Hi Chris (Anatech),
Thanks for the reply.
I was searching for related topic regarding suggested replacements for the LV105 MOSFETs and this site just turned up with interesting information.I am a bit electronics literate but obviously not that seasoned and well trained as most of the veteran guys here.
Since the original parts are already unobtainable, tried the replacements 2sk1058,2sj162 (as suggested here without any change in the drivers,etc). Have correctly installed them though they are not pin to pin compatible -vertical vs lateral type description.
The DC offsets I measured before the relay contacts are -4mv & 8mv for the 2 channels, and seem ok (?).
At lost what is triggering the relay to go into protect mode when volume pot is adjusted past 11 o clock setting.
Just trying my luck to get this unit singing again.
Good,honest and seasoned technicians seems to be rare in my area.
Thanks for the reply.
I was searching for related topic regarding suggested replacements for the LV105 MOSFETs and this site just turned up with interesting information.I am a bit electronics literate but obviously not that seasoned and well trained as most of the veteran guys here.
Since the original parts are already unobtainable, tried the replacements 2sk1058,2sj162 (as suggested here without any change in the drivers,etc). Have correctly installed them though they are not pin to pin compatible -vertical vs lateral type description.
The DC offsets I measured before the relay contacts are -4mv & 8mv for the 2 channels, and seem ok (?).
At lost what is triggering the relay to go into protect mode when volume pot is adjusted past 11 o clock setting.
Just trying my luck to get this unit singing again.
Good,honest and seasoned technicians seems to be rare in my area.
Hi dana09,
That's fair enough. Most technicians can get an amp working without really understanding what they are doing. They don't know enough to check for other possible problems. Therefore, fixing an amplifier seems easy, and sometimes it is.
I can rebuild an engine, and have done so a few times. But there is no way I'm qualified to fix one for someone else. I don't know enough, but just enough to understand there is a lot I don't know. It's the same as when people attempt to service amplifiers and the like.
The problem is that the Luxman amps in this series are more difficult to service, and I received many for service over the years, victims of failed repair attempts.
Also, you may have a problem that causes the output to be asymmetrical, inducing a signal related DC offset. Again, the oscilloscope is the instrument you need to confirm this.
-Chris
That's fair enough. Most technicians can get an amp working without really understanding what they are doing. They don't know enough to check for other possible problems. Therefore, fixing an amplifier seems easy, and sometimes it is.
I can rebuild an engine, and have done so a few times. But there is no way I'm qualified to fix one for someone else. I don't know enough, but just enough to understand there is a lot I don't know. It's the same as when people attempt to service amplifiers and the like.
The problem is that the Luxman amps in this series are more difficult to service, and I received many for service over the years, victims of failed repair attempts.
Yes, those are actually pretty good numbers. Have you checked with an oscilloscope to see if anything is oscillating? How is the bias current?
Also, you may have a problem that causes the output to be asymmetrical, inducing a signal related DC offset. Again, the oscilloscope is the instrument you need to confirm this.
Unfortunately, that is a world wide problem. It normally doesn't pay to be an audio service technician. There is a member, "clemo" closer to you. He has some experience with analog electronics and may be able to help you out.
-Chris
Hi Dana,
it is true honest and reliable tech are hard to come by, surely they can not know everything.....but they are mostly underpaid where you are...
try checking the resistors sensing the source resistors, i believe they are 0.330hms, the white ones, a drastic change in values can trigger the protective IC. i do not have the schematic in front of me now....but that is a good place to start.
most dvms have low enough test voltages that you don't even have to unsolder anything just to get an idea of the supected ones, however once you find one, just unsolder one leg, lift and test...i know this will take longer, but .....worth a try...imho...
i have succesfuly repaired one such unit only becasue there was another unit where we got the good parts parts from..
i don't remember if that amp has a pot for off-set adjustment though, would have been easier to adjust it.
the speaker relay takes a while to close, so if you want to check output offsets do it at the mosfet side, not at the speaker side.....
i have exchanged emails with clem_o, he is a college proffesor at the La Salle University...will try to get you two meet....
good luck....
it is true honest and reliable tech are hard to come by, surely they can not know everything.....but they are mostly underpaid where you are...
try checking the resistors sensing the source resistors, i believe they are 0.330hms, the white ones, a drastic change in values can trigger the protective IC. i do not have the schematic in front of me now....but that is a good place to start.
most dvms have low enough test voltages that you don't even have to unsolder anything just to get an idea of the supected ones, however once you find one, just unsolder one leg, lift and test...i know this will take longer, but .....worth a try...imho...
i have succesfuly repaired one such unit only becasue there was another unit where we got the good parts parts from..
i don't remember if that amp has a pot for off-set adjustment though, would have been easier to adjust it.
the speaker relay takes a while to close, so if you want to check output offsets do it at the mosfet side, not at the speaker side.....
i have exchanged emails with clem_o, he is a college proffesor at the La Salle University...will try to get you two meet....
good luck....
Risky move, considering the cost of parts. Well, the outputs can be expensive. All the more reason to user new parts!
Hi Chris.
Hi Tony...i i know you also maintain active presence here with the seasoned/veteran guys.Also, thanks for the usual support,advices and encouragement to the local forum/guys,also into this hobby here in our country.
Thanks for your helpful inputs, appreciate them.
Will give it a look again once the inspiration sets in...maybe another long holiday, like this week,Chinese New Yr ...we are on forced leave (5 days, use SL/VL credits ) due to low company production brought about by Global slowdown, our main client customer,US and European markets...not sure in the coming days
There is a bias pot to adjust but none for the DC offset.
Will try to check with my scope around...have to set it up first again...im just relying lately with my DVM...need more passion to set it up and find the trouble...just looking for the easy way out to fix and give it a listen .
Else, ill just pass the headache to another pal waiting for a good challenge.Hey Tony, Rascal our friend here, is waiting for me to donate it in behalf of his personal R&D.
Hoping to try my usual luck working on this unit with a simple solution...as it always proved to be true for me and the other gears I had worked on before and currently enjoying.
Many thanks!
Hi Tony...i i know you also maintain active presence here with the seasoned/veteran guys.Also, thanks for the usual support,advices and encouragement to the local forum/guys,also into this hobby here in our country.
Thanks for your helpful inputs, appreciate them.
Will give it a look again once the inspiration sets in...maybe another long holiday, like this week,Chinese New Yr ...we are on forced leave (5 days, use SL/VL credits ) due to low company production brought about by Global slowdown, our main client customer,US and European markets...not sure in the coming days
There is a bias pot to adjust but none for the DC offset.
Will try to check with my scope around...have to set it up first again...im just relying lately with my DVM...need more passion to set it up and find the trouble...just looking for the easy way out to fix and give it a listen
.Else, ill just pass the headache to another pal waiting for a good challenge.Hey Tony, Rascal our friend here, is waiting for me to donate it in behalf of his personal R&D.
Hoping to try my usual luck working on this unit with a simple solution...as it always proved to be true for me and the other gears I had worked on before and currently enjoying.
Many thanks!
Hi Dana,
If you keep your eyes and mind open, you are sure to solve the problems. Make sure all your power supplies are working properly, an oscilloscope would be the instrument that is needed to give you the rest of the picture.
I haven't seen this said yet, but make sure all the red LEDs are lit normally. If one or more are not, you probably have trouble there. Also, solder connections can be a problem. To fix, remove the old solder and resolder the connection after cleaning the component lead.
-Chris
If you keep your eyes and mind open, you are sure to solve the problems. Make sure all your power supplies are working properly, an oscilloscope would be the instrument that is needed to give you the rest of the picture.
I haven't seen this said yet, but make sure all the red LEDs are lit normally. If one or more are not, you probably have trouble there. Also, solder connections can be a problem. To fix, remove the old solder and resolder the connection after cleaning the component lead.
-Chris
dana09 said:Hi Chris.
Hi Tony...i i know you also maintain active presence here with the seasoned/veteran guys.Also, thanks for the usual support,advices and encouragement to the local forum/guys,also into this hobby here in our country.
Thanks for your helpful inputs, appreciate them.
Will give it a look again once the inspiration sets in...maybe another long holiday, like this week,Chinese New Yr ...we are on forced leave (5 days, use SL/VL credits ) due to low company production brought about by Global slowdown, our main client customer,US and European markets...not sure in the coming days
There is a bias pot to adjust but none for the DC offset.
Will try to check with my scope around...have to set it up first again...im just relying lately with my DVM...need more passion to set it up and find the trouble...just looking for the easy way out to fix and give it a listen
Else, ill just pass the headache to another pal waiting for a good challenge.Hey Tony, Rascal our friend here, is waiting for me to donate it in behalf of his personal R&D.
Hoping to try my usual luck working on this unit with a simple solution...as it always proved to be true for me and the other gears I had worked on before and currently enjoying.
Many thanks!
I was able to use IRF9640/IRF640 in the LV-103 but i had to modify bias since more was required....there is an issue with crakling sound in one channel that i have yet to fix...next time i have my hands on it i am going to convert to 220 volts...
also check for dried up electros, these LV's are old units, a re-capping is not a bad idea....
i would follow chris's suggestions as well...good luck...
don't give up just as yet...
Thanks Tony. Yes, have tried those technique : unsolder 1 leg,lift and test. Tested suspected parts & also,replaced some caps...Will check the others.The source sensing resistors are 0.22 ohms, btw.
Thanks Chris. , just taking my time.I will use the scope this time. Btw, the 4 LEDs in the pcb are are all lit up normally.
Again,thanks for your inputs and advises.
Yes, it will take patience and i will do my best to get this unit working. Together with the nice vintage gears,silver faced beauties,they aint no more making this kind of toy, nowadays!
best regards!
Thanks Chris. , just taking my time.I will use the scope this time. Btw, the 4 LEDs in the pcb are are all lit up normally.
Again,thanks for your inputs and advises.
Yes, it will take patience and i will do my best to get this unit working. Together with the nice vintage gears,silver faced beauties,they aint no more making this kind of toy, nowadays!
best regards!
Hi Marc,
A couple other factors come into this. Cosmetic condition normally has a large effect on price, as do manuals and original packaging. So much for the visible stuff. Now for the issues you can't see, namely the operating environment the unit "lived in", and also related to this, how it was used. If the amp was left on most of the time with possibly restricted air flow, it's actual condition will be far worse than a unit that was recently "blown up", but otherwise operated with clear air space and not left on. Heat damage is very serious, and it occurs slowly over time. This type of problem will affect every component in the unit, and also the actual PCB. I have seen cases where the unit in question simply was not worth repair because the repair may never be reliable. Dust accumulation will also result in overheated components, even if the unit is out in the open. Cat hair is about the worst, and cats have a tendency to urinate inside warm devices. Cat urine will rot the leads right off the components, and also the traces under the board. Sometimes you can't smell it until you attempt to clean the board up. Man, that stinks!
This holds true for all equipment. Remember too, a person who never plays it loud may have people who "crank it up" when they are not there. We even have seen a case where a maid turned it up all day while she worked throughout the house. Amp was baked and the CD player was worn out. Tweeters where also open, and the owner knew they didn't so this, but they forget about other people who have had access to their equipment. Remember that as you buy that unit from someone you swear wouldn't abuse anything.
I always recommend that a new acquisition be inspected by the technician you normally use for service. Sometimes the tech will not charge you if you have a good relationship with them. See? It's important to have a good relationship with a technician, along with your doctor, mechanic and any other professional people. There is a cost for anything in life, and these are the people who can reduce your costs in the long run, not to mention more enjoyment from stuff that works properly to begin with.
Additionally, if you have a problem that is reported to the seller soon after the purchase, be it a person or store, you are more likely to have things sorted out more in your favor. If the thing you bough breaks, you need to see your technician anyway, right?
-Chris
Now, there is a loaded question if ever I did see one.
A couple other factors come into this. Cosmetic condition normally has a large effect on price, as do manuals and original packaging. So much for the visible stuff. Now for the issues you can't see, namely the operating environment the unit "lived in", and also related to this, how it was used. If the amp was left on most of the time with possibly restricted air flow, it's actual condition will be far worse than a unit that was recently "blown up", but otherwise operated with clear air space and not left on. Heat damage is very serious, and it occurs slowly over time. This type of problem will affect every component in the unit, and also the actual PCB. I have seen cases where the unit in question simply was not worth repair because the repair may never be reliable. Dust accumulation will also result in overheated components, even if the unit is out in the open. Cat hair is about the worst, and cats have a tendency to urinate inside warm devices. Cat urine will rot the leads right off the components, and also the traces under the board. Sometimes you can't smell it until you attempt to clean the board up. Man, that stinks!
This holds true for all equipment. Remember too, a person who never plays it loud may have people who "crank it up" when they are not there. We even have seen a case where a maid turned it up all day while she worked throughout the house. Amp was baked and the CD player was worn out. Tweeters where also open, and the owner knew they didn't so this, but they forget about other people who have had access to their equipment. Remember that as you buy that unit from someone you swear wouldn't abuse anything.
I always recommend that a new acquisition be inspected by the technician you normally use for service. Sometimes the tech will not charge you if you have a good relationship with them. See? It's important to have a good relationship with a technician, along with your doctor, mechanic and any other professional people. There is a cost for anything in life, and these are the people who can reduce your costs in the long run, not to mention more enjoyment from stuff that works properly to begin with.
Additionally, if you have a problem that is reported to the seller soon after the purchase, be it a person or store, you are more likely to have things sorted out more in your favor. If the thing you bough breaks, you need to see your technician anyway, right?
-Chris
ok here is another link for LV-103 and LV-103U Servie Manuals
I Just bought one lv-103 unit that I intend to use as reference with Energy Pro-22 .
First tests: - Noisy Source selector.
- Bias control dead (Make amp run into protection)
- Balance button stiff and noisy ....OEM Parts???
- Sound test wihtout tone control - Great!.
I've been told by the seller this unit never been cleaned anor repaired. Visual inspection can tell for the cleaning part.....As for the repair we will have to see. Caps need to be replaced that is for sure (they are 1.5x the original size)..... Now that I have the manual I 'll give it a try......Otherwise I'll have to pay a Coffee to Anatech...........
PS: Is Georgetown near Ottawa? I'm 25 Minutes From Ottawa.
LINKS:
http://rs787.rapidshare.com/files/236829878/LUXMAN_LV103.pdf
http://rapidshare.com/files/236829879/LUXMAN_LV103U.pdf
Marc
I Just bought one lv-103 unit that I intend to use as reference with Energy Pro-22 .
First tests: - Noisy Source selector.
- Bias control dead (Make amp run into protection)
- Balance button stiff and noisy ....OEM Parts???
- Sound test wihtout tone control - Great!.
I've been told by the seller this unit never been cleaned anor repaired. Visual inspection can tell for the cleaning part.....As for the repair we will have to see. Caps need to be replaced that is for sure (they are 1.5x the original size)..... Now that I have the manual I 'll give it a try......Otherwise I'll have to pay a Coffee to Anatech...........
PS: Is Georgetown near Ottawa? I'm 25 Minutes From Ottawa.
LINKS:
http://rs787.rapidshare.com/files/236829878/LUXMAN_LV103.pdf
http://rapidshare.com/files/236829879/LUXMAN_LV103U.pdf
Marc
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LV-105 one channel trouble..
I'm trying to fix a LV-105 that one channel was fried and the outputs was changed and some resistors (also the EE resistor was fried). But now I cant set the bias, everything else works
Cant find any other faults, have double checked all components and used the f word a number of times..
I'm trying to fix a LV-105 that one channel was fried and the outputs was changed and some resistors (also the EE resistor was fried). But now I cant set the bias, everything else works
Cant find any other faults, have double checked all components and used the f word a number of times..
lv105 as a main amplfier is DC coupled ... that means there is no capacitor to block DC in the input of the amplifier .... that will also mean that any problems that might exist in the tone control and the power supply of it might be directly transfered to the input of the amplifier
anything can cause that fom a scratchy pot to boiled capacitors or soldering issues in the tone control and the power supply of it
kind regards sakis
anything can cause that fom a scratchy pot to boiled capacitors or soldering issues in the tone control and the power supply of it
kind regards sakis
Thanks for you input.
I'll check the tone control completely. As for what I can see from the beginning , the caps are 1½ the size so I suspect in the first place that relacing them would be a good place to start. As for the potentiometer, I have the specs but i do not know if this kind of part is easy to find.
Regards....
Marc
I'll check the tone control completely. As for what I can see from the beginning , the caps are 1½ the size so I suspect in the first place that relacing them would be a good place to start. As for the potentiometer, I have the specs but i do not know if this kind of part is easy to find.
Regards....
Marc
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