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Problems with Tamiya Finespec FM transmitter/receiver

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Hi,

I received a brand new Tamiya FineSpec FM trasmitter with TRU-05 receiver yesterday.

This has been pulled from a TT-01 Type-E XB set.

Transmitter and receiver look perfectly fine and new, with no marks. The tape was even still on the battery door of the transmitter.

However, I cannot get these to work. I've hooked up the receiver with a battery pack with 4 fresh batteries and put 8 fresh batteries in the transmitter. I use Panasonic Eneloop rechargables, and have verified that they're all fully charged. They're brand new and I just charged them. They work perfectly fine in an AM set I also received yesterday.

I've tried connecting one or two servos of various brands to the receiver. I know that everything is connected correctly, because I've used Futaba-type connectors with the little guide tabs still on them to verify orientation. The battery pack has the tab.

When I turn the system on (transmitter first) I only get interference type twitching from the servos. I have no control at all when I use the transmitter. However, if I wave the transmitter a bit, I get more interference.

Both transmitter and receiver use the red channel 2 (27.045 MHz) crystals that came with the set. I've tried reseating both to ensure a good connection and antennas are fully extended of course.

I've never had a FM radio system before. I'm leaning towards calling this a dud and returning it to the seller, but before I do I'd like to know if there are some more things I should try with an FM system before giving up on it.

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You could try taking it out side to the middle of nowhere and try it. I tried to set a set up in my kitchen once and almost wrote if off as faulty because of all the interference from my mobile phone that was sat close.

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You could try taking it out side to the middle of nowhere and try it. I tried to set a set up in my kitchen once and almost wrote if off as faulty because of all the interference from my mobile phone that was sat close.

Thanks,

I'll try taking it outside with no phone or electrics nearby.

I tried it in my office-area where I test my AM radios as well. AM radios work fine. Is FM more susceptible to certain kinds of radio interference?

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Are the crystals plugged in to the correct devices?

I mean, there is a TX crystal and an RX crystal. Usually (but not always) they are labeled as such on each crystal.

I've heard that things do not work if they are plugged in backwards (never tried this myself so have no idea what happens).

Could also be a bad crystal or broken antenna or any number of things.

If you turn on the receiver only (no transmitter), do the servos still twitch? They should not. If they do, it's likely a problem with the receiver.

FM is generally less susceptible to interference than AM, which is why plane pilots were the first to switch back in the day.

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Thanks for the calrifications Champ85.

The crystals came with the set and the set is brand new. The crystal in the transmitter sits in a little plastic holder that fits perfectly in the transmitter, and the receiver has a slot for the crystal that is too small for this holder. The receiver crystal says "Rx" on it, so that confirms it further.

There is no twitching when the transmitter is off and receiver on. The only thing that happens is the usual centering of the servos when I turn on the receiver. There isn't always any twitching when I turn the transmitter on either.

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Well, that's all I had. On the surface everything appears OK, but obviously something is very wrong.

Could be a bad crystal in the transmitter. Could be a bad transmitter (any number of things could be wrong including bad connection between control and signal generation circuitry, bad amplifier, a disconnected antenna wire, or who knows what).

Could be a bad receiver or receiver crystal, too, although it appears to "act" normally alone. Introducing the transmitter into the mix is when the trouble starts.

At this point you'd need to diagnose the issue using a multimeter and scope to see where the fault lies or find a second identical radio system (and swap crystals around) and play around to find the problem.

If you are adventurous, you could try opening the transmitter case and poking around to see if there are any obvious problems like a crushed/broken wire, disconnected circuit board connector going between modules, etc.

Barring that, best to return to seller if possible as "defective" before time runs out to do it. You've done all of the reasonable things to verify operation and find the fault, if any. The set just doesn't work.

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Thanks Champ85,

I've contacted the seller, who has asked me to contact Tamiya so I've done that as well.

I really want to add a Finespec FM system to my collection at some point, so it would always be useful to have an extra crystal set even if I return this one.

I'm trying to find a compatible crystal set. I understand that I can use a Futaba crystal set, but they come in short and long versions. Which one should I get? The receiver crystal is the same size as a modern (Futaba 2DR) AM crystal.

(The crystal body is about 11 mm tall)

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And the Tamiya USA contact email I found on Tamiya.com bounces. I cannot find a way to contact Tamiya USA support directly.

Does anybody know?

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Have you tried the contact options on tamiyausa.com yet?

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Have you tried the contact options on tamiyausa.com yet?

Thanks, yes I did, but I had to have a US address as they would only support US customers.

I borrowed a US address to complete the form.

The response was quick and all they said was that they recommended I return the unit to the seller since it was a discontinued product and they don't support it any longer.

I'm going to get some HPI crystals that are from a set also made by Futaba and test with those (couldn't get a Futaba set nearby). If it doesn't work the seller has offered a full refund.

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To follow up on this story,

Tamiya sent me a brand new Finespec 2.4GHz system as a replacement via the seller.

I've been able to find another 27 MHz FM system to cross test and it turns out the receiver is the broken part. I've taken it apart, but there are no visible problems, so this is probably a faulty IC.

Now to hunt for another TRU-05 receiver. They don't show up often.

Great support by Tamiya and the ebay seller coldbeerhobbies in the end :)

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Thanks for the update. That's good to hear. I've bought parts from CBH a few times and had good transactions with him, so it's good to know he worked with Tamiya and you to rectify the problem.

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