(This was originally a Twitter post from September 4, 2021)
September 4, 2021
On the bench today: I’ve had this Sony PS-F9 turntable for a few years but haven’t been able to fix it. Power LED lights in button held down. Otherwise, nothing. Any ideas?
Note: Own a Sony PS-F5 or Sony PS-F9 and missing the dust cover? You can purchase new 3D printed reproductions!
September 5, 2021
Opening the Sony PS-F9 turntable today. Lots of discrete transistors and a hot mess of wires. The LEDs don’t light at all now so there’s definitely a power issue. Guess I’ll start in the power section.
Single sided board means no vias means de-soldering is easy with copper braid. Q319 and Q320 seem ok.
First suspect, Q321. A 2SA1048-GR PNP bipolar transistor. Looks to be long out of production. How do you determine a suitable substitute?
Going to go with this A1015-GR transistor since it has somewhat close specs (499mW) to the 2SA1048-GR and I have some on hand.
Hey that worked! The Sony PS-F9 has sprung to life. Pressing the disc hold button toggles the record clamp at the top.
It goes through all the motions to play a record but it spins way way too fast! I suspect a problem with the “FG” speed detection. It looks like a coil of magnet wire. One of the two leads was broken off. A repair was attempted but I don’t think it’s good.
I should be able to measure a resistance across the two leads, right? If not, it’s open somewhere or not making contact?
I removed the “FG” sensor. The enamel wire is so incredibly thin (measured about 0.035mm)! It’s testing open or I’m not getting good contact.
To fix this, does one unwind the bad wire, count the number of turns, and then rewind good wire back on? Can that even work right? Is it a fools errand?
After more poking with a meter, I finally made a connection and got 540ohms for resistance. So it’s not broken inside. But the interior lead (pictured, circled) also broke so pondering how to connect to this tiny stub. Housing is plastic and withered at the iron instantly.
September 6, 2022
Hmmm. Some Kapton tape to protect the plastic bobbin and copper tape to make some terminals. Will it blend?
Wow!! I’m amazed that actually worked! I just played an entire side of an album all the way through without issue!! Hope this idea helps someone else fix their Sony PS-F5 or Sony PS-F9.
The Sony PS-F9 manages power very efficiently. While playing, it only draws an average of 140mA of current at 5.5v. It prefers 6v (4xAA batteries) but will work on USB 5v and lower.