[sdiy] tr606 sequencer problem

[Julian]

Hi, 

I have a 606 here that i recieved in a very bad state.  Multiple torn tracks, melted wires, suspect soldering - generally a mess.

Ive removed what was left of the non-functioning midi kit, and set right all that i can find thats wrong, but i still cant get the sequencer working.

The symptoms are:

In any mode, only one led is initially lit - the pattern group one.

In pattern mode (either write or play) no pattern leds are lit, except if group more then one pattern together in the way that you normally do (press and hold first, press and release last, release first).  If this is done all the grouped patterns leds light *but not the first in the group*

It makes no difference which led is showing the first pattern in the group (ie if you group different patterns), but always the first in the group dosnt light.

Hitting the run/stop button lights the run/stop led as youd expect, but theres no led tracking across the steps.  Pressing the steps (like youd normally enter drum hits) has no effect.


Where im at so far:

Ive swapped out the cpu, memory, the various cmos ics of the sequencer with those of a known good machine.  The known good machine is running with the parts from the bad machine flawlessly.

Ive replaced all wires to/from the switchboard and checked the others.

Ive made sure that the 2.2us clock is present at the CPU
Probing pins of IC2 clearly show that the tempo ocilator is working, and responding to responding to changes of the tempo dial, but i havent followd the clock beyond IC2 yet.



Im getting to the edge of what i should check.  Any suggestions?

Thankyou, Julian
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