Roter_Flieger Posted October 27, 2006 Report Share Posted October 27, 2006 Hi there,I completed my CORE module today and powered it by an optimized C64 PSU. The voltages of the PSU are just 5V and around 14V as they are expected to be. But the core gives me a headache.The core is not stuffed with the 7805, instead, I shorted its input and output lines. I accidentally connected the PSU to J1 instead of J2 as suggested in the optimized PSU guidelines but I though that does not matter at all? Anyways, the moment I wanted to start measuring my voltages, I realized that familiar smell of burning electronics. I quickly disconnected everything and found the rectifier burning hot. Everything else seemed to be cool.So I reconnected everything, this time with the PSU at J2. The rectifier stays cool, but the voltage is only around 0,5V at all points within the circuit. Even at the PSu output, the voltage is not correct anymore, as soon as I connect the core (it is 5V as long as the core stays unconnected).I checked my soldering for any shorts but was not able to find any. Everything seems to be ok. When I measure the resistance between +5V and GND on the board, I get a steadily increasing value (natural because of all the capacitors in there) so there is no obvious short between the power lines.Now, I do not know what else to check. Can you give me some piece of advice? Quote Link to comment Share on other sites More sharing options...
toxictv101 Posted October 28, 2006 Report Share Posted October 28, 2006 i dont know but, one time i ve Destroy a picand when i puted it into the core , Voltage falled Down,, dont know why Quote Link to comment Share on other sites More sharing options...
HL-SDK Posted October 28, 2006 Report Share Posted October 28, 2006 Ok this is what you can do to easily solve your problem:Buy a new PIC (I am), check all connections and read the schematic of the core module.Make sure you know what you are doing with the voltage regulator holes... Voltage regulators usually go ICO (Input, common (ground), output) when you are looking at it...You want to ground the middle pin, put 5V into the output pin, and test socket voltages.I wish you the best of luck, removing this PIC and getting a fresh, tested one is good but costly... It's what I'm doing :-/ Quote Link to comment Share on other sites More sharing options...
Roter_Flieger Posted October 28, 2006 Author Report Share Posted October 28, 2006 Well, the PIC was not put into the IC-Socket yet, same is true for the optocoupler. I will never put expensive ICs into a circuit without verifying the voltages first. I have not even unpacked the PIC from its shipping box yet, so it definitely cannot be blamed for this.I am still not sure about the voltage regulator and the rectifier though. Since I am using the optimized C64 PSU, I already have stabilized 5V right out of it, so I do not need the 7805 and left it out. I shortened the leftmost and the rightmost pin of the mounting holes for the 7805, leaving the middle pin (i.e. ground) untouched. Is that correct? May I still use the same capacitor values as if the 7805 was in there?And why does a rectifier get hot? I connected my 5V DC to the AC input of the rectifier (I double checked that it was soldered in properly and that its terminals are in the right place) but I thought this would be ok and also gives me 5V DC with the right polarity at the output. Does a rectifier get damaged when it is fed with DC current?Also, the problem still persists when the rectifier is soldered out and the CORE modules is supplied by J2.I checked the schematics and the circuit almost all night and I still have no clue. Maybe I should get some sleep before I proceed... Quote Link to comment Share on other sites More sharing options...
HL-SDK Posted October 29, 2006 Report Share Posted October 29, 2006 Always give voltage regulators 2 volts more than what they put out.Always.Thie means, never feed your core 5, even 6 volts, it wants 7+SID module wants 11 (for the newer SID and 14 volts for the older one Quote Link to comment Share on other sites More sharing options...
Roter_Flieger Posted October 29, 2006 Author Report Share Posted October 29, 2006 As I already said, there is NO voltage regulator on my CORE module, so I can easily feed 5 V into it. ;) (BTW: since I have read the 78xx datasheet, I know about this particular fact :))The problem was totally different. I still do not know why I fried my rectifier, but apparently the C64 PSU was broken. The C64 I got it with was not functional and I now guess the PSU was the cause. Without any load, it delivered 12V at its 5V output which dropped below 1V with a load applied. Strange...I now connected an old standard PC PSU with regulated 5V and 12V lines and finally, the CORE had all the required voltages. The bootstrap loader kindly asked for its OS and everything seems to work fine now.I would still like to know why the fscking rectifier heated up that much, but that will probably remain a mystery. Quote Link to comment Share on other sites More sharing options...
HL-SDK Posted October 29, 2006 Report Share Posted October 29, 2006 Rectifiers heating up even a little bit seems strange, unless there is a short, but you'd probably notice that when yout transformer heats up and starts to fail...Rectifier is all in the correct position?If it's DC, bypass the rectifier, just be extremely careful of polarity Quote Link to comment Share on other sites More sharing options...
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