What you're describing is one of several types of "security" screw heads, designed to keep the "unauthorized" out of the box. That's so you go to the mfr. for service, and don't do something dangerous yourself, that you can sue them for.
Your local hardware store that has a good tool selection should have cordless screwdriver nut and screw driver bits that fit the variety you have. You may have to buy a six to eight piece assortment to get the one size you need.
Alternative: use an external double pole, double throw switch to change polarity. Inputs connect to left end; Outputs connect to the center pins. The end connectors are connected diagonally: upper left to lower right, and lower left to upper right.
+ input-------------O upper left center (output) O upper right
- input--------------O lower left center (output) O lower right
Drosman,
I took a small Sears Craftsman flathead screwdriver and filed the outside edges down ~1/16" so that the middle third protrude above the edges. It fit right into the slot in the top of the tamper-proof screws and I was able to open and reassemble the 1370 enclosure with no problem.
Like you, Drosman, I went with the Bachmann E-Z Command for a year before going ugrading to NCE Power Cab. Since I only paid $53 originally for my E-Z Command new and was able to sell it later to recoup some of that cost, I considered it a worthwhile ~$25 investment for trying out and learning about DCC to see if I wanted to pursue it further. Boy! - I'm glad I did...
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
Yes, those little things are a pain. One of the MRC 6200's I use had a loose part rattling around inside when it came in after being purchased on ebay. Before returning it I decided to open it up and take a look. The only problem with that was the "security" screws holding the unit together. I opened it with a pair of needle nose pliers and some spare time. After I got it open though I discovered that the rattling was just a loose screw. After tightening that screw, I decided to make it easier to open the transformer up if it ever needs it again. So I mounted each of the screws in a hobby vise and cut a notch in them with a Dremel tool and cut off disk (Warning these get HOT, don't use a vise with a rubber protector or you'll melt it like I did). The notch is strangely enough the perfect size for a flat head screwdriver.... MRC might not like it but it's cheaper then returning it to them to have a screw tightened.
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You will be able to find a bit for them, but as said you might have to buy a small kit with multiple pieces. Years ago, I think it was christmas, my parents got me a nice little Craftsman bit set, either 100 or 110 pieces. It was the kind that slips into changable screw drivers or electric drivers, had every bit possible up to the time. It had what you are looking for, had the 6 blade star bits with the pit in the middle. Ever see the screws with the slot that looks like a bow tie?? Had that bit too. Now the bad part of story, that piece set has been missing for years. When I first moved to the city I live in now I worked at a junk yard. Everything was fine untill after I left that job and realized I had less tools than when I started working there. I know I lost while scrapping vehicles but not half my tools! Needless to say I finally figured out the little punk rat that worked there and everyone hated was probably stealing them. Probably even had them sitting in the pile of junk he had that he was stealing from the junk yard. I almost got fired because suddenly one day a stereo went missing from the inventory and it just happened to be the less fancy model of the stereo I happened to have in my car. Short story shorter, I had to call my dad so he could go through the last 3 years of reciepts and pray to the all mighty that it was saved (it was), drive 90 minutes back home to get, drive 90 minutes back up here, and then even after having seen the dang reciept for the thing and one of the other workers saying that he's seen my car with that radio since the first day I worked there, I still had to put up with the "co-owners" treating me like I was a petty thief. The actual owner saw the reciept, knew it was real and dropped the hole thing, he had the proof he needed. Hmmm, that was 4 years ago, that little punk should be getting out of jail pretty soon.... Sorry I rambled. I haven't been sleeping well lately again and it doesn't help having to by the wifes alarm clock in the morning. I just couldn't fall back to sleep.
On a side note, and maybe a thought for the OP too since he will have the power pack apart, could momentum control device be made and added to the unit? I was wondering this because I will be using an older Tech II if I go with DC and it doesn't have momentum or braking, but I really think I want it. There wouldn't be much momentum to model with only a max 10 car train but still, I like the added realism.
MILW-RODR On a side note, and maybe a thought for the OP too since he will have the power pack apart, could momentum control device be made and added to the unit? I was wondering this because I will be using an older Tech II if I go with DC and it doesn't have momentum or braking, but I really think I want it. There wouldn't be much momentum to model with only a max 10 car train but still, I like the added realism.
There is precious little commercial new development in the DC world. And MRC was nearly as proprietary about their DC designs as they are with their DCC products. Which means that merging a brake and or momentum into an existing transistor/IC power pack (Tech series) will require some knowledge and ability to reverse engineer the fairly simple existing throttle. The reverse engineering knowledge is needed to know where to hook the momentum and brake circuits into the existing throttle. And is needed to any needed modifications to the existing throttle circuit. You don't have to be a degreed electrical engineer, but you do need the ability to recognize the individual components and the role they play in making the throttle work.
There are circuits readily available for building your own brake and momentum modules to a throttle - but you can't buy a commercial unit to stick in a commercial power pack. And compatibility between the circuits is key - where the limited reverse engineering comes in.
A much easier approach is to build your own throttle, with the desired features, from a published circuit. Then use the MRC power pack as a power supply for the home-built throttle. I've done that for a very simple hand-held transistor throttle that ties to the AC terminals of an otherwise broken AHM train set pwoer pack. Pictures to follow when I can get Kalmbach to fix my screen name so I can post from home.
Since you are simulating momentum electronically, adjustment of the amount of momentum is a feature of most momentum circuits - and certainly is desirable.
my thoughts, your choices
Fred W