HM3000 Repair & Schematic

Hammant & Morgan HM3000 Controller Repair

The HM3000 is a model railway controller built in the 1980's by Hammant & Morgan of Watford, England. The company was bought by Hornby at which time the production of this model was discontinued.

Further information about the HM3000 and other H&M products can be found in the following HM brochure (11th Edition, 1980): download large (50MB) brochure pdf here.

It seems that the design knowledge, including the schematic, was lost though during the process. I have recreated the schematic by reverse-engineering two of the controllers I have. This information is available to any individual that might need it for repair of their own controllers, i.e. 'not for profit': I am not making it available for commercial use.

Due to the nature of the process, please be aware that there may be errors in the schematic. Please report them to me should you find any.

Alternatively, if you require assistance with the repair of your controller, please

1. Fault = no output when APR turned on. Cause = Op amp IC (CA324G/LM324) pin 7 output failed to go high. Solution = replaced IC.

2. Fault = intermittent problem whereby no control of output and track stuck at full power. Cause = dry solder joint on TR1.

3. Fault = Track power LED failing. Cause = Force on LED front lifted pcb track and broke connection.. Solution: repair broken track.

4. Fault: Intermittent loss of power. Cause = dry solder joints around TR1.

Errata:

1. Diode D8 should be from VCC to GND (not as shown in line) and is probably 15-18V zener diode (e.g. BZX61C15).

2. LED L2 is shown reversed.

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