Voltage for PS3 number board lights?

The PS/3 lights are LED's, so they nominally 3V DC operating voltage.  However, measuring the voltage may be problematic as they're driven by PWM signals and you won't get an accurate measurement with a DC meter.

For your issue, perhaps the sound and/or chain files for the engine in question doesn't support that output.  George surely knows what should be on those if he saw the engine.

I recently did a PS/2 upgrade and had to hunt around for an SD-40 sound file that had the strobe, no reason to believe the PS/3 might not have similar configuration issues, depending on the software loaded.

John,

   Both these engines were wired for number board lights. I sent the two PCBs to George and he just swapped the sound files for me. The B&P GP40 has the best crossing signal of any I have heard and I wanted it in the donor board. I just thought it strange that they both ended up without having the lights. My PC power supply has a 3vdc output. OK to use that to test the lights?

Measuring 0.7V DC is a reasonable value; the good news is it turns on and off under command control.  As GRJ says a voltmeter reading can be deceptive when measuring the pulsed signal (PWM) as used on PS3 LED outputs.  The meter simply reads the average voltage.  For example, if a 3V LED is operating (lit up) but you read only 0.7V DC, it is really turned on at 3V but only 23% of the time (0.7 / 3 = 23%).  An LED turned on to 3V 23% of the time (and 0V the other 77%) is quite visible....in contrast to a 3V LED driven by a steady 0.7V which would be dark.  In both cases the voltmeter says 0.7 V DC!

I don't know what kind of LED is used for your number board circuit but note that when you say 3V PC power supply note that this may be 3.3V.  The extra 0.3V may seem like nothing but depends on the LED.  So, assuming you don't have current limiting resistors lying around, if you do test your LED with a 3.3V PC power supply capable of deliver Amps of current, do so ever so briefly just long enough to see the LED turn on (or not).

John i would use the ps3 pinout from the other recent post and see where the number boards connect.  I would also check if these are hardwired or using contact springs.  G

As far as testing LED's with a power supply, I always use a current limiting resistor.  There's a 1k resistor sitting on my bench that I grab to run in series with the power supply.  I usually crank it up to around 10 volts with the series resistor.

First, thanks to everyone for your replies. The front lights are wired direct; the rear are on the spring contacts in both engines. I do have resistors, so I will use that method. They are on pin 33 in the diagram. The .7 volts was at the unconnected 2 pin connector. I have been chopping hay every night til 8:30 with 300 more acres to go so it might be the weekend before I can test the lights. I have this time consuming thing called a job that really cuts into my train time this time of year.

Work, the curse of the drinking class.

I finally took the donor engine apart to test the lights. I can't get light from the front or rear pair using the 1K resistor up to 10 volts. I can light a 3mm led off the pads in back and the 2 pin connector in front. I have enough 3mm ww 20ma leds on hand. Any reason I shouldn't just replace all four with them? I thought I would try it with the front pair, as they are easier to work with. I might check the other engine later today. It sure is odd that all eight could be blown. Good to have a day to do some drinkin' instead of workin'.

Make sure polarity is not the issue, but yes you can replace them, or check solder connections under heat shrink.  Could be a broke wire.  G

G,

Just checked the engine that received the "good" donor board and the leds are ok. I can't light  a test led on the pads or the two pin connector. Maybe that board had a problem and blew the leds in the donor engine. I can't remember if they worked before I removed the board and sent it to you. I pulled the 40 pin connector and the pins are all straight and the wire on 33 is tight.

You have me confused now, you mentioned above you could light an LED off both pads?  G

Sorry if I wasn't clear. I can only light an led off the pads in the donor engine. That engine has the original problem board and blown LEDs. The "good" donor board won't light a test led at the pins or pads, but the NB LEDs are ok

Ok,  May be hey did not work at the time, or blew some how.  Are you sure wire from 40 pin to the contact pad has good continuity no break in the wire?  G

 G

I can't find a wiring problem. The PS3 wiring diagram I have form a recent post has the NB lights at pin 33. That is an orange wire that goes to both the pads and the front 2 pin connector. I put  2 new LEDs in the front of the  donor engine with the problem board and they work now. I can't light an LED off the pad or 2 pin connector in the other board. Is there a circuit I could tap to light the 4 LEDs? Or, do you think a repair is possible if I send it to you?

You can certainly light the lights if that's all you want to do.  Easiest way is to use track power with suitable resistors and wiring.

I'm confused.  You say: I put  2 new LEDs in the front of the  donor engine with the problem board and they work now. 

If the problem board is working, does the other board work in the donor engine for the lighting?

I know this is confusing. The problem board has started behaving since GGG swapped sound files for me. I put it in the donor engine after the swap, just to have a working engine. It turns out the NB LEDs were blown in that engine, but the board works for the NB lights. The lights work in the engine that originally had the problem board, but the replacement board from the donor engine won't light them. Probably the simple solution is to wire the four lights with track power as you suggest. The B&P GP40 is the engine I wanted to save and it has the best crossing signal horn sound of any of my engines; thus the reason for swapping sound files. I could switch boards again, but would have to switch sound files again to match the engines.

It sounds to me since the donor engine had blown LEDs and now the donor board won't light the good LEDS that the board got damaged too.  It is possible the current limiting resistor is bad, but it may have gotten the buffer too.  That chip is not one I can replace.  So I can check it and we can see were we are at on the board.  G

G, I will contact you privately about checking the board. I can use John's solution if it can't be fixed. Thanks to all for the help.