Webb Steel Guitar Operating Manual - page 13
3
Webb Factory Mechanical Inspection Procedure
[Note: All tests are performed at 500Hz. Repair technicians should obtain copies of the schematics, bill of
materials (BOM) and layout diagrams before proceeding with repairs. These items can be purchased from
the factory.]
Rear Panel
•
Check jack, sockets, and power switch placements.
•
Check fuse values, 6A (top) & 10A (lower), and fuse condition.
•
Confirm that fuse holders and AC sockets are secure.
•
Confirm the absence of capacitors “connected” to the chassis ground lug.
•
Visually inspect all soldering of the jacks, fuses and AC socket.
•
Visually inspect all power supply wiring and soldering. (Note: filtering caps will have one lead
unused.)
•
Visually inspect all PCBs for problems, i.e. deformed parts, loose wires, unattached parts, etc.
•
Tighten all screws and jack nuts and tighten all jack nuts, screws and locking nuts (inside panel).
Front Panel
•
Check knobs for proper positioning, looseness and numerical alignment. (Note: pots will have slight
amount of give if pulled.)
•
Check that LEDs are secure.
•
Confirm that fiber washers are included on input jacks.
•
Tighten input jacks.
Bottom Panel
•
Carefully turn over chassis to examine bottom panel.
•
Check all screws for tightness (except for front bezel), including transformer attachments and power
transistors.
•
Check that all 4 plastic “ears” are in place.
•
Check that there is silicone over diodes and that there is sufficient thermal paste for power
transistors.
•
Remove front bezel screws and lock-washers located on bottom panel.
Preamp PCB
•
Carefully turn over chassis.
•
Remove both screws and lock-washers attaching front bezel.
•
Carefully remove the front panel and turn it over onto towel to avoid scratching faceplate so the
bottom of Preamp and EQ PCB can be examined.
•
Disconnect Preamp/Power Amp PCB connector plug and cut wire ties as necessary to examine PCB.
•
Check all solder joints for poor soldering, solder balls, cold solder joints, and unsoldered parts.
•
Check for sufficient solder so potentiometers can securely hold to PCB.
•
Replace front bezel and attach using different black screws for the bottom of bezel.
•
Make sure Preamp and EQ PCBs are not touching bottom of chassis. If so, gently bend their soldered
attachments to the potentiometers sufficiently for slight distance from chassis frame.
Power Amp PCB
•
Remove Power Amp PCB screws and lock-washers and turn over to examine bottom side of PCB.
•
Check all solder joints for proper soldering (absence of solder balls, cold solder joints, and
unsoldered parts).
•
Note: There are 7 unused donuts on the left side of PCB and a missing regulator IC and surrounding
parts on the right side of the PCB.
•
Check soldering of power transistors and diodes on heat sink, and make sure there is sufficient space
between conductors.
•
Bend and press down power transistor wires so they do not stick up and push against the bottom of
the PCB.
•
Replace PCB, making sure to dress wires around (i.e. not under) standoffs of PCBs.
•
Use two screws to secure PCB; others will be added after testing.