26
Fender
Champion “600”
•
Mercury Upgrade Kit
This project and its documentation is the result of technical investigations made by the engineering staff of
Mercury Magnetics
. The disclosure of the information herein may pertain to proprietary rights and
the furnishing of these documents does not constitute an expresed or implied license to use such materials.
Tips ’n Tricks for
Working on PCBs
A PCB (printed circuit board) begins life as a solid
sheet of thin copper foil across a backing material
made of epoxy resin. Then, using a photographic
process, a circuit is imprinted onto the foil and
all unnecessary copper is etched away. What’s
left are copper foil “traces” that take the place of
wires. To prevent shorts, PCBs are laminated with
a colored insulating material that functions just like
the shielding around insulated wire. Although PCBs
may be many layers thick, the PCB used in the this
kit is single-layered, which makes it easier to work
on or modify.
PCBs cost substantially less to produce than their
predecessors, i.e.
point-to-point
circuit boards.
And are used by amp manufacturers to maintain
affordable prices for consumers.
On a PCB components are often attached to the
top of the board and then soldered from the back
via pass-through conductive “eyelets” where they
follow the traces that make up the circuit.
Asian-made PCBs are typically not as resilient as
those made in the west. Therefore they’re likely to
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Damaged
eyelet
Intact
eyelet
Repair to a damaged eyelet:
The lead from component bypass-
es the damaged eyelet and is soldered to either a revealed trace
or another terminal on the same trace (as in this example).
Various examples:
1. Jumper. 2. Jumper. 3. Trace repair
(jumper soldered from terminal to terminal on same trace). 4.
Trace repair (ditto). 5. Damaged eyelet repair (lead is soldered to
a revealed trace).
1
2
3
4
5
require patching and repair work as you make the
Upgrade
. This is normal, and easy to do – as long
as you know a few tricks.
Revealing a Trace
: Sometimes we need to “reveal”
traces so that the PCB can be modified or repaired.
An easy way to do this is to take a sharp knife or
Exacto
and carefully scrape away the lamination
to “reveal” the copper foil under it. Use high-grade
(99%) Isopropyl alcohol and a Q-tip to clean these
new contacts before soldering to them.
How to Repair Damaged Eyelets
: The PCB’s
conductive eyelets are easily damaged and
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