[XCSSA] Can you break transformers?

[X-otic Computer Systems of San Antonio]

On Sep 4, 2008, at 10:56 PM, X-otic Computer Systems of San Antonio  
wrote:

> X-otic Computer Systems of San Antonio wrote:
>> I'm not sure how I'm doing it but it appears as though I've killed
>> both my C64 PSU and now another 12VAC wall-wart. The thing is, I was
>> able to get inside the wall-wart, and all I found was a transformer.
>> No fuse or anything. However, before I started tinkering with things,
>> my multimeter showed about 15VAC from the thing (I guess 12VAC  
>> assumes
>> it's going into some sort of rectification/regulation? Well, my
>> initial tests with my new power board worked great - I was getting  
>> the
>> DC voltages I was expecting (namely 12 and 9VDC). Well, I hooked up  
>> my
>> PIC board without the PIC itself and got the proper voltages. Then I
>> stuff it with chips and, after that, now my wall-wart reads 3VAC with
>> no load.
>>
> Yes, you can break transformers, you are not the only one who have  
> done
> it... ;-)
> If you overload them they can short out in the windings which can  
> result
> in either over voltages or under voltages...

Hmmm...that must've been what I did then. Poop. That's two power  
supplies in like a week :)

> It can be tricky to accurately measure AC, if your meter registers  
> 15VAC
> it might be measuring the peak values.
> 12VAC should have a peak voltage of sqrt(2)x12 which is about 17V  
> and if
> you have rectifier diodes in your meter, they might drop a volt or two
> so 15 is probably the peak values...

Yes Charles mentioned that, though that function is good to know.

>
>> It's just spools of wire! How in the heck am I so good at nuking  
>> these
>> things? :P Any thoughts?
>>
> Use a fuse and check your wiring, I'm talking from my own  
> experience... ;-)
> The fuse should go on the 110V side or whatever side is feeding the
> transformer...

That might be a bit tricky for a wall-wart. I'm guessing I just should  
likely buy one with a fuse inside (that I can get to if I blow it).  
Also probably won't hurt to put a fuse on the other side as well. The  
regulators shut off at 1 amp but I'd like to have an indicator I'm  
using more than that and I think a fuse would help there.

>
>> Good news is that I have other adapters, but they are DC and while
>> it's not a big deal it's likely going to be fantastically noisy for  
>> my
>> SIDs :/
>>
>> Help would be appreciated!
>>
> If all you need is 5V and 12 V DC, try the white Commodore PSU that
> already outputs these voltages...
> Or do you think that Commodore put the filtering for the SID on the
> actual motherboard ?

That's odd. I was using the white one and actually was getting 5VDC  
and 9VAC. Either way, my C64 had a 6581 on it which requires 12V. So I  
have a feeling they are doing the same thing I was doing, which was to  
feed the +5VDC to the ground pin of the 7809 regulator which, after  
regulation, produces 14VDC that you can then step down as appropriate  
to whatever SID is being used. That said, if some C64 PSU's do 5V and  
12V, my power board would basically work the same way (the 7809 would  
just get a bit hotter I suppose).

>
>> Tim
>>
>> P.S. Frederick, if I can figure out how to keep my MidiBox SID  
>> powered
>> up, I'll go ahead and test your SIDs next :)
>>
> No hurry...
>
> You are not the only one breaking things, my Windoze box just crashed
> one of it's hard drives... ;-)
> Of course it's the boot drive and I lost the Install CD somewhere so
> it's going to take a while to get it back up and running...
> My old Win XP CD don't detect the drives since they are SATA and not  
> IDE...

If you have a working machine still, try searching for "Win XP SATA  
install". There are some programs which can help you make a  
slipstreamed (I think that's what they call it) Windows XP, complete  
with SATA drivers. You can actually install any drivers you want on  
the CD too so that, once you're done, it is already ready to go!  
That's how I had to install onto my SATA drives. It's not very fun but  
it works.
>
> So I transfered the mail to my Ubuntu Box and 20 minutes later it died
> too... ;-)
> The monitor went black but I can hear the hard drives spinning...
> So I put in a new graphics card but still nothing so I'm going to  
> see if
> the PSU is OK or not...

Holy crap that sucks! I feel your pain though as I've definitely been  
there! Some days it seems like any computer I would touch just breaks :P

> So I dusted off a third computer that I haven't used for eight years  
> and
> transferred the mail again...
> This one has managed to stay alive for a few hours...
>
> I guess I upset the Apple and Commodore gods with the Appledore...
> By the way, the Appledore works now, I found a short when I folded the
> ribbon cable and it has been working fine ever since I fixed it... ;-)

Woohoo! You're bringing this to the next meeting right?

Tim