tach tape fix for slow engine

Hey Joe:

I have an MTH UP AC-6000 20-2511-1 circa 2004 from the MTH 2004 Vol.2 catalog. I was searching the board for a possible solution and found myself reading your post on your G Scale F7 that was a slow mover. Funny sometimes but not always when you find someone on the board with your same problem there are not many responses. My AC6000 has the same symptoms. I have a pretty good amount of MTH engines and this is the only one with this problem. The situation is so similar to yours I had to message you to see if your solution worked. Love this engine love the sounds but I was forced to leave it by itself like yours and eventually it just became a shelf queen. Under the hood everything looks fine, its lubed, oiled, good traction tires, motor wires to motors are great, just runs slow. Needs a high setting to run the proper speed. At 40mph on the DCS remote it moves like 25 compared to my other engines. I too purchased this engine off of eBay a while back. From your experience, did your solution of new tach tape help? What exactly did you do? Where did you download the tach tape? What orientations in the spaces on the tach tape achieve different variations in speed? Closer or furthur apart? What kind of avery label did you use? 

EDIT: Listen, I am not a MTH tech. So others here could help out better. I have bought many used engines and some had issues. So I learned to go inside and fix them. That's not a job for everyone to do. MTH engines running slow is not normal. Usually there's something causing this...

 I forgot about this one and have always kept it running alone. I don't remember trying it with a consist of engines much after I fixed it? Just a single test that showed it ran at the correct speed after replacing the tape.  So I'll have to re-test it and make sure it works correctly still. I believe the reader was having trouble with seeing the stripes by what I posted. I just don't remember!  

 I can also report that I had another slow engine. I got that one bought used as well. It cured itself after a month of use. I always re-lube them and I could only guess that it had sat too long as the owner was sick and later passed. I remember taking her apart and everything looked good. Usually it's either too big of tach spacing for me, or grease on the gears that has hardened. I think MTH has used a thinner grease over the years and that cured that issue.

 I had an idea that sometimes the reader doesn't see the stripes accurately for whatever reason. Maybe they're weaker or just get some film on them? Usually they've run too fast when the spacing is too much. I'm guessing that the board gets fooled and can adjust the speed either way?

 I would first put the frame on a set of rollers or even just jack it up with wires attached. Simply try and adjust the gap of the tach (push it slightly closer) and see if anything changes. Most of the time the gap needs to be made slightly smaller in my instances. If you block the reader with a card, the engine should accelerate rapidly. Make sure the stripes are clean and you could go over them with a sharpie. I've had the sharpie fix some stripes on a flywheel that were being missed by the tach. Just draw a straight line with the sharpie. I doesn't have to do the whole stripe perfectly. I think it just makes it clearer for the tach to see.

 I printed my own tapes on Avery labels. If you add stripes the engine will run slower. So you would need to remove some stripes to trick it to run faster. Be careful as there are limits to what the tach reader can see. Because yours is so far off, I would bet the reader is not counting the stripes correctly.There was a post here on the forum with a sample tach tape that I copied and kept re-sizing. I bet you could just scan the MTH tach tapes and re-size them. I mainly print them for converting other brands. I don't think you need this for your engine running that slow. I bet it's not seeing them correctly.

 I just remembered that I had an AC6000 that had an issue. The lights above the cab are on a metal stand. When the shell is attached the wires can get crushed. That can cause a short to the chassis.

 If the board is being drawn down by an intermittent short, maybe that could cause it to stumble or run slow? I'm not sure??

Hey Joe

Thanks for the response. I'll try all of your suggestions and hopefully it works out. I did clean out all of the old MTH grease and put some new grease in the gears and separated the motors from the trucks and did the same. Seems to be running a little bit better. I'll take a really good look at the tach tape and try and tweak a few things. I understand that ur not a tech but appreciate the advice. And yes ur right it's rare for an MTH to run slow. Always good to compare notes with someone with the same issue.