sc50 plus transformer wiring

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sc50 plus transformer wiring

Postby ampcabinets on Sun Jan 17, 2016 2:56 am

anyone have this.
Myy trannies are the following wiring schemes

PT:
green and green are the heaters, of course.
brown and brown are the bias windings determined by one side was to ground with the grey shield wire.

red and black pair seem to be the Hot tap

and the other side has a white wire which seems to be connected to nothing
and 3 ac wires, black, red and yellow

the normal scheme for these trannies is the input side has 4 wires, plus neutral [(105v, 115v, 220v, and 245v) and neutral]
I seem to be missing an orange wire or something.

OT:
double wiring on the output side for 4, 8, 16 and 100v taps and the other side has 4 wires as:
red/black as a single pair and orange and black as another separate pair.
I assume both blacks are centre tap and the orange and red are tube outputs, but then I am asking, too.

The schematics I have seen, do not show separate transformers on the output side and only show 3 wires, as per usual.
and although most schematics do show the wiring, they do not show which color codes come off the transformer(s).

easy enough for the output impedances, but the input throws me with dual wiring. I would assume both blacks go to the rectifier, and the red and orange are the tube supplies.

I just don't want to fry my trannies before I get a chance to use them, which is why I am asking if anyone has these trannies in their SC 50 watt with similar wiring.

thanks in advance if you can help.

I tried to add a pic of the diagram, but the board says "board attachment quota has been reached", so someone may need to purge something.

when it lets me, I'll attach photo's of the tranny ies and their respective diagrams.
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Re: sc50 plus transformer wiring

Postby BruceF on Mon Jan 18, 2016 8:26 pm

I am working on my 200+ and the voltage selector only has 3 wires from the power transformer connected to it. On the outside it says 105, 115, 225 and 245; however on the inside there is no wire connected to the 105 position.

105-no connection
115-Green
225-Yellow
245-Red
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Re: sc50 plus transformer wiring

Postby pdf64 on Tue Jan 19, 2016 3:18 pm

After messing with such things, always power up via a light bulb limiter.
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Re: sc50 plus transformer wiring

Postby ampcabinets on Tue Jan 19, 2016 10:54 pm

Please...I am always careful, but thanks for the reminder.
40 years +

Bruce, thanks, but my primary side of the PT only has black, yellow and red.
I appreciate your taking the time to respond.
I am trying to upload pics as we speak, so you can see what I have.

Most of the partridge power transformers seem to follow the same scheme, when using the connections, 110, 120, 225 and 245.
The diagrams suggest the orange (105v line is virtully the same wire as the 110v line
Mine, "seems" to be missing the orange wires. but again, who knows for sure...

resistances seem to be black-to-red 5 ohms
black-to-yellow 10 ohms
red-to-yellow 15 ohms

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Re: sc50 plus transformer wiring

Postby Mr. Foxen on Tue Jan 19, 2016 11:59 pm

Those are not Partridge transformers. Those are the Electro voice ones, so don't assume they are same wire codes.
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Re: sc50 plus transformer wiring

Postby ampcabinets on Wed Jan 20, 2016 8:04 pm

ok, thanks.
However, can you elaborate on the give-away?
And have you seen them before,
and do you know the correct wiring?

possibly the dual wiring on the input end of the OT?, I am just guessing...........
Mercury told me they have never seen a partridge before with this wiring, either.
I can post the numbers on them if you like.
They 'do' show signs of a partridge label, or one similar.

I would have had no idea, on either account.


Also, I would think electrovoice anything would be up to snuff,. but how do they compare to the partridge.

I noticed an amp, on ebay, in england, that has a partridge and an electrovoice.
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Re: sc50 plus transformer wiring

Postby Papa Dog on Thu Jan 21, 2016 2:38 pm

This is by no means authoritative. All I can tell you is what I have heard from other guys into these amps.
Some time, ca. '74-'75, after the change from D/A to DMI, Partridge stopped making transformers for amps.
Some builders started having transformers built by "Electro Voice", but it isn't the American company which builds speakers.
This is a British company and i do not know much about them.
Anyway, it looks like DMI did not change over all at once, They seem to have used up the Partridge stocks and substituted Electro Voice as they ran out of Partridges...so, an amp with both either came from a "transitional" time or has had one of the transformers replaced. If the burnout happened after the transition then the obvious result would have been that the replacement unit was from the "new stock".
Id anyone would know the difference it would be Mr. Foxen. He has likely had his hands on as many, if not more, Sound City amps than anyone else except DMI.
Suffice it to say, the obvious difference is the lack of varnish on the Electro voice one.. They obviously went to some trouble to replicate the partridges, but they do not have the "yellow" colour and even the frame on the Partridges have that varnish on them. (Usually...I haven't seen them all so I can't say definitively)
I have no experiential knowledge as the any differences in performance.

Do you have an estimated fate for the build? Or did you buy these transformers as "pulls"?
Please do post pics of any stickers and codes that might be there. I am trying to accumulate sufficient information to compile a database.
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Re: sc50 plus transformer wiring

Postby pdf64 on Thu Jan 21, 2016 9:41 pm

I've got a 50+ at my band room that I'm fairly sure has these tx.
If you can hold on for a few days, I'll bring it back next time I'm up there, and report back regarding the wire colour arrangement.
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Re: sc50 plus transformer wiring

Postby ampcabinets on Sun Jan 24, 2016 8:23 pm

yup, they are dedicated to my "last"..[yeah, that's what they all say]...amp I am going to build and it is for me.

I bought them as a pair.
The lack of varnish, I, also, assumed was going to be a give-away, once it was mentioned, elsewhere.
Looking at my 120 and 100 versions, the 'are' "completely" lacquered, as you said.

I prefer the partridges, especially for output.
They always seem to be clean and have lots of push or punch behind them.
These seem to be the first EV I have run across, for a power transformer.

What I did find out, is that the EV's for this series, it seems, only has 120 and 220 taps for supply voltage.
The red/black secondary pair are the Hot-taps, grey is a shield on one side, and white is a shield on the other side, the browns are the bias leads, one to ground.
Red on the primary is 120v, black is neutral and yellow is 220, in my case, not used.
Which is right, because I have hooked them up already, and measured voltages.
Nothing like, just doing it.
It would be nice to have someone, with one of these, to actually look inside a 50+ to see how or if it differs.
That is appreciated if you get around to it.
We can get soundcitysite to post them for all to have for reference, since we know they exist and it would be nice to have them 'for' reference.

Also, I beileve the OT I keep saying is a partridge is actually an EV, although it does have the correct wiring, with one exception....the input wires on the OT 'ARE' separate windings. They show no connections between them (each pair) and use the center/inside wires from each winding for the HT, soldered together, as I got the transformer.
It would be nice if someone else had this particular style transformer, also, for reference/verification.
There has been some kind of verification, theough another person, who didn't go inside but took measurement and the only connections ARE 120 and 220v. He does know he has the same PT, but is not sure of his OT, and I don't blame him for not wanting to look further, although he may, later. I will post all I find.

To note, also, the numbers are on a long white sticker, NOT painted on, as are all of the partridges I have seen, in the past. Although they do seem to have the same numbering scheme.

I will say this, all of the real partridge power transformers, seem to have the same exact input AC wiring, although the output may differ slightly in the bias, Heater and HT colors (I think to mark different sizes [120, 100 50 and 20 watt versions] . Although, like you, I haven't seen them all, by any means. I haven't seen a 200 watt, but I would assume the input is the same as the rest. It woiuld be interesting to note the output colors on the 200PT, as well as the entire OT.
This would be another 'give away' I think.

Unless there is some kind of rapture, I have all the time in the world, as I am ordering a classictone stand-up jtm-45 style, [very versatile] power transformer as I decided to go with tube rectification, although I may do a dual rectification, just because I can.
The trannies being on the outside leaves tons of room, inside for even a [dual-bias-board-type], to go with the dual rectification, so it always sees the correct current/bias settings.

The amp, itself is built, and is a basic jtm-45, modified, to add a few bells and whistles.
single channel, single input,and the Controls are [MV, Ga, Pres, V, B, M,T, Spd, Int.], with switches for deep, bright, and hi/lo impedance.
It should be somewhere in the 45-50 watt range, with 6L6's, or 5881's, possibly KT-66's, probably not el34's.

I'll get some shots and post a prelim pic, of the wired chassis, waiting for trannies.

and thanks for the replies,
Last edited by ampcabinets on Sun Jan 24, 2016 8:52 pm, edited 4 times in total.
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Re: sc50 plus transformer wiring

Postby Papa Dog on Sun Jan 24, 2016 8:46 pm

send me an e-mail with all the pics and specs.
I will make a place for it
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Re: sc50 plus transformer wiring

Postby ampcabinets on Sun Jan 24, 2016 9:16 pm

will do. I'll send you what I ave scrounged and you can sort through it. Use what you need, and toss the rest. If I collect more, I send the additional to you.

I think the sound city amps are far under-rated.
The only thing I have seen about them is age, seems to get their Electrolytics dry up, faster than others, but beyond that, they are like army tanks, and the tone is fantastic.
I do have one that I converted to hiwatt 103 circuit (my 120LB), and it is absolute killer, with master volume and 6 power tubes. It will go from fairly quiet, to blow you out of the room or off stage, if you like, with ease and stay clean up to about 9 on the dial with GT 6L6 10's and a full GT preamp front end, although I normally prefer a sovtek front end. I wanted to see the difference betwen active and passive tone circuits, between a sound city and hiwatt.
I, already have a dr103 and a Lead 100R , no comparison between the 2. The original kills the 80's series.
with 2 custom built hiwatt style cabinets, 1-2x12 and 1-4x12, in a stack, loaded with JBL's, red hiwatt tolex/wheat cane grill cloth.

and a little off topic, then there is the marshall custom stack, with the deep 2x12 bottom to go UNDER the slant 1960a cabinet, all loaded with eminence legends, 200 watts each speaker. blonde, with wheat grills, white piping, wheel slots in the 2x12 to hold the 4x12 in place, both ported cabinets. A JMP-100 watt model on top, sporting, you guessed it, partridge transformers. And it kills.
The matching 50 watt (sitting on top of the 100) is a blend of fender hardware, and marshall circuits, blended with a bit of fenderish tone in the normal channel, marshall on the bright side.

If I can, I always collect what partridges I find. I have a waiting list for them and an amp to go with them, when I 'do' find them.
no phone, no pool no pets....I ain't got no cigarettes!...............Roger MIller
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Re: sc50 plus transformer wiring

Postby ampcabinets on Tue Jan 26, 2016 10:33 pm

here are some things I found and modified for the EV transformers.
I used the picture of the insides of one, just like, apparently, the ones these trannies came from, ... to verify the diagrams.
Image
Image
Image

other things I said I would post
Yep, sitting in the dining room, so I can play while I eat.
Great for playing that stereo, just a bit loud.

Image
Image
Image

hiwatt lead 100R pics

note the lousy bendable handle on top.
The inside is circuit boards and I will post pics as soon as I get it on the bench.

Anyone have a diagram for the hiwatt lead 100 (or anything else with reverb) of early days, or did they even exist?

Image
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That new amp


Image
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Re: sc50 plus transformer wiring

Postby monsterwool on Thu Oct 06, 2016 7:58 pm

bumping this old thread, I recently got a sound city 50 that showed up here dead, someone has screwed w the output section, preamp sounds great but the output section barely passes signal. Could anyone with a 50+ post a close up photo of the output section wiring in the chassis? Cant see the photo posted in this thread earlier with enough detail to make heads or tails of things here. Any help is wildly appreciated.

thanks!
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Re: sc50 plus transformer wiring

Postby Papa Dog on Thu Oct 06, 2016 8:57 pm

Image
There Ain't No Such Thing As A Free Lunch.

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Of cabbages--and kings--"
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