Korg SDD-1000 Schematic needed

[pvision]

Info needed on Korg SDD-1000... Not the SDE-1000, SDD-3000 or other versions

It's an early DDL. Power transformer is U/S

I am looking for a schematic or details on the secondaries of the transformer, or a replacement transformer

Primary is 220 Volts

Transformer is a Bando SL 68-30 2. It is also marked BANDO TB-802 4BBE1

It has five wires from the secondary and the plug on the pcb is set out as 1 + 4. The psu has three regulators, +15, -15 and +5

I assume the transformer secondaries are ground, +15 & -15 (or thereabouts) then +8 (or thereabouts) with a separate ground

Thanks!

 

[Whoops]

Hi,
I don't have a schematic for it, but maybe we can help you get info on that transformer so you can choose a proper replacement

Take some pictures,
is there any text or markings on the transformer?

 

[PRR]

is there any text or markings on the transformer?

"Transformer is a Bando SL 68-30 2. It is also marked BANDO TB-802 4BBE1"

 

[pvision]

I've done my homework since I posted. The schematic for the SDD-3000 is available so I used it to cross-reference the board layouts & etc with the SDD-1000. They are clearly related & have similar board numbers

Based on that I've ordered a Block ± 14, +9 transformer from RS. I think it should give me just enough volts to run the ± 15 regulators but, if it doesn't, I'll pop some LDO regs in there

One thing the SDD-3000 schematics make obvious is why the links from the PSU to the audio & logic boards have "too many" pins for the voltages they are carrying. The +5 & earth feeds are across multiple paralleled pins, which makes lots of sense

I haven't come across a three-output transformer from usual suppliers before. The one I have ordered is:

9V ac, ±14V ac 2 Output Through Hole PCB Transformer, 18VA
Radiospares Stock no.:201-8794
About £17

There are 10, 18, 30 & 45 VA versions but the 10 & 18 VA versions look to be the only ones that will fit in a 1U case

The original trafo primary has three connections for 110 & 220. One half is open circuit. The fuses after the transformer are OK so I am pretty confident the DDL will spring back into life with a new trafo

I should have the trafo tomorrow & will report back

Nick Froome

 

[pvision]

Success. The new transformer has identical mounting hole spacing as the original one so it can be bolted in. The mounting holes don't pass all the way through the transformer case but they can drilled out

Photos show a lash-up to test everything works: it does, so this transformer might be a useful choice for other projects that need ± 15 and +5 supplies.

Thanks for the help along the way

https://uk.rs-online.com/web/p/pcb-transformers/2018823/

Nick Froome

 

[tommia]

Who has got the schematics?

 

[gyraf]

..have you googled it thoroughly..?