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Old 24th September 2006, 04:41 PM   #1
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Question Another Tranny Question

I pulled a mulitap transformer from an Technics receiver - model SA 121 (35watts per channel) that I would like to use in a gainclone. The transformer is a Panosonic SLT5M373. There are 4 secondary leads (brown, blue, black, blue). I measured voltages as follows:

Meter on brown and 1st blue - 18.5v
brown and black - 11.0v
brown and 2nd blue - 41.5v

Is this transformer suitable for a 3886 gainclone and what is the best way to hook it up. Any suggestions greatly appreciated.
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Old 24th September 2006, 05:25 PM   #2
AndrewT is offline AndrewT  Scotland
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Hi,
did you try measuring between the other combinations?
Blu1 to blu2.
blu1 to blk.
blu2 to blk.
Just to be sure they are actually connected.
Sometimes capacitive coupling can give misleading voltages when using a high impedance meter.
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Old 24th September 2006, 08:14 PM   #3
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Andrew,

Blue 1 to Blue 2 = 60v, Blue 1 to Black = 30v, Blue 2 to Black = 30v. What do you think? Can I use this tranny for a 3886 gain clone and what voltage should I use? Know any links to a simple power supply design? Thanks for your help.

Bruce
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Old 25th September 2006, 03:37 AM   #4
jaycee is offline jaycee  United Kingdom
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Sounds like a 30-0-30 with an 11v winding in there for control circuitry to run from. That's too high for a Gainclone as it would produce +/-42v when rectified and filtered.

It's a bit odd that the reciever was only 35W per channel... those rails would be good for 90W into 8 ohms. Depending on the VA rating of that transformer it'd be good for powering two ESP P3A amplifiers
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Old 25th September 2006, 07:22 AM   #5
AndrewT is offline AndrewT  Scotland
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Hi,
the two blues are the main 30Vac secondary outputs.
The Black is the centre tap.
The brown is 11Vac single secondary referenced to the same centre tap.

What mains voltage was there when you took the measurements?
What load (or none) was on the secondary when you took the measurements?

You may have a 25-0-9-25 transformer when loaded to rated output.
You need to check voltage after the rectifier and smoothing when under quiescent load.
But, it might still be a bit high.
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Old 25th September 2006, 08:06 AM   #6
Nordic is offline Nordic  South Africa
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2 regulators should easily handle the little voltage drop,
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Old 25th September 2006, 11:43 PM   #7
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Thanks for all the input. I didn't measure but I assume the mains voltage is 120v. My secondary measurements were with no load. I'll use the blue leads and use regulators to set to best voltage. What voltage should I be shooting for? 28V?
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Old 26th September 2006, 04:42 AM   #8
jaycee is offline jaycee  United Kingdom
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You can use up to 35V with the LM3886 amps, just dont go running them into 4 ohm loads in that case
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