T.J. FROGGATT 08/04/2019

CIRCUIT DIAGRAM D6:
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The three boards underneath an MCB24 are, in order:
ÊÊ FrontÊÊ 4006Ê MR2 volts =0 & >12Ê therefore +6v,
ÊÊ MiddleÊ 4006Ê MR2 volts <0 & >6ÊÊ therefore -6v,
ÊÊ RearÊÊÊ 4009ÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊÊ therefore +15v.
The layout of 2N3055 transistors is:
ÊÊ RelaysÊ CapacitorsÊ Transformer
ÊÊ FrontÊÊÊ +15v +15v +15v
ÊÊ MiddleÊÊÊ +5vÊ -5vÊ -5v
ÊÊ RearÊÊÊÊÊ +5vÊ +5vÊ +5v
Wiring colour code: Emitter resistorsÊBlue wires (6),
ÊÊ Bases Yellow wiresÊ(4), and Collectors Mounting bolts (3).
The three heatsinks appear to be identical, but with the middle
ÊÊ one the opposite way up, so that its transistors line up with
ÊÊ the holes in the other two, thus reversing their E & B pins.
The middle row +5v transistor is isolated from its heat sink.
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Errors in circuit diagram D6.
ÊÊ D6 shows differing numbers of transistors on each of
ÊÊÊÊÊ the 3 boards, and a total of seven off-board 2N2055s.
ÊÊ In fact there are 6 transistors on each board, including
ÊÊÊÊÊ one 2N3055 on each, and a total of nine off-board 2N3055s.
ÊÊ Specifically, VT3 & VT13, shown on-board, are off-board.
ÊÊ Each board has three STO5 transistors,
ÊÊÊÊÊ VT24 & VT26 on board 4009 are shown as PNP,
ÊÊÊÊÊ the other seven as NPN, all nine should be NPN.
ÊÊÊÊÊ (See "Radio Valve Data" 8th edition page 109, Iliffe 1966)
Although there are two 4006 boards, circuit diagram D6
ÊÊ correctly shows that they differ regardingÊR4-v-R22.
Values in circuit diagram D6.
ÊÊ D6 shows R1 R19 R34 as 1Kohm.
ÊÊÊÊÊ R1 is actually 820ohm on Santype & Warwick MCB24s.
ÊÊ D6 shows R5-8 R23-24 as 1ohm & R41-43 as 2.2ohm.
ÊÊÊÊÊ All nine are actually 1ohm on Santype MCB24.
ÊÊ D6 shows R4 as 330ohm & R22 as 470ohm.
ÊÊÊÊÊ R4 is actually 270ohm on Santype & MobilX8K MCB24s.
ÊÊ I have NOT checked these values on all four of my MCB24s.
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