A4000 Liteon PSU Schematic

[arongooch]

Just wondering if anyone out there in the incredible land of Amiga would have a circuit schematic of the Amiga 4000 Liteon PE-3151-5 power supply?

Would be greatly appreciated.

And no i'm not interested in converting the PSU or replacing it with something else

[Acill]

Just wondering if anyone out there in the incredible land of Amiga would have a circuit schematic of the Amiga 4000 Liteon PE-3151-5 power supply?

Would be greatly appreciated.

And no i'm not interested in converting the PSU or replacing it with something else

Here are some good starts I use a lot.

http://www.devili.iki.fi/mirrors/4x4.hopto.org/

[arongooch]

Cheers for the link. I have come across that website before but I cannot for the life of me find a schematic for the A4000 PSU in there. Is it under the "Tech Topics" links at all? I don't really want to download them all to go through them all if im not 100% sure it's in there.

[Marmes]

It's a normal AT PSU with a diferent connector. Check some AT PSU schematics, you will find similiarities.
I would check the fuses, change the capacitors, then see the power transistors, and check for burned resistors.
Beware when fixing those PSUs , voltage is high, it will make you cry, if you touch the wrong part at wrong time.

[Acill]

Cheers for the link. I have come across that website before but I cannot for the life of me find a schematic for the A4000 PSU in there. Is it under the "Tech Topics" links at all? I don't really want to download them all to go through them all if im not 100% sure it's in there.

Not sure, honestly this is why I convert a modern PSU and put it into the original A4000 PSU shell. They work very well and still look original.

[arongooch]

Absolutely, Ive repaired many SMPS's in the past, definitely know what Im doing here but a schematic still goes a long way

Im fairly sure the chopper controller IC is non functional. Has power etc going to it but nothing on the output side. Easy enough to replace but pretty much nearly every single capacitor's ESR has gone out the window as well.

Since then I have now put that board aside and completed a modern mini ATX PSU board retro fit into the housing of the old PSU case. Works absolutely perfectly now and have access to a lot more power if required.

Cheers for the tips

[dalek]

Not sure who did this or if it's the one you need, but there is this:

https://docs.google.com/file/d/1cDIQxiods_OiHDF0qdnpnkavwFg8-aHhWdWtOuHQWHBsgZeJ_GIKpLn_OoS_/edit

What I'd really like to know is how to tune the +5V rail on these.  Mine is a little weak at 4.94V but not sure where to start trying to raise it up a little.

[shaf]

Check the capacitance for C21 and C22 they affect the +5V Rail.

[arongooch]

I have the old board set aside at the moment but that circuit schematic does look very close to it, no exactly the same but fairly close. I would have to check but I think the Amiga supply uses the +5v rail as the feedback as like this schematic but I there are a couple of trimpots on board from memory. One of them might adjust the +5v rail? Would have to take a closer look. Thanks for the schematic too

I think C21 and C22 are out of tolerance for ESR but I was definitely not getting a thing from the chopper IC so I couldn't even get anything on the secondary side anyway.

When I get some spare time I think I will replace all capacitors and the chopper IC and see if it powers up. Im mostly sure that IC is the main culprit.

[Amiwest]

check out
http://amiga.serveftp.net/A4000_HardwareGuide/index.html -5V problem &
http://amiga.serveftp.net/Schematics/A4000_schematics/A4000_Skynet_PSU_schematics.pdf - Same schematic
I have the Skynet ps so I do not know if it matches.

[arongooch]

Cheers. The Skynet one does seem very close to the Liteon but there are a few differences.