Hello I am new to the site and am hoping someone with knowledge of the Luxman Lv105 can chime in with some information .. I purchased this unit as a fixer upper ,I have a LV103 and love it . Had a chance and a Lv105 not the U version , for very cheap because it's been messed with by a real hack. Anyway my first problem is getting a usable schematic for this amp ,I downloaded one but the numbers on my board are not the same as the schematic making it impossible to get your bearings . first thing I need to identify is a resistor on the protection board , it's been removed for some reason so I have nothing to go by .. on the board it's printed R-7376 . More questions to come but thought I would start simple . cheers and thanks in advance for any help .. Roger
Thanks for that Ilorev but mine is the lv 105 not the u model .looking at your manual of the U model I see it is very much different .. I did manage to find a sketchy manual with the protection board but it does not list values for the resistors and some resistors are marked differently in the schematic as is on my board. On my board The blue wires to the protector board go to R7376 & R7371.. On the schematic the blue wires are going to R7376 & R7375 but layout seems the same just numbered differently . Parts list does not show any resistors below 1/4w , states to refer to the schematic and that shows no values at all ..Question ,, as the protector board monitors 2 channels is it possible to copy the values of the resistors on the good channel , Risky but what do you do short of having another lv 105 to look at .Saying that I do have a functioning lv 103 with protector board would it be worth examining the lv103 to see if it's the same layout ?? Sorry for all the stupid questions with the proper schematic this would be a lot more straight forward.. thanks Roger
Thanks so much guys , I'm normally pretty good at figuring this stuff out but with sketchy manuals it's proving a bit of a challenge , Been a automotive tech for 45 years so I don't have quit in me LOL ,also been involved in hobby electronics since I was a kid building r/c radio kits and capacitor discharge ignitions for my gas engines also fixed a few guitar amps .. I do this as a hobby and a learning experience ,something to keep the grey matter working . Thanks Chris I'm sure I will have plenty of questions for you ,when I can PM I will send you my contact information ..And Ilorev thanks so much for the manuals I will go check them now .. cheers Roger
Hello Chris I will have to wait until the moderators allow it , must be a minimum amount of posts before I can send PM's . I see your in Canada . I'm in the Parry Sound area but travel to TO quite often .. I ordered a new cap set and think it might not be a bad Idea to change or at least check all the transistors as a couple of resistors were fired on the main board and the D1266 looks like it got pretty toasty ,I see a couple of places selling reclaimed 2sk405 and 2sj115 , or should I just go to the K1529&J200 , or is there something better now.. When I received my lv105 someone had tried to repair the right channel with a k1529/j200 and had the factory k405/j115 on the right. Mosfets Were not even soldered in ??I will test them tonight to see if I can figure out if any of the main drivers are good ..
Hi Roger,
Yes, you have to be a member before you can PM or post in the vendor's bazaar.
I'm to the west of Toronto. Sticking it on the bench would answer many questions and I can point you in the right direction. I'd have to look up each transistor type to give you a valid answer. I rarely need to replace outputs on these amps. It does happen. There may well be a current part that will work sold by someone. "New manufacture" generally means made in China using the original part number. It is therefore a fake. Good or bad - who knows? Pulls are something I only use if I must and I pulled it knowing they are good, or from another technician I know. Pulls by unknowns may have been blown just through handling or storage even though they were good when in circuit.
Generally speaking, don't order capacitor kits. They often have the wrong parts (values), most often are poor quality and you need to have the unit in front of you and select the replacements by hand while looking at the unit.
-Chris
Yes, you have to be a member before you can PM or post in the vendor's bazaar.
I'm to the west of Toronto. Sticking it on the bench would answer many questions and I can point you in the right direction. I'd have to look up each transistor type to give you a valid answer. I rarely need to replace outputs on these amps. It does happen. There may well be a current part that will work sold by someone. "New manufacture" generally means made in China using the original part number. It is therefore a fake. Good or bad - who knows? Pulls are something I only use if I must and I pulled it knowing they are good, or from another technician I know. Pulls by unknowns may have been blown just through handling or storage even though they were good when in circuit.
Generally speaking, don't order capacitor kits. They often have the wrong parts (values), most often are poor quality and you need to have the unit in front of you and select the replacements by hand while looking at the unit.
-Chris
Hi Roger,
I found this here, check this thread "Luxman LV-105 hum", https://www.diyaudio.com/community/threads/luxman-lv-105-hum.318297/
I see HiFi Engine has the file, you need to join to download it. I don't have it on my drive, so I'll look for a paper copy.
-Chris
I found this here, check this thread "Luxman LV-105 hum", https://www.diyaudio.com/community/threads/luxman-lv-105-hum.318297/
I see HiFi Engine has the file, you need to join to download it. I don't have it on my drive, so I'll look for a paper copy.
-Chris
I tried to join Hifi engine but they are refusing members for some reason , abuse by members or something??
Chris I have no choice but to replace the outputs because it has 2sk405 & 2sj115 on one channel and a K1529 & j 200 on the other channel , problem is I don't trust what the previous owner did to this unit , thankfully his exploration seems to be limited to the main board .
Chris I have no choice but to replace the outputs because it has 2sk405 & 2sj115 on one channel and a K1529 & j 200 on the other channel , problem is I don't trust what the previous owner did to this unit , thankfully his exploration seems to be limited to the main board .
R7376 is the sense line resistor. If removed, the protection circuit can not detect the voltage drop across the MOSFET source resistor.
By the way, that circuit is a current-limiter circuit with an interesting approach!! The circuit shuts down the buffer/VAS by collapsing the gain (including the bias section), if there's an overload/overcurrent through output MOSFETs. Cool
I will try to neaten up the circuit diagram and will post it here... so that you can have a look yourself.
EDIT: ... argh it is password-protected...
Ok, I uploaded the file to my google drive... try here:
https://drive.google.com/file/d/1AnWlq300PskdpI43RGrQZKc3fDKBJqNb/view?usp=sharing
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It's exactly that
I am in the period of sorting, storage, sale and trash, I will see if they survive.
The 103 tried to set himself on fire to protest against the design office, the 105 is really clean and above all he was given to me, he is probably the one who will survive the purge.
Ok guys it's now clear enough that I can now see the protector board and can sort of a the blurry resistance value for R7376 ,maybe it's my eyes or the computer I'm looking at it on, but it's just short of me being able to make out the value . Is it clear enough for anyone else to read , if so I know the problem is on my end ,thanks