Brians Rev 3 LM3875 Kit and Center Tap Transformer - diyAudio
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Old 10th September 2006, 11:56 PM   #1
hotscot is offline hotscot  Scotland
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Default Brians Rev 3 LM3875 Kit and Center Tap Transformer

Gentlemen/Ladies

Building my first Gainclone. Stereo pair, single rectifier board, single transformer.

I have a Center tapped transformer, outputting on three wires. I've checked that it works and that I get +25 and -25 volts wrt to the center tap.

My problem is that I'm unclear on connecting these wires to Brians LM3875 Rev 3 board.
Believe me, I've just read about 100 posts on this subject and some of the advice has been conflicting, hence my confusion.
So has anyone actually done this correctly themselves?

With respect to Brian, part of the problem is that the manual he provided doesn't seem to be rev 3 specific but instead refers to an earlier board.
(I assume V+, V- and PG+ and PG- are the DC to the chips and that AC prefix means Alternating Current?)

I don't want to make connections until I'm clear that they are correct.

I've attached a jpeg of the board in question.

Regards
Alan
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Old 12th September 2006, 06:35 AM   #2
sangram is offline sangram  India
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There's a page in the manual on how to connect a center-tapped transformer, but you have to use only 4 diodes, not 8.

It's also referenced in one post on Peter's huge thread in the 'Vendor's Bazaar' section, but finding that will be tough.

Ok, wait, here goes:
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Old 12th September 2006, 06:43 PM   #3
hotscot is offline hotscot  Scotland
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Thanks. I do have this info but it shows an earlier board whereas I'm using the rev 3.
That's probably no different but I'm just making sure that the procedure is the same.
Thanks Again
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Old 4th October 2006, 05:19 PM   #4
keps is offline keps  Philippines
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Quote:
Originally posted by hotscot
Thanks. I do have this info but it shows an earlier board whereas I'm using the rev 3.
That's probably no different but I'm just making sure that the procedure is the same.
Thanks Again
I also have a rev3 board and initially it is confusing that the manula talks mostly of the previous revision.

If you check with the PS board, PG- and PG+ is not in anyway connected. But if you check with the amp board they are common for each channel, thus, if tou have a center tap transformer, you can just split up the centertap to connect to PG- and PG+ on each of the PS board.

PG-+ is 0volts.
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