Astro Saber transmitting dead air (Maybe a bad RF board?)

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Tony.RI
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Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Tony.RI »

I seem to have unearthed a problem with my Astro Saber this weekend. It is only transmitting dead air when I PTT. Receive and controls are perfectly fine; only transmit is screwed up. It is the same with both analog and digital. This started out as an intermittent problem this morning, but now I can't get it to work normally at all. (It won't even MDC post-ID, so I doubt it is mic related.)

It is a VHF AS2, 7.08.00/N08.02.02 I have not had this problem anytime before this weekend, and its very disheartening as my AS is one of my favorite HT's. I just checked the interior connectors and I believe it all looks in working order. I did a quick search and couldn't find anything about it here. Does anyone know what may be wrong and how to fix it?

Thank you!
Last edited by Tony.RI on Sun Apr 11, 2010 2:38 pm, edited 1 time in total.
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Tony.RI
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Re: Astro Saber transmitting only dead air

Post by Tony.RI »

Ok, so upon closer inspection there seems to be a blown-out component on the RF board.

Image

Could this be the source of the problem? Can this be fixed or do I need to find a replacement board?
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Code3
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Code3 »

That looks like the laser trimmed microstrip for tuning the VCO at the factory. I don't think that is the source of your problems. Have you reseated the VOCON to the RF board, and given it another try?
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alex
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by alex »

I'd try another front shield as well.... Maybe you just have a bad microphone. Do you get audio when using a speaker mic?

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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by escomm »

alex wrote:I'd try another front shield as well.... Maybe you just have a bad microphone. Do you get audio when using a speaker mic?

-Alex
How would a bad mic preclude the MDC post from being sent?
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by alex »

escomm wrote:
alex wrote:I'd try another front shield as well.... Maybe you just have a bad microphone. Do you get audio when using a speaker mic?

-Alex
How would a bad mic preclude the MDC post from being sent?
Damn. I should stop replying to posts before my coffee... Thanks Jeff.
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Tony.RI »

Thank you for the replies! So, that component is supposed to look burnt?

I've opened the radio and reseated all the boards and all that did was make a mostly intermittent problem now a continual problem. I'm at a loss as to what may be wrong, though the evidence makes me think the RF board and VOCON aren't talking properly. (There's nothing wrong with the header from what I can tell.)
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escomm
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by escomm »

alex wrote:
escomm wrote:
alex wrote:I'd try another front shield as well.... Maybe you just have a bad microphone. Do you get audio when using a speaker mic?

-Alex
How would a bad mic preclude the MDC post from being sent?
Damn. I should stop replying to posts before my coffee... Thanks Jeff.
I thought the same thing... and wondered if the problem would go away with a speaker mic as well, but when I re-read the part about the lack of Post then I thought better of it. XD

For more troubleshooting, OP, does the radio transmit dead air when it's in service mode? Or does it star modulating again? I have had some wonky things happen in the past with a 3k that went away when the radio was in service mode... wonder if this might be a similar thing
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Tony.RI
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Tony.RI »

escomm wrote:...
For more troubleshooting, OP, does the radio transmit dead air when it's in service mode? Or does it star modulating again? I have had some wonky things happen in the past with a 3k that went away when the radio was in service mode... wonder if this might be a similar thing
How do you transmit in service mode? (Thats the mode after it displays the serial, flashcode, and options, correct?) I'm just a lowly ham, so I don't have access to a service monitor or any other fancy tools outside of an oscilloscope and multimeter.
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Tom in D.C. »

No, that's not service mode. That readout is just for quick grins. You should have a companion CPS program that opens separately and enables you to tune and adjust the radio. That's what they're talking about. I stay away from it as much as possible to avoid making problems for myself.

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Tony.RI
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Tony.RI »

Tom in D.C. wrote:No, that's not service mode. That readout is just for quick grins. You should have a companion CPS program that opens separately and enables you to tune and adjust the radio. That's what they're talking about. I stay away from it as much as possible to avoid making problems for myself.

Regards,
Thank you. Same here, I didn't want to screw up any tuning parameters so I've never used it before today. Ok, I tried the test transmissions and absolutely none of them worked. Just sent out dead air, though some of the dead air sounded a little different, but it was all just emptiness.
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by akardam »

Tony.RI wrote:How do you transmit in service mode? (Thats the mode after it displays the serial, flashcode, and options, correct?)
Tom in D.C. wrote:No, that's not service mode.
Well, actually, that is what Motorola calls service mode. More specifically, the OP is referring to the RF Test mode that is available after the radio has entered into service mode and read off all the information about firmware, model, serial, flashcode, etc.

To the OP, you really should get yourself a copy of the BSM for your radio if you want to try advanced troubleshooting, but in a nutshell, RF Test mode allows you to cycle between several builtin frequency test points, squelch types, and modulation types that cover the entire operating range of the radio. This allows you to test the radio across its range while operating independently of the frequencies and modes that the radio is normally programmed with. The BSM goes into detail on how to use this test mode to troubleshoot problems.
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Tony.RI
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Tony.RI »

akardam wrote:
Tony.RI wrote:How do you transmit in service mode? (Thats the mode after it displays the serial, flashcode, and options, correct?)
Tom in D.C. wrote:No, that's not service mode.
Well, actually, that is what Motorola calls service mode. More specifically, the OP is referring to the RF Test mode that is available after the radio has entered into service mode and read off all the information about firmware, model, serial, flashcode, etc.

To the OP, you really should get yourself a copy of the BSM for your radio if you want to try advanced troubleshooting, but in a nutshell, RF Test mode allows you to cycle between several builtin frequency test points, squelch types, and modulation types that cover the entire operating range of the radio. This allows you to test the radio across its range while operating independently of the frequencies and modes that the radio is normally programmed with. The BSM goes into detail on how to use this test mode to troubleshoot problems.
"Item Number. 6881076C05 * Item has been cancelled"
Image I hate being the latecomer to the party...

I may just have to pray its the RF board and try to find another inexpensive VHF AS to swap boards... (That shouldn't affect my programming/flashcode/options outside of tuning properties, correct?)
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Elroy Jetson »

I think you have an intermittent solder connection somewhere, probably right on the RF deck. If it's a component not covered by those soldered-on shields,
reflowing it wouldn't be too tricky. But, if it's under those shields, it gets a bit more complicated.


However, I will tell you what I have done with success in the very recent past. Attempt this strictly at your own risk.

Obtain a small refillable propane torch, aka "crack torch", and find some SCRAP circuit board to practice on. Learn to use it to reflow solder, with the aid of solder flux such as the kind you can buy at Radio Shack. With a little practice you'll be able to reflow components without scorching anything. The only real risk here is that the hot blast coming off the torch is enough to blow the smallest components off the bench and right into the shag carpet. :lol: This is why
you get a small torch, not a big one, and you back the flame down to as small as you can get away with and still have it run right.

I've fixed a lot of problems simply by reflowing the solder around surface mount components. Intermittents are very likely to respond to this.



Elroy
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Tony.RI »

Elroy Jetson wrote:I think you have an intermittent solder connection somewhere, probably right on the RF deck. If it's a component not covered by those soldered-on shields,
reflowing it wouldn't be too tricky. But, if it's under those shields, it gets a bit more complicated.


However, I will tell you what I have done with success in the very recent past. Attempt this strictly at your own risk.

Obtain a small refillable propane torch, aka "crack torch", and find some SCRAP circuit board to practice on. Learn to use it to reflow solder, with the aid of solder flux such as the kind you can buy at Radio Shack. With a little practice you'll be able to reflow components without scorching anything. The only real risk here is that the hot blast coming off the torch is enough to blow the smallest components off the bench and right into the shag carpet. :lol: This is why
you get a small torch, not a big one, and you back the flame down to as small as you can get away with and still have it run right.

I've fixed a lot of problems simply by reflowing the solder around surface mount components. Intermittents are very likely to respond to this.



Elroy

You know, I bet thats what it is. Tapping on the radio kinda got it to work for a while and it would be explained by some broken connection somewhere. I'll have to take a much closer look at the components.
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by xmo »

...
"Item Number. 6881076C05 * Item has been cancelled"
...

The printed version is cancelled but the good news is that the Astro Spectra basic and detailed service manuals are available for download on MOL.
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Re: Astro Saber transmitting dead air (Maybe a bad RF board?)

Post by Tony.RI »

Ok, I'm scaring myself now. It won't even transmit or receive now, and I don't want to ruin a good VOCON with a nice flash by mucking around with this anymore than necessary. Should I find someone who can tell whats wrong and what I need to replace, or should I just shelve it till I can get another RF board and hope that's what the problem was?
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