MTH AS-616 ERR conversion, smoke on causes TMCC signal loss

Did you change the smoke resistor? I think MTH uses 2 ,16 ohm resistors in parallel for 8 ohms. May be drawing to much current , causing the radio board to overheat.

Judd posted:

Did you change the smoke resistor? I think MTH uses 2 ,16 ohm resistors in parallel for 8 ohms. May be drawing to much current , causing the radio board to overheat.

I did not change anything in the smoke unit. It's still as factory stock as it was when it left MTH in the mid 90's. So if the MTH factory resistors are drawing too much current that could explain the issue.

Any idea what resistors I should replace the factory ones with? The other option is to just wire the smoke unit through the on/off switch and lose the remote smoke on/off.

Smoke resistor should be between 20 and 30 ohms, and at least a 3 watt rating.  I use 20 ohm 5 watt wire wound ceramic that I break the  ceramic off. creates a lot of smoke for steam engines,you may want a higher resistance for a diesel. If your smoke unit has 2 resistors you might be able to rewire them in series. Depending on how much smoke you want.

The smoke unit in question is the PS/1 smoke unit, and I've used them successfully in TMCC conversions without modification.  However, I will say, you are probably running close to the current limit of the triac on the R2LC in command mode.  Have you tried swapping in a new triac?

gunrunnerjohn posted:

The smoke unit in question is the PS/1 smoke unit, and I've used them successfully in TMCC conversions without modification.  However, I will say, you are probably running close to the current limit of the triac on the R2LC in command mode.  Have you tried swapping in a new triac?

The ERR kit I used is one of the newer ones from 3rd Rail that came with a R4LC. I have not modified the R4LC at all, so it still has its original smoke triac.

The R2LC and the R4LC from ERR are interchangeable and they use the same smoke triac.  You may want to consider a heatsink on the triac, though it's not insulated so you have to use the insulating hardware to mount it.

gunrunnerjohn posted:

The R2LC and the R4LC from ERR are interchangeable and they use the same smoke triac.  You may want to consider a heatsink on the triac, though it's not insulated so you have to use the insulating hardware to mount it.

How would I heat sink that triac? I'm a little fuzzy on how to do it. Thanks.

Can you run this on transformer with amp meter?  Is current jumping high?  Is the smoke unit really smoking heavily?  If you some damage on the PS-1 smoke board it may not jump in the second resistor in series to raise the ohms to 32, vice the low voltage 16 ohms.  Or maybe the spec on the R4LC is a little low and the triac is overheating as john stated.  You can try swapping a different R2LC or TMCC R4LC in.  See if that fixes it, or else you may want to inspect the smoke unit.  G

Lou1985 posted:

How would I heat sink that triac? I'm a little fuzzy on how to do it. Thanks.

Just look for a TO-126 package heatsink and use one that fits where the R2LC lives.  You can also "roll your own" with an insulating pad and washer to attach it.

GGG posted:

Can you run this on transformer with amp meter?  Is current jumping high?  Is the smoke unit really smoking heavily?  If you some damage on the PS-1 smoke board it may not jump in the second resistor in series to raise the ohms to 32, vice the low voltage 16 ohms.  Or maybe the spec on the R4LC is a little low and the triac is overheating as john stated.  You can try swapping a different R2LC or TMCC R4LC in.  See if that fixes it, or else you may want to inspect the smoke unit.  G

I don't have an amp meter on my layout but I can try testing the smoke unit draw at my LHS. They have a Z4000 hooked up to their store test track. If the smoke unit draw isn't excessive I'll try swapping a R4LC out of a different locomotive and see if that helps. 

Well I swapped the R4LC from another locomotive in and all seems fine after an hour of running with the smoke on. So I'll just leave the R4LC with the "weak" smoke triac in the locomotive that doesn't have smoke.