Atlas SD 35 coupler height

[NtheBasement]

Guys, I appreciate the advice but I'm not going to do anything to jeopardize me returning the loco.  These shells are maybe 1/64 inch thick so a dremel would be fatal.  There is no plug or socket for an E24 decoder.  I do see small differences in this V4 decoder with the one in the Spookshow photo - the large boxy components seem taller as mentioned above.

What gets me is every Atlas loco that I have runs superbly.  What is going on at Atlas that caused them to release a loco that can't even pull a train?

[peteski]

So this is a factory-installed decoder which doesn't allow the shell to sit properly?

I have reviewed both LokSound V4 (part# 73199) and LokSound 5 (part# 58721). Their component layout looks very similar, except that the LokSound 5 has 6 LEDs on the bottom side where V4 only has 2.



I measured the V4 decoder's total thickness to be 0.128" and version 5 is 0.133". That's only 0.005" difference That is just about a thickens of 3 sheets of typing paper. I'm really surprised that the decoders are too thick for this model. While I'm not questioning your experience, I'm surprised that since the coupler sits high enough not to work properly, that not more modelers have mentioned the problem.  I'm also surprised that Atlas sells them in that condition.

[spookshow]

Weird! The decoder installed in your model, and the chassiss itself are identical to the one  in Spookshow's SD35, and he doesn't mention anything about the fit (or coupler height) issue.

I didn't notice any problems with the coupler height, but then again that's not the kind of thing I'd typically spend a lot of time checking. However, I always do a max pull test with as many freight cars as a loco can handle and I didn't encounter any coupler issues there.

But anyway, I've had my eye on one of those Cargill units, so I'll snag one and give it another look.

-Mark

[shawnfinley@att.net]

I had to work the shell on the Cargill 606 SD35 to clear the mylar caps. There is room, but its tedious work that has risk. All good now. Firm report when shell locks down and enough clearance to not lose contact with chassis.

[NtheBasement]

I had to work the shell on the Cargill 606 SD35 to clear the mylar caps. There is room, but its tedious work that has risk. All good now. Firm report when shell locks down and enough clearance to not lose contact with chassis.

Can you describe what you mean by "work the shell"?

Are mylar caps the five rectangular blocks toward the front of the decoder?

What decoder do you have?  Mine is the 23198 in @peteski's photo.

[peteski]

There are no Mylar caps on that decoder, but there are Tantalum caps.  Those are the more or less in the center of the decoder.  They have  "107J" mark on them.  They are the tallest components on that board (total decoder thickness is mentioned in my earlier post). The decoder is LokSound 5 part number 58721.

I'm still surprised  that Atlas sells models where the shell does not fully sit on the chassis causing the couplers to sit high enough to cause problems.

[shawnfinley@att.net]

I stand corrected on the caps. I ended up using a pencil grinder with a Dremel bit similar to an endmill and removing about .020" from the inside roof. I lowered the decoder by removing the insulating panel under it but retaining the portion of it that isolates the contact terminals. That yielded another .030" I contacted Don @ Atlas in June when it arrived about a decoder, he said it takes a 58925 Nano E24. When i asked about a board for that decoder he was confused and asked for pictures. His explanation was China changed the design without telling him. This was a dc sound ready unit. I did a trial fit with a 58721 from a GP20 which worked but discovered the clearance issue. Don had no solution and said I Should return it for a refund. I rolled the dice and after a Kato wheel swap, .030" Fiber optic light pipe from aux1 LED to the nose headlight and the fitting mods it is a runner. I'll try to get some pictures posted

[NtheBasement]

Thanks for the info @shawnfinley@att.net.  Any details on where you ground down the shell?  Did you try removing the black insert from the frame?

I contacted Atlas by website "case", by e-mail and by phone.  Customer service on the phone said they do not accept returns.  I told him I was not the only one with the problem (he knew) and could I exchange it or get a decoder that fits?  He transferred me to a higher up and I left a message.  No response from Atlas for any of that.

If I am stuck with Atlas's mistake I will certainly never buy Atlas again.  @spookshow, might want to update your SD35 description to include this mess.  They are still selling them.

I took the step of removing the molded black spacer under the decoder and covering the frame with Kapton tape, left over from when I converted my old Atlas and Atlas Kato locos to DCC.  This got the coupler down to maybe half way overlapping the gauge coupler, not enough to avoid uncoupling unfortunately.

Any suggestions on how to tell precisely what is hitting the frame where?  That would help.

Trying to figure out my options:
1) Does anyone know of a decoder that will fit, possibly without sound?
2) See if I can get an MTL coupler low enough (I have doubts).  Any suggestions there?
3) There is that black plastic insert in the shell under the cab, see photo above.  This replaces the old U-shaped black plastic bit seen in Spookshow's photo.  For all I know this is what is causing the problem.  Is there a way to remove it?
4) I do have some other SD and GP shells, could try a swap. [ Guests cannot view attachments ]

[jjb62556]

I had a GP40 that the shell was having problems seating. My problem was the decoder was a little too long and was hitting theclear plastic tubes for the ditch lights. I cut the light tubes so they were even with the back cab piece. I also carefully file the end of the decoder on the cab end. That took care of the problem.  Jim

[shawnfinley@att.net]

Yes on the frame insulator removal. I trimmed everything horizontal from it so just the four squares for separating the motor and speaker contacts. I can’t post pics on here yet, I could send some pics of the build through PM?

[peteski]

I don't believe that removing the black plastic frame insulator will do anythign to lower the decoder.  The decoder is floatign over that piece, resting in the slots in the chassis halves.

I suspect that if Atlas would sell you the new PC board with E24 connector without a decoder as I described in https://www.therailwire.net/forum/index.php?topic=58111.msg821900#msg821900 and that there is enough clearance for E24 decoder to fit between the board and the top of the chassis, that might solve the problem.  Just speculating here.  Then you can buy and install one of several E24 decoders (available with or without sound).

As for finding out where to grind inside of the shell to clear those caps, I would put a thin layer of some sort of putty (I use modeling clay) in the top of the shell in the general area of where the caps will be . Then cover the clay with a piece of cling wrap. Place the chassi iini the shell as far as it will go, then pull it out. The caps will leave impression in the clay exactly where they are located and the cling wrap prevents the clay from sticking to the decoder.  I use this trick frequently to find out the clearances inside model shells.

[shawnfinley@att.net]

That version 2 board @peteski  posted with the E24 connector would solve the problem, I found that info from your research of these locomotive decoders Invaluable, Thank you for the work. I forwarded a link to Atlas asking about that board and the answer was they had no way of knowing what it was without part # and suggested I ask for a refund. Another great Idea with modeling clay. You are correct on the insulator being minimal, but i was looking for a few .000" without going through the roof.

[NtheBasement]

@peteski mentions in https://www.therailwire.net/forum/index.php?topic=58111.msg821900#msg821900 that a ESU 58721 LokSound 5 Decoder could replace the connector board.  Has anyone tried one of these on an SD 35?  I would not want spend another $100 on one if it won't solve the problem, not feeling so lucky right now.  Seems to me if there was a proven option that Atlas would suggest it.  Then again...

Not sure I understand what is involved in using the connector decoder but has anyone successfully used that option on an SD 35?

[signalmaintainer]

I stand corrected on the caps. I ended up using a pencil grinder with a Dremel bit similar to an endmill and removing about .020" from the inside roof. I lowered the decoder by removing the insulating panel under it but retaining the portion of it that isolates the contact terminals. That yielded another .030" I contacted Don @ Atlas in June when it arrived about a decoder, he said it takes a 58925 Nano E24. When i asked about a board for that decoder he was confused and asked for pictures. His explanation was China changed the design without telling him. This was a dc sound ready unit. I did a trial fit with a 58721 from a GP20 which worked but discovered the clearance issue. Don had no solution and said I Should return it for a refund. I rolled the dice and after a Kato wheel swap, .030" Fiber optic light pipe from aux1 LED to the nose headlight and the fitting mods it is a runner. I'll try to get some pictures posted

You're saying then that this did unit not come with the newest lightboard that has an E24 receptacle? If it didn't and Atlas is saying it's designed for the E24, Atlas owes you the correct lightboard. What went on between Atlas and China re: the design is up to Atlas to make right with the customer.

Based on photo above by @NtheBasement, it's the same basic frame design as the newer GP38/40 and SD-7/9s, which have lightboards equipped with E24 receptacles. The frame isn't designed for the decoder you've selected, although congrats to you for getting it to fit.

I forwarded a link to Atlas asking about that board and the answer was they had no way of knowing what it was without part # and suggested I ask for a refund.

Someone or someones at Atlas cannot look at their own parts catalog or exploded view drawing and help you figure out a part number for their product? Am I understanding that correctly? 

Even if you do give Atlas the correct part number for lightboard with E24 receptacle, you might not receive the correct product. A couple months ago, I contacted Atlas to purchase an E24 lightboard for the SD-9. I took the part number off Atlas's exploded view drawing for the SD-9. What I was sent was the E24 lightboard for the GP38. WTF? My decades-long trust in Atlas (going back to 1970) is eroding and fast.

[signalmaintainer]

@peteski mentions in https://www.therailwire.net/forum/index.php?topic=58111.msg821900#msg821900 that a ESU 58721 LokSound 5 Decoder could replace the connector board.  Has anyone tried one of these on an SD 35?  I would not want spend another $100 on one if it won't solve the problem, not feeling so lucky right now.  Seems to me if there was a proven option that Atlas would suggest it.  Then again...

Not sure I understand what is involved in using the connector decoder but has anyone successfully used that option on an SD 35?

Essentially the same as every other E24 receptacle. Carefully push the decoder into the receptacle. The board and decoder must be almost perfectly parallel to each other. You can't "rock" the decoder into the receptacle.

After the decoder's in place, I apply two wraps of Kapton tape around the receptacle area to help keep the decoder in place. You could use heat-shrink as well; I did at first, but didn't like the bulkiness. Don't trust the friction alone of the receptacle to keep the E24-type decoder in place. As a safeguard, I also apply Kapton tape atop the frame underneath the decoder.

ESU, Zimo and Digitrax make silent and sound E24 decoders for newer Atlas and Scale Trains locomotives. There may be others I'm not aware of.