X68000 PSU replacement parts

[eidis]

 Ladies and Gentlemen,

Due to age most of the PSU spare parts are no longer manufactured but replacement parts with the same or improved parameters are readily available. Please share your experience and post part numbers of original and replaced parts so we can make another great Wiki article and save a ton of original power supplies.

Keep the scene alive !
Eidis

[eidis]

Here comes another Wiki article which was inspired by A24Tanabe San and  http://x68k.net/x68dengen/

Power Supply Unit Repair
http://www.gamesx.com/wiki/doku.php?id=preface:why_x68000_s_caps_are_almost_broken&#expert_super_xvi_030_sh4_unit

Keep the scene alive !
Eidis

[BlueBMW]

I believe the Ace power supply is the same design as the later ones but it just had lower rated capacitors.   Ive replaced the caps in an Ace supply using the ratings from an expert supply and it worked great.  Also we have a power supply schematic somewhere in the wiki, might be good to have a link to it.

As far as compact supplies they dont seem to burn up like the tower models do.  Their caps leak but usually a recap is all that is needed to repair them.

[eidis]

 Hi BlueBMW !

Added links to schematics and quotes, the article is shaping up nicely. I get a feeling that something very important was forgotten.

Power Supply Unit Repair
http://www.gamesx.com/wiki/doku.php?id=preface:why_x68000_s_caps_are_almost_broken

Keep the scene alive !
Eidis

[Arcade]

I've gone through a quite a few of the "tetris block" type power supplies at this point.  Most of the capacitors are just being used for bulk bypass and, as such, are not critical to match for capacity.  (Indeed, larger values and higher working voltages can easily be had now and don't present any problem and are likely more robust-- a smaller physical package just allows for better air flow in the PSU enclosure, which is a good thing.)

The 'original' values seem to be:

c24 = 820uF, 25v
c27 = 120uF, 25v
c25 = 680uF, 16v
c28 = 100uF, 16v
c35 = 10uF, 25v
c40, c41 = 3900uF,10V
c42 = 2200uF, 6.3V
c31 = 100uF, 10v
c33 = 220uF, 16v
c38 = 3.3uF, 50v
c34 = 100uF, 6.3V

In order to make for the smallest list of replacement parts (and since many values are now available in physically smaller packages) I've been doing this:

c24 = 820uF, 25v -> 1000uF @ 25V
c27 = 120uF, 25v -> 220uF @ 50V
c25 = 680uF, 16v -> 1000uF @ 25V
c28 = 100uF, 16v -> 100uF @ 50V
c35 = 10uF, 25v -> 10uF @ 50V
c40, c41 = 3900uF,10V -> 4700uF @ 10V
c42 = 2200uF, 6.3V -> 4700uF @10V
c31 = 100uF, 10v -> 100uF @ 50V
c33 = 220uF, 16v -> 220uF @ 50V
c38 = 3.3uF, 50v -> 3.3uF @ 50V
c34 = 100uF, 6.3V -> 100uF @ 50V

(That way you only need to buy six different types to replace all the caps in the supply.  Any 105F caps are fine. Panasonic makes good ones.)

Other than that, I've literally only found two semiconductor failures so far-- both have been ZD31 (a 6.8V zener diode).

The PCB's under ZD31 have all shown signs of significant heating in the supplies I've taken apart, so I've been replacing the (tiny) ZD31 original parts with 1N4736A's (1W) instead and mounting the part up off the board about ~5mm and then tilting C31 away to further avoid radiated heat from ZD31.  (The primary enemy of electrolytic capacitors is heat.)

Most of the rest of the parts are still available (or at least have close equivalents and/or better spec'd modern options if need be).  I collected datasheets for the bulk of the original semiconductors just by checking the part numbers on the original parts and grabbing the datasheets off the web.  (I can zip 'em up and email if someone wants to include them on the wiki.)

-Clay

[BlueBMW]

It may also be worth adding a link to the atx/pico psu swap guide.