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#602268 07/13/16 11:59 PM
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Hello all,

I have a Bogen TPU100B that has 2 leaked Capacitors on the main board. Leaked "goo" over a number of components. UGLY!!!

The result is that it keeps tripping the breaker.

Anyone know of a repair service or a source of a replacement board??

This amp is set up for a 70v system. There are a number of speakers (maybe 12 to 15). The resistance at the connection wires is 2.5 ohms. Before I start tearing the wiring apart to look for a short can anyone tell me if this resistance value is approximately correct??

Thanks in advance for any insight.

Les



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ABLE1 #602269 07/14/16 12:03 AM
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At 70V 2.5 ohms you have a nearly 2000 watt load, which is not acceptable for 12-15 speakers nor the TPU100B. Did you check with a DMM in resistance mode or with a proper impedance bridge such as a TOA ZM-104?

You can also check for ground faults by measuring with a DMM between earth and each leg of the speaker wire.

Bogen is still in business so you can contact them for repair or a new part once you verify with the proper tool whether or not you have an overload. https://www.bogen.com/

tim10 #602271 07/14/16 12:35 AM
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Tim,

I used a DMM to get the 2.5 ohms. I know it is not the proper device but it all I have. I was in a rush and should have checked each leg to ground. Will do that tomorrow.

I get the feeling that I may have a bigger problem and should start dissecting the speaker wiring.

I was not sure about Bogen doing repairs or not. Customer may just go for a new replacement. Just need to work up the cost numbers.

Thanks,

Les



ABLE1 #602293 07/14/16 04:16 PM
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I used a DMM to get the 2.5 ohms. I know it is not the proper device but it all I have.

Then you might as well not have bothered because DC resistance means nothing. You need an impedance meter.

That aside, what makes you think those leaking caps have anything to do with a speaker or line problem?

Is the amp old? Is the ambient where its located hot? Do you know how to simply replace them? You don't need a new amp or board. If it trips the breaker they are power supply filter caps.

-Hal


CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
hbiss #602299 07/14/16 08:52 PM
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I get it, I really do. But am limited to what I have (at this time) to work with.

As I see it the caps could have died due to age. Approx 30+ years.
Environment not hot.

It could have be a bad wiring short or speaker txfmr. Again 30++ years.

I could replace the caps, clean up the board and then find that the there are other problems. Wasted time and effort.

Just got green light from customer to install new amp.
Need to check the speaker grid to make sure I don't have a problem that the new amp will not like.

Searching locally to see if to see if another contract has impedance meter I can borrow for a while.

Thanks for the assist.

Les





ABLE1 #602302 07/14/16 10:31 PM
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Without an impedance meter (Sandman used to sell them) you are whistling in the wind. For years I thought I was good enough to service sound systems with nothing more than a VOM and a speaker. 50 years ago, one could get away with that.

When I was running service for a National and most of the work was trying to get miserable and butchered sound systems to work in large stores, I bought an impedance meter. That is one of the BEST investments I have ever made. Not only will the meter tell you where the problem is, it can also tell you if the amplifier can handle the load. It was easy to find all the 8 ohm speakers "glommed" onto the 70 volt lines. What used to take 1/2 a day to sort out and track down because a 15 minute job.

Rcaman


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ABLE1 #602313 07/15/16 12:32 PM
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It's not the best meter but it will do the job for a cheap price.

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ABLE1 #602314 07/15/16 12:42 PM
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LOL I have one of those...it sucks. My old analog U-100? whatever, works a whole lot better.

Carl

ABLE1 #602317 07/15/16 04:09 PM
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It was easy to find all the 8 ohm speakers "glommed" onto the 70 volt lines.

Even faster is to disconnect the speaker line from the amp and put 120v on it. Heck, you won't even have to remove them after that. devil

Quote
Need to check the speaker grid to make sure I don't have a problem that the new amp will not like.

Searching locally to see if to see if another contract has impedance meter I can borrow for a while.


Probably a good idea but I wouldn't go out of my way right yet if you don't have an impedance meter. How many and what kind of speakers are there anyway?

Connect the new amp and see what it does. Watch the clipping indicator as you increase the level. If it illuminates with little output from the speakers you have a problem. If you get proper volume at a reasonable gain setting everythings probably OK. Walk around and listen to each speaker. If you have one that is a lot louder than the others it's probably one without a transformer.

These amps are pretty well protected and as long as you don't leave them connected to a dead short and crank the level up they will be OK. That old amp died from old age NOT from a speaker problem. There should have been a hum problem long before those caps self destructed so your customer should have known something was up long ago.

-Hal


CALIFORNIA PROPOSITION 65 WARNING: Some comments made by me are known to the State of California to cause irreversible brain damage and serious mental disorders leading to confinement.
hbiss #602327 07/15/16 09:58 PM
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Ok, I have a TOA ZM-104 on to way to me. Should have by mid week(I hope). Really should have bought one a long time ago but I do minimal audio systems so it never was a bid priority.

Mostly is was a new install so proper planning and install problems did not happen. Rarely was there a problem after the install. I installed this amp on existing speaker grid and all was good 30+ years ago. Now it is a new building owner and the amp needs help.

The impedance meter will be a good thing, no question. It will pay for itself just on this one job so I am happy.

I agree that just throwing in the amp and see what happen is possible. However, I know Murphy all too well. If I am not pro-active Murphy will win. At least getting the meter will absolutely confirm that the speakers are all good. I do know how reverse logic works.

So, I am good to go.

Thanks for all the extra input.

Les



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