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Old 3rd June 2012, 03:35 AM   #1
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Default THRESHOLD STASIS/500 RUNNING HOT

HI, Ibought my threshold s/500 from woodbridge stereo in new jersey in 1988. i have never had a problem till moving to mexico city,mexico. and not with the electricity. in reconecting my infinity kappa nine speakers one day. a fuse blew out and i replaced it with a higher value. stupid me. 3 years later the amp lost a channel . i found a krell dealer here in mexico who sent me a tech who has repaired the unit replacing ,i think 6 transisters. but my power amp is running hotter than usual. whats wrong and how to fix it. the tech told me when he comes back from vacation in a month ,hell recalibrate the bias. to what id like to know. why wasnt it done right the first time as he told me he did recalibrate the bias?. can anyone help me> THANK YOU, ALLAN ROTHMAN
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Old 3rd June 2012, 03:58 AM   #2
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No telling what was done.

Are both channels running equally hot?
Both channels different?
Is this change recent, and some time after the repair?

The fuse likely had nothing to do with the problem, unless you also had a blown/defective speaker. I don't use fuses in my speakers, so that's really a non-issue.

Also, HOW HOT?
There are inexpensive hand held infrared non-contact thermometers now, you can ebay order or mail order or Harbor Freight order them. that will tell you what the real temperature is of the heatsinks, and of each device, if you point it at it...

...can you hold your hand/fingers on the heatsinks without discomfort?

Likely the transistors should have been matched, fyi, and fwiw, although I am not certain that it matters much in your amp, someone else will know this.

Also were BOTH channels repaired, or just one?

Keep in mind that with a higher average temperature in Mexico (likely so) compared to New England USA, the heatsinks will be hotter to the touch.
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Old 3rd June 2012, 04:29 AM   #3
6L6 is online now 6L6  United States
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Higher ambient temperature, and significantly less dense air due to the altitude of the city means that your amp can't cool itself optimally. It's going to run hot.
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Old 3rd June 2012, 05:41 AM   #4
a.wayne is offline a.wayne  United States
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S500's run relatively cool , takes some heavy running to get them hot to the touch ...
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Old 3rd June 2012, 09:12 PM   #5
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HI GUYS, all of you ar3e really great ,thanks. the amp was just repaired, both channels, 6 motorola transisters,i think. the fuses that were wrong were the fuses on the power amp. yes its running very hot,i am using it with a fan blowing right on top of it to keep it cool. its working fine with the fan but obviously its not right to run so hot. i need to be able to suggest to the tech ,who readjusted the bias when repairing it ,and who also told me that pover time the bias had changed . i need to know what to tell him is correct in case he is just trying out different numbers. again thanks for your input,i really appreceate it. ALLAN ROTHMAN. ----OH I HAVE BEEN LIVING HERE IN MEXICO CITY FOR THE LAST 18 YEARS WITH NO PROBLEM ,TILL NOW.
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Old 3rd June 2012, 09:33 PM   #6
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Quote:
Originally Posted by BANANABRAIN View Post
HI, Ibought my threshold s/500 from woodbridge stereo in new jersey in 1988. i have never had a problem till moving to mexico city,mexico. and not with the electricity. in reconecting my infinity kappa nine speakers one day. a fuse blew out and i replaced it with a higher value. stupid me. 3 years later the amp lost a channel . i found a krell dealer here in mexico who sent me a tech who has repaired the unit replacing ,i think 6 transisters. but my power amp is running hotter than usual. whats wrong and how to fix it. the tech told me when he comes back from vacation in a month ,hell recalibrate the bias. to what id like to know. why wasnt it done right the first time as he told me he did recalibrate the bias?. can anyone help me> THANK YOU, ALLAN ROTHMAN
I don't understand this term:
but my power amp is running hotter than usual
which temperature is usual and which temperature is now present (both channels and both heatsink and ambient) ??
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Old 3rd June 2012, 10:01 PM   #7
Zen Mod is offline Zen Mod  Serbia
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Default here it is

.
Attached Files
File Type: zip thresholdadjust.zip (180.7 KB, 101 views)
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Old 3rd June 2012, 11:36 PM   #8
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HI TIEFBASSUEBERTR and ZEN MOD , Thanks to both of you, esp. ZEN MOD for the specs. what i mean about running hotter than usual is, I just now turned on the amp without any signal, after about an hour and a half it got hot , but i was able to just about leave my hand on top near the back for more than 5 or 7 seconds. the left side seemed a little hotter than the right. but when i play music i remeber it got much hotter and couldnt touch it. does that answer running hotter than usual? and i see that it needs veery careful adjustment to the bias to 90 mv. and needs to stay at 49 degrees. ok ill tell the tech when he returns from his vacation. hope he can do this in my home and dont need to lose the amp for anther month. thank you again, sincerely,ALLAN ROTHMAN
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