BOSS SD-2 DUAL OVERDRIVE BYPASS FAULT..NEED HELP PLEASE

[wordstep]

Make sure there is no misunderstanding. Push the foot switch each time (push and release),
the side(connect to thr rotary switch) of R10, should be 8.x V or 0 V.

Let me quote the words from amptramp , these are the same as what I mean, in  a different way.
"The SD-2 has the usual transistor flip-flop and the NAND gates are used to select which channels are enabled.  The first thing to determine is whether the flip-flop section consisting of the pair of 2SC2459GR transistors, the associated four capacitors and six resistors and the switch debounce circuit consisting of R2, C2 and R12 are actually capable of changing the state of the flip-flop each time the effect on/off switch is pushed.  This can be determined by checking the voltage at pin 12 of the board.  If this is toggling i.e. changing state each time the button is pushed, then that part of the circuit is OK.  If not, fix it.  (How's that for helpful advice?) "

" changing the state of the flip-flop each time the effect on/off switch is pushed. " = Push the foot switch each time (push and release), the side(connect to thr rotary switch) of R10, should be 8.x V or 0 V.

If your measurement is right, it is obvious, the flip-flop part is not working. Change the 2 trainsistors.....
"If the flip-flop part is not working, check all the traces and solder joints of the flip-flop part, and try to replace parts,
try the 2 transistors first, then caps, then....   Good luck."

[lukewright]

hi yes my answer is right from what i got, with no miss understanding i pressed and released the switch as it would if i stood on it to select bypass mode etc, you say to change the 2 transistors, but can you tell me which numbers i need to change as i dont wanna do the wrong ones   , i have checked all solder joints and none of them are dry.
thanks you guys are real helpful 

[amptramp]

According to the schematic, the transistors are Q1 and Q2.  On the third picture on your own site, you can see Q2 at the lower left of the picture and Q1 is probably under the jumble of wiring to its left.  If you move up one row of components from where Q2 is, you can see a row of components that include C7 just below the white shielded wire.  Two components to the left of C7 is another transistor.  Although I cannot see the designator in the picture, this is probably Q1.  On photo 1 of the series on your site, this appears to be the upper left.  The soldering looks OK from here, so I assume there is a component failure.  Incidentally, Boss redesigned the circuit to take both transistor emitters through a single diode to ground in some of their other pedals - maybe the switching was not reliable enough at high temperatures or something like that.

Incidentally, the problem may not necessarily be transistors - that is just the most likely item.  If C2 was shorted, you would also never switch, so make sure what has failed before you do anything.  If you try a wholesale replacement of the parts in that circuit, you may burn the board or lift traces.

[lukewright]

so what would be your suggestions then replacing q1-q2 and see how it is?...where would i get them from and what would i ask for?
are they a specific thing i know nothing about transistors etc so wouldnt know  what to get lol  
i have found some on ebay...with the same numbers on ....heres the link these ar the right ones yes?
http://shop.ebay.co.uk/i.html?_nkw=c2458&_sacat=0&_odkw=transistors&_osacat=0&_trksid=p3286.c0.m270.l1313


cheers luke

[wordstep]

In your second picture, left top, you can see Q1,Q2.

Troubleshooting a flip-flop circuit might be extremely easy, also might be extremely hard.
In some cases, even the bad componment is replaced with a good one, the flip-flop might not work.

Google " flip flop" you will find a lot links like:
http://en.wikipedia.org/wiki/Flip-flop_(electronics)
http://talkingelectronics.com/FreeProjects/5-Projects/Page16.html
...

Then you should learn how to test a tranisitor, capacitor, and resistor....

If you want to save the hassles, ask a friend in electronic field to do it.

[amptramp]

In your second picture, left top, you can see Q1,Q2.

How did I miss that?  Absolutely correct.  It might be easier to check with a DC scope - you would be able to see voltages move when the button is pushed.  The problem with DMM measurements is that the pushbutton is capacitively coupled into the flip-flop, so the voltage at the base that does the switching only appears briefly.

[lukewright]

ok well thanks for your guys help, i think i will read up about doing it but may put it to a specialist to test, keep checking to see my progress and ill post how i get on in a few days or something...you guys have been great. cheers.
luke