Yamaha 01 mixer repair help

[HTH]

Hi folks,

I've acquired a Yamaha 01 digital mixing desk recently, but there are some issues - the main one being that a number of the channels cannot be 'selected' on the front panel. I've got the guts out and they're momentary switches by the look of it. Channels 1-4 are ok, channel 5-10 will not select, then the remaining channels plus the main out and effects send channels are fine.

This is way out of my confort zone, so any help would be greatly appreciated as it's pretty much unusable for gigging in its current state.

[Steve Conner]

Which 01 is it? 01R, 01V, or what?

Irrespective of which desk it is, check the switches with the continuity test function on a multimeter, and check the PCB for hairline cracks in the traces, and corrosion caused by spilled beverages. I think I see some suspicious looking gunge in the left-hand corner of the pic.

[HTH]

Its the 01 Pro Mix. I've cleaned up the white 'matter'. Was thinking that since those switches are all the same and this has 16 channels, I could take the 'good' switches from 14/15/16 and relocate them for the channel select buttons on 5-10. Will also check continuity too - seems odd to have a bank of channels ALL go off, rather than the odd one.

Thanks for the suggestions Steve.

[g1]

As you said, seems a bit odd for the whole bank to go off. Unless a previous user only used that bank . Easy enough to check any of the bad switches for continuity when pressed.
Seems more likely it would be a connection or IC that is common to that bank of channels.

[Enzo]

It has been MANY years since I saw one of those. Since you just got it, may I assume you do not have a lot of stored work? First thing I would do would be to reinitialize the thing. Do that before looking for bad parts. You can verify the switch function easily enough. Knowing Yamaha, I'd be very surprised if there was no diagnostic stage that was a switch test anyways. Even the old DX7 had that.


Find or buy the service manual, no one makes those better than Yamaha.

[g1]

One of these should work for service manual:
http://www.koston.us/files/ypm01sm.pdf
YAMAHA PRO MIX 01 Service Manual free download, schematics, eeprom, repair info for electronics

[km6xz]

Since the other channels are being selected and the same matrix for column and row selection using the same gate array, it is probably not a digital problem. The same two scan rows that are common to all the dead channels are also used for good channels, a pc board defect like a crack somewhere around the impacted switches is the most likely cause that disables a small cluster of switches but does not interfere with the rest of the switches on the same two scan rows. Scan lines SC4 are needed to select 1-8 and SC5 is needed for 9-16.
The Column scan lines(SD0-SD7) are unlikely to be at fault because that would require 6 separate lines of the 8 total to be at fault.

The very first step before taking anything apart is to do the test routine that can be used to test the switch functions among other important tests.

[HTH]

Thanks for the replies guys, much appreciated. However, I can't locate the column scan lines you're talking about - maybe its the terminology? I have the service manual and have tried going through the test procedures, but it doesn't seem to enter any test mode. I'm holding down 'meter' and 'cue' while turning on the power (as per page 51 of the service manual).

[km6xz]

Look for the control panel schematic that has the matrix of switches and you will see each switch has two lines connected to 1, all in a row are connected to the same row line and each switch in a column is connected to the same column line. They are labeled SC-0, SC-1, SC-2 etc for rows and SD-0, SD-1, SD-2 etc for each column at the two connectors which leave that board. Look of cracks of the board on the row lines SC 4 and 5, just after the the line leave channel 4.
This is a very complex unit that most techs do not even take in so before getting too far into it, think about taking it to a tech who works on the often.

[Steve Conner]

What if one of the Meter and Cue buttons was faulty too?

[HTH]

Thanks for the responses guys, this is my own mixer so I'm not too concerned with my time spent repairing it - I'll check out those traces you suggested.