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103.2 shutting down to often

 
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cameron
Introductory Contributor


Joined: 29 Aug 2005
Posts: 2
Location: chapel hill nc usa

PostPosted: Mon Aug 29, 2005 3:28 am    Post subject: 103.2 shutting down to often Reply with quote

I have a set of black 103.2's I bought from Intratec(the KEF USA distributor in the 1980's). I have loved these speakers but recently when turning them up to a moderately loud volume, the protection mode is cutting on too much(red light on front of speaker panel). I am running these on older linn equipment(LK-1 and LK-2). The sound is excellent and when I switch channels the same speaker shuts down.

Can I replace the crossover, tweeter or woofer I don't want to get rid of these gems but I am getting annoyed.

Any suggestions???

thanks cameron
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ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Mon Aug 29, 2005 1:03 pm    Post subject: Reply with quote

Bit late today as I've been to a bank holiday market, got a box of 48 Creme Eggs Very Happy .

The next part carries no guarantees whatsoever as I'm not an electronics expert, but if you are using a smallish ac signal which has limits on current and voltage you can only rectify it in a couple of ways to power a relay.
Now as you have a late pair, the two red elements TF2 - diode pack to power the relay and TF1 - a two transistor switch with two Zener diodes under reverse bias, which does the switching.
TF1 could be faulty - why? Have your speakers ever met a big HK or Krell?
The two orange blocking capacitors,plus R3 and R5 should be ok.

Back to normal Cool .

You can swap bass units over as they use automotive type terminals.

Have you ever turned the bass units? A slight rub will increase the current drawn and potentially trip the circuit

Tweeters and the crossovers require some surgery to the tweeter leads, although the input wires have ring terminals.

Removing the boards from the cabinets will be a pain btw. Remove nut and bolt and use a razor blade to cut through the double sided foam tape on the long dimesion at each corner and 1cm in on the input/output wire side, unless it comes out easily.

You could remove the switch TF1 and use Polyswitch protection for the drivers.

You could borrow a Quad 405-2 to drive the speakers. This amplifier is very good a showing up faulty bass units as the heatsink shows marked diffferential warming. i.e. one side gets hotter quicker and stays that way.
This is to save swapping the bass units and potentially loosing the metal shims inside the rubber mounts.

Replacement crossovers can be found, I have a pair, which took me about ten years to find for a "project" and they are as yet "untested" so I don't know whether the protection circuit works properly or not. Note, shipping the circuit boards outside of the UK would be prohibitive, so don't ask unless you're in my neck of the woods.
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cameron
Introductory Contributor


Joined: 29 Aug 2005
Posts: 2
Location: chapel hill nc usa

PostPosted: Tue Aug 30, 2005 1:47 am    Post subject: Reply with quote

Thanks for the quick reply, I appreciate it. Let me see if I understand. It sounds as though I should first, switch the bass drivers and see if the problem moves to the other speaker. If is remains in the same speaker it will probably be a crossover or tweeter problem. If the problem switches speakers i should then try to rotate the bass driver that is causing the problem. If this does not solve it I will need to puchase a new bass driver, model #?. I did not quite understand your comment of removing the tf-1 switch and using a polyswitch to protect the drivers???

where would i get this??

Perhaps I could also switch the tweeters and see if the problem shifts to the other speaker.

Pardon my lack of understanding it may be a language thing!!

Again thanks for your time,

Cameron
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ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Tue Aug 30, 2005 12:00 pm    Post subject: Reply with quote

Quote:
will need to puchase a new bass driver, model #?.


SP1075.

Quote:
I did not quite understand your comment of removing the tf-1 switch and using a polyswitch to protect the drivers???


TF pictured here, if you remove the switch it can't switch off.

http://www.hifiloudspeakers.info/Anatomy/SpeakerSystems/103.2/ColinRoyle/KEF103.2XOver.jpg


0.5, 0.8, 1.6 amp Polyswitch sources Falcon Acoustics, Parts Express, etc, do a "Google".

Woofer damage is statistically your most likely problem judging by the numbers of moans and groans about KEF 103-2's on various International and Country specific Internet Newsgroups.

For local speaker repairs in the U.S. seek out a dealer who can recone Bozak and Advent marques, they seem to have their act together regarding rare and expensive drive units.
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