Acom ACOM1000 - Maintenance and Servicing; Cleaning the Amplifier; Fuses Replacement Procedure; Tube Replacement Instructions

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Two lines, three groups by six symbols (36 symbols in total) are to be copied concerning every one of
the 7 memorized events from 1A-1B through 7A-7B.
To decode the signatures please see S.6-5 (Troubleshooting).
N O T E
After every signature listing the tube warm-up time is reset to 150 seconds regardless
of the time being in OFF LINE state.
6. MAINTENANCE
If no characters are seen on the LCD at power on maybe its contrast needs adjustment - see S.5-1.
6-1. Cleaning
W A R N I N G
Do not use solvents for cleaning - they may be dangerous both for you and
for the amplifier paint or plastics.
Do not open the amplifier. Cleaning of the amplifier outer surface can be done with a piece of soft
cotton cloth lightly moistened with clean water.
6-2. Fuses Replacement
If it is necessary to replace the mains fuses, use only standard ones.
The two Primary Mains Fuses of the amplifier are located on the rear panel (Fig. 2-1). They are 10A/
250V Quick blow, 1-1/4 x 1/4 inch Cartridge Fuses, Size 0 Ceramic.
Besides the primary fuses, on the MAINS PCB (inside the amplifier) there are two more small glass
fuses (5x20mm, 100mA and 2A slow-blow type) which are not replaced by the user. Should one of
these fuses be blown, it may be indicative of other failures. This is a complex and potentially dangerous
operation. For this reason, we recommend this work be carried out by a trained service technician.
6-3. Tube Replacement
A single 4CX800A (GU74B) high-performance ceramic-metal tetrode manufactured by Svetlana is
employed in the amplifier. Replacement is a complex and potentially dangerous operation. For this
reason, we recommend this work be carried out by a trained service technician.
6-4. The ACOM1000 Simplified Schematic Diagram
See Fig.6-1 ACOM1000 Simplified Schematic Diagram. * The 4CX800A (GU74B) Svetlana high
performance ceramic-metal tetrode (V1) with plate dissipation of 800W is grid-driven. The input signal
from the RF INPUT jack is passed through a broadband input matching circuit, which comprises some
components in the INPUT PCB and Rsw. This circuit tunes out the input capacitance of the tube. The
swamping resistor Rsw is a termination load for this circuit and can dissipate up to 100W of RF drive
power.