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Old 27th May 2010, 09:23 PM   #1
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Default Problematic receiver - Luxman R-1050

I bought a Luxman R-1050 last month for $50. It had a bad lamp, a bad channel, a misaligned tuner with too much hiss, bad knobs and dirty pots.

A local tech fixed the bad channel. He noticed the receiver was blowing fuses. He told me there was something else going wrong, though the Luxman had played for hours after he repaired the bad channel. I paid him and thanked him for the warning.

I got the receiver home and crossed my fingers. It sounded fine; I have several vintage Luxman receivers, the sound is warm and detailed. But, after about two weeks of use, steadily running it with the volume knob at 9:00 o'clock... POP.

The left speaker made that noise as I was listening to the radio.
I disconnected the speakers and turned off the receiver. Then, I checked the speakers, they seemed undamaged. After a few hours, I left the speakers disconnected and turned the receiver back on. The R-1050's power protection kicked in. I turned it back off and fumed.

Later, I removed the wood case and looked for trouble signs. No leaking capacitors. No smoke or smell of burnt components. Just a decent amount of glue on the boards. I left it bare and turned it back on. It worked again.

This is the worst kind of snafu, since it's intermittent. As you know, many of the Luxman's parts are unobtainable. I'll borrow a multimeter this weekend and try to check for DC offset. I'd hate to have to trash this amplifier, but I know a problem child can be expensive and frustrating. I had an old Denon tape deck that wasted a lot of my time and a decent amount of money before I finally tossed it.

The Denon deck was irreparable in the end. I am hoping the R-1050 isn't. I'll buy some new caps if the DC offset readings are okay.

If anyone knows from my description what's going wrong with the problem child, let me know. If the DC is bad, I'll have to add about 30 pounds to the local landfill.

Thanks for any help that you can render.
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Old 28th May 2010, 04:45 PM   #2
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read carefully if you have the time cause here is how the story goes ....

if your "local tech guy " found one faulty transitor and replaced it simply the repair doesnt stop there for a number of reasons

if the replaced transitor is acrossreference and not the original probabaly the amplifier is out of balance probably working for a while and then brobably stop

if the replaced transistor is the same ... or at least the same number there is a grate chance that this "same " number is a good fake...then agaian you are close to boooom

there is almost no such thing as """many of the Luxman's parts are unobtainable""" cause you may choose to anything available in the market that is good quality and close or even better from the original .... only to parameters to look at one is quality of the product and then symmetric changes .... ( given as a fact that specs are close /same /better )

please notice that if you have the npn transitor brooken in one amplifier you need also to replace the npn that is complemenatry to it and then to be fair you need to replace the oposite chanels working transistors just for reasons of symmetric performance .

to make this plane Greek you cant have a car that uses michelen tyres in the left side and pirelli on the right ....its not the point if one ore the other is better ....it is importand to be symmetric

then again you are not done there .... in a machine like that of this age will not more carefull checks that just a fuse replacement ...its a fact that you cannot see leacking capacitors with a naked eye ... you need to check them ...if not replace them all without asking

as about the not working tuner this will be probably 5 minutes for an average tech guy that is capable to measure a few voltage


if you need a schmatic of your amp i willbe more than happy to sent you one ( please email me )

happy regards sakis
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SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr
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Old 28th May 2010, 06:35 PM   #3
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Default The Luxman

Sakis, thanks for your reply.

The tech's a good guy, and I trust that he used the right component(s) when he fixed the left channel. He's worked on my other Luxman amplifiers before, and they ran well.

I defer to your knowledge regarding the complimentary electronics. I agree that the 30 year old capacitors need replacing; I have been checking prices at Mouser. I can get all of the properly spec'd caps, most of which ought to be improvements, without breaking the bank.

Thanks for offering the schematic. As it happens, I downloaded it last night. Today, I found out from some engineer friends that I may have to check Mouser for replacement transistors.

Thanks for letting me know what I am in for.
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Old 28th May 2010, 07:42 PM   #4
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here is some aditional information vintage amplifier repair/upgrade manual

and let me know if you need any help if this can be provided by posts...been repairing few of these in the past

regards sakis
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SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr
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Old 28th May 2010, 09:03 PM   #5
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Default Luxman R-1050

Sakis:

The guide was helpful. Thanks for posting it.
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Old 30th May 2010, 02:45 AM   #6
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Default Old tape

One discovery since last time: I turned the receiver over, to see if anything jumped out at me as problematic.

I found old packaging tape on the end of one of the PCBs just below the volume knob. I know it was old tape because of the dust that resulted when I tore off the tape.
I couldn't remove all of it without extracting the board, but I got some of it. I blew out the dust with canned air.

People have found worse things in components, but this was still a surprise. I'll get hold of a multimeter soon.
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Old 3rd July 2010, 10:33 PM   #7
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Default Receiver is back in the shop

I couldn't find a cheap multimeter, and I have no soldering skills. This led me to back off on my repair attempts.

The local technician has the amp again. Today, he told me he found a bad transistor. A transistor that is no longer manufactured, naturally. He located a similar one and special ordered it. He isn't sure that bad component is the extent of the R-1050's problems, and he'll let me know once the replacement transistor arrives next week.

I'm going to pay out for the labor on this repair. At least a new transistor shouldn't break the bank.
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Old 4th July 2010, 09:33 AM   #8
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your approach is wrong and you are messing up with the wrong guy .... i think he is fooling you arround

there is no chance that a tranistor of a LUxman cannot be found in the market ...and if for one chance this is the reason ....and trouly it canot be found ...then you hardly need to replace one .... you have to replace the complementary ( if fault lays in amplifier board ) and you need probably to replace the other chanels working transistors just for reasons of symmetry ....

so the approach is wrong


then again schematic is availble for this machine ... you may as well verify the transitors existance /replacement /upgrade your shelf

then again another option will be to give the repair manual to the tech guy to read that might help a lot more ....

and finally as is clearly stated in the manual many of the small electrolytics inside will need replacement if not all ...that is a fact either you like it or not ... ( also that is that starting point for the repair of one amplifier ....)

about tranistors replacement i will try to explain this in plain greek ... you have an old car with a broken tyre ... there is no chance that you replace one if the rest four are pirelli with a michelen tyre .... they need to be all michelen or all pirelli .... sipmle as that ...

kind regards sakis
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Old 4th July 2010, 11:01 AM   #9
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This model I get sometimes for service, and it is for me easy to repair.

Before you start the actually trouble shooting
you must carry out follow steps:
1) download of Service Manual, e. g. about
HiFi Engine | Download Free User/ Service Manuals, Amplifier, Receiver, CD, Tape, Tuner, Video.
2) Replace all electrolytic caps (at least in both power amp stages)
3) Relace fuses f101A/B/101A/B, even it isn't defective/damage (sometimes dynamical/sporadic transiston resistances present - perhaps through oxydation effects)
4) replace Q101/102 a/b (often faulty through internal oxydation of the silver plated legs)
5) Replace zener diode D101 a/b
6) disass'y the relais for speaker DC protect and clean/polish the contacts carefully

For all follow checks operate without connected speakers !!!

If there is still DC present at the output, you must splitting the power amp stages in it's consist two parts for separately investigation (this is not only to use by R1050 but by nearly all the other power stages):

Isolating the voltage amplifier from the actually power stage (power buffer) and vice versa, in all cases include the appropriate necessary preparing (new NFB connection for investigation of only the voltage gain stage and separately CS for the power buffer idle current adjust to investigation of the power buffer without voltage gain stage).

Please note: If you are beginner and not professional, avoid the last steps and go to a professional service center that can do this
Attached Images
File Type: jpeg Luxman R1050.jpeg (46.2 KB, 219 views)
Attached Files
File Type: pdf Luxman R1050 power amp schema one ch.pdf (56.4 KB, 85 views)
File Type: pdf Luxman R1050 power amp schema other ch.pdf (56.8 KB, 45 views)
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Old 10th July 2010, 07:58 PM   #10
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Default The tech and the R-1050

I understand your skepticism. I called him this morning, and he is waiting for more transistors for the Luxman's left channel. These are on the way. If he called MCM Electronics for the parts, I know from my own experience they don't always ship things quickly. I will try to be patient.

I disagree that he's messing with me, though. There is a history here; I've been doing business with him for ten years. The only component that he disappointed me on was my Denon cassette deck, which was made in 1984. The parts for that deck are a pain to track down. He didn't fix the Denon, and he just charged me for looking at it. The money I spent on that non-repair was less than I paid for this Luxman. Speaking frankly, he can make more money on quick, easy stuff like busted CRT TVs and blown speakers than he can from a flaky 30 year old receiver. Given the intermittent nature of this amp's problem, at least he's making some progress. I think we can agree this is the most difficult type of technical issue to deal with.

If you find a good tech, you stay with him; that's something I have learned. Around here (DC metropolitan area), they are scarce.

Also, I haven't ruled out replacing the caps. I am still looking for a soldering iron.

Last, he asked me for the schematic a while ago, and I downloaded it and gave it to him.



Quote:
Originally Posted by sakis View Post
your approach is wrong and you are messing up with the wrong guy .... i think he is fooling you arround

there is no chance that a tranistor of a LUxman cannot be found in the market ...and if for one chance this is the reason ....and trouly it canot be found ...then you hardly need to replace one .... you have to replace the complementary ( if fault lays in amplifier board ) and you need probably to replace the other chanels working transistors just for reasons of symmetry ....

so the approach is wrong


then again schematic is availble for this machine ... you may as well verify the transitors existance /replacement /upgrade your shelf

then again another option will be to give the repair manual to the tech guy to read that might help a lot more ....

and finally as is clearly stated in the manual many of the small electrolytics inside will need replacement if not all ...that is a fact either you like it or not ... ( also that is that starting point for the repair of one amplifier ....)

about tranistors replacement i will try to explain this in plain greek ... you have an old car with a broken tyre ... there is no chance that you replace one if the rest four are pirelli with a michelen tyre .... they need to be all michelen or all pirelli .... sipmle as that ...

kind regards sakis
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