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Post by mastertech on Mar 27, 2019 17:53:49 GMT -5
Nice....  |
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nashou
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Post by nashou on Mar 27, 2019 19:55:40 GMT -5
Nice.... Not only do they look nice they sound nice!! Bottom end tightened up for sure ! Cant wait till the transistors come in and those are replaced , that should remove the background hiss/Noise. The smaller board here also has those 2SC900's . I think this board is the pre amp board and the tone board may be the phono board, or maybe not? I don't know, Not sure hard to follow the wires after the input wafer switch .   Lamps installed . Looking better now!!.  |
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nashou
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Post by nashou on Mar 28, 2019 18:54:11 GMT -5
Mac I do have some of those 2SC1845FTA with an hFE of 500 in stock. I could try them as I don't think that circuit will produce more than the 50 mA rating of the
1845. Tomorrow I should get the lower noise and higher mA versions, the BC550's
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nashou
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Post by nashou on Mar 28, 2019 19:59:07 GMT -5
Noise is way down now but gain is also down. That might be part of why noise is down.
These actually were hFE or 426, the old 900's had hFe of 698 . Need to use something higher gain. Before I did think volume went up
to quickly, so something in between those two should be perfect.
Nashou
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nashou
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Post by nashou on Apr 1, 2019 16:36:50 GMT -5
Just found out this is the same model as the Telefunken TR-616. But no info on that either .
Any way to find out how much power this amp produces?
Nashou
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nashou
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Post by nashou on Apr 1, 2019 17:58:44 GMT -5
Just found out this is the same model as the Telefunken TR-616. But no info on that either . Any way to find out how much power this amp produces? Nashou Just tried it this way. Used my iPhone with a 100hz signal into the AUX amp. 8 ohm load connected to both outputs. Stereo set to mono . Volt meter on AC connected to speaker outs as, same as dummy load. Played signal turned volume all the way up ( no scope to check for clipping , maybe next time but it played pretty clear at full volume last night) . Measured AC . noted it at 18.35 VAC. Measured 8 ohm dummy load a few seconds after powered off, read 6.5 ohms, so using the formula everyone uses I got just over 51 watts . Nashou |
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nashou
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Post by nashou on Apr 1, 2019 18:57:18 GMT -5
Here she is all together. I also changed all the transistors on the Head amp/Phono board, those were all over the place on hFE readings. Now they are all closer matched using BC550 transistors crossing the C and B legs to match the 2SC900 legs . Sounds much better now with a quieter background.    Athanasios |
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Post by mastertech on Apr 2, 2019 20:03:47 GMT -5
Nice work. On to the next project. |
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nashou
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Post by nashou on Apr 24, 2019 9:04:05 GMT -5
Nice work. On to the next project. Nope back to this again, ugh The bias voltage kept drifting , So as I was adjusting and measuring the clip slipped off a pin and there was a spark, It took out the 2SC853 and 2SA545 on the driver board. So I found originals from Beer city electronics for the 545's but had to go to honking for the 853's. Now I need a 3.5 trip pot, not sure what to use, I prefer multi turns. any suggestions? |
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nashou
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Post by nashou on Apr 24, 2019 20:18:51 GMT -5
Well I don't think its a 3.5 kohm trim pot. It measure that way but this one had no markings. But the one on the other board has this ......Looks like a 500 ohm pot right? I guess I need to remove the other pot and measure that one as well. Might be why this board kept drifting higher after I got it to where I wanted it.  |
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Post by mastertech on Apr 25, 2019 16:36:04 GMT -5
yeah, that one is pretty clear. I would pull them both and get measurements.
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nashou
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Post by nashou on Apr 25, 2019 23:18:35 GMT -5
yeah, that one is pretty clear. I would pull them both and get measurements. Yep the other one measured 523 ohm's . I ordered new pots before you replied back . Got a bunch of different ones too to have in stock. I'm still pissed that the clip slipped off!!! And its the kind that should spring back to prevent shorting, well it got twisted and was exposed not fully returned to its safe position after it slipped off . Hopefully the NOS parts will be of the same hFE as the other boards so I wont have to replace them all. Nashou |
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