Discussion in 'Marantz Audio' started by pjf610, Dec 23, 2017.
OK get back tomorrow
Hi all, I checked the voltage out J709 here is what i got:
right channel has a definite problem then . matched pair of input differential transistors might fix that .
35v supply needs fixing first though .
left channel being 0v rings an alarm .. are you sure its not a few mv ?
fluctuating between 0 and 0.001 maybe 0.003
if its on dbt the 35v may well be low
left channel bias is very high . where did you measure it from ?
1st I measured from the speaker output and adjusted R707, then i connected to pin 708 and 710 and adjusted R719
r719 is for idle bias . so why is set way high ? and why is offset high ?
i guess it wont adjust ?
Correct can not make adjustments
sanity check outputs emitter resistors .
I will check R732 and R733 on both channels and see what I get
Here is the results of the R732/R733
in meant check how many ohms .
are the outputs getting hot ?
No the outputs are no getting hot
I put a 1K resistor across R718 and was able to get the bias done between 3.5 and 3.8mv and checked the values of the H701 Zener Diode on the good channel (right side) i got 18.5 v checked the left side it bounces from .01 to.06v so i guess we have a problem their, will change it out and see what happens. I have to ask this stupid question there is a right way to install the diode how would i tell which way to put it??
The cathode (-) end of the diode should be marked with a band, cathode is the line on a diode circuit symbol.
check voltage each side r713 . and polarity c702
Had to replace R713 it was blown, will check, Got it with the diode
OK replaced the H701 Zener diode and the left channel came to life there is a hum on it though i was able to get the bias down to 10mv but the trimming resistor is extremely sensitive and i was keeping an eye on it and it started to drop in voltage very slowly
is it a new trimmer ?
Separate names with a comma.