Circuit board changes in AZL

grymg Feb 13, 2020 at 4:59 PM

  1. grymg

    grymg TrainBoard Member

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    I recently got a discontinued BNSF GP38-2. In comparison to the one I just bought last year, the older one has a bright white LED and also the speed control is faster on the bottom end. Whereas the newer one has a soft white LED and takes more voltage to match the same speeds. So did AZL make running changes to their boards out of a response to some issue or did the seller change the board out to an aftermarket one? Could I have gotten one with a DCC board? I did notice the electrical isolator tape from the motor tabs to the chassis.
    IMG_0424.jpg
     
  2. markm

    markm TrainBoard Supporter

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    As I understand it, AZL changed manufacturers after the first run. An image or two would help, but a DCC board will have a CPU chip on it and looks something like one of these:

    DCC cropped.jpg
     
    eXact Modellbau likes this.
  3. SJ Z-man

    SJ Z-man TrainBoard Member

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    Don’t remember. Some locos came with ‘orange’ LED’ on-board, some on extended leads. But for running, has nothing to do with the boards. The slower one could be as Mark mentions, a DCC version (note the large square chip) but the DCC decoders that Z used don’t run on DC mode (they can but the common practice for the ~10 years, the manufacturers have pre-set them to ‘no’).

    I suspect it is more of an ‘tighter’ chassis/truck, causing enough friction that needs to be overcome.

    The shells and trucks are all the same. But there were 2 runs of the chassis. The earlier run with the embrittlement and the second with the proper metal casting.
     
  4. grymg

    grymg TrainBoard Member

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    Interesting about the "tighter" chassis theory. The one I bought brand new is slower. Weird that it came out of the factory screwed on tight. I'll check it next time I have a chance.
     
  5. markm

    markm TrainBoard Supporter

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    I didn't comment on the speed differences as you didn't mention the amount. I measure the performance of all the locomotives I acquire and I typically see 10% variation between units and expect it. I do agree with Jeff that an almost imperceptible change in the chassis screw tension can make a big difference in performance.

    Having been a manufacturing guy, I will point out that there are acceptable manufacturing tolerances and in the case of injection plastic, dimensions may increase by a couple of mils over the life of the mold. So the gearing in a brand new unit may be just a hair (actually more like 1/4 of a hair) larger and you may not be able to get the units to run exactly the same.

    Mark
     
  6. shamoo737

    shamoo737 Staff Member TrainBoard Supporter

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    There’s two runs of GP38. The first version doesn’t run as well compare to the second run. I can’t put my finger why, but there’s a significant difference between the two runs.
     
  7. grymg

    grymg TrainBoard Member

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    OK well the board is just a regular board as we all thought.
    My conclusion is that they both perform pretty much the same, but the new one is quieter and feels like it is geared lower (I know it actually isn't, so probably due to differences in tolerances and also chassis/truck tightness).
    Working on the AZL to dismantle it makes me not want to do it again. The parts flying everywhere after prying the halves open. Had trouble making motor contact with the board a few times before i wised up and bent the tabs. And me mucking up one of the voltage pickup strips during the truck reinsertion, had to bend it back again.
     
  8. husafreak

    husafreak TrainBoard Member

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    “Parts flying everywhere” yikes!
    Does anyone have pictures or a video of an AZL loco completely opened (split)? I have a pair of ES44AC’s that ran the same speed (easily within 5%) before I monkeyed around a great deal with one trying to get it to run smoothly after DCC conversion, now it requires over 50% more power to reach the same speed. So I want to open it up and see if there’s a restriction or somehow play with it’s tolerances and get it back to normal. Without parts flying everywhere!
     
  9. grymg

    grymg TrainBoard Member

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    "parts flying"
    yup, it's usually operations 1) when you finally get the last part of the shell off, the chassis drops to the table due to the shell springing off the notch, and 2) trying to pry apart the chassis halves after you remove the screws.

    But seriously opening up the GP is not too bad. The downside is the size. N scale is a breeze compared to this. Make sure the two black motor retaining brackets are installed correctly, they are keyed to fit. Also make sure the square shaped bushings on each worm gear are installed in the correct orientations - should be tapered to the worm in order to fit nicely back into the chassis. The drive axles need to be fully inserted in the motor cups. Upon installation of the board I had to bend the motor tabs forward a bit to get good contact with the board.

    Try all of this w/o tweezers or a loupe and you will feel my pain...

    I opened up my newer loco and unscrewed the chassis halves a hair but no difference in performance. So it has to be binding somewhere else which I don't have the patience to hunt for =)

    Or maybe because it's new it takes a while to break in? I probably have an hour run time on it though.
     
  10. markm

    markm TrainBoard Supporter

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    Probably my only real complaint about AZL locomotives is that they don't come with instructions. Not a big deal for those of us who first experienced the "parts flying" situation sometime late in the Reagan administration, but for people new to Z or model railroading in general, it's can be really discouraging.

    Early on they published exploded diagrams for the first GP7 and RDC releases, but I'm not sure how much that helps. I spent half a day reassembling my first RDC getting the drive shaft, drive sockets, body slots and truck tabs just right. It was a hands-on learning experience. MTL provides instructions for their locomotives, yet people will reassemble them and find that they run backwards.

    The husafreak's idea of some videos is a good idea. I'm aware of such videos in other scales, but nothing in Z. Perhaps something some of us should discuss. I like to work under a digital microscope and it wouldn't be hard to press the record button. But I don't know how to convey: "...feels right."

    There is a great deal of information on line. The search can be challenging as frequently the real gems of information can be hidden in an unlikely place. Both this forum and the AZL site are good sources, but a number of retail sites such as ZSM have information. Märklin has information on joint project locomotives. Ztrack can be another good source, particularly in recent years. When you find good information, SAVE it. Links break and websites change or disappear. I send useful information to a OneNote notebook.

    A couple of practical notes:

    Always run a locomotive through a "burn-in" cycle before judging them. I run forward and reverse at 100% and 50% throttle clockwise and CCW on a oval for about a half hour total before I judge them. Sometimes it makes a big difference, sometimes nothing at all. As I have said, 10% speed variation is not unusual between locomotives.

    I like to work on a white flannel sheet: parts stay put and are easier to find. Don't work on carpet. Have a good set of fine screwdrivers and multiple normally open and normally closed fine point tweezers. It's good to have a cradle to hold the locomotive. I have a soft foam one. I don't know if they are still available, but if not there is soft shipping foam sheets scored on 1" grid that works well.


    Mark
     
  11. husafreak

    husafreak TrainBoard Member

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    Always happy to have your advice Mark, and “grymg” , at least there are no springs in there!
    I got quite good at restoring Marklin loco’s last year. Of course my indoctrination into Z and trains in general was buying a bunch of older Marklin’s! But I enjoyed the challenge. I cut a foam block for support and got some magnifying goggles so I have good equipment. If I ever get to spend some time at home I’ll see what I can accomplish. But I really want to have these running by the Pleasanton show. Smooth running DCC consists of AZL locos blew me away last year and that’s been a goal of mine since.
     
    bostonjim likes this.
  12. husafreak

    husafreak TrainBoard Member

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    On topic I emailed AZL earlier this year and received a reply right away so maybe you could ask them?
     

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