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Help! Trashed ribbons?

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chopduc

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Post Sat Dec 20, 2008 6:23 pm

Help! Trashed ribbons?

How does one confirm that 48" ribbons are dead?

The speakers are Carver ALS Silver Editions pushed by a Carver PT-2400.

During an extended high volume session I witnessed a bright flash from behind one of the ALS Silvers immediately followed by loss of ribbon output from both speakers.

The fuses are intact so not sure what caused the bright flash.

No visible burn marks on or near the crossovers.

All 6 woofers still functioning but at a seemingly greatly reduced sound level. Have never heard the ALS Silvers without the ribbons so my idea of "reduced" woofer output may be the normal/correct output. Have done the 9v battery test on the woofers and they each push out.

By-passed the largest of the two black capacitors, but still nothing from the ribbons. This cap by-pass test also resulted in no output from the woofersd during the test. Woofers were responsive after the by-pass was removed.

Tried other amps, preamps and cables with the damaged ALS Silvers and still have the same problem.

Most likely the ribbons are fried but I'd appreciate being able to confirm this with something other than my ears.
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maddmaxxx

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Post Sat Dec 20, 2008 6:47 pm

Re: Help! Trashed ribbons?

-hi mr duc; most likely the biggest capacitors on you xovers...never had both ribbons go out at the same time

-but, cut [twist and heat shrink after], your ribbon leads...red and black wires...wherever easiest



-set volt meter to ohms...the 2 leads should read at least 2ohms

-if 0.00 or infinity...trace wire in the ribbons went south and need a jump...use a light to visualize


-go slo
-* © Küül ®™ /mx...
-Too hip gotta book
-"Don't BAN me Bro!"...el/doro
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OBI56

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Post Sat Dec 20, 2008 8:20 pm

Re: Help! Trashed ribbons?

What Maddmaxxx said. Use a flashlight to shine through the ribbons looking for a broken trace. Depending on where is is and how bad it is and as long as the Kapton is not burned away, you "might'" be able to make a temporary fix by jumping over the broken area. Otherwise, you are looking at a ribbon rebuild and should call DaveS.

You loss of bass is normal as those 3 woofers are actually more like subwoofers since they only operate below about 150Hz; the ribbons reproduce a large part of what we percieve as bass.

Good luck and please keep us posted.
Why let facts or common sense get in the way of your opinions.
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BillD

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Post Sat Dec 20, 2008 8:32 pm

Re: Help! Trashed ribbons?

Circuitwriter pens can repair a trace.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
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Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
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OBI56

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Post Sat Dec 20, 2008 8:57 pm

Re: Help! Trashed ribbons?

BillD wrote:Circuitwriter pens can repair a trace.


They sure can Bill but just as long as the break isn't too wide or the Kapton hasn't melted away. I've heard of dozens of guys how have salvaged ribbons that way and a few who's ribbons were just too far gone to be repaired that way. We can only hope for the best, but at least the fix is cheap and works pretty well.
Why let facts or common sense get in the way of your opinions.
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maddmaxxx

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Post Sat Dec 20, 2008 8:57 pm

Re: Help! Trashed ribbons?

BillD wrote:Circuitwriter pens can repair a trace.




-cept i can never find where i left the darn thing...our knuck friends cannot get them at radio shack on-line, for sum reason


-i think the larger trace repairs [temporary], has been agreed tin foil and scotch tape, for flexability
-* © Küül ®™ /mx...
-Too hip gotta book
-"Don't BAN me Bro!"...el/doro
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BillD

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Post Sat Dec 20, 2008 9:02 pm

Re: Help! Trashed ribbons?

The blue flash doesn't sound too good [-o<
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
_________________
Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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chopduc

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Post Sat Dec 20, 2008 10:47 pm

Re: Help! Trashed ribbons?

Novice at work here.

I'm unclear as to what constitutes a "trace".

Is the Kapton the gold hued material (mistakenly called mylar?). If so, I don't see obvious signs of the Kapton being burned or otherwise damaged.

I'm tempted to disassemble the panels in search of damage.

Will a novice be unlikely to successfully reassemble?

Somewhere on this forum I found a suggestion to jump across the larger of the two black caps and if the ribbons come to life then the cap is the culprit. I tried this, but no success.
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OBI56

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Post Sun Dec 21, 2008 1:01 am

Re: Help! Trashed ribbons?

chopduc wrote:Novice at work here.

I'm unclear as to what constitutes a "trace".

Is the Kapton the gold hued material (mistakenly called mylar?). If so, I don't see obvious signs of the Kapton being burned or otherwise damaged.

I'm tempted to disassemble the panels in search of damage.

Will a novice be unlikely to successfully reassemble?

Somewhere on this forum I found a suggestion to jump across the larger of the two black caps and if the ribbons come to life then the cap is the culprit. I tried this, but no success.


Carver started out in about 1986 making The Amazing Loudspeakers, and at the time the design blew people away. (2) 30" full range ribbon drivers and (4) freeair 12" subs. The ribbon design was what sold the speakers. To this day, the Carver ribbon drivers are still a hard full range speaker to beat! When Carver introduced TAL, the ribbon drivers used a dual strand (trace) Kapton membrane.

After about 3 years in production, Carver came out with the new Platinum and Silver ALS's. In these models, the new single 60" ribbons for the Platinum's were 1st seen, as well as the new 48" ribbon for the Silvers. In the new designs, a few crossover changes came about, and the Kapton now had (4) aluminum strands (traces) on it, and was crimped to slow down the response to where they needed it to be.


So, when i recommended that you shine a flashlight through them it was to look for any small breaks in the aluminium traces (light will shine through the crack). Do this AFTER you measure the ribbon with a DVM (voltmeter) to ensure that it is not shorted (0 ohms) or open (infinite ohms) which usually indicates broken or burnt traces.

If you feel uncomfortable with doing ANY of this, call DaveS on here who is THE ribbon guy. Do not attempt to disassemble the ribbon yourself.
Why let facts or common sense get in the way of your opinions.
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TNRabbit

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Post Sun Dec 21, 2008 3:21 am

Re: Help! Trashed ribbons?

"Do not attempt to disassemble the ribbon yourself."

Heed this advice!!!
TNRabbit
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chopduc

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Post Sun Dec 21, 2008 10:39 am

Re: Help! Trashed ribbons?

Cut the two ribbon leads and found a reading of zero on the ohm meter.

Confused about "trace wires"

Are the "traces" the two vertical lines running the length of each ribbon?

Peering from the back of the speaker through the ribbons into sunlight reveals that these two vertical lines (traces?) are transparent.

Everyone's patience and guidance is appreciated.

The momentary "bright flash" was most likely the frying of the ribbons, but I'm hoping to exhaust all other "easy fixes" on my end before deciding to retire the speakers or invest close to a grand in getting the ribbons rebuilt.
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OBI56

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Post Sun Dec 21, 2008 3:44 pm

Re: Help! Trashed ribbons?

These are Silvers, right? Then you should have 4 traces. The traces are opaque since they are basically like aluminum foil, you can't see through them. What is transparent (or more probably translucent) is the Kapton film. Now, if you measure zero resistance on the ribbons, this indicates a short circuit. If you had measured infilite resistance, this would have meant a total break of all the traces in the ribbon or the connection to them.

You HAVE to talk to DaveS before doing ANYTHING else.
Why let facts or common sense get in the way of your opinions.
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chopduc

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Joined: Fri Sep 26, 2008 1:47 pm

Post Fri Jan 16, 2009 10:23 pm

Re: Help! Trashed ribbons?

Found a small separation on one of the traces, applied a quicky foil patch and voila...sound!

Circuitwriter pen on the way from ebay.

The other ribbon panel isn't revealing any obvious breaks in the traces, but have yet to use a magnifying glass for closer observation.
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OBI56

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Post Fri Jan 16, 2009 10:28 pm

Re: Help! Trashed ribbons?

Chopduc, it also helps if you shine a light from behind them as you look along the trace. Any areas that show fraying hear the edges of the trace should be given a quick once over with the circuit writer pen as these are probably where hte next break is likely to happen. And BTW, hairline cracks are huge compared to what you might be look for, so using a magnifying glass or fresnel lense is also a good idea.
Why let facts or common sense get in the way of your opinions.
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Mr. M-500t

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Post Fri Jan 16, 2009 10:29 pm

Re: Help! Trashed ribbons?

TNRabbit wrote:"Do not attempt to disassemble the ribbon yourself."

Heed this advice!!!


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