[Jerry McColgan]

I have a blown LGB 50000 Central Station. The board was fried when power was connected in reverse (power fed into track output).

The burnt piece (circled) looks like a diode but I am not sure. It looks like a diode above it.

Any ideas or suggestions?

Thanks,

Jerry

 

[Dan Pierce]

Looks like a surface mounted diode and is there for when someone accidently hooks power up backwards. Diode shorts and protects the rest of the electronics.
Looks a lot like the one next to the red connector.
Does anyone have a picture of a good board for comparison? It is best to be sure about these things.
Also if a diode, we need to know which way to install the band end.

 

[Jerry McColgan]

Posted By Dan Pierce on 11/13/2008 5:02 AM
Looks like a surface mounted diode and is there for when someone accidently hooks power up backwards. Diode shorts and protects the rest of the electronics.
Looks a lot like the one next to the red connector.
Does anyone have a picture of a good board for comparison? It is best to be sure about these things.
Also if a diode, we need to know which way to install the band end.



Hi Dan,

That is about what I concluded so I decided to take a chance (I don't have a lot of patience).

I removed the old burnt diode(?) and put a 600 volt 1 amp diode across where it had been. I could read just enough of the old and new diodes to verify the polarity by lining up the writing on both of the diodes. Both read left to right so I guessed they should both have the band at the left.

I then put power to it with a 1 amp LGB 50081 (not wanting to risk a full 5 amps) and the lights came on so I connected a loco remote.

Unfortunately either the diode was the wrong size or something else was wrong because although I managed to get some sound from a sound car I could not control the sound and I also could not control a small motor block I put on the track.

I have no money in the Central Station as it was given to me after the owner damaged it so I may be best off by throwing it away rather than risking damaging something else with it.

The good diode(?) seems to have a 400 followed by parts of what could be a 3. Radio Shack has a 1N4003:

30A surge. Type: 1N4003. Peak Inverse Voltage (PV): 200

I did not have that one so I used a 1N4004:

30 amp surge. Type: 1N4004. Peak Inverse Voltage (PV): 400.

[*]Peak Reverse Voltage: 400V (Max) [*]DC Blocking Voltage: 400VDC (Max) [*]Forward Rectified Current: 1A [*]Silicon Rectifier [*]Diffused junction [*]Maximum Average Forward Voltage Drop: VF= 0.8 Volts [*]Non-repetitive Peak Surge Current: IFSM= 30 amps for 1 cycle [*]Maximum Reverse Current @ 25 degrees C: IR= 10uA [/list]
For whatever reasons it does not appear to have worked.

Thanks,

Jerry

 

[Dan Pierce]

All of the 1N400x diodes were 1 amp, the bigger the number the higher the voltage.

I would have gone with a 5 amp diode minimum but since you are using a 1 amp test supply what you did was OK.

I suspect a transistor or mosfet on the heat sink is also defective.

Nice to notice the Lenz logo as this is probably the vendor that made the board.

 

[Jerry McColgan]

Posted By Dan Pierce on 11/14/2008 5:34 AM
All of the 1N400x diodes were 1 amp, the bigger the number the higher the voltage.

I would have gone with a 5 amp diode minimum but since you are using a 1 amp test supply what you did was OK.

I suspect a transistor or mosfet on the heat sink is also defective.

Nice to notice the Lenz logo as this is probably the vendor that made the board.


Hi Dan,

Since I would have no idea which resistor or even what a mosfet is I think it is time for me to throw in the towel on this fix.

You are correct. The original Central Stations were made by Lenz. I believe Massoth made the 2nd and 3rd Central Stations.

Regards,

Jerry