2 k (10% - 1 W).
R19 - Fixed, carbon, 47 (20% -  1/4 W).
R20 - Fixed, carbon, 47 (20% -  1/2 W).
R21 - Fixed, carbon, (see below) (5% - 1/4 W).
R22 - Fixed, carbon, 18 k (10% -  1/4 W).
RV23 - Variable, carbon, 2 M (log. law).
RV24 - Variable, carbon, 2 M (log. law).
R25 - Fixed, carbon, 1.5 M (10% -  1/4 W).
R26 - Fixed, carbon, 150 k (10% -  1/4 W).
R27 - Fixed, carbon, (see below) (20% -  1 W).
R28 - Fixed, carbon, (see below) (20% -  1 W).
  The resistors for R9 and R10 should be matched to within 5%, and the larger used for R10.
  The values of R27 and R28 depend on the winding resistances of the mains transformer and on the choice of rectifier.  They must be chosen to make the total effective limiting resistance of each anode of the rectifier up to the required value.
  The total limiting resistance, Rlim, in series with each anode of the rectifier must be a least 47 ohm for the CZ30 or at least 215 ohm for the EZ80. The amount of series resistance, Rt, contributed by the transformer is :-
  Rt = 1/2 Rs + n*n * Rp    [IS THIS CORRECT?  ORIGINAL PHOTOCOPY IS HARD TO READ]
  where Rs = resistance of secondary.
          Rp = resistance of primary.
          n = ratio of number of turns on half the secondary to the number of turns on the primary.
  Thus if Rt is less than Rlim, then R27 and R28 must both be chosen equal to the difference between them.

CAPACITORS

C1,C2 - Double Electrolytic, 50 + 50 uF 350 v.w.
C3 - Electrolytic, 10 uF 350 v.w.
C4 - Electrolytic, 10 uF 350 v.w.
C5 - Electrolytic, 100 uF 12 v.w.
C6 - Paper, 0.02 uF 350 v.w.
C7 - Paper, 0.1 uF 350 v.w.
C8 - Paper, 0.1 uF 350 v.w.
C9 - Paper, 0.1 uF 350 v.w.
C10 - Electrolytic, 100 uF 25 v.w.
C11 - Electrolytic, 100 uF 25 v.w.
C12 - Ceramic or Mica.  See below.
C13 - Ceramic, 100 pF (20%).
C14 - Ceramic, 33 pF (10%).
C15 - Ceramic or Mica, 680 pF (10%).
C16 - Ceramic or Mica, 270 pF (10%).
C17 - Ceramic or Mica, 3,300pF (10%).
  The values of  the resistor R21 and its shunt capacitor C12 in the main feedback loop depend upon the impedance of the loudspeaker. A selection of values is given below : -

Speaker Impedance                                  Tolerance
    Ohms                      C12 (pf)     R21(k)     +/- %
      3.75                         180           15           5
      7                              120          22            5
    15                                82          33            5

VALVES (Mullard)

V1 - EF86.
V2 - ECC83.
V3,V4 - 2 x EL84.
V5 - GZ30 or EZ80. See note below.
  The EZ80 must not supply a current of more than 90mA.
[Note GZ30 is used in this kit, it has 5V heater.  Equivalents include 5Z4G]



MAINS TRANSFORMER (TR1)


Primary -  10-0-200-220-240.
Secondaries - Normal loading: 300-0-300 100 mA ; 3.15-0-3.15 2A ; 0-5 2A. Low loading: 300-0-300 60mA ; 3.15-0-3.15 2A; 0-6.3 1A.