Dynaco ST-70 Restoration Module
Assembly, Installation, and Adjustment Manual
Page 4
CAE Dynaco Driver Restoration Module PC-3R – R0: 7-02
6. Visually inspect all of your solder
connections. Refer to the adjacent diagram.
Quality solder connections should be
smooth and shiny. Dull surface or large
blobs on the PC board should be cleaned
and resoldered. In this case remove the old
solder with solder wick or similar and
resolder the connection.
8. Install the 2 7199 Tubes.
B. Removing the Original Dynaco Stereo 70 PC-3 Board
OK – that was pretty easy.
1.
To begin removing the original Dynaco PC-3 board, remove the top cover (should
be held in place with either 4 or six screws (depending upon the vintage) along
the side. These screws will release both the top perforated metal cage and the
bottom “U” cover.
2.
Remove the 4 output tubes (and label them for reinstallation later). I recommend
that you clean the dust and grime from the topside both inside and outside of the
amplifier. A vacuum cleaner with a soft paintbrush will work very well here.
3.
Next begin desoldering each wire from the original PC-3 card. The original
Dynaco wires were solid PVC insulated. The PVC is not very tolerant of heat and
therefore you should be very careful not to melt the insulation. Normally a
“wetted” soldering iron tip will have better thermal transfer causing the solder to
melt quickly before the heat travels up the lead of the wire compromising the
PVC insulation. Also, when you remove the wire from the PC Board, it is not
uncommon for the wire to “snap” at the other end. I suggest having some
replacement wire available. You can use solid PVC wire as in the original
however if possible, however I strongly recommend using 22 ga. stranded Teflon
Insulated wire in this application. Please do not use anything larger – it is not
necessary and it will compromise the reliability of your amplifier as you attempt
to make reliable connections on terminals unable to withstand the strain. Note that
you may encounter original wiring that is “less than professional” in its execution,
If so, it may be necessary to lengthen or replace one or more of the original wires.
4.
Desolder each wire and using masking tape (a temporary identifier) label each
wire to make installation of the replacement module much easier.
