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MB-6582 diy PSU question


Molom
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Hi guys, 

I'm at the stage of choosing which PSU option to go with for a mb-6582 that only uses 8580 SIDs. I don't really want to pay the high cost (incl. shipping) for an old C64 PSU, especially given their age and poor reliability, so I'm thinking of building my own (option D).

I found this discussion about building replacement 64 PSUs here: http://www.eevblog.com/forum/projects/commodore-64-replacement-psu-project/msg283418/#msg283418, and this post in particular about halfway down:

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Build your own psu, this is what i have done in the past: 
combine one of these boards(+5v,5A) which is plenty with a 9VAC transformer from mpja Granted,not such a elegant roll your own solution,but why reinvent the wheel:

http://www.ebay.com/itm/25W-DC-5V-5A-Regulated-Switching-Power-Supply-/170620769059
 and this:
http://www.mpja.com/18V-2A-Center-Tapped-9-0-9-Transformer/productinfo/7843%20TR/ 

Combine them together in a old AT/ATX psu case and it makes for a reliable setup for the good old C64.

If 120/240vac operation is important,just use a transformer with dual primaries and add a switch to the case(some old at/atx psu's had 120/240 switches already) to change input voltage. the 5v switching psu can handle 120/240 already. 

 

Can any kind souls with more experience than me attest that this will work for option D? Or perhaps point me in the direction of a relatively low-cost DIY solution that will work? Ordering anything from the USA on eBay isn't really an option due to the unreasonably high shipping costs.

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There are posts here about using switch-mode supplies for various MidiBox projects since you would want 5DC and 9 or 12DC ideally. I believe you can find switchmode PSUs that offer both 5VDC and 9VDC, but if you can't, you can use a regulator to bring it down to 5VDC. Thing to be careful about here is you need one that has a high switching frequency and good filtering since you are using it for audio applications. The forum has plenty of discussion around this though.

A C64 power supply offers +5DC and 9VAC (hence the transformer mentioned up above), which is options A or B for the MB6582. Might be ok if you want to use it for a C64 when you're not using it for your MB6582, but this design dumps more heat into the 6582. And if you were going to build a C64 compatible PSU, I would recommend just buying a new C64 PSU off eBay. They at least use more modern components, are cheaper, and would get the job done without you having to work with mains AC voltage.

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If you are running 8 SIDs, .5A might not be enough, but I can't remember what the current draw was. My MB6582 power supply draw was under 1A on both as I recall (I used 78xx linear regulators, which are typically only rated at 1A). I think the first PSU would be safer as far as headroom. That said, I couldn't find the switching frequency and that's arguably the most important statistic.

Question is, do you want to trust a PSU to your irreplaceable SIDs? If you've come this far, I wouldn't skimp on the PSU (if it were me) if you are going to go with a nice switchmode. I'd suggest seeing if Meal-Well has a PSU that suits your needs (again, pretty sure there were some suitable models mentioned here on the forums or on the wiki) since they public their switching frequency and all well regarded.

In a pinch, you could run multiple wall-wart PSUs (a 5V and a 9V) if you can get nice linear regulated ones (switchmode wall-warts will likely be very noisy for audio). Jameco has some, for instance. That could get you buy while you find a better long term solution.

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Ah I see, thank you. I'm guessing the multiple wall-wart option is similar to what is shown here? http://dannygalaga.com/c64.html

Otherwise, I found an old post from Shuriken, which looks like the way I could go.

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I am currently constructing a PSU for my MB6582 unit. The PSU will consist of a Meanwell RPT60 with a LM2596 circuit to make the required 9 Volts.

 

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.5A is not going to do it.

The original c128 PSU's are decent and have better lifespan than the c64 ones which are ticking timebombs.

I had one built by Ray Carlsen...pricey but worth it. they are well built switching supplies, noise free with built in protection and the 9v side provides 1A and I believe 2.5A on the 12v (I used a mixed SID setup).

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Have you looked into @Altitude's thread on powering an MB-6582 from a single supply? IIRC, you just use any ol' 12V DC wall-wart, then regulate it on the board to 9V and 5V with a 7809 with a more efficient 5V switching regulator with a very high frequency. It requires a couple jumpers, but otherwise works with the MB-6582 PCB just fine. Seems like the simplest solution.

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