• Please review our updated Terms and Rules here

Commodore 64 PSUs

twillkickers

Experienced Member
Joined
Feb 22, 2017
Messages
152
Location
New Jersey, USA
I picked up a large C64 lot with four old PSUs (the dangerous ones) and am not sure what to do with them. I tested the 5VDC pins with my multimeter, the three without the sticker came out around 5.15V+ and the one with the sticker that says came in at about 5.07V. Should I toss these in the trash? Does anybody have a use for these? I don't want to put these out into the world and have them destroy C64s. Let me know if anyone needs these (or if I should be using ANY of them)

Also - I'm waiting on a modern C64 PSU from Europe, was wondering if I should try out the C64s with any of these while I wait or if I should not risk it.
 

Attachments

  • C64 PSUs.jpg
    C64 PSUs.jpg
    2.9 MB · Views: 8
I am ALWAYS ALWAYS ***ALWAYS*** of the opinion that you should replace the old PSU's with modern day ones just to avoid the killer 5v line. Short term for testing the lots it may be fine, but always test the voltage before use, and even then be quick with the usage.
 
I am ALWAYS ALWAYS ***ALWAYS*** of the opinion that you should replace the old PSU's with modern day ones just to avoid the killer 5v line. Short term for testing the lots it may be fine, but always test the voltage before use, and even then be quick with the usage.


The only thing going against the idea of getting rid of these old PSU's, in favor of new ones, it that the safety standards of many new psu's, especially line operated SMPS types have slipped very very badly over the last 20 years, despite ludicrous CE markings & compliance stickers and fake UL stickers (Undertaker's Laboratories) and the like, giving lip service to the notion of a safe build. A few have been reported as having no insulation between the primary and secondary windings, only the enamel of the enamel copper wire on the smps transformer.

A few out of the far East Wall wart style supplies have killed some people because the secondary side has become live, not a surprise due to the lack of insulation.

Vintage transformer based analog supplies were often safer, because at least there was some reasonable amount of insulation between the primary and secondary windings of the laminated iron core transformers. Many latter day ones use a split nylon bobbin to keep the primary and secondary windings separated (You've got to keep em separated as they recommended in the Offspring song, Come out & Play). So it might be a case of better the Devil you know with these old Commodore supplies, but I would have to study the internal design of these particular supplies to decide if they were "reasonably safe".

Of course what some consider safe is different from others. Look up the "Suicide Shower Head"
 
If anybody has a use for these, I'll send them over for a nominal cost (my time + shipping.) Otherwise I'm tossing them - I hate to toss stuff but I don't think these are much use to anyone. Also I measured the 9VAC pins and got 10.8VAC - if that's any importance to anybody.
 
If anybody has a use for these, I'll send them over for a nominal cost (my time + shipping.) Otherwise I'm tossing them - I hate to toss stuff but I don't think these are much use to anyone. Also I measured the 9VAC pins and got 10.8VAC - if that's any importance to anybody.
I'd like one for my lonely vic-20 unless the weight alone makes it cost prohibitive.
 
I'm not interested in the blocks but in the C64 ends. If they are still hanging around and you're up to cutting off the power adapter (C64 side, not the wall/outlet side) and packaging them up, I'd buy them. I drank the Kool-Aid and I'm also 'scairt' to use the actual power supply.
 
I'd love to have one of the three ridged-case ones if you've still got them. (and are willing to wait until I've got the funds)
I like to rebuild them with new components (aside from the transformer) after chipping out the epoxy.
I'd even take one without the computer-side cord if you wanna sell that to somebody else!
I have spare cords that my dad salvaged back when he did repairs on Commodores for his employer.
What would the cost be to ship to the middle of Washington state?
Not seen since Nov 20, I wonder if you're on holiday? Ah well, doesn't hurt to ask.
 
As for the 5V line: you can always crack them open and replace the linear regulator with a switching one. After that, they are safe and good as new. Cracking them open however is the hardest part.
 
The LED showing volts is a sweet hack. Is it a one piece 'LED plus circuit' to read the voltage or are the LED and the circuit two different pieces? If all one piece, do you have a part number?
 
One thing worth doing it to fit a power 6 to 7V Zener diode clamp to the +5V rail. Most TTL devices can handle up to 7V for a short period.

Also there is something else, if a logic board of any kind is powered by a power supply, and is separate from it and not hard wired to, there can also be the chance of something worse, a reverse polarity accident. In this case the power Zener clamps the voltage to less than a volt when it conducts in the reverse direction. A series fuse with it helps as it will blow when the zener conducts in either direction. When I have boards with many TTL IC's on them (that I make myself) I typically have a device, one example is the 1N6267 that I use on my Pong boards with 66 TTL IC's:


Another example happened in the Hero Jr Robot, it was powered by two 6V get cells that ran in series, but people installed 12V types by mistake, this often killed a lot of components, including the rare Votrax SC-01A speech chip, I fixed this risk with a Power Zener & a fuse:

www.worldphaco.com/uploads/SAVING_HERO_Jr_FROM_HIGH_VOLTAGE_and_REVERSE_POLARITY___Hero_Jr_Radio_Board..pdf

But, like the set of steak knives, there is more:

One issue with an smps, but it depends on the design complexity, is that some of the cheaper ones can have failure modes where the output voltage can jump up. For this reason, unless I inspect the design I seldom use them. I trust the National Semiconductors LM309k +5V regulator (still available from major supplies under the name LM309k-steel, if on a heatsink they are good for over 1A). They are also available in a mil spec version on the bay. The reason is, I have never seen one over-voltage its output yet as a failure mode (they practically never fail in any mode due to the internal protection systems, and there is negligible noise in its output). I would rather not worry about the efficiency issues over reliability & safety for the devices they power, unless the thing was battery operated perhaps. Some replacement switching modules have been made to replace TO-3 cased & TO-220 cased regulators,with the same footprint, but I would not go anywhere near them with a barge pole.

I recognized the genius of National's LM309k back in the late 1970's, by then they already had nearly a decade of reliable service and over the last 50 years, I have not been disappointed, even once.The manufacturers were so confident they called them "blowout proof", though they probably should not have, that is like saying the Titanic was unsinkable and tempting fate. Whether any clone versions are as good, I could not say.

I bought a box of them from Surplus Sales in Nebraska and use then in restorations, not to replace failed parts but if the originals are badly corroded externally, or for my own projects. I trust these over any smps, but it is just my opinion that I offer here.
 

Attachments

  • TheLM309k.jpg
    TheLM309k.jpg
    170.7 KB · Views: 6
I picked up a large C64 lot with four old PSUs (the dangerous ones) and am not sure what to do with them. I tested the 5VDC pins with my multimeter, the three without the sticker came out around 5.15V+ and the one with the sticker that says came in at about 5.07V. Should I toss these in the trash? Does anybody have a use for these? I don't want to put these out into the world and have them destroy C64s. Let me know if anyone needs these (or if I should be using ANY of them)

Also - I'm waiting on a modern C64 PSU from Europe, was wondering if I should try out the C64s with any of these while I wait or if I should not risk it.
I received the c64 power ends, thanks!
 
I suppose I should mention I got my ridged/finned-case power-supply just fine too, eh?
Arrived earlier than forecast, box and contents in good shape, functional as described.
Soon after disassembled, epoxy chipped away, components/PCB salvaged, and awaiting semi-modernized rebuild.
 
Back
Top