Mth Dash 9 ps1 sound problems

Could you start with the actual model of the unit?  Both PS/1 and PS/2 models have had 9V batteries.  If you don't know the model, how about the cab #?

Thanks for the replies.  Unfortunately, I am away from home until Saturday and don't remember the cab number.  Also unfortunate, I did not get the original box.  I spoke to Midge at MTH and the only information I could find was the cab number and some info on the front of the electronics package.  She seemed to think the unit may have had the cab replaced. She was not able to turn anything up with the cab number I gave her.  I didn't try powering the smoke motor with an independent power supply but I will do it.  The smoke unit has a heater pot with a brass funnel type of chimney.  The motor is attached to a plastic housing but there are is no circuitry directly attached to the unit.  At any rate I will post all of the info I can find on the unit when I return home on Saturday.  I can do pictures if it would help.

A picture of the inside will get you all the info you want.

Marty's right, a picture of the board set is probably the only thing that will help for this Frankenstein engine.

Sounds like a PS-2 smoke unit.  So possibly a PS-2 5V system.  The picture will do it.  What road name and what is the Cab #?

Thanks again for the response.  The battery is definately 9 volts as I removed it and measured it.  I also put a load on it(bulb) for approx 5 minutes and it's terminal voltage did not slump. The system could be 5 volts which is common for logic circuitry.  I noticed a TO-220 package device mounted to the chassis of the unit.  The device brand was LMxxx which could be a voltage regulator.  I would need to make some measurements to confirm it. I will dig into this again when I return home on Saturday.

The TO-220 package mounted to the chassis sounds like the PS/2 package, it's a 5V regulator, probably the LM2937, a -5V regulator.  The PS/1 doesn't normally have a loose regulator like that.

If it runs and has bell and horn, but no diesel sounds, and no smoke fan, the regulator is fine.

Do you have speed control (engine operates at scale speeds) or does it respond to voltage rapidly like a conventional train?

Did you try the feature reset (1 Whistle followed by 5 bells)  You will need a bell button added to your 1033 set up to do this.

The 5V speakers had a problem with flaking of the metalic coating around the magnet, so a bad speaker can be causing some of your sound issue.  Smoke fans also fail.  If the fan runs on a battery, I would look at the bottom front edge of the PS-2 board in the vicinity of where the 4 wire connector(Smoke harness) plugs into the board.  There are small FETs near the pins of that connector.  Do any look burned.  2 oppose each other and control the smoke fan.

You can also have pinched wires or partially connected connectors.  So alot depends on whether the engine still has speed control and what you find when you examine the speaker.

PS-2 DO NOT use chassis ground as part of the DC circuit so be careful testing fan and speaker.  If you ground them you risk damaging the PS-2 board which gets you into a costly repair.  G

GGG:  Thanks for the reply and information.  I am back at home and did the following:  I replaced the 1033 with a KW which I know has a good whistle control and added a sound activation button for the bell.  With this set up, I had good speed control and the bell and whistle both worked fine.  I tried the reset feature to no avail.  I then switched to DCS remote commander and had no response from the unit at all.  I then tried the Z750 with the transformer controller.  The speed control seemed to vary from normal to jackrabbit start.  The horn and bell would operate with no input and I could not stop them without turning off the power.  Finally, I went o the bench and powerd it up.  The smoke motor measured 0 v directly across the terminals. The heater is working since it was emitting smoke when iforced air into it.  I looked at the board which i should have done first.  The two devices down in the corner look o.k.  i.e. no evidence of huge overstress.  With the unit oriented so the tach motor is on my left, there are two of the sot devices located a the rght end of the board whose packages are cracked form a typical overstress situation.  This is all surface mount and my question is do these typically get repaired or is a board replacement in order.

The remote commander not working is possible for a used loco.  If the engine was run on DCS the address changed and the engine won't recognize the remote commander address.  A factory reset with DCS is necessary to get it to work with Remote Commander.

The bell whistle combination takes time getting use too.  Ashame the z-750 is blowing the horn and bell (happens with some).

I need a picture to see which FETs are cracked.  The board can be in the engine in many different configurations, so knowing which end has the motor with tach doesn't mean much.

FETs can be replaced.  Hard to measure fan voltage since it is pulsed DC.  Can you unplug the fan via a 2 pin connector, or is it wired to the 4 pin on the board.  If so pull the 4 pin out of the board and try to run the fan with a battery, and measure the fan ohm without power applied.  Most likely you need a new fan motor $6 and then the FET replaced.   G

Yes the 2 FETs closest to the L3055 (which is the Heating element FET) control the smoke fan.  The one closest to the edge is Q307 (FDN352AP) and it shorts the fan motor to Positive 5V to stop it. Fan runs on positive 5V in via the gray wire and is pulsed to DC ground via the green wire through the FETs.  The other is Q306 (a FDN5630) which controls the return to DC Ground.  If Q307 shorted the fan won't run.  If Q306 is bad it won't run.

The other looks like Q209 which is Ditch 2 light control.  Does this have ditch lights up front and do they work?  Some times ditch lights have one bulb to DITCH 1 and one to Ditch 2.  Other applications have a 2 bulb harness to DITCH 1, and DITCH 2 may be rear ditch lights, or number boards etc.

Be cautious if a light FET is shorted.  Lights get 19-22VDC from the bridge rectifier as input power.  When a FET fails shorted it is no longer modulating voltage to the lower effective voltage of 6VDC.  So the bulb burns at high Voltage depending on the resistance of the shorted FET.  Either the bulb blows, or worst it burns hot enough to melt plastic.   G

One last thing.  Worth replacing the smoke fan.  Historically, they can have partial shorts and still run.  They can cause lots of issues because they are powered from the regulator that powers all the 5V processors.  Noise has caused issues including damaged components on the board.  The 5V board is the older board, and isn't as robust as the newer PS-2 3V 2 piece board.

If you need the parts I have them in stock and you can contact me via my e-mail in my profile.  G

It's an early PS2 engine number 20-2269-1

Has no original charge port to charge the 8.4 battery

Battery in the fuel tank (that's why you don't see it)

The trucks have to be removed to get the side trucks off to replace the tires

I learned working  on a friends same engine replacing the speaker which failed. It maybe a good idea to check it while apart for flaking metal.