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.
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.
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
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
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.
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.
here is some aditional information http://www.diyaudio.com/forums/solid-state/136261-vintage-amplifier-repair-upgrade-manual.html
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
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
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.
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.
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.
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.
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
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
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
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
Attachments
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.
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.
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
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
Replacing the caps
A few people I have mentioned the steps that you listed.
No doubt, you know more about these repairs than I do.
I figure I can handle replacing capacitors. I am probably not the guy to disassemble the speaker relays, let alone clean and polish anything in there.
If the tech can't fix this Luxman with the transistors, then I just pay him for his time and toss the old receiver. I can't be the audio equivalent of the car lover who buys a classic 12 cylinder Jaguar E type in very bad shape, and spends more than the car's blue book value on repairs. If I am going to learn to work on audio equipment (which is why I like this site), I don't want to learn on this Luxman. If I buy another H/K, Denon or Onkyo amplifier, then I'll learn on one of those. If I fry one of those amps in my attempts to fix it, then I won't be too upset.
If I ruin an amp like this... that's cause for gnashing of teeth and breaking screwdrivers.
A few people I have mentioned the steps that you listed.
No doubt, you know more about these repairs than I do.
I figure I can handle replacing capacitors. I am probably not the guy to disassemble the speaker relays, let alone clean and polish anything in there.
If the tech can't fix this Luxman with the transistors, then I just pay him for his time and toss the old receiver. I can't be the audio equivalent of the car lover who buys a classic 12 cylinder Jaguar E type in very bad shape, and spends more than the car's blue book value on repairs. If I am going to learn to work on audio equipment (which is why I like this site), I don't want to learn on this Luxman. If I buy another H/K, Denon or Onkyo amplifier, then I'll learn on one of those. If I fry one of those amps in my attempts to fix it, then I won't be too upset.
If I ruin an amp like this... that's cause for gnashing of teeth and breaking screwdrivers.
Finally back from the shop.
Got it back today.
I think the tech replaced pretty much every transistor on the amp's left channel. He had to go hunting for the right replacements as they were hard to find, he said. On the invoice for the repairs, one pair of these transistors cost eleven dollars total with shipping. The others were $12, totaling $23 total in parts.
Thanks for all of the information. I won't buy another amp with a bad channel. The labor cost isn't what aggravated me. The time and effort to figure out an intermittent problem was the true aggravation. I got this amp in May. It's August.
Had it playing for about 90 minutes so far. Not a hiccup. It sounds just great.
Got it back today.
I think the tech replaced pretty much every transistor on the amp's left channel. He had to go hunting for the right replacements as they were hard to find, he said. On the invoice for the repairs, one pair of these transistors cost eleven dollars total with shipping. The others were $12, totaling $23 total in parts.
Thanks for all of the information. I won't buy another amp with a bad channel. The labor cost isn't what aggravated me. The time and effort to figure out an intermittent problem was the true aggravation. I got this amp in May. It's August.
Had it playing for about 90 minutes so far. Not a hiccup. It sounds just great.
It stays in protection mode
As you can tell, I have had a LOT of trouble out of this receiver since I bought it a few years ago. It was in the shop for weeks, and needed several parts and a decent amount of labor.
I was cleaning the receiver's volume, balance and tuning pots with generic contact cleaner. After I cleaned the tuning pot and turned it back on, there was a loud POP through the speakers, and the protection circuit kicked in. I'm fairly certain folks heard that noise in Charlottesville.
Now the receiver will not work, it just pops goes into protection mode.
It's been doing that since last night. I disconnected the speakers and everything else after the second pop.
How bad is this problem? Is it a "take it to the tech and pray" kind of issue? Or is it "the receiver's toast, part it out and buy an L-480" thing?
As you can tell, I have had a LOT of trouble out of this receiver since I bought it a few years ago. It was in the shop for weeks, and needed several parts and a decent amount of labor.
I was cleaning the receiver's volume, balance and tuning pots with generic contact cleaner. After I cleaned the tuning pot and turned it back on, there was a loud POP through the speakers, and the protection circuit kicked in. I'm fairly certain folks heard that noise in Charlottesville.
Now the receiver will not work, it just pops goes into protection mode.
It's been doing that since last night. I disconnected the speakers and everything else after the second pop.
How bad is this problem? Is it a "take it to the tech and pray" kind of issue? Or is it "the receiver's toast, part it out and buy an L-480" thing?
As you can tell, I have had a LOT of trouble out of this receiver since I bought it a few years ago. It was in the shop for weeks, and needed several parts and a decent amount of labor.
I was cleaning the receiver's volume, balance and tuning pots with generic contact cleaner. After I cleaned the tuning pot and turned it back on, there was a loud POP through the speakers, and the protection circuit kicked in. I'm fairly certain folks heard that noise in Charlottesville.
Now the receiver will not work, it just pops goes into protection mode.
It's been doing that since last night. I disconnected the speakers and everything else after the second pop.
How bad is this problem? Is it a "take it to the tech and pray" kind of issue? Or is it "the receiver's toast, part it out and buy an L-480" thing?
After I read this, I called just two users, that use receivers of the same model and where I perform the same steps mentioned about post #9 (one resp. two years ago). Both users told me, that no problems have occurred until know. Thus your problems are no typical issues by this model.
.
The described issue indicates to an error in the power amp stage (DC occurs for a short time at the speaker output). Until error is found, one must work only with voltmeter and oscilloscope - otherwise you risk the damage of the voice coil from your speakers.
Last edited:
Luxman aggravation
Thanks for the info.
I did disconnect the speakers, and everything else. I have an update on this.
Wednesday, after two days of the receiver staying in protection mode, I grabbed a flashlight and looked into the volume potentiometer area. I had already checked the tuning knob area and the balance and tone controls. Almost out of sight, at the top of the volume pot opening was a folded up bit of masking tape, lodged there near the small printed circuit board behind the potentiometer. I pried the tape out of there. There was mucilage or some other adhesive on it to hold the damn tape in place.
Why put that tape back there?
I saw no reason for it. What tech (or DIY wannabe, like myself) would do that?
I kept looking. The case is real wood. I found a small piece if that wood, maybe two inches long, near the edge of the main PCB. I cursed mightily, and used nearly half a can of compressed air to get any other detritus out of that receiver's various recesses.
After a while, I turned it back on.
No POP, and no protection mode. I crossed my fingers and let it sit, with the FM going. So far, so good. I plugged in my Grado 'phones and listened. Loud and clear.
All that trouble, from masking tape and a glorified splinter? I can't believe it.
Thanks for the info.
I did disconnect the speakers, and everything else. I have an update on this.
Wednesday, after two days of the receiver staying in protection mode, I grabbed a flashlight and looked into the volume potentiometer area. I had already checked the tuning knob area and the balance and tone controls. Almost out of sight, at the top of the volume pot opening was a folded up bit of masking tape, lodged there near the small printed circuit board behind the potentiometer. I pried the tape out of there. There was mucilage or some other adhesive on it to hold the damn tape in place.
Why put that tape back there?
I saw no reason for it. What tech (or DIY wannabe, like myself) would do that?I kept looking. The case is real wood. I found a small piece if that wood, maybe two inches long, near the edge of the main PCB. I cursed mightily, and used nearly half a can of compressed air to get any other detritus out of that receiver's various recesses.
After a while, I turned it back on.
No POP, and no protection mode. I crossed my fingers and let it sit, with the FM going. So far, so good. I plugged in my Grado 'phones and listened. Loud and clear.
All that trouble, from masking tape and a glorified splinter? I can't believe it.
with rare resp. sporadic occurrence of such errors your way for troubleshooting isn't the right way.
Download the sm from hifi engine.
Disconnect the volume control completly (except GND connectors) so as one line input (e. g. AUX or Tape-IN) and C101a/b.
Replace C101a/b against a foil (MKT/MKP) type between 1uF and 4,7uF (not critical).
connect the middle pins of the volume control to the disconnect end of C101a/b
and the outer pin of volume control with the disconnect end of the line cinch terminal.
Now only the power amp section work (maintain for long time investigation).
After removing all issues next step is the investigate of the preamp section.
This means that all changes must be undone (of course except the replace of C101).
Before start trouble shooting for the preamp section keep in mind, that I have already provided, all electrolytic caps in the signal path are already replace through foil types.
Download the sm from hifi engine.
Disconnect the volume control completly (except GND connectors) so as one line input (e. g. AUX or Tape-IN) and C101a/b.
Replace C101a/b against a foil (MKT/MKP) type between 1uF and 4,7uF (not critical).
connect the middle pins of the volume control to the disconnect end of C101a/b
and the outer pin of volume control with the disconnect end of the line cinch terminal.
Now only the power amp section work (maintain for long time investigation).
After removing all issues next step is the investigate of the preamp section.
This means that all changes must be undone (of course except the replace of C101).
Before start trouble shooting for the preamp section keep in mind, that I have already provided, all electrolytic caps in the signal path are already replace through foil types.
What is the DC value at the output in your case?Hello!
Does anyone know how to improve DC offset on this receiver?
I am assuming that you have to replace and match transistors? Which ones in that case?
Any info highly appreciated.
Is this value stable or do you observe temperature dependend fluctuation ?
here is a repair a joke that can put you more inside the picture on how Tv repair techs think and work
Not many know cybernet amplifiers... actually its a good average commercial Japanese amp similar to manly like Luxman or Pioneer .
One comes to the shop for repair and the story goes like that
Outputs are blown and some other small transistors inside ...outputs and drivers are easy to replace even with cross reference transistors but one of them ( the impossible to obtain was 2SC 1865 ) made all the mess ..
At first was replaced with any transistor with the wrong pin out that resulted all blown again ....
then the unobtainable 1865 was replaced with the closest much resulting the amplifier not to be working properly again and here was the final stop for the tech guy ...
you see the 1865 was buffering for the VAs so actually its not an easy thing to replace drop in ... many parameters might cause complications ...
So since the 1865 was not possible to get the tech gave up
The tech guy in his conquest to find or replace the 2SC 1865 he missed that the amplifier all ready included about 24 pcs of 2SC 1865 in the VU meter area ( with a very light duty IE on and off one led so it can be replaced with almost everything ) and another 4 pcs of 2SC 1865 in local supply working as voltage regulators and also possible to replace with any available transistor
got another one for you .....
Luxman LV 105 U is a hybrid .. first stage is transistor second stage is mosfet next stage is tubes and final stage is mosfets again
Tech guy replaced the outputs with the next available mosfet quite ok job amplifier works dlivered to the costumer ...
few days later amplifier stops and come to my shop .... There was nothing wrong with the repair outputs worked properly but the tech guy missed the obvious ....Luxman amplifiers of that age suffer from thermal stress and soldering issues .... meaning while he was plugging in and out headers and plugs the soldering down under got even worst so amp stopped due to soldering issues .... only
The tech spend time searching on the internet regarding output recommendations and missed to look at the compete picture of the device ....
As about the offset if its a faulty part can be easily located but if its a replaced part that doesn't fit into the picture you have a nightmare in front of you
kind regards sakis
Not many know cybernet amplifiers... actually its a good average commercial Japanese amp similar to manly like Luxman or Pioneer .
One comes to the shop for repair and the story goes like that
Outputs are blown and some other small transistors inside ...outputs and drivers are easy to replace even with cross reference transistors but one of them ( the impossible to obtain was 2SC 1865 ) made all the mess ..
At first was replaced with any transistor with the wrong pin out that resulted all blown again ....
then the unobtainable 1865 was replaced with the closest much resulting the amplifier not to be working properly again and here was the final stop for the tech guy ...
you see the 1865 was buffering for the VAs so actually its not an easy thing to replace drop in ... many parameters might cause complications ...
So since the 1865 was not possible to get the tech gave up
The tech guy in his conquest to find or replace the 2SC 1865 he missed that the amplifier all ready included about 24 pcs of 2SC 1865 in the VU meter area ( with a very light duty IE on and off one led so it can be replaced with almost everything ) and another 4 pcs of 2SC 1865 in local supply working as voltage regulators and also possible to replace with any available transistor
got another one for you .....
Luxman LV 105 U is a hybrid .. first stage is transistor second stage is mosfet next stage is tubes and final stage is mosfets again
Tech guy replaced the outputs with the next available mosfet quite ok job amplifier works dlivered to the costumer ...
few days later amplifier stops and come to my shop .... There was nothing wrong with the repair outputs worked properly but the tech guy missed the obvious ....Luxman amplifiers of that age suffer from thermal stress and soldering issues .... meaning while he was plugging in and out headers and plugs the soldering down under got even worst so amp stopped due to soldering issues .... only
The tech spend time searching on the internet regarding output recommendations and missed to look at the compete picture of the device ....
As about the offset if its a faulty part can be easily located but if its a replaced part that doesn't fit into the picture you have a nightmare in front of you
kind regards sakis
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