 | Byer / Rola 66 Mk II Revisions |
The Byer/Rola 66 Mk II was revised during the life of this model, 1956 to mid 1960's?. In the PDF of the Byer 66 Mk II Operation Manual there are schematics for the earliest version which includes the head demagnetizer socket on the rear of the transport, S/N 1 to 470 and schematics from nearly two years later. The second set of drawings are likely to be the first "Rola" drawing for the 66 but the drawing numbers jump from CD.66-1 & CD.66-2 to CD.66-5 and CD.66-6. I suspect that the missing drawings CD.66-3 and CD.66-4 would have been the "Byer" changes when the head demagnetizer socket was removed from S/N 471 onward.
Apart from one revision all other changes have a record of the serial number when the change was implemented but no dates for these changes. On the amplifier drawing I think Modification "E" should start from S/N 1248 not 1247. This information comes from the Rola 66 Mk II Instruction Manual which is the most recent printing I have found, the amplifier schematic includes a Rola drawing number (120019).
General information about this model can be found on the Byer 66 Mk II page.
AMPLIFIER REVISION HISTORY
| REV | S/N | COMMENTS |
|---|---|---|
| 1 to 909 | Initial drawing release | |
| A | 910 to 1006 | R120 was 220k now 470k 1W |
| A | 910 to 1006 | R121 was 1k8 now 1k2 1/2W |
| A | 910 to 1006 | R124 was 2k2 now 1k 1/2W |
| A | 910 to 1006 | R126 was 1k now 680R 1/2W |
| A | 910 to 1006 | R129 was 47k now 15k 1W |
| A | 910 to 1006 | R137 was 175R now 250R 5W |
| A | 910 to 1006 | V104 was N78 now EL84 |
| A | 910 to 1006 | V105 was N78 now EL84 |
| A | 910 to 1006 | Valve Sockets were ST27G now ST29G |
| B | 1007 to 1009 | R144 was 2k2 now 1k8 1/2W |
| B | 1007 to 1009 | R146 was 330R now 270R 1/2W |
| B | 1007 to 1009 | R147 was 330R now 270R 1/2W |
| C | 1010 to 1246 | C102 was 100uF 12V now 150uF 3V |
| D | 1247 to 1247 | C112 was 0.01uF no 0.0056uF |
| D | 1247 to 1247 | C113 was 0.05uF no 0.033uF |
| E | 1248 to -- | R104 Deleted |
| E | 1248 to -- | R144 was 1k8 now 2k2 1/2W |
| E | 1248 to -- | R133 was 10k 1W now 10k 5W |
| E | 1248 to -- | R139 was 2k 5W now 2k 10W |
| E | 1248 to -- | R130 was 680R 1/2W now 680R 1W |
| E | 1248 to -- | D101 was OA72 now OA73 |
| F | Unknown | C101 was 0.02 350V now 0.022 400V |
| F | Unknown | C107 was 0.005 350V now 0.0047 400V |
| F | Unknown | C113 was 0.033 200V now 0.039 200V |
| F | Unknown | C117 was 0.5 350V now 0.47 400V |
| F | Unknown | C118 was 0.05 350V now 0.047 400V |
| F | Unknown | C119 was 0.05 350V now 0.047 400V |
TAPE TRANSPORT REVISION HISTORY
| REV | S/N | COMMENTS |
|---|---|---|
| 1 to 470 | Initial drawing release (Iss 2) | |
| A | 471 to -- | Head Demagnetizer Jack Socket Deleted |
| A | 471 to -- | R203 5k pot added |
| A | 471 to -- | R213 560R added |
| A | 471 to -- | Resistor "Value as fitted" Deleted |