Help with Spectra problem

Max · Post by **Max** » Fri Oct 07, 2005 6:33 pm

I have a Spectra 800Mhz, dash mount. This is the problem i am having.Once i power up the radio and toggle the mode or volume buttons i get a loud crackling nose ,when someone talks it just crackles ,you can almost make out work they are saying.I have tryed a different head,interconnect board tryed a different speaker and still no difference.I have played around with Spectra's for years ,but never got into the technical end of the radio.Any ideas would the problem might be.I have a lot of parts from Spectra's i have collected over the years.What board would you suggest i change?

Thanks
Max

jcobb · Post by **jcobb** » Fri Oct 07, 2005 9:16 pm

Try this: http://batboard.batlabs.com/viewtopic.php?t=46873

Jack

kc7gr · Post by **kc7gr** » Sat Oct 08, 2005 7:39 am

Max wrote:I have a Spectra 800Mhz, dash mount. This is the problem i am having.Once i power up the radio and toggle the mode or volume buttons i get a loud crackling nose ,when someone talks it just crackles ,you can almost make out work they are saying.I have tryed a different head,interconnect board tryed a different speaker and still no difference.I have played around with Spectra's for years ,but never got into the technical end of the radio.Any ideas would the problem might be.I have a lot of parts from Spectra's i have collected over the years.What board would you suggest i change?

Thanks
Max

Plenty of threads on this already. In summary, you have a series of bad electrolytic surface-mount caps on the RF and command boards that are leaking, or have already leaked dry.

Your problem goes beyond bad audio. The electrolyte in the capacitors is highly corrosive. If not cleaned up, it'll eat away at the copper traces on the board. If it penetrates to other layers, you're sunk outside of getting new boards.

Repair of the problem requires removal of both boards, cleaning of electrolyte residue, removal of the bad caps, and soldering on replacements. Easy enough, if you have the appropriate desoldering tools and test equipment to verify the repairs, pure horror if you don't.

Check your PMs.

kb0nly · Post by **kb0nly** » Sat Oct 08, 2005 9:29 am

One thing nobody has mentioned in previous posts, none that i can find anyway, is what caps go bad.

Anyone have a list of the component numbers and values that normally need replacement??

Will · Post by **Will** » Sun Oct 09, 2005 12:59 pm

ALL of them eventually!

and the replacement ones from Motorola are the same old leaking ones.

There are 1, possibly 4 caps that go bad on the command board in the audio PA section.

From the sound of your problem, the corrosion dammage has allready occured.

Can you say " piss poor design"

kc7gr · Post by **kc7gr** » Tue Oct 11, 2005 10:12 am

kb0nly wrote:One thing nobody has mentioned in previous posts, none that i can find anyway, is what caps go bad.

Anyone have a list of the component numbers and values that normally need replacement??

Gahh... I thought I'd posted that at some point. Sorry about that.

The caps that go bad are easy to spot. They're all aluminum-can electrolytics. There are four on the command board, and five on the RF board. You've got seven 10uF/16V, one 10uF/50V, and one 47uF/16V.

I don't have exact component numbers handy, but they're the only electrolytic aluminums on the boards, so it's nearly impossible to miss them.

Keep the peace(es).

GlennD · Post by **GlennD** » Tue Oct 11, 2005 11:31 am

Do not forget the two on the control head and the one in the pa. Every single electrolitic cap in a spectra leaks. Two 10mfd 50v in the head, one 10mfd 50v in the pa, one 10mfd 50v and three 10mfd 16v in the command board, four 10mfd 16v and one 47mfd 16v on the rf board.

EVERY ONE A TICKING TIME BOMB!

kb0nly · Post by **kb0nly** » Sat Nov 12, 2005 12:23 pm

Just wanted to revive this thread since it deals with exactly the question i have, didn't see the need in starting a new thread.

So, the aluminum can electrolytics are the nasty culprits.. What do recommend replacing them with? It seems its not recommended to get replacement from Moto since they will be just as bad. Also, there is plenty of room height wise to put a better quality replacement in there.

Also, though the black label Spectra is a later production run, i assume that they still will suffer from this problem eventually? Otherwise if they changed the capacitor type i wouldn't expect you guys to be saying that the caps from Moto are still no good.

kc7gr · Post by **kc7gr** » Sat Nov 12, 2005 2:11 pm

kb0nly wrote:Just wanted to revive this thread since it deals with exactly the question i have, didn't see the need in starting a new thread.

So, the aluminum can electrolytics are the nasty culprits.. What do recommend replacing them with? It seems its not recommended to get replacement from Moto since they will be just as bad. Also, there is plenty of room height wise to put a better quality replacement in there.

Also, though the black label Spectra is a later production run, i assume that they still will suffer from this problem eventually? Otherwise if they changed the capacitor type i wouldn't expect you guys to be saying that the caps from Moto are still no good.

Eventually, yes. What I've done is order replacement caps from DigiKey. I usually buy the high-hour, high-temp (5000 hour at 50 degrees C) rated parts. I've already used them in a number of Spectras (just did one last week, in fact, for Sheridan Lum), and have not had any problems to date.

The only kicker with the replacements is that they can, depending on who the manufacturer is, be a hair larger at the base than the Moto originals. This can make soldering a bit tricky. I've found that a 'needlepoint' tip on a Weller mini-station does a good job.

I recall that the ones I get are made by Panasonic (or at least carry the Panasonic name). Next time I order I can post part numbers if you'd like.

kb0nly · Post by **kb0nly** » Sat Nov 12, 2005 2:35 pm

That's what i was thinking, spend the extra bucks for higher quality, probably never have to replace them again for the life of the radio.

Either post the part numbers or PM or Email them my way whenever you get a chance.

I plan on making notes on all this and tucking it away! I'm bound to come across one needing replacements now that i have started playing around with them.

GlennD · Post by **GlennD** » Sat Nov 12, 2005 5:43 pm

You should automatically replace all of the caps. Even if you do not see any signs you will see leakage under the caps when they are removed.

In our city we have hundreds of Spectras in service. When we PM one all the caps are replaced and we write the date changed inside the radio. It only adds about an hour to our normal PM and clean up time.

Our parts guy gets the caps from Mauser. Since he put them into the system under the Moto part numbers I do not have the real numbers handy.

kb0nly · Post by **kb0nly** » Sat Nov 12, 2005 8:30 pm

Do you recommend doing it to a later production black label model? I haven't checked the date of manufacture on it yet.

The only reason i ask is this radio is working perfectly now, but, if recommended i would definitely put the time and money into replacing them.

I just got the new Mouser catalog on CD a couple weeks ago, so no problem searching for subs.

Will · Post by **Will** » Sat Nov 12, 2005 11:36 pm

Tin man, unless you are really good at surface mount rework, I would recomend radial leaded caps that are easeir to solder in.

Getting rid of the corrosive 'yuck' is the hard part, we have seen lots of radios with the caps replaced but the corrosive 'yuck' still very much at work.

GlennD · Post by **GlennD** » Sun Nov 13, 2005 6:33 am

Ten years seems to be the point that they are goners. I have to echo Will that clean up is very important! It is much easier to change them out before they start leaking.

Last week I had one where the cap near the 109Mhz VCO leaked into the cage and ate the through hole from the stearing line. Let me tell you, getting into the cage was a real pain.

We use two irons with small tips to remove the caps. The traces on the command board are small and very easy to lift, Do not even think about changing them with the boards in place.

One tip off that the caps are on their way out is if the receive audio pops at turn on. If the caps are not the same value one half of the amp turns on faster than the other.

On my radio at home the caps are dipped tantilum. This is only because thats what I had on hand and I did not want to steal caps from the city.

kb0nly · Post by **kb0nly** » Sun Nov 13, 2005 10:25 am

So what is the best cleaner, or solution, to eliminate the corrosive guts from one that leaked?

Will · Post by **Will** » Mon Nov 14, 2005 12:00 am

"On my radio at home the caps are dipped tantilum. "

Very good idea, radial leaded dipped tants, Kemmet brand work well. Also available at the Shack!

philn · Post by **philn** » Mon Nov 14, 2005 10:09 am

What's the best way to clean the boards if the caps have already leaked? I saw the question above but didn't see an answer. The caps in my radios look ok, but I'd rather be proactive and change them out. Thanks.

GlennD · Post by **GlennD** » Mon Nov 14, 2005 6:43 pm

I clean them with an acid brush cut to .25 inch and isopropyl alcohol. After I install the replacement caps I clean the whole area with a toothbrush and more alcohol.

Zap · Post by **Zap** » Mon Nov 14, 2005 10:33 pm

If I spill coke on my duplexer and clean it with alcohol, a toothbrush and toothpaste, what will it do to the cavities?

jackhackett · Post by **jackhackett** » Tue Nov 15, 2005 5:43 am

[quote="Will"]Tin man, unless you are really good at surface mount rework, I would recomend radial leaded caps that are easeir to solder in.

Getting rid of the corrosive 'yuck' is the hard part, we have seen lots of radios with the caps replaced but the corrosive 'yuck' still very much at work.[/quote]

Especially around the control head ones... I've had a couple of radios that still didn't work right after changing those caps (kept getting a fail code if I recall correctly), I had cleaned the board, but apparently if there's even a little residue on the board it would mess it up, I think it must have caused enough current leakage to throw off one of the opamps. Doing an extra thorough cleaning solved the problem.

The one cap that gave me the most trouble replacing is the big one near the audio PA, one side of it is right up against the shield around the MLM, hard to get an iron in there. What I've been doing is taking that shield off the board to get to the cap, which is usually the point where I start intermixing the word Motorola with various obscenities.

The one question I still have.. just what do they make those things out of? Every time I do one the rest of the guys in the shop are wondering who had fish for lunch.. what an unpleasant smell.. I just hope it's not too toxic..

GlennD · Post by **GlennD** » Tue Nov 15, 2005 6:52 am

The electrolitic in electrolitic caps is boric acid.

I have never had to remove the MLM shield and I have changed out 50-100 caps so far. just use a long narrow tip.

Splat · Post by **Splat** » Tue Nov 15, 2005 8:12 am

I did one Spectra "work over" and without a long thin soldering tip, like GlennD says, it's gotta be more a PITA. I used isopropyl alcohol, as well, and went very thoroughly over the boards. It's not something you want to do more than once so I took my time and did it right the first time. Of course, this goes against the old proverb, "We do it right, 'cause we do it thrice!"

Will · Post by **Will** » Tue Nov 15, 2005 3:14 pm

Alcohol does not work, even the 98% pure stuff. Too many failures later down the road, even on some of our repairs done about one year or more ago. Even seen a whole lot of other personn's/shops' repairs go bad in a very short time due to the 'yuck' comming back.

MEK, Acitone, ect have not worked any better. (this is why I did not offer any sujestions earlier in the thread)

And the part about having to remove the shield to get at the cap on the Command board, this is why I mentioned using radial leaded caps. Not too many of us have the surface mount rework equipment needed or the knowhow to do the SM atuff, so again using the radial leaded caps will be easier.

Even the replacement SM caps used by most are failing.

spareparts · Post by **spareparts** » Tue Nov 15, 2005 4:57 pm

Will wrote:Even the replacement SM caps used by most are failing.

So unless you get to it prior the caps leaking, it's a lost cause??

Martin

60hzEE · Post by **60hzEE** » Tue Nov 15, 2005 4:58 pm

GlennD wrote:The electrolitic in electrolitic caps is boric acid.

I have never had to remove the MLM shield and I have changed out 50-100 caps so far. just use a long narrow tip.

OK. If the "goop" remains to continue the process of corrosion, the boric acid has been absorbed into the board substrate somehow. The old rule from high school and college chemistry: Neutralize an acid with a mild base. So, some household ammonia (dilute ammonium hydroxide) on a q-tip should do the trick. I would suggest trying some baking soda, but that's a bit messier as it would tend to leave a residue and probably would be conductive.

So, hold your nose and replace the 'fish smell' with that of ammonia. The small amount of soap in the ammonia should help with the cleaning process as well.

Lee

GlennD · Post by **GlennD** » Tue Nov 15, 2005 6:42 pm

We have not had any returned bouncers. It has been just over a year that we started changing them out on every radio that comes through the shop. We throughly scrub with a stiff brush. It takes more than a quick slop of alcohol.

On the other hand our objective is to keep our old X9000s and Spectras going until we go to 700Mhz, not forever. With a 70m deficit, money is tight in our small city of 450k.

Help with Spectra problem

Help with Spectra problem

Re: Help with Spectra problem