Specifications
(B+). The voltage here should be something close to +460 +/-
10 volts (photo 8.1b).
Step 10 – Remove AC power
by disconnecting the AC
power cord from the AC
source.
Step 11 – Install both
preamplifier tubes.
Step 12 – Plug the amplifier's
AC power cord into the AC
power source at the wall.
Step 13 - The panel indicator
should illuminate. Monitor for any smoke, unusual odors,
or blown fuse.
If anything unusual occurs, disconnect power immediately and review
connections.
Step 14 – Let the amplifier warm up for 2 minutes. With a multimeter on the
20 volt range, carefully connect the meter's black lead to chassis ground and
the red lead to the positive side of C3. The voltage here should be close to
+1.5 +/- .5 volts (photo 8.1c).
Step 15 – Move the red lead to the positive side of
C6. The voltage here should be close to +1.5 +/- .5
volts (photo 8.1d).
Step 16 – Move the red meter lead to the lower lead
of resistor R14. The voltage here should read +63V
+/- 2.0V volts.
Step 17 – If these measurements are correct,
remove the AC power by disconnecting the AC
power cord from the AC source.
Step 18 – Install the two power tubes.
Step 19 – Connect speaker to either output jack.
Step 20 – Turn all volume and tone controls to
minimum position with both amp switches to “on”.
Step 21 – Plug the amplifier's AC power cord into
the AC power source at the wall.
Step 22 – The panel indicator should illuminate. Monitor for any smoke, unusual odors, or
blown fuse. If anything unusual occurs, disconnect power immediately and review
connections.
Step 23 – Let the amplifier warm for 2 minutes. With a multimeter on the 200 volt DC range,
Whenever testing voltages, it is recommended to keep your free hand off of the chassis. In
this way, there isn't a path for significant current to flow through the body to ground in case the
measuring hand accidentally comes in contact with high voltages.
WARNING
The presence of voltages at steps 14 & 15 indicates that V1 and V2 are correctly sourcing
current.
NOTE
Photo 8.1c
30 TubeDepot.com
These voltages are being measured without power and preamp tubes installed. These
values will decrease with the added load of the tubes.
NOTE
photo 8.1b
Photo 8.1a
photo 8.1d photo 8.1e