Hammond 290GX 50W JCM 800/JMP Marshall Power Transformer

The 290GX is a Hammond 290 Series power transformer listed as a replacement for Marshall guitar amplifiers, specifically the JCM 800 and JMP 50 watt models. It is intended for technicians and players keeping these amps running with a drop-in replacement.

The primary is rated 120/220/240 VAC 50/60 Hz, so the same part can serve amps on different mains voltages. The ordering table lists a 690Vct @ 200 mA high-voltage secondary and a 6.3Vct @ 5A heater winding; the part page short description reads 345-0-345, 6.3VCT@5A. The winding is listed as bobbin.

Hammond designed the 290 Series for drop-in replacement of original units, with parts made to look similar to the original factory transformers where possible and materials and design specs kept as close as possible to the original part to preserve the stock tone.

The 290GX ships at 8.7 lbs (3.95 kg), is RoHS and REACH compliant, and is identified by UPC 623980094250 and UNSPSC 39121301. No similar amp part number is listed. Amp model references are for reference only; for the 100 watt JCM 800 and JMP, the 290HX is listed instead.