Hum or buzz in static Legacy Diesel 6-28302

The exact model number would be useful here.

Sorry, was in the topic heading.  Lionel 6-28302. BNSF SD70ACE. TW

Anyone?   Thx in advance

My first step would be to pop the top and check all the wiring.  Make sure the speaker leads are NOT contacting the frame as well.

Next step would be to swap out the power supply, it's generic from modular TMCC and early Legacy, so you should have another engine to swap with.

That's a first generation legacy diesel.

Fwiw all of my first Gen legacy steamers make a bit of noise fron the speakers when sitting idle.

I can't say if yours is worse indicating a problem.

These early legacy engines merely mute the sounds instead of cutting the power completely like more recent legacy stuff, say 2011 and newer or so.

If your other diesels are newer then that's why theres a noticeable difference.

Having said all that. John is the expert here. He will help you get to the bottom of the problem if there is one.

gunrunnerjohn posted:

My first step would be to pop the top and check all the wiring.  Make sure the speaker leads are NOT contacting the frame as well.

Next step would be to swap out the power supply, it's generic from modular TMCC and early Legacy, so you should have another engine to swap with.

 

RickO posted:

That's a first generation legacy diesel.

These early legacy engines merely mute the sounds instead of cutting the power completely like more recent legacy stuff, say 2011 and newer or so.

If your other diesels are newer then that's why theres a noticeable difference.

Rick, The only other one I have is KCS ES44ac 6-82214 (2015 catalog). Quiet like you say.

Will take the shell off n check wiring.  

GRJ, do you mean swap out a power supply from another engine to check for bad supply?  Only have two other legacy besides the KCS, and they are steam.  Make a difference?

If they're modular electronics with the two RS boards, they all use the same power supply.

The louder AC hum sounds a little more than normal, but swapping the power supply will tell you if that's the issue.  If it follows the P/S. you need a new one.  If it doesn't, you can try swapping in a different audio board, we just looking for hum when it's silent, so it's easy enough to check.

I took an older Legacy GP-7 out with the modular electronics, on my phone's sound meter, the background sound was 60db half an inch from the locomotive.  You could hear a faint 60hz hum if you listened close, and that seems normal.  Your video seemed to indicate you have more volume in the hum, obviously it's hard to tell from a video.

Good idea on sound meter. Of course the buzz loudness goes up n down with volume control, but at max volume at your 1/2" away, mine was 64db-A max with 59db-A average in a quiet environment(once the dang air conditioner turned off). So, not so sure it's as bad as I am thinking it is. Perhaps the comparison to the newer engines is causing more concern than necessary. Will still check wiring, etc. to see what I find out. Or, maybe I'm trying to wish the problem away also. Thx for the ideas

gunrunnerjohn posted:

If they're modular electronics with the two RS boards, they all use the same power supply.

The louder AC hum sounds a little more than normal, but swapping the power supply will tell you if that's the issue.  If it follows the P/S. you need a new one.  If it doesn't, you can try swapping in a different audio board, we just looking for hum when it's silent, so it's easy enough to check.

Is it possible to make some sort of modification using electronic components to clean up that AC current to help get rid of the hum?

Hard to say, I've never tracked it down.  I can hear a faint hum when the engine is silent with the volume all the way up, but it's never bothered me enough to do anything about it.  It's quite possible you could reduce it, but the question would be if the reduction would be worth the time and effort.

Bruk posted:

gunrunnerjohn posted:

If they're modular electronics with the two RS boards, they all use the same power supply.

The louder AC hum sounds a little more than normal, but swapping the power supply will tell you if that's the issue.  If it follows the P/S. you need a new one.  If it doesn't, you can try swapping in a different audio board, we just looking for hum when it's silent, so it's easy enough to check.

Is it possible to make some sort of modification using electronic components to clean up that AC current to help get rid of the hum?

I have to agree with Bruk - I think it's track power induced. I had the 6-28555 from this era. I was getting the same sound when I was learning how to use the SC-2 to control switches. Mixed up some wiring and the engine would hum.

I would suggest placing the engine on a few pieces of test track away from the layout and connect a transformer with the legacy base connected to it.

Do you have fluorescent lighting nearby?

I don't know - it just sounds like noise generated by something out of phase, an appliance motor, something.

Once I resolved the wiring issues, I didn't get the hum.

I just think it's worth the isolation test before opening the shell.

Carl, I'll certainly try that suggestion. I have a number of track sections laying on the floor for trains I'm not running. But, they have drops from the "mainline" track. So, I could connect them to a different xfrmr, or use my test track, then add the legacy wire to test that engine in isolation. BTW, no fluorescent lighting(all led), there is an HVAC motor within 4-6 feet of track. Course it doesn't run all the time. 

I tested my GP-7 on my bench with just a transformer and a short length of track.  There is still a little hum when it's silent, but pretty faint.

I got the same results. The CW80 even "seemed" to make more buzz than hum, although the db level was pretty much the same.  I may just be making a mountain out of a molehill. As my Mom would say when I came to her whining, "Go out n play in the street".    Plan B

I have a few TMCC engines (2001 to 2002 vintage) that have the hum.  Curiously, these engines do not hum when powered using and MTH Z-4000, but do hum when I used a ZW-C or a CW-80.  I wonder if its a AC sine wave issue - pure vs chopped?

The chopped wave typically does send some extra noise through, I notice if I put the engine on the track with the PH180 brick it's quieter than when I power it on my test bench with the Z1000.

I've got a 1033, isn't that pure sine wave?  Maybe I should test with that just for kicks.     The power is a ZWL for everything on the floor.  Ted

I think a 1033 is pure sine wave.  Give it a go and see if there is a difference.

I think if you can some how clean up the input power to the sound board from the power board it should clean up the hum you hear....I think