philips ga-312, the joys of electromechanical cue switch designs plus a few other features.

[sae-7125]

instead of photo-bombing an older thread, like the one listed below, i decided to start another new thread.

Problem with cueing mechanism on my GA-312

I have always liked the design of Philips GA-212/312 series. A Philips GA-212 was my first serious TT back in 1973. I find that I now have a problem with the switch that controls the cueing mechanism on my GA-312. The switch does lower the arm as designed, but arm immediately lifts back up as...

audiokarma.org

some youtube vids were informative but lacking in regards to intricate repair not to mention "part 5" of one persons vid ended in loathing contempt for this particular table and its unilateral idiosyncracies i.e. repair tech snarling at something with an undesirable learning curve (we all have been down that route more than a few times).

in regards to the lift/drop cue button repair or simply realigning the easy to disrupt metal lever in the sub-assembly. no weird mods or adding design "enhancements" was necessary, much to my surprise.

i will try to describe my findings with a series of photos since typing a book is too much work. the 312 being repaired, initially had a transistor go into retirement without the approval of the rest of the circuit. and so damage control was needed after the party died down. the main board was rebuilt, sorry no photos of pcb top side were take, and then the true headache started, cue switch be thy name. for those who have issues with the capacitive touch speed/off button sensitivity and it not latching with a brief touch there is a pot to adjust the sensitivity, works great.



a few basics first, brand, and yes the original power button still functions like it should.


model, even though the area lighting is too bright for the LED indicators. cue button in normal "up" position (after mech adjustment was successful)


some vinyl in not so great condition.


the particular sonic flavor being spun for a few rev's.


interior birth certificate, not that such things help to diagnose an issue. case screws are m4 15mm, if its not listed in the service manual.


pardon the mess, its the norm for this hobby.


mech removed and easily shows how badly that the control lever is out of place, a simple alignment nudge takes care of the issue.

i will finish posting the switch mech closeups in the next post once the photo storyboard is ready. lots of photos to process right now.

 

[sae-7125]

after looking through my collection of photo notes it would seem more than a few intricate shots are missing, operator error with a smartphone no doubt. so here are a few highlights of some informative points of view.


this is what the horizontal metal bar/lever should look like for proper mech actuation. the metal part that holds the wire+sleeve looks slightly bent upward because it is, to help reduce sleeve slack on both sides of the wire related mechanical connection. simple pair of pliers works fine just dont go crazy with pretensioning the system by over bending things.


here is a closeup of the main culprit for mechanical fubar, note the metal tab (upper right of photo, directly below brown wire) extending from the screw mount metal housing. this top down view does not show the overall size of the tab but it helps to convey rectangular tab for rectangular hole. you can see, after mounting the wire connected lever piece, there is some space for the tab to maneuver lower with reference to the middle mounted "neutral" position.


now the horizontal mounted lever is angling downward when toggling the cue switch. showing the designed range of motion, no 3rd party / repair tech crazy modifications needed. sorry, no duck brand duct tape for this project.

in my other photos, which apparently never happened, there were some side profile shots to help with 3d view of multiple 2d photos. depth perception can make a world of difference. either way hopefully this helps other people with slaying the increasingly common issue of cue switch mechanism has issues or as one person posted that things started working normal after reassembling without any repair attempts. good chance they bumped the crossbar lever back into place without realizing it since... its that easy to correct. took me a couple hours of inspecting and analyzing the little monster before the "ah ha" moment struck and i had a verbal homer simpson moment.

cheers, now i need to buy some fresh donuts to celebrate.

 

[mstap42]

@sae-7125 - Great write-up and photos!

I have a disassembly question: How did you separate the wood base from the motor board? I see your base is tipped up with the plastic bottom.

On my 312, which I bought new in '77, the position of the horizontal metal bar/lever seems to match yours. I want to pull out the actuator to get a better look, but that seems dependent on the wood case being off.

[The next day...

I got it. Seeing no fasteners, I tried prying it gently with a plastic putty knife, releasing it from strips of thin, double-sided tape.

I removed the actuator. Comparing mine to your high-quality pics, mine is aligned correctly.​

]

 

[Tennangler]

Your photos of the solenoid mechanism really help me understand the operation. I had removed the solenoid and the wire that connects to the solenoid screw had come off. I didnt know where to connect it. I will put the solenoid back in even though I dont know if it works. It never made a click when it was in. Is there a way to test it?
Thank you,
James

 

[sae-7125]

It never made a click when it was in. Is there a way to test it?

could do a resistance check across the solenoid to make sure its not open. probing where the wires connect to the board would be an easy way to do it.

 

[Tennangler]

One of the wires came off the solenoid when I removed it. From the photo it appears it connects to the mounting nut of the solenoid. When I connected it to the nut the turntable wound not turn. Now I am not sure where that wire is suppose to connect to. Can someone tell me where it goes?
Thanks,
James

 

[sae-7125]

PHILIPS RECORD PLAYER 22GA312 – MECHANICAL ADJUSTMENTS, SCHEMATIC DIAGRAM AND PART NUMBERS

Service Modes,Circuit Diagrams,Firmware Update process,Disassemble procedure,Universal remote control codes,Troubleshooting,electronics basics

masterelectronicsrepair.blogspot.com

*might have some useful info, although indicates 220v version (different mains txf spec)


in the upper right corner of clickable schematic #5 (fifth down from the top) shows a solenoid connected to b24 and b22 board circuit/pad locations


directly below the solenoid area is b24 location


b22 located near bottom right corner of the same schematic

would be best to compare some of the wire connections on the board you are working on vs what the schematic says to see if the schematic is accurate (testing validity of document).

the schematic also has voltage measurements on it which can be useful for troubleshooting transistors if needed.

 

[Tennangler]

My wires from the solenoid are connected at the correct places on the board. I dont know where the wire from B26 connects to the solenoid. It came loose when I removed the solenoid. The photo appears to show it connected to the mounting screw but that must not be correct. I dont see any tab on the solenoid to connect it to. Is there someone who owns this model that knows?
Also what is the white paper on the solenoid bracket? I dont understand how the solenoid assembly works.
Thanks,
James

 

[AGKY]

The turntable is working pretty much flawlessly, but there’s this one thing that’s been bugging me. The first time I press the cue button after powering it on, the switch doesn’t latch right away. I usually have to hold it down for a few seconds—sometimes even longer than it takes for the arm to lower onto the record—before it finally locks.
What’s strange is that this only happens the first time after turning it on. After that, the cue switch works normally: I press it, it latches instantly, and the lift drops as expected.

Has anyone run into this before? Could it be a solenoid issue or something mechanical with the switch? Any tips would be appreciated!