Hammond 290QX JTM30 Marshall Replacement Power Transformer
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Create Free Business AccountKey Features
- Listed for the Marshall JTM30 (reference only)
- 120/240 VAC 50/60 Hz primary
- 325V @ 270 mA high-voltage secondary
- 6.3V @ 3.1A heater and 25V @ 233 mA windings
- Pin-numbered label; bobbin-wound construction
- Hipot tested 2000V, 60Hz, 1 sec primary to secondary
- 3.25 lbs (1.47 kg); RoHS and REACH compliant
The 290QX is a Hammond 290 Series power transformer listed as a replacement for the Marshall JTM30. The part page short description reads 352VCT AC/6.3V/25V. It suits technicians servicing this amp.
The primary is rated 120/240 VAC 50/60 Hz, and the ordering table lists a 325V @ 270 mA high-voltage secondary, a 6.3V @ 3.1A heater winding and a 25V @ 233 mA winding, all bobbin wound.
Drawing test data at 120V, 60 Hz lists a 131mA maximum excitation current and no-load voltages of 120.0V on pins 5-6, 353.7V (pins 9-10), 6.890V (pins 11-12) and 27.27V (pins 13-14). The part is hipot tested primary to secondary at 2000V, 60Hz for 1 second, and a label with pin numbers is placed on the transformer. Drawing dimensions are A 3.375", B 2.813", C 2.385", D 1.820", E 0.400" and G 0.219".
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 290QX ships at 3.25 lbs (1.47 kg), is RoHS and REACH compliant, and is identified by UPC 623980252612 and UNSPSC 39121301.
Ideal For
- Marshall JTM30 power transformer replacement
- Dual-voltage tube amp repair
- Compact tube amp restoration
Overview
| Series | 290 Series (Tube Guitar Amplifier - Power Transformers) |
| Part Number | 290QX |
| Product Type | Power transformer, replacement for Marshall guitar amp, 290 series |
| Short Description | 352VCT AC/6.3V/25V |
| Amp Model (Ref. Only) | JTM30 |
| Amp Manufacturer (Ref. Only) | Marshall |
Electrical
| Secondary 1 | 325V @ 270 mA |
| Secondary 2 | 6.3V @ 3.1A |
| Secondary 3 | 25V @ 233 mA |
| Primary Volts | 120/240 VAC 50/60 Hz. |
Identifiers
| UPC | 623980252612 |
| UNSPSC | 39121301 |
Dimensions (Drawing)
| Dimension A | 3.375" ±0.063 |
| Dimension B | 2.813" ±0.063 |
| Dimension C | 2.385" ±0.063 |
| Dimension D | 1.820" ±0.030 |
| Dimension E | 0.400" ±0.030 |
| Dimension G | 0.219" ±0.010 |
Packaging & Shipping
| Shipping Weight | 3.25 lbs (1.47 kg) |
Construction & Finish
| Winding | Bobbin |
| Labeling | Label with pin numbers placed on transformer |
Compliance & Certifications
| RoHS Compliant | Yes |
| REACH Compliant | Yes |
Electrical Test Data (Drawing)
| Hipot Primary-Secondary | 2000V, 60Hz, 1 sec |
| DCR @ 20°C, Pin 2 - Pin 3 | 7.903 Ω ±20% |
| DCR @ 20°C, Pin 5 - Pin 6 | 9.569 Ω ±20% |
| DCR @ 20°C, Pin 9 - Pin 10 | 49.11 Ω ±20% |
| DCR @ 20°C, Pin 11 - Pin 12 | 0.091 Ω ±20% |
| DCR @ 20°C, Pin 13 - Pin 14 | 17.71 Ω ±20% |
| No-Load Voltage Pin 5 - Pin 6 | 120.0V ±2% |
| No-Load Voltage Pin 9 - Pin 10 | 353.7V ±2% |
| No-Load Voltage Pin 11 - Pin 12 | 6.890V ±2% |
| No-Load Voltage Pin 13 - Pin 14 | 27.27V ±2% |
| Excitation Current (Iex) @ 120V, 60Hz, Pin 2 - Pin 3 | 131mA Max. |
Amp Cross-Reference (Ref. Only)
| Listed Amp (Marshall Table) | JTM30* |
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Frequently Asked Questions
Which amp is the 290QX listed for?▾
The Marshall JTM30, for reference only.
What are the secondary ratings?▾
325V @ 270 mA, 6.3V @ 3.1A and 25V @ 233 mA.
What are its drawing dimensions?▾
A 3.375", B 2.813", C 2.385", D 1.820", E 0.400" and G 0.219".
What is the insulation test?▾
Hipot primary to secondary 2000V, 60Hz, 1 second.
What does it weigh?▾
3.25 lbs (1.47 kg) shipping weight.
