Blown outputs (maybe?) in my Forte' 3 amp. - diyAudio
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Old 9th August 2010, 08:11 PM   #1
gullaz is offline gullaz  Italy
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Join Date: Jul 2010
Location: bologna, italy
Default Blown outputs (maybe?) in my Forte' 3 amp.

Hello to all Pass Labs forum users. This is my first post on Diyaudio.
I have blown three output transistors on my recently acquired Forte' amplifier while trying to adjust the bias...
The amplifier was running rather cooler on one side so I opened it and tried to correct the difference measuring the amperes... Result: three devices on the left channel are probably gone as well as two of the emitter resistors and when I try to power it up it blows both fuses.
As a total noob I was very imprudent to mess with something I don't know...
Now my problem:
As original toshiba outputs are difficult to find
(they are 2SC3281/2SA1302) I have found out that possible replacements are 2sc5200/2sa1943... In this case may I replace only the three blown outputs with the new equivalents or should I replace all the devices in the left channel or, worse, replace all the devices in both channels (ouch!!).
Sorry for posting such a simple and banal question but I thought that here there might be many users that know this amplifier and can advice me for the best.

Thanks in advance for any kind answer you will give me.
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Old 9th August 2010, 08:20 PM   #2
The one and only
Nelson Pass's Avatar
Join Date: Mar 2001
Likely you could replace just the blown devices without
problems. Most audiophiles would be bothered by the small
asymmetry of such an approach (or by a splice in their
speaker wire).

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Old 9th August 2010, 08:35 PM   #3
gullaz is offline gullaz  Italy
diyAudio Member
Join Date: Jul 2010
Location: bologna, italy
Thanks a lot for the answer mr. Pass, I was only concerned by possible reliability issues... This cheers me up a lot: I'll change the burned devices only (and control the left channel bias trimmer which was probably gone.
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