RE: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement
At 03:38 PM 11/25/09, you wrote: Hi Mike, Thanks for the info. Yes, I've cleaned it up good... I use a q-tip with a baking soda/water combo, then wick solder on the pad till it flows... sometimes gotta scrape a shiny spot first. Then soldersuck the pad clean up with wick. Then another qtip with lacquer thinner (contains MEK) - does great job of cleaning the flux. Nice sparkly clean. The dried capacitor poop occasionally seeps under an adjacent component (capillary action) . Sometimes you have to lift an adjacent resistor or two to get access to all of it. The smell of the solder on the corroded pad reminds me of some solder I have that has a water soluble rosin. Kinda smells like fish. It's probably the audio amp, but it's not objectionable enough to make me want to change it out. It's amazing how many dead radios are coming back to life after re-capping! I agree! From the emails that WA1MIK (the author of the recapping article) and I have received over 70% of the problems in surplus Spectras are cap problems. Of course some of the problems were traces that had disappeared! Which is why Will Martin KA6LSD of Echo Communications wrote (in the recapping article) There have been cases where the corrosion has eaten away so much of the pads that I have had to use leaded components and solder to other locations on the board to restore the functionality. I saw one radio that Will fixed where he soldered one cap lead to one of the two original pads but the other lead had no pad... so he left the lead long, sleeved it and ran it a few inches over the components on the board and soldered it to another component. The guy is a genius at Spectras. He even found the manufacturer that made the audio module for Moto and buys them direct for a lot less than Moto sells them for. Things like that allow him to be more reasonable on repair pricing. I was over at his shop a while back and he had radios (awaiting service) on the shelf from a dozen 2-way shops and police agency shops in 7 states and 2 European countries - radios they couldn't fix. The outgoing shelf had radios from 4 states plus Canada and Mexico. The first thing he does is recap the radio. Then he starts working on the problems the customer complained about. Thanks, Tim Mike WA6ILQ
Re: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement
On the spectras, if you keep using the radio after the caps go bad, it can damage the audio ic chip. The popping is one of the symptoms as well as distorted audio. Another thing I have seen is a tantalum chip cap that is the isolator cap between the audio chip and the previous chip. Just follow the audio-in line backwards from the audio chip to find it. ( am doing this from memory and not looking at a book or would give part numbers) The audio chip from mot last time I bought one was about $24.00 dealer price if I remember right. Hope this helps. Happy Thanksgiving Everybody !!! Mike Specialized Communications KB5FLX - Original Message - From: Tim Ahrens To: Repeater-Builder@yahoogroups.com Sent: Tuesday, November 24, 2009 10:32 PM Subject: RE: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement Hi David, Is the Hear Clear board only on the 900 mhz spectras? I was looking in my service manual, and it talks about the board plugging into P501, but on my VHF spectras, this plug is unpopulated.. As a side note, when I went to replace the capacitors, I noticed that a fire ant had given it's life while spanning a couple of pins on the audio output TDAxxx part. There seemed to be some 'liquid ant residue' remaining, so perhaps it damaged the audio amp. I guess I'll have to look at the thing with the scope see what's going on in comparison to one that works 'correctly'. Thanks! Tim
RE: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement
Yes, you are correct. The hear clear is only used in the 900 mhz spectra. Changing the CAPS should help especially aroung the audio amp chip. I have not had any issues with the VHF Spectras giving a popping sound except I had to replace the audio amp chip in one. It was fun to do but at the same time I replaced the capacitors. I purchased the audio amp chips from Motorola and they weren't too expensive. Sounds like you may have found your problem with the audio. Good luck in the repair of the Spectra. David -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Tim Ahrens Sent: Tuesday, November 24, 2009 10:32 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement Hi David, Is the Hear Clear board only on the 900 mhz spectras? I was looking in my service manual, and it talks about the board plugging into P501, but on my VHF spectras, this plug is unpopulated.. As a side note, when I went to replace the capacitors, I noticed that a fire ant had given it's life while spanning a couple of pins on the audio output TDAxxx part. There seemed to be some 'liquid ant residue' remaining, so perhaps it damaged the audio amp. I guess I'll have to look at the thing with the scope see what's going on in comparison to one that works 'correctly'. Thanks! Tim
RE: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement
-Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tahrens301 Sent: Tuesday, November 24, 2009 2:43 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement Hi Folks, I've been working on these Spectras, and so far, the capacitors have done the trick. But on this last radio, the speaker pops whenever the audio path is open (unsquelched, signal, mode change, etc). Just curious if there's something I've missed. Thanks, Tim The popping is due to a DC voltage change at the input to the speaker amp. Leaky caps are the most common cause of this, but if you've changed the caps and not cleaned up the cap residue on the board the crud can be conductive and essentially shunt the new cap with a resistor. So cleaning the board of all leftover residue may help. I've been told the residue contains boric acid, I'm not a chemist, does anybody know what a good neutralizer is for that ? If I knew, I'd use that, then some MEK (which you can find in cans in the paint section at Home Depot). Mike WA6ILQ
RE: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement
Hi Mike, Thanks for the info. Yes, I've cleaned it up good... I use a q-tip with a baking soda/water combo, then wick solder on the pad till it flows... sometimes gotta scrape a shiny spot first. Then soldersuck the pad clean up with wick. Then another qtip with lacquer thinner (contains MEK) - does great job of cleaning the flux. Nice sparkly clean. The smell of the solder on the corroded pad reminds me of some solder I have that has a water soluble rosin. Kinda smells like fish. It's probably the audio amp, but it's not objectionable enough to make me want to change it out. It's amazing how many dead radios are coming back to life after re-capping! Of course some of the problems were traces that had disappeared! Thanks, Tim
[Repeater-Builder] Spectra Audio Popping after Capacitor replacement
Hi Folks, I've been working on these Spectras, and so far, the capacitors have done the trick. But on this last radio, the speaker pops whenever the audio path is open (unsquelched, signal, mode change, etc). Just curious if there's something I've missed. Thanks, Tim
RE: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement
Had the same problem with a 900 mhz Spectra. The hear clear board was the problem. Changed it and the popping noise went away. David -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of tahrens301 Sent: Tuesday, November 24, 2009 2:43 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement Hi Folks, I've been working on these Spectras, and so far, the capacitors have done the trick. But on this last radio, the speaker pops whenever the audio path is open (unsquelched, signal, mode change, etc). Just curious if there's something I've missed. Thanks, Tim
RE: [Repeater-Builder] Spectra Audio Popping after Capacitor replacement
Hi David, Is the Hear Clear board only on the 900 mhz spectras? I was looking in my service manual, and it talks about the board plugging into P501, but on my VHF spectras, this plug is unpopulated.. As a side note, when I went to replace the capacitors, I noticed that a fire ant had given it's life while spanning a couple of pins on the audio output TDAxxx part. There seemed to be some 'liquid ant residue' remaining, so perhaps it damaged the audio amp. I guess I'll have to look at the thing with the scope see what's going on in comparison to one that works 'correctly'. Thanks! Tim
[Repeater-Builder] Spectra Audio
I Have a Motorola Desktrac Base Station was working Fine then all of a Sudden NO AUDIO, I Tried another Speaker Etc. no Popping nothing Any Ideas before I start digging around for the Problem. I can See the Busy Light come on when I send out a Signal Also on the Programming Cable I have the one for a Ext Speaker leads nothing heard there either .Self check is fine Thanks Don KA9QJG
