Steven Tate
CEO Flat Forehead Soc.
How about the diodes?
Marantz 2216 troubleshooting RH Channel INOP
- Thread starter RadarQ2
- Start date
RadarQ2
New Member
Well. 4 diodes removed and measures are ok. 0.6V one way and OL on the other way.
Resistors R736 and R738 are 0.40 ohm. I think that it's ok even though should be 0.22 ohm. I'll continue testing all resistors on RH side circuit.Any suggestions or ideas?
RadarQ2
New Member
Ok. All resistors tested on board. These are the results for the mistaken measures.
R706 --- 240 KΩ and should be 150 KΩ. The opposite R705 reads 69 KΩ (also is wrong).
R708 --- 110 KΩ and should be 39 KΩ. The opposite R707 reads 114 KΩ (also ir wrong).
R710 --- 75 KΩ and should be 150 KΩ. The opposite R709 reads 170 KΩ (could be R709 considered good?).
R724 --- 2 KΩ and should be 8.2 KΩ. The opposite R723 reads 8.4KΩ (it´s ok).
R726 --- 1.9 KΩ and should be 3.6 KΩ. The opposite R725 reads 3.6 KΩ (it's ok).
R744 --- 1.2 KΩ and should be 10 KΩ. The opposite R743 reads 1.2 KΩ (also is wrong).
R728 --- 570 Ω and the opposite R727 440 Ω. On papers these are trimmer resistors but i don't know if the values are ok.
All resistance colours agree with manual parts list. What doy you think? Here you have the schematic. Wrong resistors with red circle.
Thanks in advance guys.
R706 --- 240 KΩ and should be 150 KΩ. The opposite R705 reads 69 KΩ (also is wrong).
R708 --- 110 KΩ and should be 39 KΩ. The opposite R707 reads 114 KΩ (also ir wrong).
R710 --- 75 KΩ and should be 150 KΩ. The opposite R709 reads 170 KΩ (could be R709 considered good?).
R724 --- 2 KΩ and should be 8.2 KΩ. The opposite R723 reads 8.4KΩ (it´s ok).
R726 --- 1.9 KΩ and should be 3.6 KΩ. The opposite R725 reads 3.6 KΩ (it's ok).
R744 --- 1.2 KΩ and should be 10 KΩ. The opposite R743 reads 1.2 KΩ (also is wrong).
R728 --- 570 Ω and the opposite R727 440 Ω. On papers these are trimmer resistors but i don't know if the values are ok.
All resistance colours agree with manual parts list. What doy you think? Here you have the schematic. Wrong resistors with red circle.
Thanks in advance guys.
Steven Tate
CEO Flat Forehead Soc.
Wow. That’s a lot of variation from spec. Do these resistors look original? Normally, I would replace them with metal film resistors if they are more than 5% out of spec. But you have to be careful, because Marantz changed a lot of values after their schematics were published. Basically, if they look original, and are out of spec, I look at the color code on the resistor. If it is close to my measurement, I leave it, and hope it is the right thing to do. Are all of these measurements in-circuit? Again, if I measure in-circuit, and they test out of spec, I raise one leg and test again to verify. The interesting thing to me is that I’ve never found so many resistors that far out of spec. When I find a problem, it’s usually one or two resistors that measure open (Mohms). Also, with that many out of spec measurements, I would check my DMM against some new resistors to make sure it isn’t in a low battery state or something.
RadarQ2
New Member
Hi Steven.
I'm puzzled. I found one pic on internet with the original P700 board and components. You can compare with mine on the next picture. In highlit are the three resistor that i have replaced.
All the colour codes of resistors installed on my board matches with the specs on Marantz schematic manual.
All the measurements have been taken in-circuit. My DMM is brand new. I could check again with my older DMM.
What do you think?
Steven Tate
CEO Flat Forehead Soc.
If the color code matches the schematic, and they test more than 5% out of spec, I would raise one leg of the resistor and measure again. If still more than 5% out of spec, replace it with a metal film resistor.
RadarQ2
New Member
Which leg i have to raise? Anyone?
Steven Tate
CEO Flat Forehead Soc.
Either leg will take it out of the circuit. Desolder the leg, raise it from the board, and measure across the resistor. If within 5% of spec, put the leg back in place and resolder.
RadarQ2
New Member
Hi Steven,
Finally i have run the right channel.
Now the two channels are working after replace the H704, H706 and H708 transistors. I think that the transistor H706 was the blame of trouble.
But the right channel sounds too bad with broken sound. Left channel still ok and sounds fine. What do you think about? Take note that all capacitors were replaced two months ago.
Thanks in advance and regards.
Steven Tate
CEO Flat Forehead Soc.
Have you tried to set bias with R727 and R728 per the service manual? Will both sides set to 4.5 mV?
RadarQ2
New Member
LH CH is set to 96 mV and sounds ok.
RH CH is set to 79 mV and distorded sound.
I don't think that trouble cames from those resistors.
What do you think?
Steven Tate
CEO Flat Forehead Soc.
I guess the question is, did you try to set them to 4.5 mV? Whether or not it can be adjusted to spec tells a lot about the health of the board. There is no way I would leave a bias at 96 mV or 79 mV. I would set them, and if they would not set, I would try to find out why. It does no good to evaluate the sound until bias has been set to spec, because you can't tell if distortion is due to the bias or something else.
RadarQ2
New Member
Who is the exactly process to adjust the BIAS? Should i do it with the amp running or disconnect the amp every time that I modify the trim and measure the voltage?
Steven Tate
CEO Flat Forehead Soc.
To set bias, follow the directions from the service manual below. With power off, use minigrabber leads, if possible, to connect to each side of one of the resistors, R735 or R736. With input select set to Aux, volume at zero, balance centered, turn unit on. You should see mV DC on your DMM. If it is high, try turning the appropriate trimmer, R727 or R728 and watch the DMM. Try to set it at 4.5 mV. When setting bias, it tends to rise slowly for about 15 minutes, so you have to watch and reset during that time until it stabilizes. If bias will not set close to spec, something is wrong, and diagnosis is needed. Always attach and remove test leads with power off to prevent shorts. Good luck!
RadarQ2
New Member
RadarQ2
New Member
Could be the Capacitor C722 be the guilty of this trouble?
When i describe the trouble at the beginning of the post i touched the C722 and it was really hot until the lamp M702 started to smoke. Now the C722 it's not hot when the amp is running, but may be it could be damaged at the initial trouble of transistros short condition. Could be this possible? The noise continues. RH CH sounds broken but sometimes it try to sound better but immediately comes to the distorded sound.
When i describe the trouble at the beginning of the post i touched the C722 and it was really hot until the lamp M702 started to smoke. Now the C722 it's not hot when the amp is running, but may be it could be damaged at the initial trouble of transistros short condition. Could be this possible? The noise continues. RH CH sounds broken but sometimes it try to sound better but immediately comes to the distorded sound.
Steven Tate
CEO Flat Forehead Soc.
I would sure replace any component that I knew had gotten very hot during a short situation. Are you saying right channel bias is always 0 as you turn R728? If so, that is the reason the right channel is distorted. But the problem could be anywhere. C722 could be it, but pretty much everything on that side needs to be tested if changing C722 doesn’t fix it.
RadarQ2
New Member
Yes, BIAS is always 0 on RH channel. No changes if i turn R728.
All resistors in RH CH were tested and are ok. All transistors checked ok. The only ones left are the caps. Maybe they suffered overheat and now are the guilty of the distorded sound. Could it possible?
Steven Tate
CEO Flat Forehead Soc.
It's definitely possible. Caps are at the bottom of my list of suspects usually, but in a situation where there has been short damage, they are candidates.
RadarQ2
New Member
I'll try to change the caps then.