The Harmony 420
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The chassis is mounted in the rear 'tweed style.' This mounting style is different from any of the other amplifiers in the similar amplifiers category. The output transformers that I have seen have carried the same T3778 part number as those used on the S6420 Thunderbolt. The power transformers also carry the same number as is found on the S6420 Thunderbolt. 
Three inputs, two for guitar or bass and one labeled accordian or mic. The guitar and bass input plus the accordian input are padded with a 470K resistor. The mic input has a 47K resistor. The 47K input is the same a the S6420 Thunderbolt.
The schematic
This schematic was redrawn from the version found at Schematic Heaven . That site has been up and down so much I decided to local host my own copy.
The similar amplifiers:
- Wards GIM-9074A
- Wards GVC-9064A
- Wards GIM-9111A
I have not been able to find any info on the amps listed above.
Based on what I can figure out, the Harmony 525 is electrically the same as this amplifier.
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