Tom

I don’t know the controller in question, but here’s all you need to know about LM399

https://www.analog.com/en/products/lm399.html#part-details

MichaelG.

On 14 September 2024 at 14:41 tmcc Said:

Thanks Michael, it a 24V 100A controller and it’s more the MOSFET side that is the issue. […]

Oops … no sign of the aforementioned LM399 there

MichaelG.

Aha … catching-up slowly

MichaelG.

Hi  Phil,  unfortunately no additional info or circuits etc. I have identified 7 out of the 10 mosfets are blown. Waiting on replacements to arrive before working out what the connections are and power it up.

Tom.

Many thanks Clive,  this is really useful.

I’m wondering how long I can extend the 7W DIN lead, so I can “pipe through” wagons for push-pull operation.

Also, the PWM provides too much current control with the motor I have, so its difficult to maintain a constant low speed.  A small movement in the control sends the loco accelerating off.  Anyone any ideas how to make it more like a tram / DC  electric, with a notch or two slowly moving the train to a constant speed, before a weak field simulation is applied?

… also attached a couple of photos for reference.

The control lead will probably be all low voltage low current so you can probably extend it as far as you like. Beware a loose unconstrained lead though as they have a lemming like desire to leap under the wheels.

The sudden start problem may be the control potentiometer just not providing a smooth progression from a low value which is not uncommon. Assuming all 3 wires from the potentiometer are used try putting a resistor, say 1k between the wiper connection and the connection at the end when it is stipped, probably battery -ve. This will help the voltage be lower at the start.

I know that this is an old thread but I recently came across it and, because I have a Parkside controller like the one being discussed, I thought that the following might help.
My controller system consists of a ‘Power Unit’ – like the one pictured – housed in a die-cast enclosure and a separate, remote ‘Control Unit’ that provides both Forward:Reverse and Drive:Brake control functions. This contains two PCBs and appears to be similar to the one shown in PhilBarber’s post above…mine differs in that it also provides a ‘Horn’ function controlled by an eighth wire in the DIN plug. I have traced out the circuit diagrams of the two PCBs and they are attached below.

The OpAmp Board provides two mutually exclusive control voltages both of which idle at 0V when the Control Pot is centred. As the Pot (joystick) is moved in either direction – Drive or Brake – the respective control signal (Drive:Blue Wire / Brake:Black Wire) ‘lifts off’ 0V and rises toward its maximum value of about 24V. On my unit the joystick output voltage ranges from about 9.6V (full Brake) to about 15.0V (full Drive) with the Neutral position giving about 12.2V. This approximately +/-2.5V swing is amplified by about x10 by the two op-amps to provide the two separate 0-24V outputs to the Power Unit.

The Logic Board provides the circuitry for the Direction Change Control Logic shown on Clive’s SHT3 drawing and works as follows:-
The Direction Control switch and its pull-up resistors (2 x 10k) provide the ‘D’ inputs to the two halves of the CD4013 flip-flop – a logic low in the selected position, Fwd or Rev, with the level at the other gate at a logic high. With the joystick centred – and so both the Drive and Brake control voltages are at 0V – the flip-flop’s CLOCK inputs are at a logic low. Moving the joystick a fraction in either direction lifts one of the control voltages off 0V and causes a positive-going clock pulse. This latches the current state of the Direction Switch and provides a mutually exclusive drive to the direction control relays in the Power Unit. Additionally, because the positive-going edge of the clock pulse can ONLY be produced as the joystick leaves the Neutral position, motor direction changes can only be actioned under conditions of ‘zero-drive’.

A couple of points on Clive’s drawings:
1. I think that the ENABLE switch shown on SHT3 should be connected to BATT+ not 0V. When closed this would apply 24V to the base circuit of TR1 turning it on, closing RL1 and so applying power to the MOSFET stages.

2. I think that the left-hand end of the 100R:1k resistor pair feeding RL2 and RL3 shoud be connected to the cathode of the upstream reverse polarity diode. The relays used have 12V 90ohm coils and the resistor-pairs (100R||1k = 91 ohms) are used in series with the coils to permit operation from a 24V supply. As an aside, the 100R resistors dissipate about 2W and both of them show signs of overheating in my unit – two 180R in parallel would probably have been a better choice.

I hope that some of this helps.

Martin.

PS: I’m sorry that the images are not particularly clear but I hope that you can read them OK.

Sounds like shorted MOSFET(s). Do you have a multimeter?