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Category: Recap / Capacitor Lists

As a normal precaution, I disconnected the motherboard from the PSU and when powering it up, every fuse on the board blew. All three large capacitors were shorted.

The large capacitors have 4 legs, middle pin is positive (+) and the outer ring legs are negative.

Positive pin marked with red, and negative pins marked with green.
You can replace these with a standard 2 leg radial capacitor (r=11), just make sure the negative planes have continuity.

After a full recap and replacing the rectifier bridge (with better specs to run cooler) the PSU powered up and gave stable +5/+12/-20V.


Wires from the transformer to the PSU PCB were brittle and snapped off just by touching them.

New solder, shrinking tube and a zip-tie to the rescue.


Electrical Shock Hazard

Work should not be attempted if not having experience with
powersupplies and understanding the dangers with it.




The primary side capacitor had leaked, it was about time for some maintenance.


Main board capacitor list

PSU (110V) capacitor list

CDTV Main PCB Rev 2.3

The front panel connectors (CN14,CN15,CN16) can be replaced with a 10 pin JST-PH (2.0mm pitch) connector. Desolder the old connectors by removing one pin at a time.

Some of the capacitors have large ground planes which can be a bit tricky to desolder.


Electrical Shock Hazard

Work should not be attempted if not having experience with
powersupplies and understanding the dangers with it.


Low ESR, high temperature(105°) and well known manufacturer capacitors should be used.


The CDROM-unit will need a recap sooner or later, here is a list of capacitors and pictures of the PCB where you can see locations and orientation of the capacitors. When handling the main PCB, pay attention not to alter the potentiometer settings for the laser by mistake.

For a mechanical fixup of the CDROM unit, go here.

Note: Some CDROM Units have the C206 polarity reversed, mine was not reversed and I kept it that way. More information may be needed on this specific issue.






Atari 600XL Recap


Original capacitor values and sizes. h=height, d=diameter, r=lead spacing, l=length(axial).



64K Memory upgrade

A standard Atari 600XL has 16K RAM memory, but its easily upgraded to 64K.

* U11, U12: Replace 16K DRAM with 64K DRAM (64K x 4 bit)
* U5: Lift leg 3, connect to pad ( A15 )
* U6: Lift leg 10, connect to pad ( A14 )
* U16: Lift leg 8, connect to R36
* R36: Lift leg and connect to U16
After the modifications above, PRINT FRE(0) should return 37902. You can also launch the 600XL self test by holding OPTION while powering on.


Leg lifted out of the socket. Desolder the IC:s and add sockets if they are not socketed.



S-Video Modification


Atari 600XL PAL was not shipped with S-Video, this mod restores it to the same pin-out as some of the other Atari models. There are some variations for the S-Video mod, but this one was chosen for its simplicity and it gives a good picture quality. Note that this modification removes the composite video output.


1 – Remove R137
2 – Remove C112
3 – Remove C109


4 – Cut PCB trace between legs 2 and 5 on the monitor port connector.
5 – Solder 75 ohm resistor from Pin 1 to transistor Q6 emitter.
6 – Solder 75 ohm resistor from Pin 5 to transistor Q9 emitter.



Power supply replacement

I replaced the original powersupply (rated 5V, 1.5A) with a new +5V switched powersupply.

64K upgrade :
S-Video :

For the Eagle Term II v1.9 Sourcecode I had to repair and recap a SFD-1001 drive.

A very common issue on these drives are leaking capacitors causing damage on the motor control PCB. These should be replaced as soon as possible.

A few important notes on the way:
1. The screws holding the rotor(magnet) and especially the PCB screws are ridiculously tight, it’s almost as they are not loosening up at all. Make sure to have an exact size screwdriver and use correct amount of force to unscrew them, you don’t want to end up with destroyed screw heads.
2. There is a fragile flat cable on the underside, be aware of it before lifting up the PCB.


Remove the three screws and lift the rotor(magnet).


Remove the four screws holding the PCB marked with red circles and remove the spacers (mine had three of them).


Desolder the two connectors marked with red squares.


Close up of the cable in the lower left corner, be careful desoldering it.


Drive motor control PCB.


Original capacitor values and sizes. h=height, d=diameter, r=lead spacing.


Component list and manufacturer part numbers, some caps are rated higher than the original voltage value. There is limited space for the capacitors but the components above will fit. Capacitors C13/C14/C15 are bipolar.


Part numbers for IEEE-488 Connectors also available from DigiKey.



SFD-1001 Head Resistance check.

Resistance RW1 or RW2 to CT : 37 ± 30% Ohms
Resistance ERASE to CT : 8.0 ± 30% Ohms
Information above from 8250LP SFD-1001 Disk Drive Technical Manual


Measurements from the field on working drives for reference.