I need some help selecting a transformer for old hardware

[AnswersInGeneSimmons]

I need some help selecting a transformer for really old hardware.

So my project is an early 70's synthesizer/keyboard that I am trying to rehab.

I had it sort of working before but at one point, I realized that the transformer was damaged and needs to be replaced. While looking at it, the wires that go to the main body of the instrument came out and it has been sitting in my closet while I try to figure out what to do next. So right now, I can't even get power into the thing to see what other work I will have to do. Once I get a new transformer though, enough of it will work for me to look at the next step.

OK, that being said, I have found a couple of sets of schematics online. However, they only give me the voltage that I need (and one says I need +15-15, the other says I need +18-18) and not the original part number. For all that I know, the original part may not even be in production any more.

Anyway, I don't even know how to describe this part well enough to search any web site. If a drop-in part exists, that would be nice. If I can't find that, well there is plenty of room in the box for something of similar size.

Does anyone have any ideas for me?

 

[samppa]

Re: I need some help selecting a transformer for old hardwar

So the old tranformer is an external wall-pluggable power supply? Just pick it up and look at the specifications written on it. If you need help, report the specs here. There is not much we can do otherwise. If the synth needs dual voltages like +/-15V, it's just a matter of tranformer selection. Do you have any idea if the old power supply was regulated or not?

Btw, can I ask what synth this is? You should take pictures of the old transformer and the synth, preferably also of the synth's Pcbs so we could try to judge things.

-samppa

 

[karesz]

HI,
For me is not clear You have a transformer or a power adapter pls?

You must have some notes over PCBs, maybe you can see the +/- supply voltages in the synth if you dont know, than you must check what kind of regulator is to drive from the Transformer, some older realizations need 3-5 Volts! integrated circuits as i.e. LM 317/337 need at 2-2.5 V minimum..
On these way you can calcultae; is my voltage i.e. +/- 15V DC, for that i must give to that inputs min. 3 Volts more, also +/- 18-, better 19.5-20V DC_after rectifier!
Remember pls: rectifier needs i.e. another + 0.7-1V (bridges ~2V) DC.
So calculated(inclusive ca. -5% reserve for lower input /line voltages) you need a transformer MINIMUM with nominal secondary voltage of ca. 15Veff.
K.

 

[AnswersInGeneSimmons]

Re: I need some help selecting a transformer for old hardwar

Hey thanks for the replies and questions. That alone tells me that I might have a chance at this. Let me do this in an order that makes sense to me.

Pics: My current camera is 15 MP and I don't have the software installed to make the images forum friendly. That can come soon enough but a pic that I found on google may give an idea of what I am working with.

So, samppa, it is not a wall wart type. It is a cord that comes out of the unit. I think that it is US standard 12/3.

@karsz: Yah, I am really out of my depth here. I did have a friend who used to repair TVs in the 70's look at it (he was actually the guy who broke the transformer wires). He says that I have ICs in it.

 

[ProEngineer]

Post the links to the schematics and I'll bet we can figure out what transformer you need.

 

[karesz]

If you need pictures to edit, change i.e. to some lower pixel Nr etc...:
download irfanwiev_its free & really good!
K.
Forget all depressives_chance have you every times; max you (dont) will see/realize it!