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Post by prime on Oct 9, 2022 12:48:32 GMT
Hi guys troubleshooting an issue with low volume on right channel, the amp is a SHFA-5 . Ive tried switching tubes from left to right no change, if i remove the 6eu7 tube for that channel volume increases, when i first start up unit volume is good then decreases, i have switched speakers no change. pete
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Post by emelaich on Oct 9, 2022 13:53:59 GMT
Don't have a schematic handy but check any electrolytics and resistors in that tube's signal path and B+ sections. Might also look for a cold solder joint at the socket as well as any dirty contacts. A voltage check with a socket extender while in actual operation-pre- and post- fault would be ideal.
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Post by prime on Oct 9, 2022 14:26:26 GMT
I notice that on the weak channel i can test both 047 1000vlt caps while in circuit and get the caps value, on the side where the channel is good ,the same caps can only be tested with one leg removed, if no legs removed i get ol on both caps, both circuits look the same so i feel they should both act the same, also on the good side those same caps show ohm resistance but the bad side 0 I compared all resistors going to the sockets and they match side to side. I will check socket solder joints. pete
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Post by prime on Oct 10, 2022 0:01:09 GMT
Problem solved, When I decided not to use the 6973s due to stock issue , I had read that the 8 to 1 had to be jumped due to the newer tubes not being internally connected. I was also informed the the 6to 3 would not be an issue. On my unit channel 1 the factory connected the 7199 to the two 6973 using the pin 6 , unfortunately For some reason on channel 2 they connected one to the 6 and one to the 3. I rewired the 3 to 6. All is right again.
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