I recently toasted my only sound card. It appears to be from either a short or overvoltage. I am looking for any suggestions on protection, ie fuses, rectifiers, voltage regulators, etc. If further information is needed, ask away.
Thanks,
Bob C.
What is your setup that could allow overvoltage? This is not a common problem.
Are you running battery, etc?
In other words, a lot more information of how you run, power, types of installations would most likely help with better suggestions.
Regards, Greg
What brand and model is the sound?
The card is installed in a Bachmann K27. The power is tapped off the power pickups in the tender to the trucks. The trucks are the early type with the wipers on the axles. I had someone else install the card for me, so I am after the fact. One of the power leads show heavy heat in the insulation. The card is a Phoenix PB9, track powered with all B’mann electronics still in place. The Chuff is triggered with reed switch and magnets. I was thinking along the lines of a Zener diode or voltage regulator in line with a low amperage fast blow fuse, but lack the technical to know how to calculate what I need. I have a couple of pics, as soon as I get them on my server I will post them. Thanks Bob C. Let’s try…
Hard to say what caused it, but it got hot enough to melt two of the input diodes right off the card.
Over voltage may have done it. How much voltage is the speed controller capable of giving?
I have had only one or two diode failures with Phoenix over the years. Phoenix actually made good with a replacement system.
Tony,
They are doing the same here, but I am really trying to do my best to make sure it does not happen again. As I indicated above, I know just enough about electronics to be really dangerous. I do intend in the future to go to battery power with a switch to allow track power as well.
Current situation is either at home I use an Aristo starter set power pack, or at the club we use a 24v switching power supply with the Aristo Train Engineer. I don’t remember any derailments that shorted anything out, but then memory …
Not sure what else will help, but pointed questions I can work on.
Thanks again.
Bob C.
I’m bustin’ at the seams here…I can’t take it anymore!
(http://upload.wikimedia.org/wikipedia/commons/8/89/Bomba_atomowa.gif)
Sorry…I’ll be in my corner:(
Do you have only one Train Engineer?
Do you have common return wiring?
Home is a single loop. The club has five loops that although can be switched between, I believe are isolated on both rails at the cross overs. Each loop has it’s own power supply and TE, with it’s own wiring to allow isolation of a loop in the event of electrical issues. I have never switched between loops, so i don’t believe that to be the source, but then again, I can’t really be certain. Due to the large size of the K, I always run on one of the outer loops (all 20’ dia curves), it looks better there. We have had some issues with the hot frogs on the Aristo extra wide turnouts, which we are in the process of de-activating, but only with the short trucked diesels as I understood it.
OK. Where di you toast it? As in at home or at the club.
The reason I ask about multiple TE’s and common wiring is that if multiple controllers are run using common return wiring it is possible in unusual circumstances to end up with double voltage going to the track.
My money would be with faulty diodes on the PB9.
I am relatively certain it was at the club layout. As I mentioned earlier, it could have been a derailment, but I would not place a bet either way. I do believe our electrical guy at the club has done his homework on the power wiring.
My concern now is 'How do I keep this from happening again?" I would prefer to put a much cheaper ‘sacrificial lamb’ in the circuit somewhere to protect the sound card. It has been suggested to put a bridge rectifier in line to guarantee prover polarity, which makes sense. I was also thinking a low amperage fast blowing fuse, but don’t know what that low amperage might be. Or possibly a low amperage zener diode keeping the voltage in check but failing on high current.
…enough knowledge to be dangerous…
Thanks for you time and assistance Tony.
Bob C.
Bob, The PB9 already has a bridge rectifier made up of 4 x diodes. It is two of those diodes that have melted off the pcb.
That unit has a battery charging circuit too, right?
If I am not mistaken this board also has the “bigboost” where it has a DC to DC inverter to run on low track voltages… of course using the same power at a lower input voltage means more current.
Recently people have reported that they have had these things go toast on their own (remember the big hullabaloo on the Aristo site where the new mallet caught on fire, and it was blamed on the phoenix?)
The person with the mallet, after he ran out of breath praising Aristo and saying it was not their fault, stated, several times, that Phoenix knows about this problem where the Phoenix units self destruct.
I’m not sure I believe all of the story, but there might be nothing better to do than put a simple fuse on the input.
3 watts at 24 volts is very little amps (1/8 amp), so throw a 1 amp fuse on there first. Set yourself up with an automotive blade type fuse holder, and start with a 1 amp fuse unless it keeps blowing them.
What is unknown is amperage draw at lower voltages.
Phoenix claims it will run at 3 volts. Just taking the audio amp output of 3 watts alone means 1 amp, so maybe start with a 3 amp fuse.
Regards, Greg
Thanks Greg!! That was what I was looking for - a starting point.
“Phoenix claims it will run at 3 volts.” I gather that is what the small 3.? volt battery pack is connected to the card for. Is that supposed to charge during normal operation to keep the battery up, or does it need a separate charging circuit?
BTW … Fuses are far cheaper than sound cards, no matter the vendor. I may slot the bottom of the tender to allow changing without having to dis-assemble the tender. When I get the new card and get it installed I will post pics of how I do it. I am also going to install an on/off switch so I can turn the sound off for ‘silent running’. As much as I love the sound of the K, it will get old after a couple of hours of running.
Bob C.
Greg Elmassian said:Greg said Unit!
That unit
The 3 volts is how low a voltage the “big boost” circuit works on… basically the additional circuit allows it to up convert 3 volts up to enough voltage to run the board. This means you are not running on battery at 3 volts and up.
Without that circuitry, I believe the dividing line between running from the battery or track power is 7 volts…
What was happening was that people were running at slow speeds and using up the battery.
Yes, definitely make the fuse accessible from the outside!
Hope that explanation helps.
Greg
Greg Elmassian said:
......SNIPYes, definitely make the fuse accessible from the outside!
SNIP…
Greg
Or use a suitable Polyswitch.
even better… thanks Tony!
While you are at it, a polyswitch on each track pickup lead will protect from melted wires if you derail.
Greg
A quick look on the net during lunch, and it seems that one of those for a 3 amp hold with a 6 amp trip will take about 10 seconds (if I read the data sheet correctly) to trip. If that is correct, you could incinerate a bunch of electronics in that time. Looked at both Polyswitch and Littlefuse web sites.
Bob C.
There are people on this forum that insist they trip faster…
You should try them out, but my suggestion was on the track pickup wires, they will trip before the wires completely overheat.
On the unit itself, maybe the auto fuse is best.
Regards, Greg