Marantz 2216B odd tuner issue

Uncle Bambi

Funky Tut
I received this unit as a "barn find", and after fixing a right channel issue and De-Oxiting the controls, got it to work very nicely. So, I proceeded to clean, adjust, and re-cap it. I took a chance at re-capping the tuner because there was a lot of corrosion/cleanup that the board needed.

I carefully removed one capacitor at a time, replaced it, and tested. The uner sounded great. I finished it up, and listened to it for a while..... no issues.

Today, I turn it on and notice that FM was pulling in OK, but the "Stereo" light was intermittent and usually either flickered or did not come on at all, and if it did come on it was with e the FM signal needle way off-center to the right. And here's the weird part......... no left channel at all. Not on the speakers, not on the headphones. AM has a good right/left, as does the AUX port.

Just the FM is goofy. So....... What did I screw up? Any ideas or suggestions on what to do or where to look? I do not have the ability or tools to align the tuner, so if that's what's next I'm screwed.
 
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It worked before the recap, so start by triple checking the tuner board for cold solder joints, cap polarity, solder bridges, etc. When I work on a board and it stops working, I have usually slipped up somewhere.
 
It worked before the recap, so start by triple checking the tuner board for cold solder joints, cap polarity, solder bridges, etc. When I work on a board and it stops working, I have usually slipped up somewhere.

Yeah, I'll start doing that. I've already triple-checked the caps to see if any are in backwards, but they are all oriented properly as far as I can tell. The thing is, it worked after the re-cap for a while. I'm looking at the schematics, and I'm at a loss to figure out where the left channel FM signal comes from on the tuner board. If I can trace it through, I might have a better chance to find the culprit.

It seems odd to me that the FM is missing the left channel, but all the other outputs seem just fine.
 
Sounds like what Steve mentioned . I just had a similar experience and what I did found was a broken trace . I wiggled every component I had soldered and while looking on the (back side) I found two separate broken traces . Hope this helps.
 
Sounds like what Steve mentioned . I just had a similar experience and what I did found was a broken trace . I wiggled every component I had soldered and while looking on the (back side) I found two separate broken traces . Hope this helps.

So - I should be looking from the selector switch back to the tuner board? What I'm trying to get at is, would the likely source of the issue be on the tuner board itself, or perhaps somewhere else I haven't thought to look?

Logically it would seem to me that once the FM signal reaches the selector switch, it shares a common path to the speaker/headphones as every other source. So - if every other source has both channels, the issue would have to be confined to everything upstream from the selector switch.... no?
 
Seems like a connection issue . Also check the Mono button .

The "mono button"? The mono function is a selection on the selector switch. When selected, it also has no left channel. I've been all up and down my work on the tuner board, checking for bridges, poor connections, and lifted traces. I've re-flowed a few joints, but that it. I just don't see where the problem is.

I'm going to have to figure out where the FM left channel signal originates from, and try to chase it through the schematic. If anyone can help me with that, I'd be eternally grateful. :)
 
Here is the path from the IC. L202 is the FM detector adjustment to center it on the IF frequency. An issue in this area can cause the center tuning meter to be off and issues with the FM stereo light.

Pins 4 an 5 are the left and right audio output.


upload_2017-11-23_17-29-52.png

The advice in previous posts is a good place to start.
 
Here is the path from the IC. L202 is the FM detector adjustment to center it on the IF frequency. An issue in this area can cause the center tuning meter to be off and issues with the FM stereo light.

Pins 4 an 5 are the left and right audio output.


View attachment 1051851

The advice in previous posts is a good place to start.


Very helpful, thanks. I just measured pins 4 and 5 at IC Q302, and have about 8.5 volts on both. I'll track the signal path down from there and hopefully find the culprit. I took the previous advice to heart, but have been unable to find a bridge, cold joint, or other issue. I'll target this specific path and see if I can run down the problem. There aer a few caps in that signal path that I have changed out - maybe one is bad or incorrectly installed.....
 
So - I've checked the voltage at Q303 ans Q304. They are a bit of of what the schematic state, but are pretty close:

Q303
B = 1.79 should be 2.1
C = 6.18 should be 5.6
E = 1.18 should be 1.5

Q304
B = 1.71 should be 2.1
C = 6.7 should be 5.3
E = 1.08 should be 1.5

Also, at the source IC Q302:
Pin 4 = 8.7
Pin 5 = 8.56

I also checked for voltage at test points J217 and J218 since they were right downstream. There is no voltage value listed on the schematic here, and when probed the value on both pins was 0v. This has me a bit confused, as both transistors seem to have good outputs. Wouldn't that indicate that everything upstream from them is ok? Also - if one channel is working and the other is not, shouldn't I expect to see some sort of voltage on one of the J217 and J218 points?
 
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I would check for a signal before the L.P. filter and after.
Poor man's "O" scope:
With the set tuned to a strong FM station, with your meter set to ACmV's, black probe to chassis. Look for a bouncing meter (To the music) indicating a signal at:
R235 and R236. Probe the leg from the LP filter not the ground.
If not there check for it before the LP filter at the caps C313 and C314. By the way, what kind of Caps are those?
Then look for the signal at pins J217 and J218.
 
I would check for a signal before the L.P. filter and after.
Poor man's "O" scope:
With the set tuned to a strong FM station, with your meter set to ACmV's, black probe to chassis. Look for a bouncing meter (To the music) indicating a signal at:
R235 and R236. Probe the leg from the LP filter not the ground.
If not there check for it before the LP filter at the caps C313 and C314. By the way, what kind of Caps are those?
Then look for the signal at pins J217 and J218.

You post says "R235 and R236"...... I could not find those. Did you mean R325 and R326, that are directly connected to the LP Filter? Also, C313 and C314 are electrolytic caps, Nichicon UKL (low leakage)

Following your advice, I get these results:

R325 - .005v and steady
R326 - bouncing meter, to the music (more or less)

C313 (negative lead) - bouncing meter, .250 to .319v
C314 (negative lead) - bouncing meter, .112 to .165v

J217 - .005 and steady
J218 - bouncing meter.

R325, C313, and J217 are apparently the left channel, which is where the issue is. Seems odd to me that the meter would be bouncing at C313 but not at R325 on the other side of the LP Filter. Where does this information lead me? The LP Filter is suspect? Should I change out those capacitors and see what happens? I have the originals, and can put them back easily enough..............

Damn!! things have changed now. Both channels on FM are now dead and there is minimal output at the source Q302 pins 4 and 5. I did not do anything to cause this, as far as I can tell. I always powered off before applying test probe.

SHIT.
 
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Sorry, I meant R325 and R326.
Reflow the LP filter connections?
Those are the signals for the left and right FM channels.
The tuner components have hair whisker leads and can corrode easily.
 
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Something is fishy at or with the LP filter.

I suppose I could completely remove the LP filter clean the connections and then put it back. Other than that, I'm out of ideas...... unless you have a spare filter in your back pocket. :)

Seriously, if you have any other ideas I can try I would love to hear them. Thank you for your help so far.
 
I looked for one here in the shop but came up short.
Remove the filter and check it over visually. Ohm out the pins and see what you come up with.
 
I looked for one here in the shop but came up short.
Remove the filter and check it over visually. Ohm out the pins and see what you come up with.

Will do. I'm done for the night, and probably won't get back to it until Sunday. I was joking about you having a replacement filter, but I'm impressed that you actually might have had one, and also went to look for it on my behalf. Thank you for that!
 
I looked for one here in the shop but came up short.
Remove the filter and check it over visually. Ohm out the pins and see what you come up with.

OK - I have the filter out, and am ohming them out.

Looking at the back (pin side) with the three pins up top, I get 138 ohms on the right side, and infinite (open) on the left. The left side pin is directly connected to C313 which is the left channel.

Am I to presume then that my LP filter is bad? If so, are there any user serviceable parts inside the black plastic box, or is there any work around such as putting a resistor in line with left side pins that are open?
 
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