Foot-Switchable
Boost Modification
Roland
BC-60 (Blues Cube 60)
Now FOR SALE!!
Since I don't use the amp much anymore I've decided to sell :( I can accept NO less than $350 CDN. I am located in Toronto, Canada. Email me: DOLHOP at GMAIL dot COM if you are interested.
Figure 1: Roland BC-60
Overview
This modification will allow owners of the Roland BC-60 guitar
amplifier to use their footswitch to enable/disable the boost setting
on the lead channel. It involves rewiring the amp to use the
reverb footswitch (useless in practical situations, IMHO) for boost
instead. Let me reiterate that: you will no longer be able to
switch reverb with the footswitch - reverb will always be on (the
amount of reverb still controllable via the reverb knob). The
modification involves opening the unit, desoldering and soldering of
some components and wires.
Difficulty Level:
Medium. You must be
comfortable with soldering and electonics.
Disclaimer
If you choose to make this
modification you are taking your life and the life of your amplifier
into your own hands. I will not be held liable or responsible if
you destroy your amp. The instructions given below worked for me
but the guts of my amp might be different than yours - I suggest you
have a qualified technician perform the modification for you so that
they can verify that the changes will not be detrimental. As for
your life, any time you open up a piece of electrical equipment you run
the risk of electrocution. Again, I will not be held responsible
- it is your responsibility to ensure that you are following all safety
precautions possible. If you don't know them - take the time to
learn them! And please take the time to read ALL of the
instructions before proceeding. Good luck!
Tools Required
- Phillips #2 screwdriver
- Soldering Iron
- De-soldering tool (solder sucker)
- Wire cutters
Parts Required
- Glue (contact cement)
- Solder
- 3 * 6" pieces of wire (18-24 guage)
Disassembling The Unit
The first step is to disconnect the speaker and reverb
unit.
Figure 2 below shows the speaker connections - simply pull the wires
off of the terminals. Take note that the red wire connects to the
+ terminal and the black wire connects to the -
terminal.
Additionally you'll need to disconnect the green ground wire from the
speaker. In Figure 2 below you'll see (circled in yellow) that I
already broke mine and will be sure to replace the lug and reconnect
it. This is a safety feature - make sure you reconnect it later!
Figure 2: Speaker Connections
In order to disconnect the reverb unit you only need to disconnect the
two RCA connectors from the tank. The connections are shown in
Figure 3 below. Notice that the black jack connects to the tank
input and the red jack to the output. Remember this for later
when you need to put it back together!
Figure 3: Reverb Tank Connections
Once you have disconnected all wires from the chassis, remove the five
large bolts on the top of the unit and one from each side. Some
of these bolts are circled in Figure 4 below. Don't let the
electonics chassis fall onto the speaker!
Figure 4: Chassis Bolts
Slowly remove the electronics chassis from the speaker chassis and
remove all of
the knobs.
Figure 5: Disassembled
Once you have all of the knobs removed, you have to remove all of the
nuts from each jack and pot. Tedious, yes, but it has to be
done. The pots are 11mm and the jacks 14mm. Flip the unit
over and remove the four screws from the back plate that are
highlighted in Figure 6 below.
\
Figure 6: Separating The Backplate
Identifying The Components
After you've disassembled the unit you'll notice that there are two
main boards inside which I have termed "LEAD" and "NORMAL" based on the
majority of functionality they contain. These are identified in
Figure 7 below. Also, notice the two important
components: the Reverb Footswitch
Jack on the "NORMAL" board and the Boost Switch on the "LEAD"
board. These are the two we'll be dealing with.
Figure 7: Identifying The Components
Making The Modifications
Are you ready? Here we go. The first step is to remove the
reverb jack from the board. Using the solder sucker, de-solder
the three large terminals as shown below in Figure 8. Do not hold
the soldering iron on the board too long or the pads will start to lift.
Figure 8: Removing the Reverb Jack
Pay special attention to the labels I've placed on the terminals of the
jack: point 1, 2, 3. In the following diagrams these same
labels will be used to when looking at the boost switch and the wires
that will go between the boards. Once removed, flip the jack over
and glue it to the board (in the same location it came from!) with the
pins looking up at you - this is depicted below in Figure
9. I used contact cement, but you can use whatever you
think will work for you.. Take special care to place the jack in
the correct location. Use the jacks on the other board as a
reference for positioning.
Figure 9: Glue The Jack To The Board
Once the glue has dried and the jack is firmly positioned, solder a
wire to each pin. These wires should each be about six (6) inches
long. I recommend using insulated stranded wire between 18 and 24
gauge. Anything else will be too difficult to work with unless
you've done a lot of soldering in a previous life. Pre-strip each
end of the wire - about 2mm is all that's needed. The other ends
of these wires are going to be soldered to the boost switch to give you
a feeling for how long they need to be. Figure 10 shows my board
- notice the labels again..
Figure 10: Solder A Wire To Each Terminal
Now to the LEAD board and the boost switch. Carefully examine
Figure 11 below.
Figure 11: Boost Switch PCB
There are six closely located pins, up and to the left of the RED LED -
this is the boost switch. The labels point 1, 2, 3 do not
necessarily point directly to the switch terminals. I have chosen
convenient solder points. Point 1 is electrically connected to
thd middle terminals of the switch, point 2 is connected to the top
terminals of the switch and point 3 is on the other side of a via that WAS connected to the top terminals
of the boost switch. Notice that I said WAS. You have two
options here: the first is to cut the identified trace which connects
point 3 and the top left pin of the switch. This is done using a
utility knife. Use a voltmeter to ensure that there is no
electrical connectivity between the two points after you cut the
trace. Be careful to not cut other traces.
If you are uncomfortable cutting a trace, option two is to desolder
point 3 and lift the resistor out of the hole. The loose end of
the resistor will become your point 3. I think the resistor is
R113, but don't quote me on that. I will only show the first
option.
Next, solder the wire from point 1 on the reverb jack to point 1 of the
boost switch as depicted below in Figure 11. Then do the same for
points 2 and 3.
Figure 11: Solder The Wires To The Boost Switch
You're done! Now wasn't that easy? Maybe not - let's test
it out first.
Testing The Change
You can't just plug in the unit and test it - you'll need to do a bit
of re-assembly to prevent electrical shorts. I suggest putting
each board into the chassis and putting on one nut at each end to hold
them in place and in order to be safe, put the electrical chassis into
the cabinet and stick in at least two screws to hold it in place.
Connect the speaker, ground wire and reverb unit. Plug it in,
plug in your guitar and give it a try. Ensure that the reverb
still works and that the boost is foot-switchable. Remember, the
boost only applies to the LEAD channel.
If everything checks out okay reassemble the unit (in the opposite
order as you disassembled it - but I didn't have to tell you that, did
I?).
ENJOY!
Before You Close Up Shop
While you still have the unit open you have the opportunity to do a
couple of other things:
- Replace the LEDs with something cool - blinking LEDs or a funky
blue colour!
- Replace the wire from the board to the speaker with some quality
speaker cable!
- ???? Suggestions ?????
Before You Ask
- What if
I want the reverb to still be foot-switchable in addition to the
boost? This might be do-able if you changed the reverb
footswitch jack with a switchable stereo jack and wired it correctly,
but I really haven't put any thought into it.
- Is it
possible to make the "crunch" setting on the NORMAL channel
foot-switchable? I'm sure it is with some digital
electronics. It might even be possible with normal footswitches,
however I doubt it. Due to the nature of the crunch switch - it's
a three position switch - the simple footswitches don't lend themselves
to this type of application. It might be easy to select between
two of the crunch settings, but again, I haven't put much thought into
it.
Feedback
I welcome feedback - comments, criticism, suggestions and
improvements. Email me: DOLHOP at GMAIL dot
COM.
Copyright 2004
