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In Reply to: sword repair posted by Ron on October 17, 2000 at 15:04:15:
Found this on the 7 series digest. Thought it might help.
Scott McFarland
Scramento, CA
Date: Tue, 10 Oct 2000 13:04:48 EDT
From: PANDROLLH@aol.com
Subject: Procedure for SWORD repair
I recently reconditioned my Sword, and thought I'd share the details.
Component cost was $3.52. I purchased my electronic parts from Mouser
electronics (www.mouser.com), and have listed their stock numbers (no
affiliation).
You will need the following parts:
(4) BUZ71A MOSFETS, type TO-220 mouser# 511-BUZ71A
N-channel, 50V, 13A
(4) 8-32 x 1/4" machine screws
(4) 8-32 x 3/8" machine screws
(12) #8 flat washers
(4) 1/4 x 1/4 bronze threaded standoffs mouser# 534-1692A
Assuming you've gotten the Sword out...
1. Remove screw from plastic housing on sword handle and remove cover.
2. Remove locnut attaching electrical component from PCB to "wave" plate
3. Using a hacksaw blade without damaging nearby resistor, cut through epoxy
that attaches PCB to wave plate at each MOSFET.
4. Grind epoxy carefully (dremel or bench grinder) on side of PCB opposite
wave plate till you hit copper. Three bonding sites should be
exposed at each location. Should be able to twist old MOSFETs off wave plate
with pliers.
5. Drill 1/16" diameter hole thru PCB as close to each of 12 MOSFET pins as
possible.
6. Drill 3/16" diameter throught the swaged-over ends of each standoff. You
can now separate the PCB from the wave plate. Careful with the 2-lead
component that you unbolted previously.
7. Drill .172 diameter through PCB and wave plate where standoffs went
through. Carefully hold each MOSFET in a vise by the edges of the metal tab,
and drill it out to .172 also.
8. Bend MOSFET leads 90°, holding leads with pliers at the attached end.
Use old MOSFET to determine bend location. Take antistatic precautions
(ground yourself) before handling MOSFETs.
9. Assemble 8-32 x 1/4 screws thru PCB, and attach standoffs with loctite.
10. Solder in MOSFET with 25W iron, deflux (mouser# 577-1676-125 12oz
aerosol defluxer).
11. Lightly sand the contact patch for the MOSFET on the wave plate.
Conductivity is very important. Some people use a special conductive grease
under the MOSFET Assemble wave plate to upstands with 3 washers under the
head of each 3/8" long screw, or grind screws to correct length - no washers
required. Use loctite. Attach your 2-wire component from #2 at this time.
12. Spray plate and PCB (whatever is exposed to oxidation) with Fin-L-Kote
UR (3577-2104-125 12oz aerosol) or use spray lacquer like I did.
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