[RESOLVED] Loud hum and noise from Legacy unit

I have #6-28302 BNSF SD70ACe #9380.  It does the same thing.  I started this thread for answers, but was unable to fix it.  As a matter of fact I think you got further in an attempt to diagnose than I did.  But there are some strategies you may try.  It runs like a champ, but does hum pretty loud while sitting.

SD70ACe hums

Same with my 28302.  For a Legacy.  But it's no louder than Lionmaster diesels I have.   One more reason for sidings with on/off power switches.  RICH

All the early ones do buzz quite loudly. All the ones I have at least do. 

I have a Lionel genset with a buzz as well.  I had the same experience as GRJ from Ted's other thread.  I used to have a MTH Z1000 for track power where the buzz was from the genset was pretty loud.  I switched to a PH180 (I needed more power, not due to the buzz) and the buzz is not as loud.  Mine is speaker buzz and goes away of I turn the volume off.  In my case I can live with it using the PH180.

Tanner111 posted:

I have a Lionel genset with a buzz as well.  I had the same experience as GRJ from Ted's other thread.  I used to have a MTH Z1000 for track power where the buzz was from the genset was pretty loud.  I switched to a PH180 (I needed more power, not due to the buzz) and the buzz is not as loud.  Mine is speaker buzz and goes away of I turn the volume off.  In my case I can live with it using the PH180.

which genset? I have 6-28355 BNSF Genset and it seems pretty quiet.

TedW posted:

Tanner111 posted:

I have a Lionel genset with a buzz as well.  I had the same experience as GRJ from Ted's other thread.  I used to have a MTH Z1000 for track power where the buzz was from the genset was pretty loud.  I switched to a PH180 (I needed more power, not due to the buzz) and the buzz is not as loud.  Mine is speaker buzz and goes away of I turn the volume off.  In my case I can live with it using the PH180.

which genset? I have 6-28355 BNSF Genset and it seems pretty quiet.

I have the UP one and the KCS one.  The UP has a buzz and the KCS does not.  There were some threads on here talking about the buzz when the vision line gensets came out. From what I read it sounds like the buzz is isolated to the VL gensets - UP and NS.

My two engines look the same on the outside, other than colors obviously, but they are very different on the inside. I believe the non VL gensets including the BNSF, KSC, CSX etc have the same electronics. 

I'm glad to see that I'm not alone with this issue.

Thanks for the link to the hums thread.

Highroller2000 posted:

I'm glad to see that I'm not alone with this issue.

You’re not alone if it’s speaker buzz. Does it go away when you turn down the volume?  If so not much you can do about it. 

The CW-80 transformer chopped wave circuit is definitively the culprit for the hum/noise on old TMCC/Legacy unit !

I opened the case of an old CW-80 transformer and made a parallel connection of my tracks and CAB-1L setup just at the secondary of the AC transformer inside the unit to bypass the chopped wave circuit and voila, the hum/noise is completely gone ! I tested both my Union Pacific SD70Ace and CN SD-40-2 which were noisy like hell  and they are now both dead silent  !!!!!

It seem without any doubt that the old TMCC/Legacy engines are more sensitive to the chopped wave thand the newer stuff.

I don't have a Powerhouse brick to test but I assume those who run their train with them don't have the issue.

Have the buzz on the UP Genset with a powerhouse 180 brick.

Gweedo, I have the same buzz

My Genset is nice and quiet with audio off, I run with the PH180 here.

Highroller2000 posted:

The CW-80 transformer chopped wave circuit is definitively the culprit for the hum/noise on old TMCC/Legacy unit !

I opened the case of an old CW-80 transformer and made a parallel connection of my tracks and CAB-1L setup just at the secondary of the AC transformer inside the unit to bypass the chopped wave circuit and voila, the hum/noise is completely gone ! I tested both my Union Pacific SD70Ace and CN SD-40-2 which were noisy like hell  and they are now both dead silent  !!!!!

It seem without any doubt that the old TMCC/Legacy engines are more sensitive to the chopped wave thand the newer stuff.

I don't have a Powerhouse brick to test but I assume those who run their train with them don't have the issue.

 

 

 

Chopped sine waves are the bane of my existence being an operator of both modern and postwar equipment. Until now, I believed they only adversely impacted operation of AC motors and E-units. Apparently I was wrong. I have a toggle switch on my layout which instantly switches from pure sine wave power to chopped wave power.  When I toggle over to sine wave, motors instantly go from a jarring, grinding noise, to smooth operation. Chopped waves are the electro-mechanical equivalent of a concrete jack-hammer. The severe chatter and grinding probably contributes to premature wear on Pullmor motored trains too. But, to be positive, at least smoke production increases...

GregR posted:

 

I have a toggle switch on my layout which instantly switches from pure sine wave power to chopped wave power.  When I toggle over to sine wave, motors instantly go from a jarring, grinding noise, to smooth operation. 

Can you share how you did this?  Is this part of a transformer or did you do it yourself?  Photos, instructions, parts needed.

I assume the PH180 is just a power transformer core with switches so it must be pure sine wave out of it, I'm I right on this ? 

Yep, here's the schematic for the older one, I haven't seen a tear-down of the new one that just shipped this year.  You will note that the secondary winding goes right out to the external connections.

gunrunnerjohn posted:

Yep, here's the schematic for the older one, I haven't seen a tear-down of the new one that just shipped this year.  You will note that the secondary winding goes right out to the external connections.

 

The PH180 is as pure a sine wave as you're going to get unless your power company sends out distorted power.

I think I will get a PH135 or PH180 instead of using the secondary of the CW-80 which show 19,6 volt with a locomotive on the tracks. I think it is a little too high for Legacy components and bulbs wich required no more than 18 V.

I have two of the original PH180 Powerhouse transformers on my layout.  I run DCS and Legacy, and I get no noise. 

Highroller2000 posted:

I think I will get a PH135 or PH180 instead of using the secondary of the CW-80 which show 19,6 volt with a locomotive on the tracks. I think it is a little too high for Legacy components and bulbs wich required no more than 18 V.

Go for the PH180, it has a MUCH better circuit breaker.  The PH135 has a plain thermal breaker and is pretty slow.

gunrunnerjohn posted:

The PH180 is as pure a sine wave as you're going to get unless your power company sends out distorted power.

Thanks John.  That's what I wanted to know.

Thanks for the advice.