Herr Doc's Famo

[Meter rat]

Are Famo’s smaller than the 18t half track, or the same thing? The official line was that two 18t half tracks were required to pull a Tiger.

[Herr Dr. Professor]

"You know static Famos are cool too." Oh, Eric, this has crossed my mind, especially when I am feeling cross about the strange electronic phenomena (which did not happen with the first SGS Module) and the incessant track problems. However, I have not given up yet. I have more ideas to try. When I get really frustrated, I'll jump back to my T26E3 D-Day Build, for which more needed supplies arrived yesterday amid a bit of snow.

Meter rat: The "FAMO" (Fahrzeug- und Motoren-Werke of Breslau, a division of Junkers) is the common name for the 18 ton SdKfz. 9 (Sonderkraft Fahrzeug: Special Purpose Vehicle) the largest WWII German half track. (There were SdKfz. 2, 10, 11, 6, 7, 8, and 9.) While the less monstrous half tracks were often put to personnel transport as well as general step-and-fetch-it duty, the FAMO was for big jobs. Here's one source that explains and compares:

Ranger, Alan. Sd.Kfz. 8 & Sd.Kfz. 9: Schwerer Zugkraftwagen (12t & 18T). Camera On 11. Wydawnictwo Stratus/MMP, 2019. ISBN 978-83-65281-88-3/

[Herr Dr. Professor]

On October 24 (page 9 of this long build thread), I reported that the SGS MFU I had installed and was using in the FAMO before going to Scotland inexplicably would not function at all upon my return. I tried various tricks about which you can read above if you are that patient and interested. Nothing worked. Because others had recommended and had success with this brand MFU for the FAMO with its coordinated ("mixed") steering, I order another SGS MFU. (I live alone, so I can eat cheap.)

On January 10 (previous page), I reported that the second SGS MFU was exhibiting "some strange behavior. When I turn the steering servo, the sound quits, to start up readily with a slight touch on the throttle." That malfunction was occurring with the Smart Flex TX and RX I was using. Since I am relatively inexperience with RC electronics, I decided to test the MFU and myself.

To test the MFU, I rebound the Smart Flex TX and RX, only to find the exact same malfunction. Then I bound my Flysky IA6X TX and FS IA6B RX and hooked these up to the SGS MFU. The same malfunction again.

To test myself, I tried my WCP Jeep, which I had set up to run with the Flysky TX. The Jeep ran fine. In fact, I fine tuned the steering servo center and throw and adjusted the throttle curve to get the best driving I could achieve.

Then I went back to the FAMO: not surprisingly, the same malfunction continued to occur and even worsened: when I turn the steering servo, the sound and the motors quit, while the light switch still functioned readily and the horn honked (sans engine sound). So I did a "factory reset." Terminology is tricky: for the MTH DCS and Lionel Legacy train electronics I have used for years, a "factory reset" resets a specified train engine's various functions to the way they were set at the factory. On the Flysky TX, a "factory reset" resets the whole TX to out-of-the-box configuration, wiping out all the models names, settings---all of it: blooie! What I wanted was "model reset." So I got even more practice as I again set up all the parameters for the Jeep. Yes, and I had more fun running the little Jeep around the modeling area.

I have now removed the SGS module from the FAMO, and soon I hope to have time to install and try to work on the original MFU that came with the FAMO from Asiatam. "Why," you might reasonably ask, "did you not do so months and months ago?" Well, others recommended the SGS module as being even better for the FAMO.

[tankme]

So are you saying the replacement SGS module is now working in the FAMO after the factory reset and you are going to put the original in for testing to see if the factory reset fixed it?

Sorry...confused...

[Herr Dr. Professor]

Alas, neither SGS MFU works. The first quit working at all.
From outset, the second one would shut down every time I turned the steering servo.
In fact, in the long post above, I didn’t even cover all the fixes and adjustments I have tried.

[tankme]

How big is the servo? I know the servo isn't as big as a 1/4 scale I used in one of my 1/6th scale tanks, but you know you can power the servo from an external source and just connect the signal line to the card. I had to externally power those big servos. Sounds like that servo may be drawing too much power from the board? A BEC circuit could provide power to the servo. Something like this might work and it's small:

https://www.amazon.com/SoloGood-UBEC-5V ... tdGY&psc=1

[Herr Dr. Professor]

I am grateful for and impressed by your suggestion, tankme. It makes good sense. I had been wondering the same, but in a less sophisticated way. When I ordered the first SGS MFU, the seller asked me for the specific application and indicated the board specifically for the FAMO (for a photo of the board, see viewtopic.php?f=81&t=33401&p=333076#p333076). The steering servo is a "standard" size, larger than the "micro" servos we more typically use for such tight spaces as barrel lift or recoil. The frame rails of the Asiatam FAMO readily fit the somewhat larger servo (you can see a photo at viewtopic.php?t=33379&start=20), and photos of other Asiatam FAMOs show the same "standard" sized servo. Nonetheless, I had wondered if the servo were hitting the full extent of the steering and then drawing high current. I quickly found that the sound and motors cut out as soon as I started to move the servo one way or another, short of the full "lock" of the steering. Nonetheless, I used the Flysky TX to set limits on the steering servo travel both directions.

For anyone who hasn't yet given up on following this build: I am setting the FAMO aside for a while lest I "burn out" on it and give up or do what in static modeling is called a "wall chuck." I have my Pershing to work on for a while. I also have another idea for electronics in the FAMO which I want to investigate a bit now. I will get back to you about just how to rig "power the servo from an external source and just connect the signal line to the card." :think"

[Herr Dr. Professor]

By the way: I have been for a few years looking at comments about others FAMOs, mostly in Germany. The variety of electronics runs from IBU to Open Panzer to Elmod to SGS. No one seems to use the Asiatam electronics provided and I can see why: they are apparently not at all specific to the FAMO, what little and grossly inadequate instructions I found are for adding them to a HengLong or Taigen or another Asiatam board not included when I asked for complete electronics (viewtopic.php?t=33379), there is no information about whether they can mix track and wheel steering. Then, too, the track and drive sprocket mesh is notoriously bad, a problem I was investigating when the first SGS MFU did its mysterious quit.

[tankme]

Well, I might be joining you in the half-track hell as I ordered one of the kits to convert the Trumpeter 251 to RC. The half-track arrived today, but the electronics and conversion won't be arriving for like a week at least. Not sure where it will fit into the project list...

[Herr Dr. Professor]

Woo Hoo! What are you going to use for electronics? I'm all eyes and ears!