at the club, we recently replaced a Digitrak PM42 circuit breaker on one booster with PSXs. PSXs were already on the 2nd booster. both are Digitrak boosters
now we have the problem that when a consist crosses the gaps, the PSX on the block occupied by the train trips causing the train to stall, but comes up after a few seconds and remains on allowing the train to continue
i'll guess that that the voltage on the 2nd booster powering the block the train is entering, is loaded down and drops enough that there is no longer the voltage difference across the gaps that caused the PSX to trip.
while it may help, it's not abundantly obvious to me that the booster voltages need to be made the same because the PSX does not trip after the train crosses the gaps. and since there are 4 other sets of gaps between the two boosters, it's not obvious that an adjustment will make all better or just some better and some worse.
i don't believe the wires lengths from the same booster to all the gaps need be significantly different "as the crow flies".
as far as i know there are no issues between PSXs on the same booster
we've had various problems with PSXs which are very early vintage (17 years old) and have sent some back to DCC Specialties to the updated. still want to examine, possibly reset the PSXs, reprogram to delay tripping (30ms) or trip at higher currents
wondering if others have had this problem and how it was delt with?
greg - Philadelphia & Reading / Reading
Does this happen every time a consist crosses a gap? Does it have to be a consist, or will a single loco do?
I have seen a similar problem with my PSX breakers, but I only have a 5 amp base station and no additional boosters. This only happens right after I power up the system, and then it's fine.
It takes an iron man to play with a toy iron horse.
I had a similar problem some while back. As it turns out mine was related to Digitrax labeling RAIL A and RAIL B differently on the DCS-200 and DBxx booster. At the time Digitrax had no documentation on this but they have since listed some here:
https://www.digitrax.com/tsd/KB534/short-circuit-when-adding-a-db100-or-db150-booster/
One thing that "hid" the problem was that either the command station or booster was set to "auto-reverse" so most times I wouldn't see the problem.
The shutdown occurred when a train was passing one set of gaps while another crossed into another set.
Do you have a tester (LED and 1K resistor will do) and read across the gap on the same rail. If it lights you have a phase problem.
I've had voltage differences of up to 2 volts or so between different boosters crossing into new districts and that hasn't caused any problems. My PSX breakers are the old variety (jumper-set, not programmable) and after more than 20 years they're still functioning OK.
More history here: https://cs.trains.com/mrr/f/744/t/148370.aspx
Regards, Ed
gmpullmanDo you have a tester (LED and 1K resistor will do) and read across the gap on the same rail. If it lights you have a phase problem.
pretty sure it's not that problem. we had that problem when we replaced PSXs with PSXXs which are reversed. if that were the problem, the problem would persist until the loco is completely across the gap.
gmpullmanI've had voltage differences of up to 2 volts or so between different boosters crossing into new districts and that hasn't caused any problems.
that's encouraging to hear. i haven't measured the voltage across gap yet. the track voltage on either gap without any load on the track is about ~0.1VAC
MisterBeasleyThis only happens right after I power up the system, and then it's fine.
curious what would cause that. (but out problem persists)
Greg, could it have to do with a (too large, it turns out) time-delay of signal between the two that forces the detection circuitry to reject one of them?
Right, I agree this particular situation might not be your cure but I post it to bring it to the attention of others that may run into a similar problem
gregc if that were the problem, the problem would persist until the loco is completely across the gap.
In my case the breaker tripped (on the booster) the very moment the wheel touched the adjoining rail across the gap. Long-wheelbase steam locomotives act as large "bridge" conductors over gaps, as do lighted passenger cars.
It certainly didn't help that Digitrax labeled Rail A and B outputs on a random basis between similar pieces of equipment. Out of phase.
My layout has three reverse sections and I have to be attentive that any of these longer pieces of powered equipment don't bridge corresponding pairs of gaps simultaneously. It can happen.
Good Luck, Ed
selectorGreg, could it have to do with a (too large, it turns out) time-delay of signal between the two that forces the detection circuitry to reject one of them?
don't understand. what time-delay and what detection circuitry?
i believe both boosters are in sync, there's neither a polarity (as Ed cautions) nor a significant phase difference, since as I said, there didn't seem to be a problem with the Digitrak PM42 circuit breakers
after the PSX restores power, it doesn't trip again and a 2nd, 3rd, ... engine can cross the gap with both PSXs active
appreciate all suggestions -- if not the cause of this problem, makes me aware of potential problems
still sounds like a phasing probem, not major ...
if it trips once on entering the second district, the just swap phases for the second district ...it shouldn't have to trip to set the correct phase
wvgcaif it trips once on entering the second district, the just swap phases for the second district ...it shouldn't have to trip to set the correct phase
it's a PSX circuit breaker, not an auto-reverser (an auto-reverser switches instantly)
wvgcastill sounds like a phasing problem
this appears to have been the problem
just happen to momentarily measure ~14 VAC across a gap and discovered that the Digitrax DB210 booster has an auto-reversing feature that was ON. flipping the faceplate switch to OFF presumably fixes the problem
not sure why the booster was swapping polarity instead of the ARs
unsure why we didn't notice this problem before replacing the Digitrax PM42 breakers
we also found that some trains happen to consistently trip the breaker near the same gaps as well as other specific locations most likely due to metal wheels touching a metal weight mounted under the car
unlikely to be the last problem on the layout. Slowly becoming familiar with the idiosyncracies of Digitrax and DCC Specialties components
at least you -maybe- found the problem, without tearing too much apart, lol
gregc wvgca still sounds like a phasing problem this appears to have been the problem
wvgca still sounds like a phasing problem
Several years back when I installed a second booster on my layout, I followed the NCE instructions, but I noticed that when a loco crossed from one booster district to the other booster district, there was a pause and then the loco continued into the other booster district. I called NCE, and Larry (now retired) suggested that I flip the two wires. That solved the problem.
Rich
Alton Junction
richhotrainThis does not surprise me.
"no surprise"?
it's easy enough to test if the "polarity" is different by measuring VAC across the gap, which was done many times in this case.
when we replaced PSXs with PSXXs, we saw the new breakers tripping at gaps between breakers on the same booster. Checking the voltage across the gap quickly identified the problem and was corrected by reversing the input side of the PSXXs. (while the input pin #s on the PSXX and PSX are the same, the connector is reversed on the PSXX)
i've heard problems described as "bizarre" or "impossible" many times over my career debugging both hardware and firmware problems. Digging into the problem and developing tests that sometimes had to run overnight usually provided clues. Sometimes those clues found a simple oversight while at other times just the first of several causes that needed to be individually investigated.
as i learn more about Digitrak and DCC Specialties products, I'm learning about features i don't recall reading about in magazines or these forums.
i was vaguely aware that Digitrak boosters had an auto-reverse feature, but since they were in use for many years, I assumed (!?) they were configured correctly.
i was surprised that the PSX/PSXX circuit breakers provide a block occupancy output, which on this layout is very useful. They also have 2 additional features that seem interesting
one is an input for an optical sensor that shuts off the block when active. I believe they intended it to be used in hidden staging to stop the train at the end of the staging block. But it could also be used at the end of a block to stop a train that doesn't stop for a STOP signal which would be useful with distracted operators
the 2nd feature is an output that indicates that the block is tripped (or off). I think this could be useful if we had some display screen up on a wall to identify problems more quickly than rushing over to the panel and lifting up the skirt to see status
ironically, it seems these features are put to use on only a thin sliver layouts
It doesn't surprise me because I once had a similar problem. So, when two other forum members mentioned this as a possibility, I thought that it could be the issue in your situation.
Are both boosters attached to a common ground?
On NCE that is something they say is important to the operation.
Dave H. Painted side goes up. My website : wnbranch.com
The NCE asks, "Do you have locos stalling or hesitating between booster sections?"
Here is their answer to this question:
https://ncedcc.zendesk.com/hc/en-us/articles/360006825794-Booster-common-Bonding-or-Floating-Ground-for-multiple-boosters
dehusmanAre both boosters attached to a common ground?
found following interesting
Next, you may have a DCC out of phase situation where the rails are not the same polarity from booster to booster.
This is easy and quickto check and resolve. Just swap the two track output wires right on the front of the booster.
yes, it doesn't take much time to check phasing, although [in most cases], you shouldn't have to ... sigh ,,
and i suppose that rail a and rail b labelling should have been kept consistant, lol
Easy/quick test I used recently when installing my new booster was to use a small lightbulb with wires. There's a gap or insulated joiner between the track with one booster providing the power on one side of the gap, and the other booster on the other side. Touch the wires from the bulb to the same rail, but on either side of the gap. If it lights up, the boosters aren't wired up right.