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JoeG · 02-19-2023, 06:10 PM

Yesterday (2/19/2023) I acquired a Commodore 128 after I saw that it was working. I think that the power supply got swapped out before I brought the 128 and a power supply home. The seller had multiple 128's and power supplies. Two of the 128's just had a flashing power lights and didn't boot. At that point, I think (not sure) the power supply was swapped out as was the 128 to a third unit. The 128 booted and worked fine. So I think I got a bad power supply and not the one that was used to test the 128 I purchased since the 128 now only has a flashing red power light on it. I know that I have the working 128 since it was the nicest looking of the three.

Does anyone by chance know if a flashing light on a Commodore 128 is a symptom of a bad power supply, or other power issue? I'm new to the 128. Any help would be greatly appreciated!

The VIC-20, C64, Commodore 1902 monitor, Commodore 1571 floppy drive, Commodore CN2 Cassette, and the Apple IIc with monitor I acquired in the bundle all work fine.

Joe

Jeff_Birt · 02-19-2023, 10:57 PM

The LED is powered directly from the 5V rail if it is flashing then the 5V is pulsating. A switching power supply will do this when overloaded. Something is WRONG.

First check that you do indeed have a C128 power supply. The Amiga 500, 600 and 1200 used the same 5-pin square DIN but have different voltages and pinout. If you got an Amiga power supply by mistake your C128 will have been damaged.

JoeG · 02-19-2023, 11:44 PM

Thank you, sir!

Well, I turned over the PSU to check the labeling. And sure enough, it's the wrong one. It has two 12vDC outputs instead of the two 9vAC outputs. It's for the Amiga apparently.
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Commodore Amiga PSU for A500
The Amiga PSU is a modern, 50W strong, replacement power supply unit for Commodore Amiga 500, 600, 1200 and CD32 computer systems. Provides stable filtered 5VDC up to 4.0A, 12VDC up to 2.0A and -12VDC up to 0.5A.
-----

At this point, would it be of any value (from a diagnostic perspective) in ordering a replacement C128 PSU to test and see if anything is damaged?

Thank you!

Joe

teenix · 02-20-2023, 03:04 AM

Looking at the schematics, not 100% sure, but it looks like pin 1 and 4 are +5V and GND for 128, but +12V and GND for Amiga. That alone will most likely have fried your logic circuits.

Maybe you can ask for a refund or exchange based on the fact that they sent an incompatible power supply.

cheers

Tony

JoeG · 02-20-2023, 04:07 AM

Thank you, Tony.

I did open up the unit and took a look for anything obvious, and to check if something smelled "fried". I didn't see anything obvious, nor did I smell anything odd. I should mention that the PSU he did provide is an aftermarket unit from Electroware.

Here's the link to the unit: https://www.c64psu.com/c64psu/56-1410-co...-no_thanks

The 128 seller is a friendly person, and a refund isn't necessary given his young age, and that he has been very forthcoming and admitted the mistake. He even mentioned that he did this before to himself, and nothing was damaged. Based on that comment, I asked him to connect an actual 128 power supply to one of the other 128 units he had that were exhibiting the same issue (flashing red power light), and to let me know if it booted. I haven't heard back from him on that yet. He even offered to send me a 128 power supply. I've made mistakes in the past that have had a cost associated, and was forgiven. I shall do the same. I can absorb the financial loss.

I'm going to order a new PSU for the 128 and give it a try. If that doesn't work, I did find a service that repairs vintage computers and game consoles. Here's their link: https://www.arcadecomponents.com/index.html

I'll send them the unit for repair, and hope for the best.

Thank you!

Joe

JoeG · 02-27-2023, 09:14 PM

I received my new Commodore-128 PSU today, all the way from Poland. I plugged it in, and all is well. Very relieved.

I guess I got lucky!

Thank you!

Joe

teenix · 02-27-2023, 09:35 PM

Good news then, maybe the power supply was a faulty unit and saved the day.

JoeG · 02-27-2023, 09:48 PM

Not faulty. Just the wrong one (Amiga). I sent it back to the seller. He used it on his Amiga and it works fine.

Joe

JoeG · 03-26-2023, 04:42 PM

As an update, my Commodore 128 revealed hardware issues. I sent the motherboard off for repair to Ray Carlsen, who is known to be very good at repairing Commodore computers. I will receive the mother board back this coming week. Ray had to replace the original SID chip with a new compatible SID chip, and he also replaced the memory chips with a memory module. I do not know if the computer had those issues when I purchased it since the only test I did was a boot up test. Doesn't matter now. It's fixed.

Joe