Well my project got complicated. I had an OK Industries SA-1001 missing the handle and they are hard to find and cost a ton. It was "female" 6 pin. I ordered a 6 pin Hakko 8001 6 pin handle which is a male plug. The pin lay out is totally backwards and nothing like like the Hakko. Ground is like pin one or two on the OKI, heater like 3 and 6 .. just odd and weird than standard. I jumper-ed them correctly and the transformer/iron works fine. The board of the OKI is either fried or don't work right. It will not control the temperature. Its full power/temp.
I said heck with it and ordered a T12 control board, handle, buck converters, and all I need to hook the T12 to the 28v transformer.
Now I have decided to just buy a large project box, a 24v 4.5 amp power supply for the T12 kit, which is a "male" 5 plug. That will cover the T12 handles.
Buy a 936 control board which uses a 5 or 6 pin "female" plug and will accept various handles. I have checked the lay out of various pin outs and resistance on heaters/sensors on Hakko style handles.
So in the end I will solve my problem by having a box with a plug and control board to control which ever handle I find cheap or have (Hakko style that is)
Messing with this OKI station... now I already have a collection of several style Hakko handles, extra tips, with female/male plugs goofing off with this OKI station.
So I already have this good 28v transformer. I hate to just buy another one and spend more $ on a new 24v one >
https://imgur.com/a/ixcBOFuIf they are a simple and cheap way to make it work with that 936 board I ordered.
The 936 board I bought is this one -
https://www.ebay.com/itm/A1321-For-HAKKO-936-Soldering-Iron-Control-Board-Controller-Station-Thermostat/112719961476I already have spent a lot of $ trying to make this OKI work but I have learnt (especially reading here at EEV and messing around) a lot so in the end it is all worth it.
mariush: I got the voltage off the transformer 14/28 unloaded it measures 16 / 33 volts VAC about 20-ish one side VDC through a bridge rectifier and smoothing capacitor unloaded