Photograph of amplifier before restoration {large files]

Top

Bottom

Circuit Diagram

Under Chassis Layout

Colour coding of this diagram: Brown=Neg Feedback . Red=HT . Pink= Stab HT . Orange=Anode . Magenta=Screened Grid . Green=control grid . Cyan=other signal wiring . Grey=cathode . Blue=floating signal earth . Black=chassisearth . Thin black=interconnections. . . Note: these are not the actual colours used in the amplifier wiring

Components List

RESISTOR	VALUE	FUNCTION	PANEL	LOCATION
1	2M0	V2 grid leak	B	12a
2	470k	V2 SG feed	B	11ab
3	240k	V2 anode load	B	11bc
4	3k0	V2 cathode bias	B	12ac
5	240k	Bass time const	B	10bc
6	5M0	V2 grid leak	B	9ab
7	3k3	V4 cathode bias	B	8bc
8	20k	V4a cathode load	B	8ab
9	100k	V4b anode load	B	6ac
10	2k0	V4b cathode bias	B	3bc
11	470k	V6a grid leak	B	3ab
12	39k	V6a anode load	A	5ab
13	2k0	V6a cathode bias	B	2ab
14	100‡	NFB divider bottom	B	2bc
15	2k0	V6b cathode bias	A	1ab
16	39k	V6b anode load	A	5bc
17	470‡	NFB divider top	B	1ab
18	50k	Paraphase divider top	A	2ab
19	330k	V9, V10, V6b grid leak	A	1bc
20	75k	Paraphase divider bottom	A	2bc
21	43k	V9 grid stopper		V9 base
22	43k	V10 grid stopper		V10 base
23	500‡	V9 cathode bias	A	9ac
24	500‡	V10 cathode bias	A	12ac
25	100‡	V9 SG feed	A	8ac
26	100‡	V10 SG feed	A	11ac
27	5k0	Phase correction	A	6bc
28
29	240k	V2 grid stopper		V2 top cap
30
31	470k	V1 grid leak	C	12c
32	470k	V2 SG feed	C	11bc
33	240k	V2 anode load	C	11ab
34	3k0	V2 cathode bias	C	12ac
35	240k	Treble time const	C	10bc
36	5M0	V2 grid leak	C	9bc
37	3k3	V4 cathode bias	C	9ab
38	20k	V4a cathode load	C	8bc
39	100k	V4b anode load	C	6ac
40	2k0	V4b cathode bias	C	3ab
41	470k	V6a grid leak	C	3bc
42	39k	V6a anode load	D	5bc
43	2k0	V6a cathode bias	C	2bc
44	100‡	NFB divider bottom	C	2ab
45	2k0	V6b cathode bias	D	1ab
46	39k	V6b anode load	D	5ab
47	470‡	NFB divider top	C	1bc
48	50k	Paraphase divider top	D	2bc
49	330k	V9, V10, V6b grid leak	D	1ab
50	75k	Paraphase divider bottom	D	2ab
51	43k	V7 grid stopper		V7 base
52	43k	V8 grid stopper		V8 base
53	500‡	V9 cathode bias	D	9ac
54	500‡	V10 cathode bias	D	12ac
55	100‡	V9 SG feed	D	8ac
56	100‡	V10 SG feed	D	11ac
57	5k0	Phase correction	D	6ab
58	68k	V11 cathode feed	D	7ac
59	240k	V1 grid stopper		V1 top cap

CAPACITOR	VALUE	Min VOLTAGE	FUNCTION	PANEL	LOCATION
1	0.25 uf	500	V2 SG decoupler	B	13a
2
3	1nf	500	Bass time const	B	10ab
4	100 nf	500	Coupling V2-V4a	B	9bc
5	100 nf	100	coupling V4a-VR1	B	7ac
6
7	100 nf	500	Coupling V4b-V6a	B	5ac
8
9	100 nf	500	V6a-V9	A	3ac
10	100 nf	500	V6b-V10	A	4ac
11	100 uf	50	Decoupling V9 cathode	A	10ac
12	100 uf	50	Decoupling V10 cathode	A	13ac
13	200pf	800 AC	Phase correction	A	6ab
31	0.25 uf	500	V1 SG decoupler	C	11c
32
33	1nf	500	Treble time const	C	10ab
34	100 nf	100	Coupling V1-V3a	C	9ab
35	100 nf	500	coupling V3a-VR2	C	7ac
36
37	100 nf	500	Coupling V3b-V5a	C	5ac
38
39	100 nf	500	Coupling V5b-V8	D	3ac
40	100 nf	500	Coupling V5a-V7	D	4ac
41	100 uf	50	Decoupling V7 cathode	D	10ac
42	100 uf	50	Decoupling V8 cathode	D	13ac
43	200 pf	800 AC	Phase correction	D	6bc

Useful source of high voltage capacitors: T.A.B. Components

Power Supply Circuit

Power Supply Layout

 Back to home page