D43 Spectra audio issue

[philn]

I have a black label D43 Spectra that powers up, but there is no audio and the yellow busy light remains on. Have tried a couple of codeplugs with no results. Also made certain securenet was off. Caps look good with no leakage. Never had this issue before. Any ideas?

[OCSD117]

Yes I had this problem and as I recall there is an audio chip on the left had side and that was bad and needed to be replaced!

[kc7gr]

Also -- Do NOT forget to check the aluminum electrolytic caps, on both the command and RF board, for signs of leakage. This was a common problem, even with the black-label analog Spectras.

Astro Spectras don't appear to have this issue. At least I've not come across any that do, just yet.

Happy tweaking.

[Will]

Astro Spectras don't appear to have this issue. At least I've not come across any that do, just yet.

Yes the Astro Spectra's have the same problem with leaking electrolytic caps.

[philn]

All of the caps look good. That was the first thing I looked at. I bought the radio, powered it up to read the codeplug and had no issues. Went back and made changes only to freq's and then started having the issue. I bought 2 of these radios and wrote the other codeplug belonging to the other good radio via the clone menu with no success. On which board is the audio chip on the spectras? Might switch out a board and see if I can narrow it down. Thanks for the help.

[jackhackett]

All of the caps look good.

You can't tell if they're good just by looking at them. What's the date code on the radio (three letters in serial number)?

The problem may also be in the mute circuit, you can check that the audio chip has proper voltages on it. It's a little hard to suggest exactly what to do, since we don't know how technical you are, and if you have test equipment and manuals.

[Rod Farva]

check the audio amp, and see if it has a burn mark in the middle of it. If the speaker leads ever get shorted to ground it will pop that amp. The best way to check the amp is with a scope. Generate a signal into the radio and look for the 1k tone in the scope before the amp. If there is signal there and not after the amp replace the amp... Common Spectra problem.

[philn]

Ok, the serial number on the D43KMA7JA5BK is 617AUG0549. Have not had a chance to dig in to the radio this past week. I'm fairly limited when it comes to working on these little buggers. I've changes out caps before with success but have not tackled any other board work. I see no goo on the board around the caps. I've had some that were so bad it was plainly visible. I'll take a look at the radio and try all of the suggestions stated above and see what I can find. My luck with radios has been bad this week. My T84 in the truck went South on me as well. I can RX and TX but it's horrible audio. Barely works at all. Caps might be bad on that one as well. Thanks for the suggestions.

[philn]

Might be it- on the HLN6094C board, I see a big crack in one of the chips. Number on the chip is 77M90 SC390022FN QDZQ9408. Looking at the radio from the front, its the first large chip on the left. I don't have any manuals on the spectras so I'm in the dark as to what all of the chips are. Might be another radio for Will to fix and keep for himself. I've sent him junk before and he manages to make it breathe again.

[jackhackett]

Might be it- on the HLN6094C board, I see a big crack in one of the chips. Number on the chip is 77M90

Audio filter IC, wow.. I've never seen one of those crack! I have no idea what would cause that. The heatsinked one next to it is the audio amp.
The 617AUGxxxx serial number indicates that the radio is 14 years old (April '94), the caps in a Spectra that old will definitely be bad unless they've already been replaced. I'd automatically replace them in any unit 10 years or more old, and be very suspicious of any approaching 10yo.

[philn]

Might be easier for me to find another command board for this radio. I'll tinker with it some more and see what turns up. I might even have an old command board to swap out. Thanks for all of the suggestions. Looks like I'll be changing out caps on all of my spectras. I've got 7 that are old and in need of work. I don't know why motorola used those electrolytic caps in the first place. Cheap maybe? Oh well, I still swear by the old bricks. Dropped a FD portable off a landing inside a water tower. Was about 3 stories up. Radio hit railing and other crap on the way down before hitting concrete. Cracked the battery. New battery and good to go!

[OCSD117]

well that would explain it! never seen that though

[Rod Farva]

if the speaker leads get shorted out it will burn the audio IC instantly which sounds like what happend. It is easy to discover it because it has either a burn mark in the middle, a crack or a big chunk of the IC missing from the middle... Common problem with spectras. especially when the speakers have been butt spliced or taped....

[depot_01_1994]

Exactly right.
Any Spectra with an audio failure, the first culprit to investigate are those SMD caps!
Telltale signs...sniff your command board, a strong fishy odor is definately bad electrolytics!
Also these caps may look ok, but they may have leakage under them, to which you cannot see.
Look for any changes in the color of the soldermask, from green to black.
I never had the chance to work on any Spectras at the Depot, and my first repair of a Spectra involved changing those caps.
On a side note, I was also shocked of the poor quality PCB substrate used in the Spectra line...never knew !