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Sequential TOM stuck on Pattern Number Function

Posted: Sun Jul 10, 2016 3:53 am
by SeventhStar
I picked up a Sequential TOM yesterday. The guy I bought it from obtained it from an Estate Sale. His only method of testing was simply plugging it in via the original Sequential E-170 power supply. He didn't have any way of hooking up the 1/4" audio out, to test audio output. Upon Power up, the proper LEDs lit up, as they were supposed to, according to the TOM Service Manual, so I bought it, with the agreement that if it didn't work I could return it.

Today, I hooked it up to my mixer and amplifier, to test it..

1) Start/Stop and All Black Trigger buttons function.

2) All 8 samples play back correctly. I hear all the sounds through my amp.

3) There are 12 patterns, currently in memory that play back. The other pattern memory locations are empty.

4) All Number pad buttons work.

5) Tempo buttons work.

6) Reverse and cartridge buttons work.

The PROBLEM.. The Function Matrix, is stuck on the "PATTERN" Column and the "Pattern Number" Row. The SONG and CONTROL buttons don't appear to function. Their LEDs don't illuminate when pressed. Same thing with the Function Select buttons, when they are pressed the row does not change. The top row LED always stays lit. So out of 39 possible function selections, it is stuck on the ONE selection..

I've tried turning the power off, then holding down the PATTERN, SONG, and CONTROL buttons simultaneously while turning the power back on. This is supposed to erase/reset the contents of the RAM memory and leave the CONTROL column selected. This doesn't work either. It just powers up like normal, with Pattern Number selected and the memory has NOT been erased.

I'm not sure what to do, at this point with it.. Try to get it fixed or return it for a refund. I thought perhaps I might get some input from other TOM owners who might have an idea of what could be causing the problem..

I'm guessing either the Matrix selection logic circuitry is faulty, or 4 to 5 of the Matrix buttons are not properly closing their circuit when pressed.

This is a very clean TOM. Cosmetically it is in excellent shape. Only thing I can nit pick about, cosmetically, is the white number pad buttons have yellowed a little bit, looking more beige in color (my Multi-Trak's white buttons are actually white!). There is almost no visible wear to any of the buttons, even the black trigger buttons.. Cosmetically it is a good match for my Multi-Trak. I was hoping it was going to function properly :(

I have $270 invested in it so far. Not sure if a Wine Country repair bill will exceed the unit's value.. Or if it would be worth going down that route or not. I'll probably contact them and find out..

Here are photos of the disfunctional TOM:

You can see the Pattern Number function illuminated, can't select any other function..




Re: Sequential TOM stuck on Pattern Number Function

Posted: Tue Jul 19, 2016 7:06 am
by SeventhStar
I got a hold of a copy of the TOM Service Manual. Studied the push button circuit schematic. Deduced that the most likely suspect was a switching diode, shared by all 5 of the inoperable buttons..

Opened TOM up, removed the PCB. And there it was! The cathode end of said switching diode had a bad solder joint. The diode was still good, but I replaced it anyway, since I had already bought a pack of 10.

After soldering in the new diode, fired TOM up, and he is now fully operational! Oh yeah, you know it! Programmed some patterns into him, and he sounds pretty damn cool! Cost of repair, less than $3 dollars..

I said, "MULTI-TRAK, do you take this handsome, fully functional TOM, to be your lawfully wedded husband? To share each others MIDI connections, and to accept TOM's MIDI clock input?"

My sweet MULTI-TRAK said, "YES.. I DO!" :friends: Now they are happily together in my humble studio.. All is now well, in my small piece of the Sequential World..