Post by: emd_16645 on October 03, 2018, 05:31:43 AM
Next, I wired in the keep alive to the rest of the board. I followed the diagram attached below. I reran the motor full load current function, and got back 690 mA. I also started having issues with the LM3 cutting out on high motor current (not surprising). Also, I am not seeing an effect from the keep alive. The track voltage did not stay stable, and fluctuated at known low points, and the motor immediately stopped when removed from the track. Didn't get much farther due to being up late enough as it is.
So where I'm at with this. First, being an early genesis model, I have low confidence in the quality of the motor. I have not tried to wire in a different motor, and see how much of a difference it makes. However, I'd expect that adding the keep alive should not affect motor current if it is working properly. Any thoughts?
Board I am using.
(https://c2.staticflickr.com/2/1910/44352138024_27aa21c0df_c.jpg)
Installed into drive.
(https://c2.staticflickr.com/2/1910/31199314158_d20ef0d341_c.jpg)
Wiring diagram for keep alive I'm following.
(https://c2.staticflickr.com/2/1962/45023889432_3c20cd682b_b.jpg)
Post by: G8B4Life on October 03, 2018, 07:23:50 AM
- Tim
Post by: emd_16645 on October 03, 2018, 07:42:11 AM
The install photo was prior to installing the 6-pin. The keep alive is wired to the fourth pin of the 6-pin plug (speaker wires occupying pins 1 and 2). I can post another photo tonight showing it.
Post by: William Brillinger on October 03, 2018, 07:55:08 AM
Post by: emd_16645 on October 03, 2018, 08:28:58 AM
Post by: Alan on October 03, 2018, 02:18:54 PM
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 leads
Post by: emd_16645 on October 03, 2018, 03:04:17 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:If 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.
- 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 leads
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.
(https://c2.staticflickr.com/2/1915/45033779672_94a33d9352_c.jpg)
Post by: emd_16645 on October 03, 2018, 03:14:18 PM
Post by: TwinStar on October 03, 2018, 05:18:13 PM
Kapton tape is recommend over the black tape. That is one of many things that I've learned here.
Good luck.
Post by: emd_16645 on October 03, 2018, 05:59:42 PM
Chris:
Kapton tape is recommend over the black tape. That is one of many things that I've learned here.
Good luck.
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.
Post by: William Brillinger on October 03, 2018, 06:34:53 PM
Post by: Alan on October 03, 2018, 06:57:47 PM
What value are the caps? It will be marked on them. I can't see in your pics well enough to determine.
Post by: emd_16645 on October 03, 2018, 08:47:46 PM
Had another thought. It is possible the caps are not super caps, just plain ole caps. If that is the case, based on their size in the photo they may not have enough capacitance to run a 600mA load long enough to be noticeable.
What value are the caps? It will be marked on them. I can't see in your pics well enough to determine.
1F 2.7v. Labeled 1802 PET if that means anything.
Post by: Alan on October 03, 2018, 09:35:35 PM
If we assume the supply voltage is 14.8V and the LM will turn off when the voltage drops to 10V and the motor has 24.6Ω resistance ( 14.8V / .600mA = 24.6Ω ) then 166,660µF should provide 1.6 seconds of full load operation. This is ideal world calculation. Realistically you should expect about 1 - 1.5 second of operation.
At this point the only logical conclusion is a fault in the wiring - incorrectly connected, cold solder joint, broken wire or board trace, etc. If you place a voltmeter on the capacitor leads while the loco is on powered track (0% throttle) what reading do you get? System voltage? What reading do you get if you turn off the track power? System voltage that slowly falls away? Same two scenarios and questions with the voltmeter connected to the LM common (blue on 9) and negative (yellow on 6) leads?
Post by: emd_16645 on October 04, 2018, 05:01:34 AM
Supply voltage is 13.6 VAC (DCC powered layout)
I am getting 13.5 VDC across the LM3. When track power is removed it drops to 1.69v rapidly (within a second) and holds.
Across the cap bank I’m getting anywhere between 2.4v and 11v at normal state, with no apprarent consistency. Voltage drops off immediately if track power is removed. Looks like I need to get into contact with the manufacturer.
Post by: Alan on October 04, 2018, 08:02:50 AM
Post by: emd_16645 on October 04, 2018, 09:39:30 AM
Post by: emd_16645 on October 04, 2018, 10:02:19 PM
Post by: Alan on October 05, 2018, 06:43:41 AM
Post by: emd_16645 on October 05, 2018, 11:50:53 AM
Post by: emd_16645 on October 09, 2018, 08:27:44 PM
Works perfectly going forward. Dead shorts at 1% throttle in reverse. Probably motor is shot, I’ve never been a fan of the first generation genesis motor. Might be time to meet a Mr. Kato product.
Post by: Alan on October 09, 2018, 08:40:07 PM
Post by: emd_16645 on October 09, 2018, 08:44:08 PM
Electric motors don't run in one direction then short out in the other. Mechanical impossibility due to the physical construction of a motor. You have a problem elsewhere.
Any thoughts as to a culprit?
Post by: Alan on October 09, 2018, 08:48:46 PM
Post by: Alan on October 09, 2018, 09:07:43 PM
Post by: emd_16645 on October 09, 2018, 09:17:12 PM
I suck at electrical, must be why I went mechanical. Lol
Post by: Alan on October 09, 2018, 09:54:29 PM
I did have to resolder the yellow wire tonight (adjacent to the gray) so possibly something is crossing there.
That would explain it. Examine closely.
However I am not using any functions currently, all outputs should be zero.
Doesn't matter. Inside the LM at each output is a transistor which has the ability to block very small voltage from causing current to flow in reverse. But as the voltage increases at some point, usually around 0.6V, the transistor will go into breakdown, labeled V(be) in the datasheet, where current begins to flow backwards and the short occurs. Whether or not you are using that function is irrelevant. It is quite possible, due to the wiring problem, you are exceeding V(be) on an LM output when the throttle reaches 1%.
I do have one LED wired in (rear light), and I believe that it is in backwards (get a function short when activated), not sure if that could factor in.
LEDs wired in backwards simply do not light up. They do not cause shorts.
As politely as I can say this, it sounds like you have multiple wiring mistakes in your installation. Suggest you rip everything out and reinstall paying very close attention to the wiring schematic you included earlier in this thread. Make all your solder connections sound and thoroughly insulate all connections.
I suck at electrical, must be why I went mechanical. Lol
Hey, everybody sucks at something. That's why we have friends to help us out.
Post by: emd_16645 on October 09, 2018, 11:11:30 PM
No offense taken, my soldering skills can't politely be described in public. My understanding of LEDs is that it wouldn't cause a short, I only mentioned it because I'm aware of how flaky wiring can be. I looked over the solder joints of the 9 pin harness and I'm not satisfied, so I have removed it. The yellow and gray wires were touching so that would be the smoking gun. I will re-wire the plug when I get a chance.