Tru-Blast horn not working

[DonTrain]

Hello, I just purchased a GP-38 with Tru-Blast II horn and with my MRC Tech II 027 the horn does sound when the horn switch is activated. It operates all my Lionel locos and MTH locos and their horns/whistles with no issues. All I get is a blink of the lights from the GP38.
The locomotive performs fine and pulls great so I am very pleased with it but I would like to hear the horn sound. Is there a bell also, that particular transformer does not have a seperate bell button, could that have something to do with the horn not working?

Thanks

[GTBob]

If the loco is used , better open her up and make certain this is a horn.  A short time ago,  I bought a used Williams and thought I got taken because the horn didn't work.  Another member told me to check for the horn---there was none and never was (duhhh).

The horn should work when you hit the horn button on the transformer.  I don't believe the bell feature should not have anything to do w/ the horn not working.

You can also call Bachman and talk to their service Dept. for advice.  Also make sure there are no broken wires, connectors, etc.

Good luck...

GTB

[DonTrain]

No, the unit was sealed and brand new. I will check for the horn and board in there. How difficult is it to install the horn and board if need be?

[GTBob]

If your GP38 is new, it should have a TB2 horn included.  It should also be covered by the Williams/Bachman warranty if it's not working properly..  Is the loco getting enuf current???  Both of my Williams locos need around 9-12 volts for the diesel horns to work.

Do you have another transformer to test the loco on??

It took me about 15 minutes to install a new TB2 horn on my Williams FP45 the other day, but, I'm old and slow.  EZ to follow instructions are included.  I'd guess the reverse board might take a bit longer, but, I never installed one.

Keep us posted---good luck.

Bob

[Joe Satnik]

Dear Don,

The True Blast II system is a sound board (with sounds stored in memory) and speaker. 

Since your MRC Tech II 027 only has a whistle(horn) button, you really can't access the bell. 

If you want to play around with the bell, swap the wires on your "lock-on", then follow the directions included with your engine, using the whistle(horn) button.

Another possible problem, the MRC Tech II 027 may be one of those "light dimmer" designs that chop up the power, which may confuse the sound board's triggers.

Ideally, your transformer would have the old style "pure AC wave" with a DC offset in one direction for whistle(horn), and a DC offset in the other direction for the bell. 

Lionel "Railsounds" are triggered by this "other direction" DC offset. 

Hope this helps.

Sincerely,

Joe Satnik



 

[DonTrain]

Yeh, I swapped the wires at the lock-on this morning, remembering this is what was needed for the MTH locos when the whistle did not function. Now I have a bell sound, a good one, but still no horn. I am going to try the other suggestion and see if more juice gives me the horn.
I gather that swapping the wires at the lock-on one way will give the bell and the other way the horn?

I am going to swap away!

[Joe Satnik]

Dear Don,

Yes, reversing the polarity to the track is the idea. 

You could try a 6 amp DPDT switch to reverse the polarity,

http://www.radioshack.com/search/index.jsp?kwCatId=&kw=dpdt&origkw=dpdt&sr=1

but the loco's reverser board could possibly drop into neutral (temporary loss of power in mid-throw of switch) if you tried to switch it on the fly.

1 2 <-back of DPDT switch
3 4
5 6

MRC line 1 --> 1 and 6

MRC line 2 --> 2 and 5

3 --> center rail lock-on

4 --> outside rail lock-on

Check your wiring/soldering for shorts. 

(End of switch wiring instructions.)

To the power waveform (as seen on an oscilloscope);

Reducing the power to the tracks with an old style variable output transformer is like going on a diet. 

Reducing the power to the tracks with a newer SCR fired light dimmer circuit is like having your midsection surgically removed.

Hope this helps.

Sincerely,

Joe Satnik 

[phillyreading]

Hi DonTrain,

Have you tried using an MTH Z-1000 transformer with the Williams TB-2 sound unit? All my Williams sound units(True Blast 2 and regular units) like the Z-1000 transformer.
Try another transformer besides the MRC transformer, and see what happens.
It is true that Williams sound units need to have the wires reversed(actually the polarity reversed) with a transformer that has only the whistle feature.

Another thing that I have noticed is that you may have to hold the whistle or bell button for three seconds for the TB-2 unit to activate.

Lee F.

[Ron Sims]

I have found that older lionel post war transformers will not blow the true blast horns. However, my Z-1000 will everytime.
Ron

[GTBob]

I have found that older Lionel post war transformers will not blow the true blast horns. However, my Z-1000 will everytime.
Ron

Guess I'm lucky--my 1952 (58 years old) Lionel ZW works fine on both of my Williams diesels w/ TB2 horns.  I did however, remove both the old rectifiers from the ZW and replaced them w/ diodes I bought online---cost $10.  Maybe that's the reason the ZW works so well??

GTBob

[3rail]

Dear All,

Several of the earlier MRC transformers are not compatible with our sound boards. Some will not trigger others will blow the horn all of the time.  This is due to the chopped sine wave output and happens on other brands with this type of output.  The MRC purepower versions work fine.

Upgrading your postwar transformers with new diodes is definitely worth the small investment.  Also, deluxe postwar transformers like the KW, ZW etc.  were equipped with a voltage boost coil.  If you have not replaced the diode this can confuse the electronic trigger circuit.  Try pressing the horn button or lever halfway, this just sends the DC offset without engaging the voltage boost and allows you to activate the horn.

Regards,

3rail