Your latest measurements are different from what you posted in post #17.R417: -63,7 Volt +60V
R419: -65,1 Volt -60V
R421: -27 Volt max ... variy up and down +60V
R423: -25 Volt max .. variy up and down -60V
D409: -63 Volt +8V 0V
D411: -64,1 Volt -8V 0V
R418: -64,4 Volt +60V
R420: -65,5 Volt -60V
R422: -64,4 Volt +60V
R424: -65,5 Volt -60V
D410: -63,5 Volt +8V 0V
D412: -65,6 Volt -8V 0V
Hence, something has changed since then. Possibly R505 is damaged and reads as open circuit.Q507 collector (Pin2) +63 Volt
Q509 collector (Pin2) -63,3 Volt
C651/R651: +17,33 Volt
C652/R652: -17,33 Volt
Thank you for the overview of the situation in the amp.
I think this is interesting and I'm learning something new every day, so if you can bear with me and are willing to help me out further i want to go for option #2, but of course, it can take some time to get the right components shipped, but i have no rush.
It's not about the money over what it's worth either, i just want to fix it, if i could do it with your great help i would be very excited over it.
So you are telling me to remove some transistors to stop smoking.
But the way it sits now, after it smoked R414 and R448 yesterday, it's no more smoke.
Has been on for a while now.
Since no smoke, I measured the voltage at each foot at R427 and R429 to GND, no voltage at all on neither of them.
Or should i remove the transistors you mentioned anyway?
Q424, Q426, Q406 and Q408
By the way, could i take out these two signal PCB's to get better access to the main PCB ?
Or do they have to be in there?
I forgot to mention that when you jumper or replace R505 don't be surprised to see components going up in smoke again.
PS. no need to edit your most recent post. Just let me know what is your next step.
Oops, we were cross posting and you beat me to it.
The light bulb in series would work in some cases but not all. The light bulb would effectively reduce the supply voltage and would continue reducing the supply voltage as the current draw increases.Hehe, i just thought i would explain, at first i thought the readinga were faulty because of me, but they were not.
Well, my next step would be what you think i should do..
I have got hold of two 6,8 ohm 0,25w resistors, so i can try to replace R505?
What about the "current limiter" @Plamen mentions?
If i use a such and nothing smokes.. i have to measure every component..?
I am just confirming what I suspected.Yes the measurements where done with CN302A disconnected.
I just measured the jumpers, so you get those readings before i connect them togheter..
J222: -13 Volt
J223: -13 Volt
J224: +36 Volt
J225: +29 Volt
Ok to proceed?
Thread starter | Similar threads | Forum | Replies | Date |
---|---|---|---|---|
Technics VX800 Extended Drive No Sound?? | Technical Repair | 30 | ||
Technics SU-VX800 amplifier parts availability | Technical Repair | 3 | ||
M | Technics current drive problem on a vx800 | General Electronics Chat | 6 | |
B | Technics SU VX800 Amp Problem | General Electronics Chat | 4 | |
Technics SU-VX800 Repair Help | General Electronics Chat | 13 |
by Duane Benson
by Jake Hertz
by Aaron Carman
by Jake Hertz