Saturday, 7 November 2015

amplifier - 1.5 kΩ resistors vs. 750 Ω resistors


The schematic of Klipsch SW-12 is on Page 15-17 of the following service manual:


http://www.audiolabga.com/pdf/SW12-15%20I.pdf



R87, R88, R89, and R90 get pretty hot.


[The schematic's Sheet 3 with the above resistors highlighted added 2/12/17.]


enter image description here


The schematic indicates they should be all 750 ohm 5W and the originals are 750 Ω 5 W 5 %; however, the service manual's part list indicates that they are 1.5 kΩ 5 W.


One of them reads only 426 Ω (off the circuit), so I'll have to replace it for sure.


Questions:



  1. What would happen if I replaced all of R87, R88, R89, and R90 with 1.5 kΩ 5 W resistors?

  2. If the amplifier operates with 1.5 kΩ resistors, will it run cooler?



[Added 2/9/17]


The four resistors are on Sheet 3 of the schematic, POWER AMP section, left side. The four resistors are vertically aligned.


[Added 2/10/17]


The following resistors do fit and seem to be stocked by distributors in the USA now.


= = = = = = = = = = = = = = =


TWM series by Ohmite:


[H x W x L: same as the original; same pin spacing]


5W 750 ohm 5%


5W 1K ohm 5%


5W 1.5K ohm 5%



Datasheet:


http://www.mouser.com/ds/2/303/tww_twm_series-25614.pdf


= = = = = = = = = = = = = = =


SQM series By TE Connectivity:


[H is 13 mm greater than the original's, but W and L are the same - will fit; same pin spacing]


7W 1K ohm 5%


Datasheet:


http://www.te.com/commerce/DocumentDelivery/DDEController?Action=srchrtrv&DocNm=1773285&DocType=DS&DocLang=English


== = = = = = = = = = = = = = =


MCPR series By Multicomp:



[H is 13 mm greater than the original's, but W and L are the same - will fit; same pin spacing]


7w 750 ohm 5%


Datasheet:


http://www.farnell.com/datasheets/1679919.pdf?_ga=1.72813905.374067655.1485773361




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