Hammond 1750P 50W JCM 900 Output Transformer, Multi-Tap Secondary
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Create Free Business AccountKey Features
- Listed for Marshall JCM 900; drawing cites JMP, JCM 800 (P-TM0100) originals
- 3,400 ohm C.T. input with 4, 8 and 16 ohm outputs (per drawing and series table)
- 50 W push-pull rating, bobbin wound
- Pin terminations; frequency response 50 Hz - 12 kHz (0/-1 dB)
- 2250 VRMS dielectric strength; -40 to 105 degC
- RoHS and REACH compliant; 4 lbs (1.81 kg) shipping weight
The 1750P is a 50 watt push-pull output transformer for tube guitar amplifiers, listed for the Marshall JCM 900. Its drawing describes it as designed for drop-in replacement of original units such as the Marshall JMP and JCM 800 (P-TM0100). Amp model names are for reference only, and the manufacturer is not affiliated with the amplifier companies.
The series ordering table and drawing give a 3,400 ohm centre-tapped primary with 4, 8 and 16 ohm outputs. The part page instead lists primary values of 126, 500 and 2,000 ohms and secondaries of 2, 4, 8 and 16 ohms; both sets of values are shown in the specifications for comparison.
The 1750P terminates on numbered pins. Typical DC resistance is 82.25 ohms across pins 4-7, 40.70 ohms pins 4-2 and 41.47 ohms pins 2-7, with 0.351, 0.506 and 0.725 ohm across secondary pins 23-21, 23-16 and 23-14. Inductance across pins 4-7 is 22.65 H (8.62K ohm) at 60 Hz, 10 V open circuit, and primary leakage inductance is 10.30 mH at 60 Hz, 10 V short circuit.
Frequency response is 50 Hz to 12 kHz (0/-1 dB reference @ 1 kHz) and distortion is under 1% at 70 Hz. The bobbin-wound unit is rated 2250 VRMS and -40 to 105 degC. Drawing dimensions are A 3.760 in, B 3.090 in, C 3.130 in, D 2.500 in and E 3.128 in. It is RoHS and REACH compliant and ships at 4 lbs (1.81 kg).
Ideal For
- Marshall JCM 900 output transformer replacement
- 50 W push-pull tube amp service
- Multi-impedance speaker matching
- Guitar amplifier repair
Overview
| Output Power | 50 W |
| Product Type | Tube guitar amplifier output transformer |
| Amplifier Type | Push-Pull |
| Original Amp Mfr | Marshall |
Dimensions
| Dimension A | 3.760 in ±0.063 |
| Dimension B | 3.090 in ±0.125 |
| Dimension C | 3.130 in ±0.063 |
| Dimension D | 2.500 in ±0.063 |
| Dimension E | 3.128 in ±0.063 |
Electrical
| Distortion | Less than 1% @ 70 Hz |
| DCR Pins 2-7 | 41.47 ohms |
| DCR Pins 4-2 | 40.70 ohms |
| DCR Pins 4-7 | 82.25 ohms |
| DCR Pins 23-14 | 0.725 ohm |
| DCR Pins 23-16 | 0.506 ohm |
| DCR Pins 23-21 | 0.351 ohm |
| Test Reference | All graphs input level 27dBu @ 1.0 kHz reference |
| Tolerance Note | Results are typical and subject to normal manufacturing and electrical tolerances |
| Temperature Range | -40 to 105 degC |
| Frequency Response | 50 Hz - 12 kHz (0/-1 dB reference @ 1 kHz) |
| Dielectric Strength | 2250 VRMS |
| Primary Impedance (Part Page) | 126, 500, 2,000 ohms |
| Secondary Impedance (Part Page) | 2, 4, 8, 16 ohms |
| Inductance Pins 4-7 (@ 60 Hz, 10 V OC) | 22.65 H / 8.62K ohm impedance |
| Primary Impedance (Series Table / Drawing) | 3,400 ohms C.T. |
| Secondary Impedance (Series Table / Drawing) | 4, 8, 16 ohms |
| Leakage Inductance Primary Blue-Red (@ 60 Hz, 10 V SC) | 10.30 mH |
Identifiers
| UPC | 623980094236 |
| UNSPSC | 39121301 |
| Part Number | 1750P |
| Short Description | OUTPUT 50W JCM 900 MARSHALL |
Replacement Fitment
| Amp Model Name(s) (Ref. Only) | JCM 900 |
| Original Units Cited On Drawing | Marshall JMP, JCM 800 (P-TM0100) |
Packaging & Shipping
| Shipping Weight | 4 lbs (1.81 kg) |
Construction & Finish
| Winding Type | Bobbin |
Compliance & Certifications
| RoHS Compliant | Yes |
| REACH Compliant | Yes |
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Frequently Asked Questions
Which Marshall amp is the 1750P listed for?▾
The part page and series table list the JCM 900; the drawing cites original units such as the JMP and JCM 800 (P-TM0100). Model names are for reference only.
What is the primary impedance?▾
The series table and drawing list 3,400 ohms C.T.; the part page lists 126, 500 and 2,000 ohms.
Does it use leads or pins?▾
The drawing specifies measurements between numbered pins, e.g. 4-7 on the primary and 23-21, 23-16 and 23-14 on the secondary.
What is the frequency response?▾
50 Hz to 12 kHz, 0/-1 dB referenced at 1 kHz.
What is the dielectric strength?▾
2250 VRMS.
