CR-640 Signal and FM Sensitivity Meters

Can anyone tell me how to test these meters to trouble shoot them? The signal meter never goes about 20 even with a perfect sounding station. When I first started working on this unit it didn't move at all... seems like maybe its gummed up? Idk. The FM Sensitivity needle moves so little you really have to stare at is to see the movement. I'm wondering again if maybe this needle is just gummed up. I want to be sure that its not something else first tho.

If it is just gummed up I don't really see how I will be able to get into it to clean it. Maybe someone has experience with this task? Thanks ahead!

Zach S. said:

Can anyone tell me how to test these meters to trouble shoot them? The signal meter never goes about 20 even with a perfect sounding station. When I first started working on this unit it didn't move at all... seems like maybe its gummed up? Idk. The FM Sensitivity needle moves so little you really have to stare at is to see the movement. I'm wondering again if maybe this needle is just gummed up. I want to be sure that its not something else first tho.

If it is just gummed up I don't really see how I will be able to get into it to clean it. Maybe someone has experience with this task? Thanks ahead!

Click to expand...

Are you using and external antenna?

Well I am using a piece of speaker wire to be honest. I put on a longer piece now and noticed i can pick up some stations up to 40 on the signal meter but the other meter still makes nearly no movement.

CR640 Signal meter

Hello Zach S
First of all you have to understand the major difference between YAMAHA tuners :thmbsp: and all the other tuners .:thumbsdn:
Yamaha always use Q Meters ( quality meter ) and not signal strengh meters !
Yamaha made this choice because this way the user can get visual confirmation about the sound he is hearing . If the reception conditions are great the sound will be fine and you will see the needle going to high numbers ! if the quality of the signal is poor the needle will stay in lower numbers (on the left ) .
On a technical point of view what is the interest to have a niddle going to maximum if the signal quality is poor ? :scratch2:
If you want to have confirmation change the frequency to another strong signal and you will see the needle mooving to the right , simple !:yes:

CR640 Signal meter

in my previous post the picture is coming from the service manual and show what the perfect reception conditions should be

What I describe in my post is true for all YAMAHA tuners using Q meters !

clinic-audio said:

in my previous post the picture is coming from the service manual and show what the perfect reception conditions should be

What I describe in my post is true for all YAMAHA tuners using Q meters !

Click to expand...

What you say makes sense. I have a Yamaha CR-800.

Unlike many tuners, it has a separate adjustment to set the signal quality to read whatever you want - independent of other adjustments used for improving actual reception.

Meaning, once you actually adjusted the tuner for highest signal strength using the associated steps to improve reception, if it still just reads 40% even though it sounds great, there's an adjustment where you can manually move the needle to read 95% or whatever you want to correspond to what you actually hear.

I see now. Its not so much a matter of wanting the needles to move incorrectly just making sure they work lol.

I have a 1040. My centering meter ("FM Tuning" in above diagram) is skewed to one side when tuned. it's as if the center for best signal has shifted to the left.
Ideas?

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CR1040 tuning meter

Hello 4Seatpilot

ok, I see perfectly what the problem is .
1) Be sure before to start this procedure that the needle of your tuning meter is just in the middle when power is OFF :thmbsp:
2) make your tuner warming up 20 minutes (because of drift after some time once the power is on )
3) disconnect any antenna
4) put your pointer aligned with the first beginning of the scale (detuned in fact)
5) now your tuning meter should have the needle just in the middle

If it's not the case your tuner need adjustments .
If you are able to do it with the right equipment , see my attached files (pages 06a and 06b ) if not , do not touch anything and give your tuner to the right tech.
Give us a report

clinic-audio said:

Hello 4Seatpilot

ok, I see perfectly what the problem is .
1) Be sure before to start this procedure that the needle of your tuning meter is just in the middle when power is OFF :thmbsp:
2) make your tuner warming up 20 minutes (because of drift after some time once the power is on )
3) disconnect any antenna
4) put your pointer aligned with the first beginning of the scale (detuned in fact)
5) now your tuning meter should have the needle just in the middle

If it's not the case your tuner need adjustments .
If you are able to do it with the right equipment , see my attached files (pages 06a and 06b ) if not , do not touch anything and give your tuner to the right tech.
Give us a report

Click to expand...

well! that sounds like helpful info! I will take a crack at it in a couple days... I am away from home at present.
It tunes well, just that the indicator needle is off centre.
Unfortunately around here the "right" tech is often me. The ones I know of fit one of two classes - either I can do pretty much whatever they can do and maybe better, or they'll only do "complete restoration" jobs for premium prices.
So hopefully it's a simple solution... I will hunt around for some of the appropriate equipment.