Lionel CW-80 1908080 (newer version) overload issue

@James Brown posted:

So I have a newer version CW-80 and all of the sudden it will not run conventional locos anymore.  As soon as I power it up the red light starts flashing and the locos will move a little and then it changes to solid red and shuts down power completely.  As a check I hooked up my "older" CW-80 and everything runs just fine, so it's not a track or loco issue.  Are these newer CW-80s subject to failure of the overload sensor?  If so, is that repairable?  Unfortunately it's more than a year old so I am sure it's out of warranty.  Suggestions?

Knowing the design, I would say no, it is not a "failure" overload current sensor.

More likely, it's a failure of one or both of the 2 FET transistors per channel.

https://www.onsemi.com/pdf/datasheet/fdp047n08-d.pdf

Again, if this model of new CW80, then you most likely blew the matched pair of fdp047n08 (the bottom two as the picture is oriented or the rightmost 2 when level.

Please review the extensive information I have posted about this transformer. https://ogrforum.ogaugerr.com/...0#161208612964634320

@Vernon Barry posted:

"Why is the unit putting out voltage when the throttle is down and is there any way to correct that?"

Easy, you blew the transistor. When you do that, they blow shorted so it's full track power.

Pictures from the latest new model

https://www.onsemi.com/pdf/datasheet/fdp047n08-d.pdf

Again, if this model of new CW80, then you most likely blew the matched pair of fdp047n08 (the bottom two as the picture is oriented or the rightmost 2 when level.

On the older models there is only one TRIAC per output so one is accessory and one is for track variable. Again, entirely different in the old model in that there is a heatsink and fan. The new models have no heatsink or fan.

@Vernon Barry posted:

FWiW, the easy way to understand the orientation of the board is the 3 pin connector for the potentiometer is the same side the handle is on, and that is the same side the track power channel is.

Remember, when you open the transformer, that board is facing the buttons up into the housing.

Further, before someone asks, no the diodes near the FETs appear to be gate drive related, and thus if they failed would not short the output (they are not output snubbers).  Also, there is no TVS or other diode to short the output. The circuit relies on the internal built in snubbers of the FETs themselves. So if there was a failure (example partial or full stuck on throttle state- or in this case an outright overload fault, my first assumption is one of the FETs has failed and that failure may include snubber diode section failing and causing high amperage thus overload).

Here is a more detailed picture of the large diodes near each of the FETs.

I think this is the data sheet? SMAZ12 Datasheet(3/3 Pages) ANOVA | Surface Mount Zener DiodesAgain, the device is definitely connected to the gate of each https://www.onsemi.com/pdf/datasheet/fdp047n08-d.pdf

FWIW, Digikey is out of them with a 41 week lead time, but Mouser does appear to have them

https://www.mouser.com/Product...aji%252BGv5pqA%3D%3D

Obviously, you can check any supplier you want.

Also, to be clear, Lionel does not list the PCB or any part of the new CW-80 for sale.

https://www.lionelsupport.com/CW80-revised-2019_2

Again, my thought on this now having seen a few, not many, folks post about this new model failing.

#1 This design I believe is shared with the larger GW-180. Reason for saying that is, this IMO, isn't all new or unproven design, or some major design flaw or common failure.

#2 In most every case I have have heard of, the failure coincided with a derailment short event that likely had significant voltage spikes from inductive kicks during the derailment and high current event.

#3 Since the board and transformer does not have any TVS devices- I personally would consider adding them externally on the output to prevent such an event (short circuit and inductive voltage spike) from blowing out the FETs.

https://ogrforum.ogaugerr.com/...6#179791711047788526

@gunrunnerjohn posted:

1500W 33.3V TVS at Digikey

TVS protects both sides of the circuit- not just your train, but people largely leave out protecting these electronically controlled variable output transformers.

I had my new CW-80 fail after just a few hours of use on a simply floor layout. I was out of warranty so Lionel wouldn't do anything but send me repair shops. I would attempted the fix but frankly am a little tied up with other reno projects...

Luckily, my local train shop where I bought it helped me out...

@Vernon Barry you posts on these units are terrific...very informative! thank you!

@Vernon Barry posted:

Again, my thought on this now having seen a few, not many, folks post about this new model failing.

#1 This design I believe is shared with the larger GW-180. Reason for saying that is, this IMO, isn't all new or unproven design, or some major design flaw or common failure.

#2 In most every case I have have heard of, the failure coincided with a derailment short event that likely had significant voltage spikes from inductive kicks during the derailment and high current event.

#3 Since the board and transformer does not have any TVS devices- I personally would consider adding them externally on the output to prevent such an event (short circuit and inductive voltage spike) from blowing out the FETs.

https://ogrforum.ogaugerr.com/...6#179791711047788526

TVS protects both sides of the circuit- not just your train, but people largely leave out protecting these electronically controlled variable output transformers.

Vernon, thank you very much for that in-depth explanation.  Very helpful.

@Arcadebrothers posted:

I had my new CW-80 fail after just a few hours of use on a simply floor layout. I was out of warranty so Lionel wouldn't do anything but send me repair shops. I would attempted the fix but frankly am a little tied up with other reno projects...

Luckily, my local train shop where I bought it helped me out...

Did you (or your local shop) do the fix that Vernon suggested?

Going back to the original question, "As soon as I power it up the red light starts flashing and the locos will move a little and then it changes to solid red and shuts down power completely." Just out of curiosity, are you running more than one high amperage loco at once on a single CW80?

@John in California posted:

Just out of curiosity, are you running more than one high amperage loco at once on a single CW80?

No, was running a single Williams F7.  I did have three passenger cars on there too, so a little more current draw from those lights.  But it was working fine, and then it wasn't.