Specifications

Now, we move to the blower, which is rated at about 40CFM under normal conditions, with
the "aux" fan installed, the flow is upped to about 50CFM, well above the CCS rating of the
tubes which is 39CFM at rated plate dissipation.
A common problem with the blower design has been excessive noise build up, most notably
in older Alpha amps such as the 76 series and the aging 86. The source of the noise is that
the blowers are mounted with an adhesive backed foam that over time decays and becomes
loose, allowing the blower body to vibrate and make contact with the metal of the cabinet.
I have a cure for this problem, which I first tried on the 76 series.
Here is the procedure: Remove the top cover, remove the tube plenum, and remove the
blower. It will be necessary to install a plug in the AC power line to the blower. With the
blower removed, it is a good time to install a plug.
Clean the chassis of the adhesive and foam. Take the blower apart to clean and lubricate it.
Wash the impeller in warm water and dish-soap, allow it to dry before re-installing it.
Next, remove the shaft, which is done by removing the end cover, and the "c" retainer that
holds it on the inner shaft. The outer shaft is hollow with felt liner inside it. Soak the felt with
high-grade machine oil or Teflon® based fine oil. Then re-assemble the shaft in reverse
order. This lubrication should be done every 5-10 years dependent on how much the amp is
used, heavy-use being the more frequent lube period.
Fig.7 "C" shows the "shipping" screws that the user is told in the operation manual to
remove after unpacking the amp. When re-installing the blower, glue two rubber grommets
to the inside panel, over the holes for these screws. The grommet should be somewhere
between 1/8
th
to 1/4" thick, with a hole large enough for the shipping screw to pass through.
Place the blower motor against these grommets and snug the screws down to the point that
slightly compresses the rubber. This mounting should drastically reduce the blower vibration
noise level. Rubber grommets are also used to mount the blower motor to the blower
housing. Be sure that these grommets are re-installed or replaced if needed.
Flaky switches
I ran into another problem with the front panel rocker switches. The switches were having
intermittent operation problems, and one of them stopped working in one position.
I thought of replacing the switches, but since these amps are long discontinued, it is not
likely that any replacement part could be found. I did not want to put a mis-matched switch
on the amp since the unit looks so nice and clean.
Fig.8