BOSS DR55 MODIFIED AND MIDIFIED by DenDer

[Circuitbenders]

I had the same problem with a DR55 i got hold of a while back, but it worked fine if i inserted a jack into the footswitch socket and held down the play button. 

If i recall correctly i just replaced IC3 which appears to be a CD4011 according to that schematic.

[nochtanseenspecht]

yeah, i think what Crusty Paul says.. maybe check the foot socced, clean it etc
good luck Dender.. very bad news

[Gordonjcp]

good luck Dender.. very bad news Cry

Nah, not really.  If it's totally borked, he can rip out the memory chip and wire some sort of microcontroller in to replace it.  A wee bit of clever firmware, and you've got a MIDIed-up DR55 with some clever tricks up its sleeve (like programmable hihats)...

[DenDer]

First of all there is nothing wrong with the footswitch. Haven't got any problems with it. I think it is what Gordon says.....CE2 is not pulsing so the memory chip isn't firing. It's strange though that the led is running

Hrm, shouldn't the hats tick all the time that the clock is running? Unless there's something drastically wrong with the memory chip, it won't stop the counters counting.

It wouldn't hurt to have a spare memory chip, but I don't think that's the problem.

Measure pin 9 of IC and check that it toggles when you press start and stop.
Check for pulses at pin 11 when the pattern is started - in PLAY this is sent to the hihat "16" setting.

If you're not getting that, the oscillator isn't running for some reason.

So you think it's maybe the 4011UB, Gordon? Yesterday i got the replacemnt memory chip from Vintage Planet which i just picked up at his home (really friendly guy Senso )
He didn't got the 4011UB otherwise i would have picked that one up at the same time.
It's early in the morning over here so first my coffee and then i will measure the pins you suggested.

Ps which IC do you mean in the quote? the 4011 right?

[Gordonjcp]

Yes, on the 4011.

Hang on, the LED pulses?  What, normally, at the start of every bar, so it's pulsing all the time you've got the drum machine running and stops when you hit stop?

I'm not sure how that would happen.  The LED is driven by Q13 and Q14.  Now R96 pulls up the base of Q13, turning the LED on all the time.  When Q14 has its base turned on, it clamps Q13's base to ground turning the LED off. 
So how do we get it to flash at the start of every bar?  Pin 10 of the 4011 goes low during a "step".  This feeds through R73 and R74 to the base of Q14.  The outputs of the address counter are also fed there through R69-R72.  So, if any of those inputs is high, Q14 is turned on and turns off the LED.  Only when the clock is low during a "step" and we're at the first step are all the inputs off.  It's a crude 4-input NOR gate ;-)

If the LED flashes normally - one little blink at the start of every bar, the counter *must* be running.  The thing is, CE2 is wired to the same clock output that clocks the counter and drives the hihat 16ths - follow the trace around from the REC/PLAY switch.  If the clock is working, it's in play mode and the hihats are set to 16ths, you should hear that even if the memory and counter are hosed.  As a quick check, you could tack a wire from pin 11 of the 4011 to the wiper of the hihat switch and leave it switched OFF, just to discount dodgy switch contacts.

HTH,
  Gordon

[DenDer]

Mayor cool update ITS WORKING AGAIN.

I've been a big big big big big ssssss........i'm almost ashamed to tell what it was...........so i won't....or maybe if you persist i will tell.......all sounds are back..........

[DenDer]

btw thanks to you all for thinking with me especially you Gordon.........big round of applausse from my side.

[Gordonjcp]

Go on, what was it then?  Stray solder splat?  Sticky switch?  Sheer stupidity?

Do tell...

[DenDer]

Okee but please don't shoot me...i feel dumb as it is.

Anyways to install the midi sync you have to remove the jumper between the start and stop button. So i did...but i soldered one wire to one of the holes and the other to cap thats above it......so when the kit didn't work i took it out but resoldered the jumper at the same place. So the clock wasn't connected anymore to the voice side.....

SO SHEER STUPIDITY ON MY BEHALVE.

This morning i got up and checked everything 20 times till i came to that conclusion.
I'm just glad it's working again so now i'll give it another go with the midi sync......

[Gordonjcp]

Ho ho ho.  I've *never* done anything like that... ;-)

[DenDer]

I don't know did you???

[Gordonjcp]

</sarcasm>

(offtopic rambling tale warning)

Just a couple of days ago, changing the fan belts in my car - put the big belt on (the one that drives the water pump and alternator), tightened it up, lovely, no squeaking.  Took the small belt off (drives the hydraulic pump).  Rain came on, put the tools away and shut the bonnet, went inside.

Fell asleep.

Woke up had dinner, met some friends in town (took the train), came back, bed.

Got up, bit late, OH NOES meeting people in town in half an hour!

Jumped in the car, started up, "Hmm nice and quiet since I did those belts... <waits>Odd, the hydraulic light's usually out by now <revs it up> Really is nice and quiet, isn't it? Wonder why the light's still on? <spots the new belt sitting on the passenger seat>Oh cock."

Run for the train, again...

[DenDer]

Why is my karma gone.........made 1 little mistake........and fixed it.........never mind anyways.

[nochtanseenspecht]

here you have a new karma
hee but congratulations you found the problem !

btw; NEVER put recharchable batteries in your dr55
mine nearly died from that..but the reason i don't know

[Gordonjcp]

Hmm, normal rechargeables are only 1.2V, perhaps it had too low a supply voltage and didn't run properly?

What was the actual problem you had?