That must be a DC heater power supply, 6CG7/12FQ7 tubes draw some big current for small triodes, 600mA at 6.3 volts but there are two of them so you have 1.2A continuous load. You need a good size bridge rectifier and filter cap to run DC heaters on those tubes and obviously the stock parts are not quite strong enough. Good video and troubleshooting!
Hi there, I did a search on TH-cam on how to remove front panel. Your videos came up but no mention on how to remove front panel. Great videos by the way!
Yes I lost the footage to that unfortunately... If you look on the inside of the front panel, there are 2 thin rectangular holes through the metal and boards depending what model you have where you need to slide something flat in to release the retaining tabs for the upper front panel, you can see it briefly in my LV-103 restoration video :)
By any chance you have the part number of the rectifier replaced? And the heat sink used on those 2 transistors on driver board? Nice video, very informative. Thx.
I believe I used a KBL type 4A rectifier. The important part is to cool it properly as they run hot. Didn't touch the other transistors other than adding a heatsink
@@whatcouldgowrong7914 it was around 190 mv at left, 24 mv at right (ok). So I found C7109 (47uf) in 1st differential on driver board totally off by a lot. Like at 300nf. So I replaced with a new one hoping to fix the issue. But instead it goes up even higher to 360 mv. I post my issue in some forum here but got no response. Totally desperately need some guidance. Probably will continue to pull and test the cap on the driver board to see.
@@ec1675 I haven’t looked at the schematics for a long tome but check the gain of the differential pair. If there is a mismatch, it will create significant offset :)
Nice job. I repaired a destroyed unit a few years ago. It must have dropped flat because the main PCB was broken in several pieces. Replaced a lot of leaking caps, many components had been eaten by leaked caps fluids and the glue used for the caps, which turned to some kind of abrasive junk. I ended up putting lots of radiators on transitors, on the rectifier, and some power resistors. It was a difficult but interesting project. The only part I absolutely coundn't find is the volume pot with a tap for loudness... (If I remember it was a 150kB) I now just finished repairing a first gen LV-105, also eaten by abrasive glue and tone pots crumbling to pieces. Much simpler than the LV-105u though.
Great result so far. Your tube driver board looks to be in fantastic condition compared most I have seen. The things are usually burned up to bits probably because folks would back in the day leave the vinyl LP sleeve lying on top blocking any chance of ventilation as they played their fave music! The plastic valve (tubes) pair holder is usually so brittle from the heat, (as with lots of the interconnect wires insulation) the thing just crumbles to bits changing them. Will the tubes you mention have the unusual large loop of heater filament at the top also? It runs between the 2 internal triodes & Luxman designers carefully arranged the tube’s orientation so as to show them off. I’ve found so many 6CG7s don’t have the big heater link so don’t display as well…
The driver board is in o…..k condition, definitely crispy but salvageable. The headers will need to be replaced but thing I found gold plated replacements. Ive recapped the board already and will follow up in the next video, most the caps were well and truely dead. 4.7uf audio caps replaced with Vishay films. Lots to do on the 105u. Way more heat related issues than the older models! Definitely a fan of it all being integrated and no wires running to and from the tube section in the newer models and much better shielding on the signal wiring
Wonder if your problem with the volume control is actually a problem with the output selectors. Mine are dirty I think and sometimes cuts out one channel and/or cracle/lowers volume? I have found something about that on the big internet.... You drill a small hole in the encapsulated switch, and spray some oxi inside. Do you know if this works? Is this your problem to?
@@whatcouldgowrong7914 I tried drilling the small holes. And it worked, more or less... On the sv-1 channel which had a speaker not connecting, it worked and the general krackle is gone. But I must say I was nervous, the "levers" go in the middle of the "capsule", so I think the risk is big you can destroy it.... I don't have the experience to disassemble it, but that is what I would do if I had the confidence 😅😅
I have a Luxman amplifier lv105u Power transistors ( 2sk405 _ 2sj115 ) are not available in the market There is available equivalent For installation , thanks
No equivalent unfortunately, would either have to find old replacements or consider a conversion to newer type MOSFETs which takes a bit of work apparently
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That must be a DC heater power supply, 6CG7/12FQ7 tubes draw some big current for small triodes, 600mA at 6.3 volts but there are two of them so you have 1.2A continuous load. You need a good size bridge rectifier and filter cap to run DC heaters on those tubes and obviously the stock parts are not quite strong enough. Good video and troubleshooting!
Hi there, I did a search on TH-cam on how to remove front panel. Your videos came up but no mention on how to remove front panel. Great videos by the way!
Yes I lost the footage to that unfortunately... If you look on the inside of the front panel, there are 2 thin rectangular holes through the metal and boards depending what model you have where you need to slide something flat in to release the retaining tabs for the upper front panel, you can see it briefly in my LV-103 restoration video :)
Well hopefully the amp is still happy and you stuck a vertical heatsink on the bridge.
Doesn’t even get warm
By any chance you have the part number of the rectifier replaced? And the heat sink used on those 2 transistors on driver board? Nice video, very informative. Thx.
I believe I used a KBL type 4A rectifier. The important part is to cool it properly as they run hot. Didn't touch the other transistors other than adding a heatsink
@@whatcouldgowrong7914 thx for your reply. Chasing my high dc offset at the left channel now. Will look into it more and the heat sink tip.
@@ec1675 How high is the DC offset?
@@whatcouldgowrong7914 it was around 190 mv at left, 24 mv at right (ok). So I found C7109 (47uf) in 1st differential on driver board totally off by a lot. Like at 300nf. So I replaced with a new one hoping to fix the issue. But instead it goes up even higher to 360 mv. I post my issue in some forum here but got no response. Totally desperately need some guidance. Probably will continue to pull and test the cap on the driver board to see.
@@ec1675 I haven’t looked at the schematics for a long tome but check the gain of the differential pair. If there is a mismatch, it will create significant offset :)
Nice job. I repaired a destroyed unit a few years ago. It must have dropped flat because the main PCB was broken in several pieces. Replaced a lot of leaking caps, many components had been eaten by leaked caps fluids and the glue used for the caps, which turned to some kind of abrasive junk. I ended up putting lots of radiators on transitors, on the rectifier, and some power resistors. It was a difficult but interesting project. The only part I absolutely coundn't find is the volume pot with a tap for loudness... (If I remember it was a 150kB)
I now just finished repairing a first gen LV-105, also eaten by abrasive glue and tone pots crumbling to pieces. Much simpler than the LV-105u though.
Great result so far. Your tube driver board looks to be in fantastic condition compared most I have seen. The things are usually burned up to bits probably because folks would back in the day leave the vinyl LP sleeve lying on top blocking any chance of ventilation as they played their fave music! The plastic valve (tubes) pair holder is usually so brittle from the heat, (as with lots of the interconnect wires insulation) the thing just crumbles to bits changing them. Will the tubes you mention have the unusual large loop of heater filament at the top also? It runs between the 2 internal triodes & Luxman designers carefully arranged the tube’s orientation so as to show them off. I’ve found so many 6CG7s don’t have the big heater link so don’t display as well…
The driver board is in o…..k condition, definitely crispy but salvageable. The headers will need to be replaced but thing I found gold plated replacements. Ive recapped the board already and will follow up in the next video, most the caps were well and truely dead. 4.7uf audio caps replaced with Vishay films. Lots to do on the 105u. Way more heat related issues than the older models! Definitely a fan of it all being integrated and no wires running to and from the tube section in the newer models and much better shielding on the signal wiring
Sorry forgot to mention. Unfortunately EH tubes only have a small glow also not like the original ones 😞
Здравствуйте, как этот усилитель по звучанию, очень интересный усилитель?
Wonder if your problem with the volume control is actually a problem with the output selectors. Mine are dirty I think and sometimes cuts out one channel and/or cracle/lowers volume? I have found something about that on the big internet.... You drill a small hole in the encapsulated switch, and spray some oxi inside. Do you know if this works? Is this your problem to?
Will be covered in an upcoming video but it was a combination of a really dirty pot and also dry joints on the speaker protect relay :)
@@whatcouldgowrong7914 I tried drilling the small holes. And it worked, more or less... On the sv-1 channel which had a speaker not connecting, it worked and the general krackle is gone. But I must say I was nervous, the "levers" go in the middle of the "capsule", so I think the risk is big you can destroy it.... I don't have the experience to disassemble it, but that is what I would do if I had the confidence 😅😅
Not sv-1 but av-1..😊
I have a Luxman amplifier lv105u
Power transistors ( 2sk405 _ 2sj115 ) are not available in the market
There is available equivalent For installation , thanks
No equivalent unfortunately, would either have to find old replacements or consider a conversion to newer type MOSFETs which takes a bit of work apparently
Can I use any Mosfet with the same specifications, type B and N channel? Thank you@@whatcouldgowrong7914
본 영상은 고마운데 럭스만
lv105와 103시리즈 앰프들
사지 마라 음질이 형편없음
ƤＲＯ𝓂Ｏ𝕤ᗰ