DIY Repair Sunfire True Subwoofer Signature, Need Help

michaelwang New member Username: Michaelwang Post Number: 1 Registered: Oct-10	Posted on Friday, October 15, 2010 - 04:00 GMT My Sunfire true subwoofer signature is out of function after accidental short circuit at the high level input posts. I try to DIY repair it. There is an electronic item in the control board of this Sunfire true sub-woofer. This electronic component is a black diode-like item without any marker on itself and is directly connected with the negative post of the high level input. There is a label of printed "FB1" on the adjacent circuit board. It measured a zero ohms by multimeter. I've no idea what this electronic component is, at all. I really appreciate any help from you. Michael
Plymouth Platinum Member Username: Plymouth Canada Post Number: 15115 Registered: Jan-08	Posted on Friday, October 15, 2010 - 12:39 GMT Hi michaelwang You must check the bot fuses FB!1and FB2 out of its socket, if those fuses are not blowed, the converter output can be blowed! From what I can see on the service manual the amp is like a car amp running on 13 volts AC using a converter to increase the voltage up to +90/-90 volts to power the amplifier section throught 2 fuses. Very bad way to make a amplifier!
michaelwang New member Username: Michaelwang Post Number: 2 Registered: Oct-10	Posted on Saturday, October 16, 2010 - 02:54 GMT Hello, Plymouth, Thank you very much for your suggestion. I'll double check the two fuses in the amp module and the converter. Attaches is the focal spot of the control board of the subwoofer. The part I'm puzzling is the one in the center, with a diode looking and a print "FB1" nearby. It again measured zero ohms by multimeter on either directions. Is it possible a resettable fuse (PPTC)? I would be very grateful, if you or any one could check this out for me, while the service manual being handy on your site.
Plymouth Platinum Member Username: Plymouth Canada Post Number: 15130 Registered: Jan-08	Posted on Saturday, October 16, 2010 - 03:04 GMT michaelwang I just found the diagram without picture! Usualy FB1 is fuse board 1 Check this diagram then tell me if it is the good one: http://www.thecarversite.com/manuals/files-manuals/Sunfire%20Downconverter.pdf
michaelwang New member Username: Michaelwang Post Number: 3 Registered: Oct-10	Posted on Saturday, October 16, 2010 - 04:31 GMT Hi, Polymouth, I'm glad your point of fuse board 1 is on the same way as I thought. The link above is the amp module including the amp drive, two down converters, auto on/off board, power source, and so. It likely leave the control module behind. The F1 and F2 are the glass tube fuse for the positive and negative down converters, respectively. I haven't found the label of "FB1" yet. Nevertheless, I'm very delighted by the new link. Many thanks.
Plymouth Platinum Member Username: Plymouth Canada Post Number: 15140 Registered: Jan-08	Posted on Saturday, October 16, 2010 - 15:37 GMT michaelwang FB1 seem to be a filter Try to use the trigger to power the sub with a little 12 volts adaptor.(if you has it) Check for the 90 volts DC, if no voltage your converter can be blowed, if you got it the power output can be blowed. You can also use a new stereo amplifier to power the woofer by-passing the actual amplifier. You can hook the woofer throught the high level in connector.
Nuck Platinum Member Username: Nuck Post Number: 15458 Registered: Dec-04	Posted on Saturday, October 16, 2010 - 19:32 GMT did you measure FB1 with the componant installed, or did you disconnect one leg? If you do not have a sufficient meter and the most basic of tools, you may end up like Plymouth, guessing whether FB1 is a fuse or a filter. Stop. Do you have an analogue meter to read capacitance bleed? Stop. Man found dead with a 15$ RS meter in hand. Stop.
michaelwang New member Username: Michaelwang Post Number: 4 Registered: Oct-10	Posted on Monday, October 18, 2010 - 05:46 GMT My measurement of the FB1 was done by having one of the FB1 legs off the board. Thanks.
michaelwang New member Username: Michaelwang Post Number: 5 Registered: Oct-10	Posted on Friday, October 22, 2010 - 20:56 GMT The problem is solved. The FB1 is either a resettable fuse (PPTC)or low pass filter. Thank you all for your attention. Good bye.
Nuck Platinum Member Username: Nuck Post Number: 15495 Registered: Dec-04	Posted on Saturday, October 23, 2010 - 02:44 GMT Live and learn, I guess. See how it is done, kiddies.

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