Repairing/Upgrading Proto-1 Boards - New Info and Questions 8-5-15

can you post some pictures of the board in question,I just want to make sure before i suggest how to change the diode

Alan

That is not a spacer that is the Full bridge rectifier.  The first diode to get AC power.

You can heat a the exposed leg to remove the round diode.  Or clip it off since your going to replace them anyway.  You may need to then remove the rectifier to clean the holes for the new diodes.  What are you running that needs 8A for the motors?  G

If you're talking about these diodes, the "heatsink" on the other side is really a bridge rectifier.

I've removed them by desoldering from the top.

Thanks guys. That's extremely helpful. I wasn't sure I could desolder the leads from above and then solder in the new ones the same way. I suppose I could just clip them and solder the new ones to the stubs. Probably easier. I guess I'll remove one and take it with me to the electronics store to make sure I get a proper replacement. 

The installation is a Williams brass N&W J that I put Proto-1 in for a friend. It has a Mabuchi 550 motor and a very big lead weight in the boiler. With the heavy boiler weight and a train behind it, it gets up close to 4 amps, which is the rating of the diodes. You may recall that I posted a while back about the high current draw, and several people advised me to try a new motor. I installed a brand new Mabuchi motor that I got from Weaver and it was still drawing 3 amps plus and the diodes were getting really hot. No evidence of a short of any kind, no excess friction in the drive train, and the board stack came out of an old Weaver engine that had worked perfectly for years, so I figure I may as well just upgrade the diodes and be done with it. Those old QSI-Proto 1 boards were notoriously underpowered, according to Art Boynton, who was the QSI factory service guy. He upgraded a lot of them, including one for our train museum. I should maybe take a look at that one and see if he clipped the leads and soldered to the stubs. 

Glad to know John confirmed what I said, is there an echo in the room....

Interesting you say they are 4 amps.  Once they went to the single diode they used a 6 Amp.   I have that Williams and it used a DRCU.  Surprised it uses 4amps to drive the motor.

The other alternative is to use 2 Bridge rectifiers.  As replacements for the removed diodes.  The wiring is more complex but it is easier to do and you can heatsink those bridges to the chassis.  G

 I didn't see your post when I posted, I must have had it sitting in the editor while you slipped in.

i have been reading on here and i have bought a MTH 30-1151-1.

im trying to find out why a model 30-1151-0 is less expensive new than a 30-1151-1 ? MTH site says either model mentioned above, both have proto 1? how can that be when one is more expensive than the other? maybe the -1 engine is standard proto 1 and the lesser -0 engine is optional?

is it the difference between loco sounds and proto 1?

when i get it im going to look and see if it has a battery, if it does im guessing its a proto-1 engine?

next question.

can i run it like all my other proto 2 engines with the remote? or do i have to adjust the track voltage with the remote?

i would really like to just up grade it so it works just like a proto 2 eninge, then all of mine operate the same, because im going to forget how to operate and also forget to maintain the battery from going dead, maybe i should just take out the battery from the proto 1 and install it when i want to run it?

id really just like to up grade it i guess.

any suggestions?

how much to upgrade it?

i was just on here not long ago trying to get my 611 j class working, it had 2 wires loose in the tender, it still runs good so far.

please let me know

thank you

i guess i just like the smoke chuff to be related to the wheel revolutions and the puffs to increase with the speed.

i also like some of the sounds from proto 2 but dont use them very much, but i do like the DCS remote finding the engine and everything going smoothly.

i also like to use the whistle while its running, and the smoke on or off when i want it to.

i guess im thinking i wont be pleased with proto1?

im learning here guys so i will try to understand it all.

thank you very much.

ron

If you clip the diode leads, as soon as you put the soldering iron on the leads to attach the new diode, the solder on the old leads will soften and the lead stub will be loose.

These are the motor diodes so you really want the stub out before you put the new diode in.  You want a clean hole so you get a solid connection.  The problem is the rectifier covers the hole.

So I would clip with a section of the lead left so that the solder can be melted and the stub removed.   G

Let me be sure I understand what to do next. I can remove the old diodes from the top, in either a one-or two-step process (clip the lead or not), and I need to remove the stub if I clip the leads. I can then solder in the new diode by inserting the lead and applying heat to the the lead from the top, without removing the bridge rectifier from the board. Of course I will cut the lead to length and tin it before soldering it in. Is this correct? I've been assuming I needed to get at the bottom of the board to solder in the new diodes, but now I understand this is not the case and I can do it from above. Correct? Thanks. 

Yes, but I would not tin the diode lead or you may find it is too difficult to get back in the hole.  That is going to be the harder part of this.  The diode leads are thick and not easy to position if the hole is not clean.

Also be careful with the heat, the traces on the QSI/PS-1 boards can be easy to lift up when removing.  G

After a long hiatus to take care of other priorities I got back to working on my friend's Williams engine. To recap briefly: At the request of a friend, I converted an old Williams brass N&W J, which had an old OTT sound system in it, to Proto-1. I used a set of boards that came out of a Weaver John Wilkes and had worked perfectly in that engine for several years. These are the old style Proto-1 boards with a battery switch. The power section overheated badly and one end of one of the diodes popped out of the board. I have no way of knowing if the solder melted from overheating or if the joint was just bad in the first place. The motor was drawing around 4 amps which is a lot for a can motor. 

Several people who posted above suggested there might be something wrong with the motor. It's not easy to find a drop-in replacement motor because the flywheel mounts to a D-section shaft, but I managed to find a replacement Mabuchi motor and found that it drew just as much current as the old one, thereby eliminating the motor as a source of the problem. I also test ran the unit off a bridge rectifier to eliminate anything in the electronics that might be drawing current due to a short, etc. 

I then replaced the 6-amp main power diodes with 10-amp. Still overheated. So I made a heat sink out of 1/4x1/2 aluminum bar stock and drilled some air holes in the tender chassis right under the power diodes. That seems to have helped the heat problem; it still gets pretty hot but I can feel a lot of heat in the sink, indicating that it's doing its job. 

Now it's developed a new trick. It will run for 30 or 40 feet in forward, then lose power and coast to a stop. Sometimes it will pick up again before it stops, but usually I have to cycle the e-unit a couple of times and then it starts forward again. The weird thing is, it only does this in forward. You can run it backwards as long as you want and it keeps going. I did clean the track, rollers and wheels but it is still doing it. I have also repeatedly gone over the engine for any mechanical problems or excessive friction and everything tests out OK. 

I'm thinking I should give up on this reverse board and try another one. I have another PS-1 stack in my junk box that I think is good. Two questions: 

1. Can anyone shed any light on why the engine stops running in forward, but not in reverse?

2. Will the upper (sound) board from the earlier style PS-1 unit work with the later style lower (reverse) board? You will recall that the early style reverse board had the battery switch. That connection is on the lower board, and the old upper will plug into the newer lower, but the two uppers are obviously different and I'd like to be sure the older upper and newer lower are compatible before swapping them. I'd prefer to do it that way because the sound set on the older sound board is a better match to the J. 

Thanks in advance. 

Well, I would still maintain that locomotive should not be drawing anything like 4 amps, so my first step would be to find out what is causing that.  My Vision Line Big Boy with four smoke units and two audio systems running draws around 4 amps underway, that Williams J should be a fraction of that!  I have a number of Williams brass locomotives of similar size, and none draw anything like that.

Your top board will work with a new bottom board.  The bottom board design is consistent with just the upgrade of the automatic battery circuit and improved versions of some of the components and maybe an additional cap or two.

The board can be kicking out on an over heating situation and either the rectifier or one of the diode stops conducting.

The motor drive circuit does split after the rectifier and 2 of the large diodes.  One of the large diodes goes to fwd relay and the other goes to reverse relay.

SO.... maybe a diode or relay for fwd is bad.  Causing the extra current draw and failure in fwd.   HAving said that, if this engine draws more current in fwd with just a rectifier, and less in reverse, you have to have a mechanical issue in fwd.  May not be binding, but increased drag causes by the motor thrust in forward.

I have this engine, and it should not be drawing that amount of current.

Clearly it is if the board is overheating and dropping out a diode.  Swapping boards, and motor have occurred, if you still have issue in fwd it has to be the engine mechanicals.

To resolve the board issue you can reverse the leads to the motor so it starts in reverse, but is being driven by the fwd diode and relay.  IF it now kicks out in reverse, the board has issues.  If it still kicks out in FWD (being driven by the reverse relay) you CONFIRM it is the mechanical.  G

What is the exact model number of the motor you're using?  Is the 4 amps with just the locomotive and tender?  If so, what kind of current does it draw with a decent sized consist?

I have a Williams FEF-3 with the big honkin' Pittman motor, running free on 6 volts it's pulling 1 1/4A, if I hold the wheels and add friction, it can get up to around 2 amps.  I don't know how I'd pull four amps with this locomotive without stalling the motor.

Of course, it could be a meter issue.  What current does a similar engine you have draw with this meter?   If it is meter error, your engine mechanicals may be fine and the issue is the board as I outlined above.  G

For diodes in the same ballpark (i.e., 6A or 10A), running the same 4A of "power draw" thru them generates the same amount of heat.  As I understand it you fabricated a heatsink.  Assuming this is efficiently (thermally) attached to the 6A diodes, it will work as well as the 10A diodes.  Your heatsink is essentially doing the same thing as using the larger packaging of the 10A diodes. You are running the diodes at "only" 3-4A.  Stated differently, you are not using the 10A diodes for their larger current carrying capacity, but for their larger bodies (same as your heatsink).

Sorry, but I still think that 4 amps to the motor is excessive, I'm having trouble moving past that feeling.

It's likely that the -0 model does not have proto one. In the early days you could buy a railking with proto one or with just a whistle and bell. The -0 models just had whistle and bell, while the -1 models had proto sounds, which we now call proto one.

The motor is a Mabuchi RS 550. According to the online spec sheet, it draws 1.4 amps no-load and 10 amps at "most efficient power." I am going to take everything back to the beginning. I'm going to take the locomotive apart, no-load test both the old and new motors running off a straight rectifier, and re-examine the drive train for any sign of excess friction, including the possibility that something is loose and it jams up only when the system is under load. 

Current draw in reverse is similar to what it draws in forward. 

Meter readings are from my Z-4000, which gives normal amperage readings for other locomotives. 

I'll need to stop by the hardware store and pick up a couple of things to make up some test leads, so I'll post again after I've done the above-mentioned tests - probably tomorrow. 

I didn't take my FEF apart, but it has the large Pittman motor that's found in many of these models.  Running on rollers I got the readings I stated, and I believe you should see something similar.  That locomotive isn't any larger than the FEF, and the motors have similar size and ratings.  I put considerable pressure on the wheels to load the motor before I got to 2 amps.  Four amps with no load just seems way out of line, that's the only reason I keep harping on this.

FWIW: I have a Weaver PRR M-1a/b with whatever original motor. It draws about 3 1/2 amps with no train behind it. Was going to go thru all the upgrade stuff until I got my 3rd rail version...

I'd also test the motors with a DC supply and ammeter, you'll get more accurate readings of what it's drawing.  When I tested my FEF, I wired the two outside pins of the tether (motor pins) and connected it to a bench supply for testing.  This gives me an accurate reading of truly what the motor is consuming.

If that motor is truly 1.4amps NL and 10 amps most efficient speed I have no clue what it can be and how it fits inside a 550 frame.  10 amps continuous requires a health wire gauge size.  I believe that chart is in error.  IF you look at the 540, 545, and even 555 which is the same motor just 5 poles vice 3 they are rated at 1/10 of the 550.  Even with the same type designator.  G

Something is not right on the charts.  G