Help Needed - Sub Amp Died - diyAudio
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Old 9th October 2012, 12:57 AM   #1
Muddler is offline Muddler  United States
diyAudio Member
Join Date: Oct 2009
Location: USA
Default Help Needed - Sub Amp Died

I have a Definitive Technology subwoofer PF15tl+ that met the reaper the other night. It’s 10+ years old and quit while being driven pretty hard. The amp is in two pieces referred to as High Level (Output) and Low Level (Input). I have attached the schematics. Nothing physically looks amiss but again it died playing hard and made a couple of “not normal sounds” before turning off.

I think the issue is with the Low Level board. Here is what I can tell you:
(Low Level Schematic – page 8)
120 VAC coming in past the fuse
27 VAC out of transformer (schematic lists 32VAC but I measure 27VAC?) (T1)
32 VDC out of rectifier (DF02)
15 VDC out of voltage regulator (LM337LZ)

(Low Level Schematic page 6 and 7)
**-> Problem: 6 pin ribbon connector between boards - pin 4 and 5 are supposed to turn on the relay on the high level board
32V+ on pin 4 BUT “–Spkrly” is not a ground.
LED does not come on but does work (one leg is “-Spkrly”)
If I jump pin 1 (ground) to pin 5 the relay does open on the high level board.
The relay on the High Level board does work fine
I did replace the diode that was across the relay’s coil on the high level board, it was reading like diode in both directions (not open backwards)

Now somewhere on page 6 or 7 is where I think the issue is but I am at a loss to figure out what to check (I am a weekend hack at best apologies up front.). Any and all thoughts would be appreciated.
Attached Files
File Type: pdf pf15tl+ high level.pdf (57.7 KB, 56 views)
File Type: pdf pf15tl+ low level.pdf (88.3 KB, 32 views)
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Old 6th December 2012, 10:03 PM   #2
diyAudio Member
Join Date: Dec 2012
I have the same problem, mine is about 11 or 12 years old just died 2 weeks ago. Sub was never driven hard, just made some crackling sound and stopped working. There is power and the auto detect lights up but no more sound. Brought Sub to a Definitive Tech dealer and was quoted about $490 to repair. I hope this can be repaired for less because I really like this Sub. Hope we have luck. Thanks
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