PS Audio 4.5 preamp

Hello. I have a PS audio 4.5 that never was powered on. I finished replacing all electrolytics with Rubycon Black Gate capacitors. My story begins with a passion on this preamp first listened to in an audio store in Dallas, TX in 1986. So, as I kept flipping the PCB to repair the far left selector switch, blue cover unsnapped. Made by Lorkin (no original part number). Don’t know if a piece was broken but the 2 wafers, plastic shaft and cover are undamaged. After reassembly I find no solid indents? Just a semi-smooth rotation was left $ right full stops.
Is this switch broken? How do I reassemble it. I tried many times but no luck. I understand there is a replacement part from Allied electronics & RS but it only shows a single wafer. Anyone know the part number andd the set-up for the 4 selector indents orientaton. Need help!!!

This is called a Lorlin switch and they were out of England. To my knowledge, they are no longer manufactured and haven’t been for many, many decades. I wish I had better news.

Most people replace them with a similar rotary selector and instead of PC mounting, figure out how to graft wires from the switch to the PCB. It’s not easy or pretty. Might be time for an upgrade?

Hello Paul:

Thank you for your quick response. I don’t think it is broken, but I can not see how it was indented to the 4 position switch. Was there there another part perhaps lost when it the cover popped off. I was always enjoyed all of your products.

Best regards,

Dr. Anthony

Can you post a picture?

Hello Paul

Here are the photos from your 4.5 preamp. I think it is a 1986 production.The blue inside cover has lettered numbers. I found a small spiral about 1 inch that may be associated with it placed through the plastic shaft holes on its side side??






The switch looks complete except for the shaft. Problem is that even complete, these Lorlin switches went bad over decades. They were, in hindsight, a poor choice we made for building a long term product. Your best bet would be to replace them with a better

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a spring and ball in the white slots in the circular mechanism 2nd pic from the bottom would give indents in the travel (if it hasn’t pinged off somewhere upon opening)?

Hello Joma
Its starting to make sense now. I did find the spring which inserts through the 2 holes. Need to find the ball. I was replacing the electrolytic when it happened. Problem is do a index the switch. The selector switch has to move 4 positions as seen on the face-plate. Any idea how to position the shaft. Thank you

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Afraid not, trial error is your (distant) friend I guess…