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128D Alternate Power Supply Schematic?

I have a 128DCR with a dead power supply.  I know you can still buy the whole supply, as they turn up on Ebay from time to time.  But I want to fix this one if at all possible.  I have a 128D service manual, but the P.S. schematic is completely different.  Has anyone ever seen an alternate one for PCB #68-4221A?    I found one with handwritten notes referring to this PS, but a lot of the components are different, not just the couple that are notated.  This one has clearly been worked on, and I've got two bad transistors, one of which has already been replaced.  The only thing I have to go on is the numbers on the transistors, which may or may not be the correct ones, so I was hoping for schematics to tell me the correct values.

Re: 128D Alternate Power Supply Schematic?

KevinO wrote:

> I know you can still buy the whole supply, as they turn up on Ebay from time to time.

At $4.95 plus shipping, this exact replacement is good --

http://www.herbach.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=HAR&...

No fuss, no mess,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug

Thanks Robert, I stumbled

Thanks Robert, I stumbled into that just yesterday.  I already spent about $13 for replacement parts that are on their way.  Hope they are the right ones!  But I'm also going to buy one or more of those $4.95 jobs.  That's just too good to pass up.
Kevin

Just get a solid +5V supply

Just get a solid +5V supply and a 9VAC transformer, like the old filiment transformers.  You might even find one at Homedepot for the doorbell or furnace.    We are loooking at taking ionly 5v and creating a 60hz 9VAC from that also.

Re: Just get a solid +5V supply

The C128DCR also needs a 12V line, in addition to 5 and 9.

Can't forget its built-in disk drive,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug

HOLY FRACKING POOP!!!! I just

HOLY FRACKING POOP!!!! I just pulled an original C128 Power Supply out of the box and was blown away at how big and heavy it was.  Time has definitely softened my memory, I remembered the supply as a lithe little accessory, barely heavy enough to hold down paper and easily hidden behind your desk stapler.   A true testament of just how macro the switching supplies of the day were.

Can you imagine if I had to have another 1.2Amps for the Z80 Cartridge?  >:P

Re: HOLY FRACKING POOP!!!! I just

Bil Herd wrote:

> I just pulled an original C128 Power Supply out of the box and was blown away at how big and heavy it was.

:) I see C128 p.s.'s regularly, and their size and weight seem normal to me. ;)

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug

Well, got it fixed!  Replaced

Well, got it fixed!  Replaced 2 transistors, one 120K 1/2 watt resistor that didn't look burned but was open, and replaced all the electrolytics for good measure.  As Robert said, I could have replaced the entire PS for less, but it was the principle of the thing!   So my spare 128DCR is now powering on properly.  Next to test and make sure it actually works, the 1571 is working, etc.
 
 
 
 

Re: Well, got it fixed! Replaced

KevinO wrote:

> ...I could have replaced the entire PS for less, but it was the principle of the thing!

:) Heh, these days I find that paying more cheaply wins out over principle.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug

Excellent!  Unfortunately I

Excellent!  Unfortunately I have seen parts get replaced but no fix.  Now I have to warn you, I got hooked on electronics after I fixed something. >:)

service manual
Dear KevinO, do you have the service manual in pdf form? I have a dead C-128D power supply and I need some documentation to fix it.. can you help me? edit: never mind, found one with Google :) thanks, ab.
Ab, Do you have test
Ab, Do you have test equipment? The switching power supply can be tricky to identify the issue due to feedback loops and I imagine there are a lot of parts that aren't available unless pulled from a s similar supply.
Re: service manual

FWIW, C= repair tech Ray Carlsen can now replace the internal power supply of a C128DCR with an upgraded one made of modern components.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm

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