request for advice/help with JBL 830 speakers

Hi all, I joined this forum because it seemed like a good place to come for some basic advice. I hope you can help me but maybe my equipment is too out of date.

I bought a set of JBL 830 speakers about 20 years ago and they gave many years of great service. For about the last 10 I've moved a few times, had a few kids and not used the speakers much at all. I knew I was developing an issue with the speakers when I started to hear cutting out at different volumes. The stereo has been basically unused for sometime because I wasn't sure if the speakers were wrecked or if the amp was. I have a Harmon Kardon PM655. Anyway, I figured that regardless of the speaker situation the amp had a problem because the left channel cut out completely. I recently got it repaired ( a solder on the main board was re-done ).
Now, when I hook up the speakers there is still a problem. At low volumes, one, then the other will cut out. One speaker seems to be muted at all volumes but the one that has good sound, will still cut out at low volumes. I know nothing about stereos really. If the amp is ok, could a problem with one or both speakers cause the cutting out? I can't decide if I should take both speakers and amp in to the shop and if I need to replace components if its worth it. I'm not an audiophile but do really enjoy having good sound. The speakers and amp were each about $1100 20 years about and I wonder how much money a person should sink into repairs. When do you abandon ship?

If anyone has any experience with these types of problems, please let me know.

thanks!

Hi and welcome. It's tough to troubleshoot on-line, but I would suspect your receiver may have a built-in turn on delay with the consequent relay that connects your speakers. I have often seen the contacts in these relays oxidise after some years. It may need cleaning or replacing.

I have no idea what labour rates are these days, but it would probably take a couple of hours if this is the problem...it's likely you may want to pick up a new receiver in the end. Your current equipment probably doesn't owe you anything after all these years.:)

You might want to hook up your speakers to a known to working set. Maybe a neighbours?

Just a few thoughts.

Good advice Chas. Thanks. I found another pair of speakers to try and could reproduce the cutting in and out with them. Also, various gymnastics with switching all the wires around convinced me that the repair on the left channel was not complete. I don't think there is actually anything wrong with the speakers, its still the amp. Back to the shop.

BTW, the labour rate is $50/hour and I'm not planning to swallow another two hour charge.

Sounds to me like a very common problem with older electronics.

Switches and contacts form an oxidation on the contacts and are often the culprit in intermittent cutouts.

I would take it right back to the repair facility and have the amp/receiver properly cleaned and serviced which should include the cleaning and lubricating of all switches and dials or POTS.

I do my own and use spray contact cleaner DEOXIT with very favorable results. It is amazing what the tiniest particle of dust or oxidation can do in an electronic circuit.

I also find it is helpfull to work all switches and dials regularly. Keep the power turned off, work each switch and dial a few times and even apply some push or pull preasure when turning the dials. This could clean or wipe the contacts sufficiently to make a positive contact when you turn it on.

Gary

Thanks Gary. I think you're right about the oxidation problem.
Its back with the electronics shop now. They were kind of mortified to find their original repair job was not adequate.

I know its old equipment but if it can be cleaned up and fixed I'd rather do that than go out and look for something new. Is that cheap or just thrifty? :-)

Quote:

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Originally Posted by kyahgirl

Thanks Gary. I think you're right about the oxidation problem.
Its back with the electronics shop now. They were kind of mortified to find their original repair job was not adequate.

I know its old equipment but if it can be cleaned up and fixed I'd rather do that than go out and look for something new. Is that cheap or just thrifty? :-)

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Not cheap at all! I have had a love affair with my Sansui G 9000s for many years and refuse to ever give them up.

I'm not familiar with your HK amp at all but in todays electronics it is very hard to match the sonic purity of many of the older top of the line units from the golden age.

My G 9000s are rated conservatively at 160 WPC but when I had it in for repairs the tech bench tested it at 212 WPC before clipping. Not bad for a unit that is over 30 years old and still sounding great.

http://img.photobucket.com/albums/v7...cs/G9000LR.jpg

http://img.photobucket.com/albums/v7...nics/TwoGs.jpg

They do require a shot of deoxit from time to time but as long as that fixes them I'll keep running them.

Gary

:applaud:

Quote:

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Originally Posted by Gary L

Not cheap at all! I have had a love affair with my Sansui G 9000s for many years and refuse to ever give them up.

I'm not familiar with your HK amp at all but in todays electronics it is very hard to match the sonic purity of many of the older top of the line units from the golden age.

My G 9000s are rated conservatively at 160 WPC but when I had it in for repairs the tech bench tested it at 212 WPC before clipping. Not bad for a unit that is over 30 years old and still sounding great.

http://img.photobucket.com/albums/v7...cs/G9000LR.jpg

http://img.photobucket.com/albums/v7...nics/TwoGs.jpg

They do require a shot of deoxit from time to time but as long as that fixes them I'll keep running them.

Gary

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Lots of pics of most of my build projects.

http://img.photobucket.com/albums/v7...inets/Cab1.jpg

http://img.photobucket.com/albums/v7...inets/Cab8.jpg