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bossmodder
Copper Member
USA
4 Posts |
 Posted - 03/30/2009 : 17:14:19
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Hi all,
Just found this thread after messing with my RC-2 this past weekend. I have been experiencing a wierd phenomena as follows:
Turn on the RC-2. All functions work normally for 30 seconds to 3 minutes. Pedal becomes unresponsive (doesn't respond to pedal clicks).
I tore into things big time and analysed the whole board as best I could without schematics. I've narrowed the problem down to the mode selector switch circuit. Here's what I've found:
The mode selector switch appears to be a resistive, 8 position pot that "passes a control voltage" to the main board. Each "mode poistion" passes a unique voltage to the main board, which is an input that controls the processor circuitry to "do what you're asking for".
This mode selector has a 3V supply and passes anywhere from 0V to 2.17V as follows:
The above measurements are when things were measured from a healthy RC-2. (I have two) After anywhere from 30 seconds to 3 minutes after I power up, the mode selector switch output voltage drops (not gradually, it's an instantaneous drop) to anywhere from 0.10 to 0.56 volts. This "final output voltage" doesn't vary or fluctuate after it drops, it's pretty much constant but it does appear to be a different level each time I repeat the process and measure the output from the switch.
As you can see, if the mode selector output voltage drops to 0.10, the processor "thinks" that the WRITE mode is selected and it ignores the foot switch signals.....that's why the pedal is unresponsive.
I've also had instances in which the mode selector output voltage never "rose" to the full 2.17 volts on startup. Several times it was only about 1.5 volts (the AUTO mode range) and the pedal did behave like it was in AUTO mode even though the mode selector was "all the way up" at the Tempo selection.
There seems to be a lot of electronics knowledge in this forum and I'm wondering if anyone has any ideas on what might be failed/failing on the board. My guess is some type of filtering cap, but why would things seemingly be "normal" for a short period and then "short to ground".
Any help on this would be appreciated. |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 03/31/2009 : 11:00:52
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Hi bossmodder
Welcome to the forum from Ausyralia.
Did anything unusual or different happen to your RC-2 before it became faulty.
Dropped, over volts, liquid spill???
These are fairly new, is it possibly still under warranty?
Regards Dr. Bob  |
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bossmodder
Copper Member
USA
4 Posts |
Posted - 03/31/2009 : 17:49:06
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It was contamination on the board. I could have sworn that I cleaned the board well the first time I had the unit open. 
Thanks for your reply. |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 03/31/2009 : 17:51:26
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quote:
Originally posted by bossmodder
It was contamination on the board. I could have sworn that I cleaned the board well the first time I had the unit open.
Thanks for your reply.
Hi bossmodder
Does that mean, that the contamination was from the manufactuing?
Or was it from a spill?
I guess it's now working?
Regards Dr. Bob |
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bossmodder
Copper Member
USA
4 Posts |
Posted - 03/31/2009 : 23:39:45
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The pedal is now working perfectly. The contamination was from a wire I soldered to the end of one of the ribbon cables to "tap" into the line and more easily record voltage readings. After I removed the wire, the contact and board were cleaned but there must have been some residual material - enough to conduct to the ground terminal next to it - left on the surface of the board.
I was investigating the "communication" between the main processor board and the selector switch board. I'm in the need for a 'stereo' looper but didn't want an RC-50 (too big and more than what I need)so I got a second RC-2 and was gathering data to design a stereo looper using two RC-2's. I wanted to set one up as a master pedal (left channel) and then set the second one (right channel) as a slave. That way I could just have one stompbox under my foot to control two pedals (the right channel remotely).
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/01/2009 : 13:17:35
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Hi bossmodder
What an interesting project.
I know lots of us here would be keen to hear how you get on with your experiments.
Can I ask if you were working blind, or had a schematic/service notes?
It's interesting to know, that what at first seem to be a multi-position switch,
is really just a custom pot with set notches-dints, that is used as an A to D to control the processor in the RC-2.
This is a common trick, the Line6 POD-2's L-O-N-G floor board, & 4 switch board, work in a similar fashion.
They use a simple one percent resistive ladder to drive the A to D on one of the inputs of the POD 2's micro/DSP.
They sense the TYPE of floorboard (4 way or Long), with some simple diode switching across the input lines.
BehringClone also do this, but with a crappy pot on some of their digital delay-reverb pedals.
And I believe that the Boss New style Cube amps, do this for their effects selector, but no notches, just a wide selection range.
Please keep us up to date..
Regards Dr. Bob
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bossmodder
Copper Member
USA
4 Posts |
Posted - 04/01/2009 : 16:27:09
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I succeeded in my efforts ("running blind" as you put it). I have two RC-2's to cover the stereo field (one loops the left channel, the other loops the right channel)and they are both controled by the left channel RC-2. Here is the list of controls that have a master/slave connection between the two RC-2's:
Phrase volume
Guide volume
Phrase Select
Tap Tempo/Select/Enter
Mode Select
Foot Stomp Switch
The mod's that I made allows both RC-2's to operate as a Master/Slave whey they are connected and they can each operate as a stand alone (just like no mods are present) when they are disconnected. There's a half dozen CMOS switches in the slave that handle the "slave/stand alone" switching.
I'm wondering if my "work" would be better shared on a new topic rather than a continuation of this one. Your thoughts?
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 04/01/2009 : 17:25:27
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quote:
Originally posted by bossmodder
I succeeded in my efforts ("running blind" as you put it). I have two RC-2's to cover the stereo field (one loops the left channel, the other loops the right channel)and they are both controled by the left channel RC-2. Here is the list of controls that have a master/slave connection between the two RC-2's:
Phrase volume
Guide volume
Phrase Select
Tap Tempo/Select/Enter
Mode Select
Foot Stomp Switch
The mod's that I made allows both RC-2's to operate as a Master/Slave whey they are connected and they can each operate as a stand alone (just like no mods are present) when they are disconnected. There's a half dozen CMOS switches in the slave that handle the "slave/stand alone" switching.
I'm wondering if my "work" would be better shared on a new topic rather than a continuation of this one. Your thoughts?
Hi bossmodder
That's probably a good/better Idea.
It isolates the topic.
You might want to leave a link back to this thread, for future reference.
Thanks for your willingness to share your work.
Like always, pictures are a bonus, & most welcome.
Regards Dr. Bob |
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Topic |
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RC-2 Mode Selector Gremlin/Short
