Technics SL-3200 vintage turntable repair - 45 not working

[max1]

Hi, first of all sorry for my lack of skill level regarding this. I have a Technics SL-3200 & the 45 speed is not working, 33 is fine. Was wondering if anyone has any knowledge of the circuitry ? I’ve got it apart & can’t see any obvious cracks/physical damage on any of the PCB’s. I can see from the schematic that the simple 33 & 45 switching circuit share the same path back to IC1 (AN630U). Im not sure how IC1 handles these two voltages though & for what reason only the 33 speed is getting triggered. Maybe I should start by reflowing some of the relevant solder points. Voltages are good for 33 position but seem a bit skewed once in 45 position, however am unsure of correct voltages for 45 position (schematic only indicates 33 position voltages). Just wondered before I went any further if someone has experience with this old AN630 chip ? Grateful for any help whatsoever. The schematic is attached.

 

[rjenkinsgb]

I'd try giving the two pots/presets a slight movement either way & operate the switch a few times, to see if it's just a bad wiper connection.

The pots appear to be the only thing different between the two speeds?

[Edit - typo]

 

[Nigel Goodwin]

Yes, there's not much there to go wrong - try measuring the voltages on the speed adjusting components.

 

[KeepItSimpleStupid]

Possibilities:

VR4. The wiper opened. leave S2 in off and measure the resistance.

S2 oxidized. Leave S2 off and make connection with external jumper.

Clean the potentiometer and switches. Deoxit.

 

[max1]

Thanks for the replies. Yes I was thinking there shouldn't be much to go wrong but I'm not familiar with how IC1 works & so wanted to check. Great - ill take all your advice & see what I can find. Thanks again.