290XEX Hammond Netztrafo Blues Junior 049967 Replacem.

Hammond 290XEX – 240 V power transformer for Blues Junior and Fender 49968

The Hammond 290XEX is a power transformer for compatible Blues Junior valve amplifiers. Its single primary winding is rated for 240 V at 50/60 Hz. The secondary windings provide 260 V at 170 mA, a separate 20 V auxiliary supply at 100 mA and a 6.3 V heater supply at 3 A.

Hammond lists the 290XEX as the international Blues Junior version and identifies Fender reference 49968. Reference 49967 is assigned to the North American 290XX in Hammond’s current application information. Check the amplifier revision, primary voltage, schematic, mounting pattern and lead colours before replacement.

Suitable applications

• Repair of compatible Blues Junior amplifiers using a 240 V power transformer
• Service applications associated by Hammond with Fender reference 49968
• Valve amplifiers requiring a non-centre-tapped 260 V winding rated at up to 170 mA
• Circuits requiring a separate 20 V auxiliary supply rated at up to 100 mA
• Amplifiers with a total 6.3 V heater demand not exceeding 3 A

Technical data

Product type

Power transformer for valve guitar amplifiers

Manufacturer application

Blues Junior 15 W amplifier family

Current Fender reference

49968 for the international 240 V version

Primary winding

One fixed 240 V winding for 50/60 Hz; no 120, 220 or 230 V tap

High-voltage winding

260 V at 170 mA between the two red leads; not centre-tapped

Auxiliary winding

20 V at 100 mA between the two brown leads; not centre-tapped

Heater winding

6.3 V at 3 A between the two green leads; no accessible centre tap

Separate 5 V winding

Not provided

260 V winding no-load reading

279.63 V at 240 V and 50 Hz, ±2% according to the Hammond drawing

20 V winding no-load reading

21.17 V at 240 V and 50 Hz, ±2%

6.3 V winding no-load reading

6.89 V at 240 V and 50 Hz, ±2%

Exciting current

160 mA maximum at 240 V and 50 Hz; this is not a permissible secondary current

Primary DC resistance

21.63 Ω black–white, ±20% at 20 °C

260 V winding DC resistance

59.58 Ω red–red, ±20% at 20 °C

20 V winding DC resistance

4.830 Ω brown–brown, ±20% at 20 °C

Heater winding DC resistance

0.080 Ω green–green, ±20% at 20 °C

Dielectric test

2,500 V AC between primary and secondary at 60 Hz for one second

Electrostatic screen

Internal screen between primary and secondary windings; the drawing does not show a separately colour-coded screen lead

Flux band

Copper band around the core and coil according to the Hammond drawing

Winding documentation

Described inconsistently as paper wound and bobbin wound in current Hammond documents

Drawing dimensions

A approx. 76.2 mm, B approx. 63.5 mm and C approx. 28.6 mm; dimension assignments follow the Hammond drawing

Mounting dimensions

D approx. 63.5 mm and E approx. 50.8 mm; threaded-stud projection F approx. 15.9 mm

Flying leads

At least 9 in or approximately 229 mm long and stripped by approximately 12.7 mm

Shipping weight

Approx. 1.16 kg according to Hammond

Connection details

240 V primary winding

Black–white; apply the mains supply between the black and white leads

260 V winding

Red–red, rated 260 V at a maximum of 170 mA

20 V auxiliary winding

Brown–brown, rated 20 V at a maximum of 100 mA

6.3 V heater winding

Green–green, rated 6.3 V at a maximum of 3 A

Comparison with the Hammond 290XX

Hammond 290XEX

International version with a fixed 240 V primary for 50/60 Hz and current Fender reference 49968

Hammond 290XX

North American version for 117 or 120 V at 60 Hz and Fender reference 49967

Selection and installation notes

The specified 260 V, 20 V and 6.3 V figures are rated values at the intended load. The Hammond drawing specifies higher no-load readings. Actual operating voltages also depend on mains voltage, rectification, filtering and amplifier current demand.

The 290XEX has no dedicated 230 V primary tap. Ideal proportional scaling at exactly 230 V gives approximately 249 V, 19.2 V and 6.04 V. These are calculated estimates; measure every supply rail under normal operating load in the completed amplifier.

The 260 V winding has no centre tap and must not be wired as a 130-0-130 V winding. The 20 V and 6.3 V windings also have no accessible centre points. Rectification, grounding and heater referencing must follow the exact Blues Junior schematic.

The complete 6.3 V load includes every connected valve and any other heater-powered device. Total demand must not exceed 3 A, while the separate 20 V winding remains limited to 100 mA.

Mains wiring, primary fusing, protective earth, strain relief, touch protection and insulation clearances must be completed by a qualified technician. Filter capacitors can retain lethal voltages after disconnection from the mains.

Questions about selection and use

Is the Hammond 290XEX suitable as a power transformer for a compatible Blues Junior associated with Fender reference 49968?

Yes, Hammond lists the 290XEX for the Blues Junior and Fender reference 49968. It is suitable when the amplifier requires a fixed 240 V primary plus 260 V/170 mA, 20 V/100 mA and 6.3 V/3 A windings and when the mounting and lead arrangement match.

Can the Hammond 290XEX be operated from a European 230 V mains supply?

Yes, its fixed primary is nominally rated for 240 V and may be used from 230 V when the correspondingly lower secondary voltages suit the circuit. Ideal scaling gives approximately 249 V, 19.2 V and 6.04 V; verify the actual values under load.

Can the Hammond 290XEX be used as the international 240 V alternative to the Hammond 290XX?

Yes, the 290XEX is the international 240 V version for a compatible Blues Junior, while the 290XX is intended for 117 or 120 V. The two models must not be connected identically on the primary side; verify the mounting and secondary wiring as well.