Astro Spectra problems

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PETNRDX
Posts: 841
Joined: Sun Nov 25, 2001 4:00 pm
What radios do you own?: Too many

Astro Spectra problems

Post by PETNRDX »

Pretty familiar with Spectra and plenty of other Moto radios. Very Familiar.
Not so much with the Astro Spectra specifically.
Does the Astro low power use the same programming cable as the analog Spectra?
Model is T99DX+089W_ASTRO with an ID of D04KKF9PW5AN.
Setup is Astro Spectra R05.03 that has worked on a consolette, with REAL RIB and home made DB 15 cable that I have used for decades.
Also, have two radios, a UHF analog Spectra, and the above mentioned Astro, and get NO RX audio out of either.
Not one tiny bit.
I am painfully aware of the electrolytics, so will change those.
But, if the previous owner had fried the audio PA (likely) is there an fairly easy way to check that audio IC?
Steve K.
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jackhackett
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Joined: Tue Jun 10, 2003 8:52 am

Re: Astro Spectra problems

Post by jackhackett »

The first thing to do is just visually inspect the audio IC, often when they are blown they will have vented either on the top or from around the pins.

If it looks okay, you can check the DC voltage on the speaker outputs. With no audio they should be around half the supply voltage. If I recall correctly the radio has to be unmuted, so inject an on frequency signal with proper PL/DPL but no audio modulation and measure the DC voltage from each speaker lead to ground with no speaker attached. Both leads should measure the same, around 6 to 7 volts.

If you get no voltage on the speaker outputs check the mute signal at the IC, you'll have to look at a schematic to see which pin it is, and be careful with your probe to not short between pins. You should see the voltage change when the squelch opens and closes, I think it goes from 0V to 12V but it's been a while since I've worked on one so I don't remember for sure. I have had several Spectras that had a transistor in the squelch circuit go bad so that the radio would never unmute.
PETNRDX
Posts: 841
Joined: Sun Nov 25, 2001 4:00 pm
What radios do you own?: Too many

Re: Astro Spectra problems

Post by PETNRDX »

thanks for reply and suggestions.
As expected, previous owner fried the IC.
Then did a crappy job trying to replace it.
I have the radio working now.
Sometimes doesn't accept programming, but works after several tries.
Good enuf for now.
Thanks again.
Steve K.
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FireCpt809
Posts: 1830
Joined: Sat Jan 19, 2002 4:00 pm
What radios do you own?: Alot..

Re: Astro Spectra problems

Post by FireCpt809 »

Yes the Astro Spectra uses the same cable as the mid power analog spectra
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