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2275 Phono Board P400 Left Channel Out

Steven Tate said:
One way to find out is swap H401 and H402 and see if the problem switches sides. Or just replace them.
Click to expand...
I changed out H401. The voltage at H405 collector is now 14.7V Then changed H403, for good measure.

R418: 5.4V Center (what I called FAR before)
34V Outside (What I called NEAR before)

R432: 14V Center
34V Outside


Will now hook up TT and do final test, and then report.
 
Ta Da! TT works both channels, I'm just gonna let it play for a while before I call this done.

Thanks to everyone who responded! You were each and every one of you lots of help and I am very grateful for this successful collaboration! AK is amazing!

Questions:
1. Would KSC1845 be a better sub? (I recall 2240s were subbed a long time ago before they went obsolete.) I had enough of the KSC1815s on hand to replace all of the H's.

Based on rated Hfe:


ORIGINAL FACTORY
2SC1344: 250
2SC458: 60 (min)

SUBSTITUTES
KSC1845: 200
KSC1815: 70 (min)

2. I used my stock of 1815s for all 6 small signal transistors, and I've read threads here where the same trans was used for all. I know there's more to substitution than just Hfe scores, but for output levels would it be better to order KSC1845s for all or just to sub for the 2SC1344s? or just leave the KSC1815s in for all?

3. The H405 collector read 16.7V on one channel and the H406 read 14.7 on the repaired channel. Are the pot adjustments made to even this out? From what I've read, it's a very sensitive and tricky subject.

Thanks once again to everyone!
 
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ZeroG said:
Ta Da! TT works both channels, I'm just gonna let it play for a while before I call this done.

Thanks to everyone who responded! You were each and every one of you lots of help and I am very grateful for this successful collaboration! AK is amazing!

Questions:
1. Would KSC1845 be a better sub? (I recall 2240s were subbed a long time ago before they went obsolete.) I had enough of the KSC1815s on hand to replace all of the H's.

Based on rated Hfe:

2SC1344: 250
2SC458: 60 (min)
KSC1845: 200
KSC1815: 70 (min)

2. I used my stock of 1815s for all 6 small signal transistors, and I've read threads here where the same trans was used for all. I know there's more to substitution than just Hfe scores, but for output levels would it be better to order KSC1845s for all or just to sub for the 2SC1344s? or just leave the KSC1815s in for all?

3. The H405 collector read 16.7V on one channel and the H406 read 14.7 on the repaired channel. Are the pot adjustments made to even this out? From what I've read, it's a very sensitive and tricky subject.

Thanks once again to everyone!
Click to expand...
That’s awesome! I wouldn’t mess with the adjustment unless you hear a distinct difference in the channel. I’m not qualified to tell you whether to change them to 1845’s. But that is the most common recommendation. 1815’s and 1845’s often work interchangeably, so may not be important here. Hopefully someone who has an educated opinion will chime in. Congrats!
 
Great that you can hear sound from both channels!! Well done!
I always used KSC1845 on this board. I would suggest using the same transistors on both channels. I never touched those pots on this board so I can not say anything about that!
 
Regarding the KSC1845: Digikey, Mouser, and Bdent are all out of stock. Any other sources for this small signal transistor?
 
LOL! Newark has the 1815s also, but min order is 2000 pieces @ $.30 each. I'll go with the 1845s, thanks, and the 100 is more than I need but it's actually the sweet spot, since I'd want to get at least 25-30 to match them properly.
 
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