gunrunnerjohn posted:... I'm one for four on getting those on
That's why you buy 10! 
It does present quite the conundrum. Since everything else about the board appears to work, how much $$ should one throw at a PS2-5V board? 
stan2004 posted:gunrunnerjohn posted:... I'm one for four on getting those on
That's why you buy 10!
It does present quite the conundrum. Since everything else about the board appears to work, how much $$ should one throw at a PS2-5V board?
Should I be putting a different kind of board in there? PS2 is all I have on my layout.
Contact GGG directly; his email should be in his profile.
If you like the MTH PS2 functionality (sounds, lights, speed control, etc.), there are MTH-designed board replacement options but you'll need to get specific $ estimates from whomever is doing the installation/upgrade. I'm thinking $200-300 after material, labor, shipping but that's just showing off my ignorance!
Again, you need to get advice from someone who is in the business. That is, I see it from the warped perspective of someone willing to mess around at the component-level where time is "free" as it's part of the hobby to me. So I'm looking at the 50-cent solution - component cost only assuming the transistors are indeed the problem. My glasses are very rose-colored! 
I routinely put the replacement PS32 board in for dead 5V PS/2 boards. Stan is correct, it's not a cheap option, MSRP on the board and heatsink is $230 and you also need the heatsink kit $16, and the 4 ohm speaker, $15. Add shipping and labor, and it runs the cost up.
GRJ, in re the PS2-5V heatsink strips, it occurs to me that the PS2-3V board set does NOT have that funky heatsink awkwardly attached to the motor drive transistor. Was there a service bulletin or advisory about replacing the transistor with a "better" one (perhaps the one used on the PS2-3V motor drive) so that you do NOT need the heatsink?
Stan, I'm guessing that the motor drive circuit must be quite different. FWIW, the Lionel Legacy motor driver on the RCMC doesn't have any heatsinking either. It never occurred to me to try it without the heatsink, I know those heatsinks get pretty warm during normal operation. My guess is that the 5V boards were pushing many components to the limit. I don't think they'd last long without the heatsink.
So, are some of you suggesting that this engine might not be worth repairing?
If I were to buy a new MTH engine, would it be compatible with my current system which is entirely PS2?
Any PS/2 or PS/3 locomotive should be compatible with your DCS system.
stan2004 posted:GRJ, in re the PS2-5V heatsink strips, it occurs to me that the PS2-3V board set does NOT have that funky heatsink awkwardly attached to the motor drive transistor. Was there a service bulletin or advisory about replacing the transistor with a "better" one (perhaps the one used on the PS2-3V motor drive) so that you do NOT need the heatsink?
I'm not positive it's what you're describing? I replace the motor transistor on stock PS2 3v upgrade boards to a heavy duty version to get them prepped for G scale use (steam). I ordered a bunch of them at once. I put them away somewhere as I stopped needing them. They only have 2 wires that get added to the traces. It was originally suggested to heat sink them. I got advice that it wasn't necessary later on. We actually shrink wrap them from shorting.
Edit: motor Diode!
The 5V boards have two gold heatsink tabs that are soldered to the FET's. Those get pretty warm in normal operation, and I'm pretty sure without them the FET's would not be happy!
I'm trying to figure what you're really replacing on the 3V board, can you identify the part? Are you talking about this FET?
Sorry John. I'll go get one and take a pic. After thinking about it, I think it's a motor diode??
What do I know!
You're talking about the big flat part with four leads. That's a common part to beef up for larger motors. Since there are four diodes in that part, and they carry all the current for the motors and drop about .7v-.8 v, it can get pretty toasty if you're pulling a few amps! Note that part has a heatsink, even for O-gauge stuff, the FET just sits on the board.
OK then. I forget what it's called!
On the very first G scale Challengers, the board's bridge rectifier and this part were both heat sinked onto the large weight on the frame.
Later it was noticed that the part didn't need the heat sinking. I'm going from memory and as you can see, I can't even remember the part name. So don't take this to the bank!
Joe, the part that is tethered is a diode. An interesting choice, odd that that was a problem part.
If 2 terminals then that's a recirculation diode and undoubtedly of the Schottky ilk. For a G-gauge motor suitable for a Challenger class engine, the winding inductance would be massive (compared to a puny O-gauge engine 
). The intrinsic "body" diode in a FET has ~3 times the voltage drop of a Schottky. Since the motor drive is PWM'd at many kHz, this diode is called into action thousands of times per second recirculating ("unloading" the energy stored in the motor winding) Amps of current.
Meanwhile, back at the ranch. My guess is MTH used a better FET in the PS2-3V motor drive that does not need the heatsink. There would be no reason for MTH or any model train motor drive to use anything other than the standard H-bridge motor configuration. The PS2-3V board has a DPDT relay whilst the PS2-5V board has an SPDT relay. That's why there are 2 FETs vs. 1 FET. In other words the incremental cost of upgrading from an SPDT relay to a DPDT relay must have been less than going from 1 FET to 2 FETs. If they used the 2 FET configuration like the PS2-5V board, they would have needed 2 external diodes to drive a G-gauge Challenger.
I still believe you could get rid of those PS2-5V heatsink strips with a better FET but I suspect when MTH moved from the PS2-5V to PS2-3V design they never looked back!
Thank you again Stan. I struggle to follow along.... but I can reread these posts until I get it!
(at least I don't have to keep asking you to repeat that!) 
Ed Welch posted:So, are some of you suggesting that this engine might not be worth repairing?
...
This is one of those philosophical questions with no definitive answer but plenty of opinions!
I see it as a $1 problem. But that is because I like to mess around at the component-level and my time is "free" as this is a hobby. I suppose it also makes me feel better about those college student loans albeit long-ago paid off last century to become an engineer.
But if messing with electronics is not in your wheelhouse or you choose to spend limited hobby time running vs. repairing trains, then I think it comes down to dollars and cents. Does your LHS give "free" estimates to repair? Or, is it worth time to pack-up and the cost of 2-way shipping ($20 each way?) of an engine to a distant OGR tech only to find it is non-repairable or what have you?
If you search OGR, there have been plenty of threads/opinions about whether it's worth repairing a PS2-5V engine...given that it was the 1st generation of MTH command-control... teething problems and such. But there are plenty of PS2-5V engines alive-and-well generating revenue carrying passengers and freight!
"I struggle to follow along...."
Joe, I hear ya dude. I'm in the same boat with a lot of this electronic stuff but still like to reread it and eventually figure it out (most times). Good thing we have a couple of guys (Stan and GRJ) sport'n the pocket protectors and slide rule on our side or we would still be using candles instead of LED's. 
If I had this engine myself I would test the board. I have that ability. But if the board tested bad I would send it to (GGG). I read over this post a few times and forget some of it. Didn't you had the shell off trying to test the motor. Was the board mounted in the boiler? The instructions Alan posted show a picture of the engine with board in the boiler. If not then you will have to remove the tender shell see it. Look at the board and decide if removing it from the engine is something you can do. Then Contact George (GGG) to see if you can have him test the board. Also see what he wants to put a Proto 32 board in if the 5 volt board cannot be fixed. Then remove the board to send him or send him the engine. If the board can be fixed he is one that can do it. If you do remove the board take lots of pictures. If the board cannot be fixed you need to decide if the cost of upgrade is worth it for this engine It was $399.99 when new. A new Proto 3 Railking Mohawk is only $479.95. Most of the larger retailer sell for less than list price.
Whether you decide on a new one or not that one can be converted to conventional only for a lot less money. No thrills, no sounds just smoke and power.
When I think of buying a new engine a different issue comes up. Since tearing down my layout and moving to a retirement community I mostly take the trains to nursing homes and assisted living facilities. I set up a couple of connecting loops of Lionel Fast track and let the people run the trains. They love it!
The problem is that the PS2 handheld can be a confusing for people with physical or mental limitations. I don't think that a phone app would be any better. But maybe (and I hate to ask this on this forum) the Lionel Chief Plus system would be better for this specific purpose. I have not tried it but the hand held looks like it would be easier to use.
Any comments?
I'm not sure exactly what the LC+ stuff is currently supplied with? But the dedicated Lion Chief or LC Universal (3-engine) remotes are definitely pretty easy to use. Those might just be ideal for your application at the assisted living facilities.
Engineer-Joe and Milwrd,
I've saved many of Stan and GRJ's (and a couple of others) over the last several years. I'm still learning, even from some that are a few years old. I go back and re-read some of them every once in a while. Learn a little here and there and something else finally starts to make sense.
I also struggle to keep up, but I can say that a little more starts making sense all the time, little by little and piece by piece. We are extremely lucky to have these good folks here helping us with the electronics stuff.
Of course, I still have a VERY LONG way to go! (Now, where did I leave those candles...)
If you want me to look at it you can contact via profile email as mentioned. G
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