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Luxman K-118 w/ New Belts Won't Play & Won't Make Sound!

Well, I measured a ~1.2V DC voltage drop across the IR LED (TLN104) which makes me think the LED is good. Soo. Hmm. Lost again.

(Although, this player was having the same issue and it was the counter - so maybe it's the sensor that's bad on mine, not the LED.)

So I should add an IR sensor to my parts list - problem is, I can't figure out what an available equivalent would be. The part # from the Luxman manual is TPS605.

Edit: All seems better (knock on wood) after I simply cleaned the LED and sensor with isopropyl alcohol on a q-tip. So I will leave that be until the new transistors & caps come in, and then cross your fingers that'll be it!
 
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Nope. New transistors (KSA992) went in at Q203a/b and Q204a/b and still nothing. And I just now realized that C203a/b are bipolar so I can't replace them with the polar caps I got. Ugh.
 
Measured the two pairs of double-transistors, Q201a/b (2SA798) and Q202a/b (2SC1583) and all 4 are fine according to my multimeter. So they are off the suspect list.

I suppose maybe a test light would help figure out where I'm losing the audio signal from the head through the amp? Is there a better way?

An important observation is that the music signal is no longer getting to those transistors I replaced. Even when I bridge them with the screwdriver like I had been doing before, now I just get a pop instead of a burst of music. This is actually making me second guess my determination that the head is OK. With everything in the amp section either new or testing OK, my finger is starting to point back to the head.
 
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Just for kicks I verified all supply voltages from the Fuse PCB and Control Supply PCB to the Main PCB. All good.
 
Measured voltages at Q201, 202, 203, and 204, and got some really wacky numbers. I need to print the diagram out so I can visually trace the source voltage in order to figure out where to go from here.

Q201: Both pins 1 and 5 should be at 0.2V

Q201a Pin 1: 1.5mV; Pin 5: 1.5V
Q201b Pin 1: 0.4mV; Pin 5: 0.6V

Q202: Pin 1 should be 13.7; Pin 5 should be 14.2

Q202a Pin 1: 15.2V; Pin 5: 13.7V
Q202b Pin 1: 13.7V; Pin 5: 15.2V

Q203: E should be 0; B should be 0.6; C should be ?

Q203a E: 11.3V; B: 15V; C: 14.3V
Q203b E: 11.8V; B: 15V; C: 14.3V

Q204: E should be -3.1; B should be -2.5; C should be ?

Q204a E: 15V; B: 15V; C: 14.6V
Q204b E: 5.5V; B: 15V; C: 14.5V

Sooo ... yeah.

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Gave my idler and capstan a treatment of Rawn Re-Grip and really improved the transport ... only to find that the counter stopped working, which caused malfunction in play, ff, and rew.

So now it has a questionable head, dead counter IR sensor and/or pickup, and unknown circuit malfunctions causing dramatically incorrect voltages in the amp circuit.

Time to throw in the towel. :( Officially gave it back.
 
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Johnny_Law said:
Ok, swapped a head from a working Technics deck (heads looked identical btw), and same symptoms. No sound until I touched the positive lead on the head with a screwdriver. So, can't be the head. Swapped the heads back.

Here's an interesting observation: insulated screwdrivers don't work. Sound only comes back if I'm holding the bare metal of the screwdriver! It must be transferring some kind of small electrical charge.

So now I'm thinking something electrical, something other than the head / tape mechanism, is causing this problem. I suppose I should try to start going upstream of the head, measuring any reference points along the way using the manual. Either that or forward from the power supply.
Click to expand...
I have the same problem, please tell me how to fix it, thanks
 
I have one with the same problem and suspect the 2SC1583 dual transistors are bad?
 
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Pretty sure I found what's causing the sound to come and go. Relay RY251 (Part# 221D012) which switches the output of the playback amp circuit has dirty contacts. I cleaned it with Deoxit and ta-da! Much louder sound coming out. Still cuts out a bit. I don't think it'll work reliably unless it's replaced.
 
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UPDATE: The output relay RY401 is bad too. Really no cleaning these things. They work for a while then you gotta fiddle with them again. These old Fujitsu relays have long been discontinued. Some sellers but NOS may have tarnished contacts since they'd be just as old and Chinese clones are probably poor quality. Adapting something from Omron would probably be the best bet since they don't make a drop-in replacement.
 
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