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Luxman Rx103

Dadrepus's picture

I just bought an RX103 Suckface off eBay. Seller says everything worked. Come to find phono stage broken. Do I send it back or fix it? Could just be the RCA's in the back as the ground was bent. So, what do you think? My first receiver with MM/MC capabilities if fixed. It looks great, with non of the scratches you normally find on these units. All other inputs work.



Re: Luxman Rx103

Contact the seller first and ask if you can open it up to take a look inside.
If you get the OK, look for the phono pre-amp board; it will start with 84D. It only has about 4 transistors and 7 resistors. I can't tell if the board is plug-in or soldered to the main board; it should be near the phono input jacks. I would check the 16 pin connector for bad soldering (on the main board). If it plugs in, try reinserting by lifting it up then reseating it. If this doesn't work then the problem is more severe like a power supply problem or bad components.

Dadrepus's picture

Re: Luxman Rx103

Can't be the power supply as everything else works. I'm of a mind to keep the thing anyway as they are very rare. I don't need it for now, I have a perfect RX102, L5, and a 404 so I can have some fun disassembling it. I'm hoping it is just poor soldering at the rca plugs. OPTIMISM ;-). It came with a bent ground plug so there's that clue.

Re: Luxman Rx103

If memory serves me, the "suck face" mechanism also controls the muting of the unit. If the mechanism isn't fully retracted it will mute the sound from the unit. Try powering the unit up while "assisting" (gently pushing on face plate) the mechanism. If that restores sound, you will either need to disable the mechanism or disassemble and replace the small belt.

-bob

Re: Luxman Rx103

After cleaning switches and controls, if both left and right Phono inputs are malfunctioning, it would likely be a power supply or switching failure. This unit uses a complex system of relays and transistors to affect input selections. RL601 and '602 are in the paths for Phono and Aux inputs. Easy test is to feed line level signals into Aux jacks while Aux input is selected, verify playback, then toggle Phono input on. If Aux signal continues to be heard, then RL602 is not switching and likely stuck. If toggling to Phono results in silence, then it is possible RL601 is not switching and possibly stuck as well. Gently tapping the relay housings may prove beneficial as it can help free stuck armatures. While rare, it is possible the low-noise dual OP amp has failed, IC601, NJM2043D. This chip is common and readily available. A broad assessment of power supply for switching can be made by simply selecting Tape, Aux and Phono functions, since the control voltages to switching transistors and relays is common. Considering that turntable usage was less common a decade ago, it is reasonable to think a relay is stuck due to lack of action, (Phono input was not used).

Dadrepus's picture

Re: Luxman Rx103

So, I tried hooking stuff up again. My kx101, a Turntable, speakers. Where, when I tested this unit before I got music from cassette, aux and radio, i now get nothing from anything. I opened it up and see 3 relays. Two near the power supply, one on the speaker board (this one seems to be a common one to fail cause ebay has these for sale all the time). Tried tapping each of the relays, to no effect. I have decided to keep the machine and have a local guy with a good reputation to look at it (no charge- imagine that). Thanks for all your advice but this seems to be way beyond my meager abilities to solder. The RCA panel is buried under the radio board? and it is mounted upside down, that is a first for me. Going to see him today.

If you are interested, I will report what he finds.

Re: Luxman Rx103

Well it appears that having technician dig into the problem is now necessary. The control circuits are complex and many failure areas exist, so voltage measurements and circuit tracing will be required. A competent repair agent should not have major difficulty locating fault. It probably won't be an esoteric component failure, so getting rig running again can happen. Having most all eletrolytic caps replaced (a k a "recapped") is logical choice while unit is being serviced. Luxman is good brand offering many well built models. Paying for repairs is good investment. FYI relay on speaker board (loudspeaker protection relay) is common replacement because it handles larger amounts of current than other two, thus fails more frequently. If time permits, post the technician's findings and repairs implemented. Best of luck with your project.