RailPro > RailPro Specific Help & Discussion
RP Keep Alive Installation
Alan:
Something isn't right. The capacitors should draw current only for a brief moment while initially charging. That will be completed rapidly, well before your finger taps the settings button on your HC. So the fact they appear to be drawing 90mA during motor current test is a big red flag.
Does the board have a resistor and diode pair in series with the capacitors? This is a common arrangement to limit the maximum capacitor charging current. That could possibly explain the 90mA but seems unlikely. The 90mA number is still out of range of what would be expected. I do not see a resistor or diode on the board in your pics.
Aged (very aged) electrolytic capacitors sometimes develop DC current leakage across the internal dielectric. Is the board very old?
You can test the capacitors in isolation:
* Disconnect the capacitors (board) from the LM and from the loco motor
* Connect a 9V transistor battery to the capacitor leads for a few seconds making sure to observe proper polarity
* Disconnect the battery
* Connect a voltmeter or LED w/series resistor to the capacitor leadsIf the capacitors are good the voltmeter should show 9 volts (or a little less) and very slowly drop voltage. Very, very slowly. If you used an LED it should glow for a long time, many minutes.
emd_16645:
--- Quote from: Alan on October 03, 2018, 02:18:54 PM ---Something isn't right. The capacitors should draw current only for a brief moment while initially charging. That will be completed rapidly, well before your finger taps the settings button on your HC. So the fact they appear to be drawing 90mA during motor current test is a big red flag.
Does the board have a resistor and diode pair in series with the capacitors? This is a common arrangement to limit the maximum capacitor charging current. That could possibly explain the 90mA but seems unlikely. The 90mA number is still out of range of what would be expected. I do not see a resistor or diode on the board in your pics.
Aged (very aged) electrolytic capacitors sometimes develop DC current leakage across the internal dielectric. Is the board very old?
You can test the capacitors in isolation:
* Disconnect the capacitors (board) from the LM and from the loco motor
* Connect a 9V transistor battery to the capacitor leads for a few seconds making sure to observe proper polarity
* Disconnect the battery
* Connect a voltmeter or LED w/series resistor to the capacitor leadsIf the capacitors are good the voltmeter should show 9 volts (or a little less) and very slowly drop voltage. Very, very slowly. If you used an LED it should glow for a long time, many minutes.
--- End quote ---
Thanks for the input Alan. I have some testing to do. It will be a little harder, because everything is hardwired in. The board was assembled last week, I do not know the age of the capacitors but I can’t image they are that old. I believe there are resistors in line with the capacitors but I’m not sure.
Board with keep alive connected.
emd_16645:
I did some more testing this afternoon. With the Max Speed set to about 70%, the motor stall current was 390 mA and the loco operated fairly smoothly. Not sure how tied the speed setting is to the stall current is. Keep alive does not seem to be functioning. I will test the capacitors tonight.
TwinStar:
Chris:
Kapton tape is recommend over the black tape. That is one of many things that I've learned here.
Good luck.
emd_16645:
--- Quote from: TwinStar on October 03, 2018, 05:18:13 PM ---Chris:
Kapton tape is recommend over the black tape. That is one of many things that I've learned here.
Good luck.
--- End quote ---
Agreed, but it’s what I have on hand. Bill was out of a stock the last time I ordered. Hopefully next time I buy from him he will have some.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version