Commodore 64C Capacitor Replacement Guide

A 250469 (E) board, PCB 252311 rev. B. The power section with C63, C65 and C66 is at the right, near the power connector.

The tables below give the electrolytic capacitors on the 250469 "E" board, one of the two boards Commodore lists for the Commodore 64C. Every value comes from Commodore's parts list for PCB assembly 250469-01 and its schematic 252312 in the Service Manual C64/C64C (March 1992, PN-314001-03). The other 64C board, the 250466 (B-3), keeps the long boards' power circuit; its list is in the Commodore 64 Capacitor Replacement Guide.

Identify the board

Commodore identifies the E board by its single combined BASIC/KERNAL ROM at U4 and the memory controller at U8, and the B-3 by its two RAM chips at U9 and U10. The E board also has only two DRAMs, at U10 and U11, so the RAM count does not tell the boards apart: the B-3 keeps separate BASIC and KERNAL ROMs at U3 and U4 and the 82S100 PLA at U17. The assembly number is printed on the board; the board in the photograph reads "PCB ASSY NO. 250469".

The power section

The E board has no 7805 or 7812. Schematic 252312 shows:

• CN7 pins 4 and 5 carry +5 V from the external supply, pins 6 and 7 carry 9 V AC, and pins 1, 2 and 3 are ground. The +5 V passes the power switch to C58 (100 µF) and the logic.
• Bridge rectifier CR2 and reservoir C63 give "9V UNREG".
• C65, CR3 and CR4 raise a second supply from the 9 V AC, filtered by C66. Transistor Q5 with zener CR7 regulates it to the SID's VDD supply, marked "+9/+12".
• CR7 sets that voltage: the schematic calls for a 12.6 V zener with a 6581 SID and a 9.6 V zener with an 8580.

Electrolytic capacitors

250469-01 electrolytics

Ref	Capacitance	Rating	Package	Commodore part no.
C63	1000 µF	16 V	Axial	900101-52
C66	470 µF	35 V	Radial	900301-35
C65	220 µF	25 V	Radial	900100-03
C43	220 µF	16 V	Radial	900100-18
C58	100 µF	16 V	Radial	900100-40
C36	47 µF	16 V	Radial	900100-33
C77	10 µF	25 V	Radial	900100-01
C59	4.7 µF	25 V	Radial	900100-11
C44	2.2 µF	50 V	Radial	251079-06

The parts list prints C63 twice, as 1000 µF 16 V (900101-52) and as 2200 µF 16 V (900101-33). Note 7 on the schematic explains the second entry: the French version requires a 2200 µF capacitor at C63 and a 20 Ω resistor at R2. The schematic marks C66 as 330 µF 35 V where the parts list gives 470 µF 35 V; read the part fitted to the board.

Parts that depend on the SID

The E board was built with either a 6581 or an 8580 SID; the parts list carries both. The schematic notes give the parts that change with it:

SID-dependent parts, schematic 252312 notes

Part	With 6581	With 8580
C70, C71 (filter capacitors)	470 pF	22000 pF
C80, C81	1800 pF	2200 pF
CR7 (supply zener)	12.6 V	9.6 V
R8	fitted	removed

Fitting a 6581 to an E board built for an 8580, or the reverse, means changing CR7, C70/C71, C80/C81 and R8 to match.

The other capacitors on the board are ceramics: C2-C4, C6, C76 and C90 are 470 pF, C74 is 1000 pF, C86-C88 are 220 pF, C94 is 150 pF, and C1, C7, C28-C30 and a dozen other positions are 0.1 µF 25 V.

Before you start

• Measure the external supply's +5 V output first. The C64-Wiki treats 4.95-5.10 V as normal and above 5.2 V as a failing supply.
• Note which SID is fitted before ordering parts.
• See Capacitor Failure Symptoms and Recommended Tools.

Related pages

• Commodore 64C · Commodore 64C General Maintenance · Commodore 64C Troubleshooting Guide
• Commodore 64 · Commodore 64 Capacitor Replacement Guide
• Commodore 64 / 64C Service Manual