geneb
08-06-2011, 01:58 PM
All the reviews I see on flight control hardware goes on and on about how the product is used and they don't tell you squat about what the guts look like on the inside. For cockpit builders as a group, a product hackability is more important than just about any other feature.
When I got my Saitek TPM module (Throttle/Pitch/Mixture) in, the first thing I did after I tested it was to tear it apart. :)
Remember kids, warranties are there to be voided and screws are there to be removed! :D
The individual linear controls are made from extruded aluminum bar. They have a 1/8" or so channel machined along their length were a rack gear is installed. This rack engages a shaft that both connects to the "regulator" mechanism as well as to the potentiometer that provides the actual input. There's a pin set in the aft end of the control rod that limits its forward travel (about 3").
The "regulator" is a device that limits the rate at which the control can be manipulated - it's very similar in design to the higher quality CD & tape deck door mechs that limit the speed at which the door opens. This provides a non-adjustable, realistic force to the linear controls - the only thing that would improve these is if they were true turnable vernier controls like you'd find in the real aircraft.
The knobs are plastic, but don't "ring hollow" - they're very solid feeling. The bulkhead mounting nuts are just there for show - they're cast into the body shell of the TPM module itself. This to be expected and presents a cost saving measure. I may mask & paint mine with some silver or chrome paint to improve the look.
The linear mechanisms are self-contained units that attach to the front body shell of the TPM with a few screws. This lends them to being pulled and mounted in a different chassis. Good call on Saitek's part I think. While pots are used, they're three wire devices which makes them voltage dividers and more accurate than the old two-wire "timed decay" method used in cheaper devices. Because of the actual duty cycle these are expected to deal with, a pot is a perfectly acceptable choice - they won't experience the wear that a rudder pedal or flight stick mechanism will. The gear trains are well (but not over) lubricated - this will help prevent excessive wear on the gears - which are all nylon and not ABS as I'd originally suspected.
The interesting thing I noted about the way it was designed is that it appeared that the engineer responsible knew that someone was going to want to tear it down - There are no sonic welded or glued parts that I could see - it's possible to completely disassemble the whole TPM just by removing screws or removing pins (you'll have to carefully drift the pins out, but it's possible). This means that as long as Saitek is willing to provide parts, you'll be able to repair any issue found with the unit.
The only problem I found with the TPM is the 9 switches that it has. The vertical spacing is ok, but the horizontal spacing is way too close. Well if you're over 8 years old anyway. :)
The switches are mounted on the main logic board. While the bat handles on the toggles are "full" sized, the actual toggle switch is using a "micro" body. If you wanted to move the switches to another panel, it's going to be really simple. I'd recommend desoldering the switch from the board and replacing the switch with either a 3 pin header (the spacing looks to be compatible with .100 pin spacing) or a 3 wire female servo lead which would be a better choice if in fact the spacing isn't .100.
If you're going to use the TPM in your GA cockpit, I would recommend thinking seriously about moving the guts to a new box - primarily to get the switches out of the box and moved elsewhere. If you do that, I'd recommend adding connectors to the pot leads so as to make it easier to move the main logic board around without stressing those - by installing either servo leads or 3 pin headers on the logic board (just like with the switches), you'll be able to move things around easily - you can also extend the leads if you need to.
I've taken a series of pictures that show the interior and how the unit is built.
If you remove the "-sm" suffix from the picture filename, you can view the full 3000x2008 resolution of the original picture.
Thanks all!
g.
http://www.geneb.org/tpm/tpm-1-sm.jpg
http://www.geneb.org/tpm/tpm-2-sm.jpg
http://www.geneb.org/tpm/tpm-3-sm.jpg
http://www.geneb.org/tpm/tpm-4-sm.jpg
http://www.geneb.org/tpm/tpm-5-sm.jpg
http://www.geneb.org/tpm/tpm-6-sm.jpg
http://www.geneb.org/tpm/tpm-7-sm.jpg
http://www.geneb.org/tpm/tpm-8-sm.jpg
http://www.geneb.org/tpm/tpm-9-sm.jpg
http://www.geneb.org/tpm/tpm-10-sm.jpg
When I got my Saitek TPM module (Throttle/Pitch/Mixture) in, the first thing I did after I tested it was to tear it apart. :)
Remember kids, warranties are there to be voided and screws are there to be removed! :D
The individual linear controls are made from extruded aluminum bar. They have a 1/8" or so channel machined along their length were a rack gear is installed. This rack engages a shaft that both connects to the "regulator" mechanism as well as to the potentiometer that provides the actual input. There's a pin set in the aft end of the control rod that limits its forward travel (about 3").
The "regulator" is a device that limits the rate at which the control can be manipulated - it's very similar in design to the higher quality CD & tape deck door mechs that limit the speed at which the door opens. This provides a non-adjustable, realistic force to the linear controls - the only thing that would improve these is if they were true turnable vernier controls like you'd find in the real aircraft.
The knobs are plastic, but don't "ring hollow" - they're very solid feeling. The bulkhead mounting nuts are just there for show - they're cast into the body shell of the TPM module itself. This to be expected and presents a cost saving measure. I may mask & paint mine with some silver or chrome paint to improve the look.
The linear mechanisms are self-contained units that attach to the front body shell of the TPM with a few screws. This lends them to being pulled and mounted in a different chassis. Good call on Saitek's part I think. While pots are used, they're three wire devices which makes them voltage dividers and more accurate than the old two-wire "timed decay" method used in cheaper devices. Because of the actual duty cycle these are expected to deal with, a pot is a perfectly acceptable choice - they won't experience the wear that a rudder pedal or flight stick mechanism will. The gear trains are well (but not over) lubricated - this will help prevent excessive wear on the gears - which are all nylon and not ABS as I'd originally suspected.
The interesting thing I noted about the way it was designed is that it appeared that the engineer responsible knew that someone was going to want to tear it down - There are no sonic welded or glued parts that I could see - it's possible to completely disassemble the whole TPM just by removing screws or removing pins (you'll have to carefully drift the pins out, but it's possible). This means that as long as Saitek is willing to provide parts, you'll be able to repair any issue found with the unit.
The only problem I found with the TPM is the 9 switches that it has. The vertical spacing is ok, but the horizontal spacing is way too close. Well if you're over 8 years old anyway. :)
The switches are mounted on the main logic board. While the bat handles on the toggles are "full" sized, the actual toggle switch is using a "micro" body. If you wanted to move the switches to another panel, it's going to be really simple. I'd recommend desoldering the switch from the board and replacing the switch with either a 3 pin header (the spacing looks to be compatible with .100 pin spacing) or a 3 wire female servo lead which would be a better choice if in fact the spacing isn't .100.
If you're going to use the TPM in your GA cockpit, I would recommend thinking seriously about moving the guts to a new box - primarily to get the switches out of the box and moved elsewhere. If you do that, I'd recommend adding connectors to the pot leads so as to make it easier to move the main logic board around without stressing those - by installing either servo leads or 3 pin headers on the logic board (just like with the switches), you'll be able to move things around easily - you can also extend the leads if you need to.
I've taken a series of pictures that show the interior and how the unit is built.
If you remove the "-sm" suffix from the picture filename, you can view the full 3000x2008 resolution of the original picture.
Thanks all!
g.
http://www.geneb.org/tpm/tpm-1-sm.jpg
http://www.geneb.org/tpm/tpm-2-sm.jpg
http://www.geneb.org/tpm/tpm-3-sm.jpg
http://www.geneb.org/tpm/tpm-4-sm.jpg
http://www.geneb.org/tpm/tpm-5-sm.jpg
http://www.geneb.org/tpm/tpm-6-sm.jpg
http://www.geneb.org/tpm/tpm-7-sm.jpg
http://www.geneb.org/tpm/tpm-8-sm.jpg
http://www.geneb.org/tpm/tpm-9-sm.jpg
http://www.geneb.org/tpm/tpm-10-sm.jpg