Hi all,
Picked up a NIB Atlas HO GP38 undecorated off eBay the other day. I'm building this up for a birthday present for my dad. He doesn't run DCC, but has been interested in eventually upgrading in the future.
I know this decoder can run on either DC and DCC. I have the jumper set for DC. Still, when I test it on DC, the lamps -- both front and rear -- won't light when the loco moves. It's not the bulbs' fault; I've tested those independently and they work fine.
Any suggestions on what I should do? Is the decoder fried? Is there something programmed within it that needs to be reverted so lights come on in DC operation?Appreciate any assistance you can lend my way. Thanks...
-Evan
CV 29 bit 1 and/or CV 51 needs to be reset using a DCC system. The person you purchased the item from on e-Bay has probably reset these CVs because they were running it on DCC. You can't change any CVs without a DCC system. If the item were truly NIB the default values of these CVs should be set for the lights come on when running on DC.
Thanks. I know you need DCC to program CVs, so I'll see if an LHS can't help me with that quest...
Not too worried about it not being NIB -- it's an undec, so I'm working it over anyways. Seems to run just fine, though -- virtually mint -- so I'm okay with it.
I just upgraded my DC Gp-38's to DCC and have the original DC board.. if you PM me your address I can mail one out to you.
If it's the kind with the jumper to select DC or DCC, it shouldn;t matter how the decoder is programmed, with the jumper in the DC position it bypasses the decoder completely and does not rely on the ability of the decoder to do analog conversion. If the original decoder was replaced by the previous owner then all bets are off and you may need to reset things using a DCC system.
Does it look like this one: [utl]http://www.gatewaynmra.org/dcc/engines/atlas-gp38ms.htm[/url]
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
That's what I thought, too, but no matter how the jumper is positioned, it won't throw power to the lamp leads. Bulbs are functional, so I'm wondering what's going on.
From what I can tell, it is the stock Atlas decoder.
Jumper or no jumper it still might matter. Won't hurt to try. I'd take up the offer earlier for the DC board. Price seemed right
Springfield PA
Sigh. The fun continues...
Eric was kind enough to send a non-DCC GP38 light board, and I started playing with that today.
No luck. Still won't light the bulbs.
I have *NO* idea why this is. I've hooked up a DMM to the output tabs, and they're pumping out voltage. Bizarre. Even more odd, if I connect said bulbs to the outer tabs (for the trucks), they throw light.
Even more unusual, if I hook these same bulbs up to my Atlas RS1 light board, *they work fine.*
Any thoughts on what's going on here? Grounding issue?Still think I need to try programming that DCC board -- running on analog, the DMM shows the light leads are getting no voltage. Swell...
Ugh. I'm so lost with this...
How much power have you been feeding to the locomotive when running it on DC? The lights won't come on until the throttle is turned up fairly high in some cases. Maybe you're running it so slow that the bulbs are on but so dim you can't see them.
I know the lights were fairly dim at 50% throttle and only got brighter at 75% or higher.
I'm running full throttle, and still nothing. Contacts read approximately 10-16 volts between 3/4 and full throttle. I'm puzzled -- voltage seems to be coming through those contacts, but the bulb won't light.
It will light, however, if I connect it to the RS1's light board and pump the same voltage through it. Wish I was a "double-E" the more I play with this...
OK, SOMETHING just has to not be making contact with the shell on. If you get voltage at the contacts for the lights when running on DC, and if connecting the bulbs directly to power makes the light up, the only POSSIBLE thing left is the connection in between. I think we already covered this but, they ARE incandescent bulbs and not LEDs, right? If LEDs they might be wired backwards.
Shell's not even on -- I'm just bench testing...
That said, I see a VERY faint glow from the bulb -- so I'm wondering if I just need to swap some other bulbs in. It's odd if Atlas built this with the wrong voltage bulbs, though...
SO what voltage did you run to the bulbs when you tested them? Compared to the voltage you see at the terminals. Are there any resistors in the bulb leads? Perhaps the previous owner swapped out the original bulbs for 1.5 or 3 volt ones so they wouldn;t get hot and melt the shell on the loco when runnign at full brightness all the time like they do with DCC. Such bulbs would need a resistor to handle a steady 12-14 volts and would probably barely glow when runnign on DC at anywhere less than full throttle.
Was pumping about 12-14 volts into the pickup leads on the light PC board. That typically drops 1-2 volts at the lamp outputs.
If I directly feed 10-11 volts into the bulb itself, it works. Not sure what's going on with the PC board...
Hoping most of my issues are just related to the DCC needing to be reprogrammed, but still curious about the adventures with this GP38 board. The RS1 board works just fine with these lights. Weird...