Adcom GFA-7807 Service Manual page 6

GFA-7807 Voltage Conversion
The GFA-7807 amplifier is produced in both a 120VAC only version and a multivoltage (120VAC or
230VAC convertible) version. The version can usually be distinguished by external inspection. The
120VAC only version has a fixed AC line cord. The convertible version has a detachable line cord.
Internally, their are two differences. The toroid transformer in the convertible version has 2 primaries; the
first primary has a black and brown lead, the second primary has a black and brown lead with white
stripe. The toroid transformer in the 120VAC only version has only the brown and black lead (1 primary
winding). Additionally, the connecting block mounted next to the power switch is different in both
versions. In the multivoltage unit, this connecting block has 5 pair of mounting leads (as is shown in the
figures below). In the 120VAC only version, the connecting block has only 3 pairs of mounts.
The conversion procedure for the multivoltage GFA-7807 unit is listed below.
Conversion of Multivoltage Units
120V to 230V
1. Unplug the amplifier and remove the top cover.
2. Locate the connecting block mounted next to the power switch.
3. Move the transformer leads so they are configured as shown in figure 1.
4. Remove 2 Jumpers 120 VAC at the Power supply board and insert to 230 VAC for detail as figure 1.
5. Place a sticker on the rear panel at the AC Line show the new value is 230 VAC 50/60 Hz
6. Test the unit with a 230VAC source.
Figure 1: Transformer lead configuration for 230VAC operation (multivoltage units)
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