Wilba Posted October 4, 2007 Report Share Posted October 4, 2007 I just bought three more C64 PSU "bricks" from eBay just like my current oneSee pic from the eBay auction:They all have correct voltages, but one makes a very loud buzzing noise.Does anyone know what could make such a buzzing noise? Note that these aren't the same internally like the solid plastic C64 PSUs... from opening up my original one, they have a 7805 on a massive aluminium heatsink, a bridge rectifier, electrolytic capacitors etc.Do capacitors make buzzing noises if they're old and worn out? What else could it be?C64 PSU.JPG Quote Link to comment Share on other sites More sharing options...
Sasha Posted October 4, 2007 Report Share Posted October 4, 2007 Not sure I understand you what actually produce buzzing. Does your SID buzz when powered from that PSU or brick buzz itself? Transformers can buzz if the its metal plates have some air between so vibration occurs because of the magnetic flow. That could produce buzz. If if buzzing happened in your speakers than it could probably be capacitor. Quote Link to comment Share on other sites More sharing options...
Wilba Posted October 4, 2007 Author Report Share Posted October 4, 2007 I'm talking about buzz in the PSU unit, I haven't connected it to the SIDs yet.I can't tell if it's exactly a 60Hz buzz either, it's certainly not a high-pitched whine sound, it's a low-pitch buzz like electric clippers.I'd like to have some idea what to look for before I start tinkering and replacing bits. Quote Link to comment Share on other sites More sharing options...
/tilted/ Posted October 4, 2007 Report Share Posted October 4, 2007 I'd hope it isn't a 60Hz buzz.Unless you've run a really long extension lead to the U.S.!!(Ours is 50Hz) Quote Link to comment Share on other sites More sharing options...
opkod Posted October 4, 2007 Report Share Posted October 4, 2007 I'd hope it isn't a 60Hz buzz.Unless you've run a really long extension lead to the U.S.!!(Ours is 50Hz)or to France *kwack*and I may have a problem with a 9v c64 powersupply (I measured 11V instead of 9v direct on the pin out), the c64 don't work, but this power supply could be safe for use with the mb6582? ??? Quote Link to comment Share on other sites More sharing options...
cavey Posted October 4, 2007 Report Share Posted October 4, 2007 probably the cap that is making the buzzing sound.This is a nice read:http://personalpages.tds.net/~rcarlsen/cbm/pstester.txtAnd the guy has plenty more interesting stuff about ancient c64 stuff.I have to test my own PSU at home as well, makes my c64 go blank at start up >_< grmblBut let me get this straight: you have 3 extra black bricks (opposed to the white/beige weird shaped bricks from even longer ago), which do NOT have epoxy on the inside?! Quote Link to comment Share on other sites More sharing options...
/tilted/ Posted October 4, 2007 Report Share Posted October 4, 2007 I dare say that 11v on a 9v line is not going to cause too many problems. Especially as this line is AC, and gets rectifed and regulated before it gets to your SIDs.Also, is your volt meter set to AC or DC volts? this might account for a strange reading... Quote Link to comment Share on other sites More sharing options...
opkod Posted October 4, 2007 Report Share Posted October 4, 2007 I dare say that 11v on a 9v line is not going to cause too many problems. Especially as this line is AC, and gets rectifed and regulated before it gets to your SIDs.Also, is your volt meter set to AC or DC volts? this might account for a strange reading...so, if it's not important, it won't be a problem. But the c64 I own is still not working after I change the previous connector which a pin as missed, but it don't change anything... :-\ I will keep the case and the 8580R5.... ::) Quote Link to comment Share on other sites More sharing options...
Wilba Posted October 4, 2007 Author Report Share Posted October 4, 2007 I'd hope it isn't a 60Hz buzz.Unless you've run a really long extension lead to the U.S.!!(Ours is 50Hz)I think I was confusing it with PAL vs. NTSC *whack* Quote Link to comment Share on other sites More sharing options...
Wilba Posted October 4, 2007 Author Report Share Posted October 4, 2007 But let me get this straight: you have 3 extra black bricks (opposed to the white/beige weird shaped bricks from even longer ago), which do NOT have epoxy on the inside?!Yes, I now have four in total that look like the picture, with vents on the sides, philips screws holding it together... three black, one beige. Quote Link to comment Share on other sites More sharing options...
Wilba Posted October 4, 2007 Author Report Share Posted October 4, 2007 and I may have a problem with a 9v c64 powersupply (I measured 11V instead of 9v direct on the pin out), the c64 don't work, but this power supply could be safe for use with the mb6582? ???There should be 9V AC on the two pins either side of the notch.If you measure with a multimeter set to AC, it should read 9V, but it might be different.To give you some idea, the 9V AC coming from my PSU is put through a bridge rectifier and then a 2200uF electrolytic and then a 7809 voltage regulator. If I measure the DC voltage on the input side of the 7809, it's approximately 11V DC, which is what you want... i.e. something rated at 9V AC is supposed to be able to deliver 9V DC after a regulator, so 2 volts above 9V is a good thing.I am confused why you read 11V AC instead of something like 9V AC, but it should be OK because of what I just said, it is regulated down to 9V by the voltage regulator V1 on the PCB. However, if you are not measuring an exact 5V DC on the other pins, don't use it, the MB-6582 PCB expects regulated 5V DC since this is what C64 PSUs are supposed to do (with an internal 7805 or equivalent circuit). Quote Link to comment Share on other sites More sharing options...
Wilba Posted October 4, 2007 Author Report Share Posted October 4, 2007 This is a nice read:http://personalpages.tds.net/~rcarlsen/cbm/pstester.txtAnd the guy has plenty more interesting stuff about ancient c64 stuff.Yes, thanks for that!This is an interesting idea, if you want to protect your SIDs from accidental overvoltage on the 5V supply line:http://personalpages.tds.net/~rcarlsen/cbm/saver.txtIt might even be worth doing something similar in the next revision of the MB-6582 base PCB! Quote Link to comment Share on other sites More sharing options...
opkod Posted October 4, 2007 Report Share Posted October 4, 2007 ok, so this power supply seems to be ok :D thats the only thing working with this c64..... >:( Quote Link to comment Share on other sites More sharing options...
/tilted/ Posted October 6, 2007 Report Share Posted October 6, 2007 You might find you have a blown fuse.Most C64s have a board mounted fuse inside.The exact location will vary by model, but it is usually within an inch or so of the power supply connector. Quote Link to comment Share on other sites More sharing options...
Goblinz Posted October 8, 2007 Report Share Posted October 8, 2007 Yes, thanks for that!This is an interesting idea, if you want to protect your SIDs from accidental overvoltage on the 5V supply line:http://personalpages.tds.net/~rcarlsen/cbm/saver.txtIt might even be worth doing something similar in the next revision of the MB-6582 base PCB! Next revision? .... I haven't even got hold of the last revision yet! :o G Quote Link to comment Share on other sites More sharing options...
julienvoirin Posted October 22, 2007 Report Share Posted October 22, 2007 i got the same problem as wilba but with a brown supply. dangerous ? Quote Link to comment Share on other sites More sharing options...
bill Posted October 22, 2007 Report Share Posted October 22, 2007 Transformers can buzz if the its metal plates have some air between so vibration occurs because of the magnetic flow.True !That's the behavior of an old transformer. ;)This is when the varnish change because of the long time, then the transmormer wires have gain some space, so they are vibrating at the local frequency, that make that 'hum'. There's nothing you can do, but change the transformer. This said, it should be no danger for you hardware. Quote Link to comment Share on other sites More sharing options...
julienvoirin Posted October 22, 2007 Report Share Posted October 22, 2007 That's the behavior of an old transformer. i didn't know that :P you learn everyday .. Quote Link to comment Share on other sites More sharing options...
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