okay heres how it is...

keithygeorge · Post by **keithygeorge** » Wed Jan 26, 2005 4:03 pm

Followed dcmodders tutorial for tricking me dc into thinking that theres a fan there. Made the curcuit finally, (had the bits for about 4 months, just lazy) and soldered it all up etc. First of all I ran into problems when ya hafta solder 3 wires to one plug. Is it okay to solder em all with the same piece of solder, or is it best to make three seperate joins, wasn't sure anyways, so just went on soldering em all together. Right, anyways, circuits built after hours of fiddlin. Turn on the dc, bla bla, turns off (obviously, i didn't exactly expect this to work {should have thought it through abit more actually before tearing me actual dc fan out of its little plug in thingy..yes, the word your looking for is MUPPET}) but anyways, I noticed that the 555 trigger is gettin proper hot after just afew seconds of bein on, so reckon dat me circuits knackered....anyone got any clues that will stop me having to buy a new dc this weekend...

btw, this wont be good if i've killed it, thats an x-box and a dc now

Cheers

keithy

Sir Savant · Post by **Sir Savant** » Wed Jan 26, 2005 4:18 pm

did you put in a fan?

keithygeorge · Post by **keithygeorge** » Wed Jan 26, 2005 4:36 pm

nope, nothing running off the psu, basically, got the curcuit plugged into where the original fan goes, and the 555 chip in the circuit is burnin up, but coz I kind of ripped the wires from the fan, can't actually tell which one is which now, mines a pal dc and the wires are blue red and orange, as opposed to the black white and red thats specified in the tut

Matt · Post by **Matt** » Wed Jan 26, 2005 5:21 pm

The idea of that circuit is to allow you to use a replacment fan, if you don't use one at all your DC will definately overheat

Pyrosurfer · Post by **Pyrosurfer** » Wed Jan 26, 2005 5:27 pm

From the other topic:
I'm pretty sure the RPM thing is crap. I measured resistance from gnd to the extra pin to gnd and it was a constant .88k. The rpm method is probably just acting as a load for the dc's current. People here have said before they just shorted the extra pin to gnd, and it worked. Both of the RPM method and shorting could be harmful to your dc, I would recommend putting a 200-2k resistor from the extra pin to gnd. I will be trying this myself soon.

Basically:
Try connecting a resistor (at least 200 ohms to be safe, but if you go above 2k it might not work) between gnd and the extra wire . If you can find a resistor around .88k that would be ideal. The dc does not detect pulses.

Matt, the dc is not going to overheat within seconds of running without a fan. It will take hours, or maybe days.

keithygeorge · Post by **keithygeorge** » Wed Jan 26, 2005 5:34 pm

cool man, but where do I slap such a resistor, i aint got a clue were i'd put it...der are 2 extra pins, 4 and 5 are spare.

I thought that revs thing was abit wierd, thought it sent a signal every so often (milliseconds) just to say it was there....but then again, probably every 10 secs coz thats how long me dc's gd-rom will run for....abit of an anal thing for sega to do really

keithygeorge · Post by **keithygeorge** » Wed Jan 26, 2005 5:39 pm

just re-read, when ya do it, ya gonna make a tut to follow??

Pyrosurfer · Post by **Pyrosurfer** » Wed Jan 26, 2005 5:39 pm

You have a multimeter? If so, set it on voltage and place the terminals on the different pins until you get +5V. Your multimeters negative terminal will be on gnd, the pin that is not connected to the multi is the key pin. Connect the key to gnd with a resistor, it should work.

I'll see if I can find which pin is which for you.

keithygeorge · Post by **keithygeorge** » Wed Jan 26, 2005 6:19 pm

oh cheers mate, keep readin bout these multimeters, gonna grab one on the weekend, next time im in preston i'll pick one up (along with another dc, prolly good 2 have more than 1, means I got spares etc)

Pyrosurfer · Post by **Pyrosurfer** » Wed Jan 26, 2005 6:20 pm

Hey, I have a dc that is just like yours. Blue is gnd, orange is key. I don't have a spare dc to mess around with right now though, but if you try it I guess we could make a tut together. Just connect the resistor from blue to orange. If your feeling a little adventurous, you can just short it, people have done it before and it worked. Using a resistor would be the safest way though.

EDIT: I'm gonna go rip apart a dc fan, see whats connected to the third pin.

EDIT: Various capacitors, resistors, and transistors are onboard. There is 1 IC 3414A P026. Google leads me here http://64.233.161.104/search?q=cache:7x ... 026+&hl=en

I just checked and the resistance on one of my dc's was 3.88k and the other was 11.02k. I dunno I could be wrong, might as well try it though.

keithygeorge · Post by **keithygeorge** » Fri Jan 28, 2005 5:39 am

right then, i'll goto maplin today and get the bits again...gonna buy another dc today so that the one I got is like a test case...

dcmodder · Post by **dcmodder** » Fri Jan 28, 2005 8:46 am

for all of you orange blue red wire people i made this just 4 u

keithygeorge · Post by **keithygeorge** » Fri Jan 28, 2005 5:47 pm

wahey, in that case...i got 2 workin dc's....lol

mint anyways, thanks for that piccy..still avn't opened me new dc up yet (well it aint exactly new) was abit ticked off about the price ?20, bids on ebay for 5 without pads or games for ?45...dats like 40 bucks and 90 bucks for you yankies....

btw, dc modder, i'm gonna take it dat the top one is da red wire

dcmodder · Post by **dcmodder** » Fri Jan 28, 2005 6:02 pm

the top wire is orange. the order goes orange blue red from top to bottom

keithygeorge · Post by **keithygeorge** » Fri Jan 28, 2005 7:02 pm

cheers geeza

SirSolBadguy · Post by **SirSolBadguy** » Fri Jan 28, 2005 10:49 pm

I was surprised DCmodder's circuit actually worked for me. I have virtually no electronics knowledge, and I somehow accomplished it. Although I havent touched the 555 chip to see if it is indeed running hot like you mentioned. I should try that.

I'm very happy though.I have a replacement 80mm fan running off the 12v, and it's too powerful, but tomorrow I'm buying this, so I can turn it down a tad:

http://www.radioshack.com/product.asp?c ... id=271-265

Alexvrb · Post by **Alexvrb** » Sat Jan 29, 2005 12:31 am

Couldn't you just try running the fan at a lower voltage first?

SirSolBadguy · Post by **SirSolBadguy** » Sat Jan 29, 2005 2:23 am

Of course. The options are 3.3v, 5v, and 12v, by using the Dreamcast's psu pins. And 5v doesn't push any air at all unless I hold it up to my eyeball. So...what are you talking about?

keithygeorge · Post by **keithygeorge** » Sat Jan 29, 2005 5:58 am

when you say its too powerful, what exactly do ya mean...i've got mine from an old heatsink, its fair chunky (not huge, but more than twice the size of the dc fan) and thats 12v's aswell...

Oh yeah, counter question to dcmodder (or anyone else who's completed this mod) will this mean that my leds are goin to be straining to find power, or will the dc psu support me new fan and say 6 led's fine??

dcmodder · Post by **dcmodder** » Sat Jan 29, 2005 11:01 am

you can hook almost n e thing up to that psu and nothing will be affected. currently i have a small 12v fan cooling my dc and it's running off of the psu and nothing's gone wrong or affected.