2270 weak left channel

I give the tape in puts a try good thought

heading down the of process of elimination path. I will check the Jacks carefully

I don't have a scope. I will try a signal trace and see if I can pick up or make a tone generator. I may be able to pick one up CL.
 
Lots of PC programs can be used to make signal generators (just a suggestion for quick and dirty test signals). But much easier with real signal generator. YMMV. Good luck.
 
I took it the front of the unit apart half I did not see any broken wires on the switches or pots including the selector switch. This one has me stumped.

The hi blend switch does affect the left channel for some reason

Sorry I am piggybacking on to this thread, but I have the very
same problem on my 2270 - low volume on one channel and the
issue seems similar.
(I'll open a new thread soon, when I start working on the unit - cleaning,
recapping...)

I get good volume from both channels using the Hi-Blend switch.
The two main amps are fine - checked by connecting the CD player
directly to the main RCA jacks.
Replaced the relay with a new one, so that is ruled out.

A dumb question - how do you get the front of the unit apart and
reach all those switches?
Do you need to remove/tape the dial pointer string, and remove all those
screws on the side holding the front section?
 
Well first I stared at it for a couple of hours:eek:


The pointer I just moved up and out left it attached to the string.

Take all the nuts off the pots and jacks pull the plastic away from the jacks watch for the stand off spacers.
Then take out the 6 screws on the sides out (three per side). pull the face out a bit to pull all the pots out of the holes( volume balance treble son on) the selector switch is a little tricky but do it the same way along with the jacks.

Then you can get at the switches. remove the tie wraps as you disassemble

I will get some pics on soon.

That's how I did it there may be a better way
 
Ok Dubbing "out" jack when I jumper the back of the plug where the yellow white & blue white wires come in. The left channel comes in. Should be normally open right?

Why does this effect the left channel only?

any help appreciated.
 
Cleaned all the pots and switches
Problem still with the Left channel. Taking a break from this 2270.

A little grease helped with placement of the springs. I almost lost those springs 3 times. Be very careful.

Pulling the face off a little bit worked better for me.
Getting to the switches took a little time, but taking them apart and putting them back together was much easier and faster.
 

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Resurrecting this old thread I know but I got back to the Marantz and it may help others.

After re reading the FM section of the manual I narrowed it down MPX stereo decoding circuit. P300 Board

The unit works fine on AUX, phono & tape. Just one side of the FM is weak.

On the P300 at J314 has a weak signal I'm guessing below 19khz test point J312 works fine( the good channel).
I don't have a scope all the voltages check out ..ok on the trans
except for base of H309 @ 2.53 v should be 2.6v

I"m happy I found the bad board,:D now I need to find the bad component.
going to look for a scope...
 
You could try replacing C322,332 and 334. It's also possible that someone has screwed with the separation control, R365. Note it's current position and try rocking it back and forth a bit.

Tom
 
I will try that tonight. first I try to adjust the pot and takes some readings on those capacitors

Reading some where on this site I could use the AC setting on my meter? poor mans scope

Thanks Tom
 
Whew.... tried the AC setting and measured each side of L305(2,4) what is that a coil or transformer?
The readings were the same on each side so that was a positive. Replace C334 the night before so I hit C332

That was it:banana:

I will replace all the caps on the board.


Thank you Tom!
 

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L305 is actually a dual channel low-pass filter. In simplest terms, it lets the audio through but blocks the high frequency switching noise left over from the stereo demodulation process.

Great job! It took a while to get here, I admire your tenacity!

Tom
 
Yes it took me a while but learned a lot. ...Thanks Great site lots of info

I did fry the tuner string while troubleshooting with my iron ...argh
 
stringed the 2270 .....the pic in the manual did not work correctly.
turning the knob to the right just pulled the spring out of the pulley slot.
manual shows going into the spring at step 4 then around twice (5 &6).

Even though the original string was tied to the spring.

I followed the manual but at step 4 went around the pulley once then into the spring. Then twice again (5&6)
Once routed hold the string finger thumb turn the tuning knob far left then loop string attach small brass fitting
squeeze brass fitting snug, tie clip on other side of string. Attach pointer to string far left don't glue it yet, Once you have fitting attached you can adjust at the brass fitting
see pic keep string taunt.
last step turn to favorite FM station set pointer. (I used another Marantz)
May be other ways but this worked for me.
 

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Whew.... tried the AC setting and measured each side of L305(2,4) what is that a coil or transformer?
The readings were the same on each side so that was a positive. Replace C334 the night before so I hit C332

That was it:banana:

I will replace all the caps on the board.


Thank you Tom!
I have the exact same issue I will try this fix it should be the same problem. Thanks
 
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