Boss RC20 loop station

[DrGonz78]

So, I have this RC20 loop station that I have fixed... Well it was really just the means of resetting the phrase memory banks 1-11. It was all malfunctioning when I got the unit and did not work at all. I was reading on another site where the guy had cracked this combination of codes to reset the unit and it worked. The only problem with the pedal now is the tempo guide effect is like that of buzz sound rather than a thud. It sound really bad but still in time and functioning enough to use it to keep time. The guy on the website that fixed his w/ the codes to reset the memory banks still had the same problem.

I am using the correct plug in adapter for this pedal: 9.6v : 200ma wall wart.

So, does anyone here have any clue at all if there is a fix or something that can be done to figure out how to get the tempo guide sounds to be normal again. Probably a long shot here but really just trying to fix this thing to see if it can be done.

[DrGonz78]

Anyone that has come across this defect in this product is encouraged to give some information about their experience. This might not be easily fixable, but seems a bit common in some regards to searches I made online.

[g1]

There are 4 types of guide tone. Are they all sounding like a "buzz"?
In case you haven't tried them all, : Q.How can I change the guide tone on the RC-20XL/RC-20?

A.While holding down [EXIT], repeatedly press [TAP TEMPO] to step through the available guide tones (eight types on the RC-20XL, four types on the RC-20).

[DrGonz78]

Hey thanks G-one but I had failed to mention that I had tried that procedure already. It just stays on the same noisy buzz metronome. First buzz is quiet to mark first beat, so it actually still functions in that regard.

Just wanted to see if some other people who had the exact same problem online might be on this site to see if they ever figured out a fix. Probably a major failure of something component wise that set all the memory into a state of malfunctioning. Once you reset the each individual memory location 1-11 then you have a functioning loop station minus the guide tone is acting funny now.

[remco1982]

Hi DrGonz,

I just found this old post regarding the buzz sound when trying to use the Guide Tone option on your Boss RC20. I have the same problem on my RC20XL and I wonder if you were able to solve this issue?

Thanks,
Remco

[DrGonz78]

That was a while ago during the first year I spent learning how to repair circuits. I had no schematic and most of the soldering on those units are SMD. So I tried to reset the thing but at first that did not work. It was not till I found a thread where a guy figured out some extra reset for the control of the memory banks. His problem was exactly like mine and in the end he even asked if anyone had a solution for the buzzing guide beat problem. After following the instructions from this poster the looper worked fine albeit the guide drum sounded like a squared wave 8 bit sample or something. I sold the unit to someone but was always curious if it could even be fixed.

Loop Station RC-20XL Repair | Harmony Central

Edit: Just looking now, I apparently did find the schematic for that unit.

[remco1982]

Thanks for the reply. That is a good forum link you forwarded
But unfortunately it isn't working for me. At this point 3 in the explanation:
3. Hold down 'EXIT' and 'AUTO START' together - at the same time, this should light up the green LED for 'LOOP PHASE'
On my RC20XL the green LED does not light up. Making me wonder if I'm doing it correctly.
I continue anyway with the procedure, but the BUZZ sound is not fixed...

[Jazz P Bass]

Unfortunately, the RC-20 loopers are all basically a computer chip with input switches.

It sounds like it is toast.

[DrGonz78]

Yeah I remember researching the main chip in that unit and it was $60-80, or something. I would have definitely destroyed the thing trying to even get the old chip out. Hey if the unit works fine without using the guide beat that aint too bad. I use to use one of those in a band situation and never once used the guide beat anyway.