, Only one speaker working.

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Liam2008-11-13 23:43

Recently I noticed an electrical frying smell (Ozone?_) coming from both of my Spectra 11 speakers are a long spell of playing them at high volume. Both speaker were still playing OK and sounding as brilliant as normal. I turned them off and had a look in side both interfaces. Nothing appears to be burnt off the circuit board, etc. However on turning them back on only one speaker is now operating. No sound is coming out of the flat panel on one speaker (the Bass speaker is still working). Also the 12 v power pack is gets hot on the faulty speaker. I love these speakers and I am keen to repair them. Long in the distant past I studied electronics and now definitely suffer from a little knowledge is dangerous/embarrassing. Can anyone suggest the most likely cause of the problem and a fault analyses procedure?


Liam2008-11-14 00:29

Hmmm...To isolate the problem I swapped over the interfaces...and guess what now both speakers are working and neither power supply is getting hot. I guess that I may have something like an intermittent soldering joint. Anyway I will leave well enough alone for the moment on the theory of if it isn\'t broke don\'t fix it

Andy Szabo2008-11-16 14:57

My guess would be that the plug for your wall transformer was not fully inserted into the jack. This could cause a short circuit, causing the transformer to get hot, and preventing the ESL portion from working. Read my story \"Ted Nugent vs Spectra 1100\" in the 1100 section. Although you have the Spectra 11\'s, they are similar enough when driven a bit too hard!

Liam2008-11-16 20:01

Thank you very much Andy. I traced the problem to a faulty power supply plug. Interesting story. The original jacks on my power supply/speakers started causing problems in the first couple of weeks of ownership way back in the early 90\'s. The local dealer swapped out the original 15V power packs for new 12V power packs ( I checked the good on and they were 12 volts with no load) he sourced locally with different two prongs pin where they insert into the speaker. (I don\'t have a clue what these plugs are called). When he soldered the new plugs on he stripped back too much insulation inside the plug and I discovered this had shorted inside the plug and yesterday afternoon this shorted enough to blow the power pack. I checked I have the 470 ohm resistor and I have changed out both power packs with 15V units. Interestingly this has significantly lifted the volume coming from the panels and improved the tonal balance of the speakers as a result. (I\'ve been missing this for 18 years!) The burning smell was from the circuit board getting fried under the 10 ohm 25 watt high pass resistors. I have temporarily spaced these 1bout 15 mm off the board until I can get some metal bodied replacements to do your recommended mod. Reading this site has got me inspired to try and source a better 8 inch driver and build replacement bottom cabinets out of MDF.

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