Stancor PT

[andrew]

Does anyone have any information on a Stancor P-6287? It is in the power section of a Lowery organ 6v6 push pull with a 6sL7 driver and rectifier tube. I would use it but there are more wires coming out of the transformer than I am used to seeing and they are all just about the same color. Also there are other tube sockets wired up and it is all very confusing. Thanks for any help!

[muchxs]

The data sheet I'm looking at for the Stancor P-6287 says it's a step down transformer 230 volts down to 115 volts.

[mhuss]

Yes, both new and old data show that as an autotransformer. Are you sure that's the right number?

--mark

[andrew]

It says P-6287 and below it there is 606921. I googled P-6287 and came up with a Stancor P-6287. I'll get some pics up tomorrow. Thanks!

[andrew]

pictures

[mhuss]

Hmm, you got the number right, but it doesn't look at all like the P-6287 in my 1961 Stancor catalog.

--mark

[Richie]

might be a Woodward-Schumacher transformer

[andrew]

I just emailed Schumachererelectronic.com to see if they have any info. Thanks!

[rhinson]

might be a Woodward-Schumacher transformer

yep if has a 606 as it's eia code it's a schumacher. rh

[muchxs]

I wouldn't worry about what it is, you have enough clues in that chassis to figure it out.

At a glance it looks like you have at least one rectifier socket. If there were sockets for two rectifiers it's just a little more complicated but you can count on enough current for anything you may want to try. I'm seeing one rectifier socket.

It looks like an NC pin on the rectifier socket is being used as a tie point for some additional circuitry which doesn't help to simplify matters.

There should be two yellow (ish) wires going to pins 2 and 8 on the rectifier socket, those are your 5 volt filament supply for the rectifier. There will be a lead coming off pin 8 to your filter network, that's your B+ lead. There will be high voltage leads on pins 4 and 6 of your rectifier socket. Measure either of these pins referenced to ground and you'll get your high voltage on either side of CT readings.

There will be a small bundle of wires strapped to ground, that's your HT CT and your filament CT. It looks like there are center taps strapped to ground in two locations.

There will be a pair of green (ish) leads that can eventually be traced to pins 2 and 7 of your 6V6s, that's your 6.3 volt filament. They may go other places first, in an organ amp they'll go to one of the oddball sockets on the chassis to supply another sub-chassis in the unit. Filament supply is wired in parallel in this application so those green leads connect to every socket in the unit besides the rectifier.

There should be black leads that trace back to the switch on the console and the AC cord, (or another oddball socket on the chassis) those are your AC primary leads. Yeah, one of the primary leads comes off the lug on the fuse holder. The AC cord connects to a socket that connects to the switch on the console which then returns to the other end of the primary winding.

Just carefully trace everything, stick a little masking tape tag on each lead when you figure out where it goes. Where it goes is a big clue to what it does.

A handy trick: If you can drill the rivets out of the rectifier tube socket you may be able to remove it from the chassis without disturbing the connections to the PT. If you don't disturb the connections to the socket it can be transplanted into another amp with less labor.

Organ amp wild card: Hammond used a mechanical tone generator so this doesn't apply to Hammond. Everyone else used tube oscillators up to the point where the tube circuits were supplanted by transistors. The earlier tube circuits demand a lot of current especially filament current so there may be an additional filament winding on the transformer. It's at least another pair of brown, yellow or green (ish) wires that seem to go nowhere except to an oddball socket on the chassis, the extra filament supply can be good news and it can be bad news. The good news is that if the extra filament supply is 6.3 volts you can hook it up without further thought to any tubes that require 6.3 filament. It's usually a relatively high current winding so if you want to use KT66s of EL34s for instance you have enough filament current, part of the bad news is that if your power amp used 6V6s the supply voltage may not be in the ideal range. Measure either pins 4 or 6 referenced to ground at the rectifier for voltage on either side of CT or pin 8 for raw voltage prior to the filter network.

The rest of the bad news: There was no reason for the extra filament winding to be 6.3 volts so it frequently isn't, it might be 12.6 volts. 12.6 volts isn't quite as useful as 6.3 although if it's center tapped it can be considered TWO 6.3 volt filament supplies. Or just ignore it and use the other filament supply.

It's a Schumacher so it would be a good transformer for a Super Reverb or a Vibroverb project.

[andrew]

Thanks muchx. I'll dive into it after the holiday.

[andrew]

I just cleaned out the Lowery project up so I can see what's going on. file:///Users/dollenemclemore/Pictures/iPhoto%20Library/Originals/2008/Roll%2071/DSC02852.JPG /Users/dollenemclemore/Pictures/iPhoto Library/Originals/2008/Roll 71/DSC02856.JPG There are three mystery wires: thick green, thick white, and a thin green/yellow(not grounded) I can't figure out which is the center tap and which is the filament ground. Any help would be Great! Thank you, Andrew

[doctord02]

Try reposting your link, thats not gonna work for any of us, it points to your local hard drive...

[andrew]

pictures The mystery wires are green/yellow at 12:00 and thick green and thick white at 7:00

[andrew]

There were white smooth wires coming off of the DC pin of the can cap. One of those wires went to the green/white wire at 12:00.