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Luxman L-85V amp rebuild - replacement parts?

Hi santaShooter have a luxman l 85 v and i am having the same problem as you had. can you please tell me finally which transistors you used for 2sd382, 2sb387. 2sa 679 and 2sc1079
 
Hi again - I have new issues with the amp :(
I have rebuilt both amp boards with NOS transistors, everything except Q05, since the manual states a SC815, but it should really be a sA915 - so a NEC SA915 is mounted. Both boards are powering up, the relay engages as it should and there is sound - BUT the channels are not identical in volume, and I can't get Bias and DC down on one of the channels :( without the output transistors mounted i took measurements of all the transistors in the hope that someone here, is able to point and say "There it is!"
I have also taken measurements across R20 to illustrate the Bias situation (It should read around 0,6VDC) and the DC readings as well.

It is all in the attached PDF.

Thank you all, for your help!
 

Attachments

Hi friends! It's been a long time since I've posted on AK, but I am still alive... In a reply to a PM, here is my opinion. It seems to me that Q507 is bad on channel 1. I think that the base-emitter junction is open, and the base-collector junction is shorted. Since the emitter voltage is almost the same as the main negative supply line, there is no current in R518. There is a current flowing into the collector of Q507, but this current is passing by D502. At one moment, there was a large current flowing in the bias transistor Q508. That large current destroyed Q508 (Vbe = 1.5V, much too high), wich is bad now. So, the voltage between the emitter of Q506 and the base of Q510 is no longer controlled by the bias transistor. It is the voltage drop in D503 (a resistor), VR502 and R519. Without the help of Q508, wich is acting like a shunt in normal situation, that voltage drop is much higher (6V) than expected (2.4V), so you have a very large bias current in the output stage.

Replace Q507 and Q508
 
Fantastic, thanks for having a look at my notes!
I will proceed with that changing Q507 and Q508...
While i do that, i have another question, in regards to channel 2: i have an issue with adjusting Bias, i can't seem to get above 20mA - I saw in an earlier post that you stated an R13 value of 5,6K was nonsene, my boards are fitted with a 5,6K resistor - could this affect my Bias adjustment?
 
santashooter said:
Fantastic, thanks for having a look at my notes!
While i do that, i have another question, in regards to channel 2: i have an issue with adjusting Bias, i can't seem to get above 20mA - I saw in an earlier post that you stated an R13 value of 5,6K was nonsene, my boards are fitted with a 5,6K resistor - could this affect my Bias adjustment?
Click to expand...
Yes if this resistor is connected in series with trimpot
 
The bias voltage source (Vce of Q508) is approximately 0.6V X (D503 + VR502 + R519) / R519. If Q508 has a very high hFE this approximation is good but if the hFE is low, the voltage source will be lower. You can increase the bias by increasing D503 or reducing R519.
 
Apologies for replying to a thread that hasn't seen activity in close to 4 years but @Zeromort yours is the only board I've seen which matches mine with regards to the resistor in place @ D03 being 2.7k.
Everywhere else I've seen in various L-85V threads, this resistor is either 4.7k or 5.6k.

It's crazy how woefully bad the Luxman service manual is for this amp. Lists parts for the PB-1037 board on one page and has totally different values on the schematic on another page and then again there is boards in the wild which match neither the part list nor the schematic.
 
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