Lionel S.P. 6-52078 SD-9 Looking for help

Mark, the blue objects on the brushplate are electrolytic capacitors designed to smooth out the current and voltage variations that occur across the brushes that might damage the electronics. The white material on the transistors on the aluminum bracket is thermally-conductive paste designed to allow heat to transfer from the transistor to the aluminum bracket which is acting as a heat sink, so getting warm to the touch is normal. This paste is not designed to be an electrical insulator. The "tabs" on the transistors are the "base" of each transistor, so you need to know if there were any plastic washers, plastic sleeves or mica pieces behind the transistor tabs or in the mounting holes on the bracket because you need to know if the transistor "bases" are supposed to be electrically connected to each other or not. If there were no plastic washers, sleeves or mica originally present, you should remove the electrical tape and bolt them back down. I can't see what's on the other side of the aluminum bracket so I don't know what components are there.

@Bill Swatos posted:

Mark, the blue objects on the brushplate are electrolytic capacitors designed to smooth out the current and voltage variations that occur across the brushes that might damage the electronics. The white material on the transistors on the aluminum bracket is thermally-conductive paste designed to allow heat to transfer from the transistor to the aluminum bracket which is acting as a heat sink, so getting warm to the touch is normal. This paste is not designed to be an electrical insulator. The "tabs" on the transistors are the "base" of each transistor, so you need to know if there were any plastic washers, plastic sleeves or mica pieces behind the transistor tabs or in the mounting holes on the bracket because you need to know if the transistor "bases" are supposed to be electrically connected to each other or not. If there were no plastic washers, sleeves or mica originally present, you should remove the electrical tape and bolt them back down. I can't see what's on the other side of the aluminum bracket so I don't know what components are there.

Thanks Bill will remove the tape, I did put the tape on the other side, I'll get another picture of the other side at post. Thanks Bill So much easier trouble shooting PW Lionel. Mark

Bill the other side, took the tape off, should I put more of that paste on now that a lot is off?  Ok won't run no horn either get a humming noise? I did see if Lionel had the parts list on the Lionel web site that was a no go. Any other ideas would be helpful. Funny It did run after degreasing and the horn worked. Thanks again Bill

Mark, if you've removed some, it's a good idea to clean off the rest of the old thermal paste and apply new as thermal paste tends to dry out over the years. I use MX-4 Thermal Compound from Arctic for the thermal paste.  It's a bit pricey, but it doesn't take much. Because the screws and nuts don't look like they were insulated with plastic washers, you likely never had the transistors on the one side insulated from the bracket with just the tape. It looks like Lionel set up a 4-transistor bridge rectifier there and all of the transistors were bolted to the aluminum bracket without any insulating washers, sleeves or mica pieces. The tab on each transistor corresponds to the center lead going to the board.  Here's an article that shows a four-transistor bridge rectifier but not from Lionel, though.

Unfortunately, if you applied any track power while any of the transistors were completely disconnected from the aluminum bracket you might have blown one or all of them. And, yes, PW stuff is a lot easier to work on and, if you lubricate and shim gears, axles and sidegear, runs just about as well:

Mark, I also forgot to mention I'm almost sure the aluminum bracket should be insulated from the frame.

@Bill Swatos posted:

Mark, I also forgot to mention I'm almost sure the aluminum bracket should be insulated from the frame.

No, not on this design. This is the precursor to the LCRU and LCRU2 both using the same basic power portion and same mounting. They are ALL frame grounded. Heck, they often use one of the screws of the heatsink with a branching eyelet to connect multiple ground wires to.

Ground lug bus connection point right on the heatsink in this picture- no insulators of any kind on the transistors to heatsink.

Again, these, all 4 TO220 TRIACs are not insulated to the heatsink, nor is the heatsink insulated to the frame- by design.

@Bill Swatos posted:

Mark, if you've removed some, it's a good idea to clean off the rest of the old thermal paste and apply new as thermal paste tends to dry out over the years. I use MX-4 Thermal Compound from Arctic for the thermal paste.  It's a bit pricey, but it doesn't take much. Because the screws and nuts don't look like they were insulated with plastic washers, you likely never had the transistors on the one side insulated from the bracket with just the tape. It looks like Lionel set up a 4-transistor bridge rectifier there and all of the transistors were bolted to the aluminum bracket without any insulating washers, sleeves or mica pieces. The tab on each transistor corresponds to the center lead going to the board.  Here's an article that shows a four-transistor bridge rectifier but not from Lionel, though.

Unfortunately, if you applied any track power while any of the transistors were completely disconnected from the aluminum bracket you might have blown one or all of them. And, yes, PW stuff is a lot easier to work on and, if you lubricate and shim gears, axles and sidegear, runs just about as well:

Thanks again Bill have a PW e-unit might hook up till I get a board, nice running 2037 well I count 30 cars.

Also, half off parts sale coming up, you could make it TMCC on the cheap. Sure, $90 list today, but $45 soon https://www.lionelsupport.com/...OTOR-ELECTRIC-DIESEL

@Vernon Barry posted:

No, not on this design. This is the precursor to the LCRU and LCRU2 both using the same basic power portion and same mounting. They are ALL frame grounded. Heck, they often use one of the screws of the heatsink with a branching eyelet to connect multiple ground wires to.

Ground lug bus connection point right on the heatsink in this picture- no insulators of any kind on the transistors to heatsink.

Again, these, all 4 TO220 TRIACs are not insulated to the heatsink, nor is the heatsink insulated to the frame- by design.

Thanks, Vernon, good to know if I get one of these. Mark, now you know what to do...

@Vernon Barry posted:

No, not on this design. This is the precursor to the LCRU and LCRU2 both using the same basic power portion and same mounting. They are ALL frame grounded. Heck, they often use one of the screws of the heatsink with a branching eyelet to connect multiple ground wires to.

Ground lug bus connection point right on the heatsink in this picture- no insulators of any kind on the transistors to heatsink.

Again, these, all 4 TO220 TRIACs are not insulated to the heatsink, nor is the heatsink insulated to the frame- by design.

Vernon, So Lionel used a white thermal past on the bottom of the alum. frame and also the four insulators where the four screws are, so when I had added the elec. tape did I damage the Reverse unit? I did have it running, then didn't run and got no horn after the tape job, so should the paste be on the frame and insulators? Thanks  Mark

@Sitka posted:

Vernon, So Lionel used a white thermal past on the bottom of the alum. frame and also the four insulators where the four screws are, so when I had added the elec. tape did I damage the Reverse unit? I did have it running, then didn't run and got no horn after the tape job, so should the paste be on the frame and insulators? Thanks  Mark

THERE ARE NO INSULATORS- PERIOD

The 4 TRIACs are DIRECTLY connected to AC frame COMMON- sometimes called ground.

My guess would be, you were open circuit with them being insulated- hence no horn. Also, calling that a horn should be a crime in and of itself when it worked. It's a beat oscillator that sounds like a dying bird giraffe on a good day- even when adjusted, even when it works as intended.

On damage- if it runs both directions, you did not damage the reverse unit.

If your "horn" stopped working- you solved a problem, and created an opportunity for an upgrade.  The horn board is also probably just not properly connected is why it is not working. It's 2 wires- one to frame and one to 3rd rail. It was not damaged by nor interacts with the reverse board in any way.

Again, the TRIACS in this AC reverse unit and then the later LCRU and LCRU2 as well as the the modular ACDR motor driver -the TRIACs are hard mounted to the heatsink, no insulator, no insulating hardware on the screws. Heck the example I have is riveted to the heatsink!!! No insulators, no grease, NOTHING. I'm not saying don't add grease and insulators just add a layer of thermal resistance so knowing the circuit- I would not even bother using them

but hey- your train, your rules- your wallet.

YES, Lionel DC reverse units like DCDRs and later the DCDS use a different setup and need insulators, but it's important- the AC variants might look similar but do not follow the same rules.

I cannot stress this enough- the horn board is a completely separate circuit. The only 2 wires it shares is frame/wheels common and 3rd rail power. It detects the waveform and DC offset in the AC waveform coming in. It suddenly not working is more likely wiring than anything related to the E unit.

You disturbed the wiring messing with this would be my first guess

@Vernon Barry posted:

I cannot stress this enough- the horn board is a completely separate circuit. The only 2 wires it shares is frame/wheels common and 3rd rail power. It detects the waveform and DC offset in the AC waveform coming in. It suddenly not working is more likely wiring than anything related to the E unit.

You disturbed the wiring messing with this would be my first guess

Thanks for the help, that mess of wires is what I found the only thing I did was disconnect the e-unit so I can clean the motor and trucks along with the frame, for that horn it sounds like a duck LOL, will start over. ok thanks again. Mark

@Bill Swatos - Very impressive 30 car consist your Post War steamer is pulling!