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CR 620 Doesn't Sound Too Good

Lukey

Lukey

Active Member
Banned
I acquired a nice clean looking Yamaha CR 620 [35 wpc] receiver for about $40 but my CR 400 [16 wpc] sounds much better. Why is this?

The man I got it from said he cleaned it with GC Wash and Deox'd it all. Why then doesn't it seem to sound too great?

I can solder in new lamps but I never recapped and I have no electrical knowledge to speak of.
I have a DMM.

The 16 WPC CR 400 seems to have as much or more power than the CR 620.

The tuner in the CR 620 doesn't pull in stations well, and the phono section seems lacking.
The tuner in my CR 400 pulls in stations really well.
 
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CR 620 Seems Unwell, but is it?

I acquired a nice clean looking Yamaha CR 620 [35 wpc] receiver for about $40 but my CR 400 [16 wpc] sounds much better. Why is this?

The man I got it from said he cleaned it with GC Wash and Deox'd it all. Why then doesn't it seem to sound too great?

I can solder in new lamps but I never recapped and I have no electrical knowledge to speak of.
I have a DMM.

The 16 WPC CR 400 seems to have as much or more power than the CR 620.

The tuner in the CR 620 doesn't pull in stations well and the phono section seems lacking. The tuner in my CR 400 pulls in stations really well.

Could it be that I just may not like some Yamaha models as well as my CR 400, or is this a sick CR 620?
 
I bought a CR400 brand new in 1976 - partly based on the superb tuner specs and low distortion numbers.
This was a new thing at the time - for most manufacturers you had to go up to their more powerful models to get the better specs.
At the time, I lived directly in the middle of the Baltimore/Washington area and there was an absolute wealth of
great radio stations in both markets, even some college stations with 10 watt transmitters, so I wanted a very sensitive tuner.

Part of it may also be due to whatever speakers you are running with your gear. I had JBL L-36 speakers back then ...
I still own the CR-400, all these years later, and currently have it hooked to a pair of JBL L19 speakers ...
no great shakes but fairly efficient and a not-complicated load.


I can't tell you what the previous owner did to the CR620 receiver - could have aged badly or just not be up to spec.
That said, there really isn't much of a change going from 17w/ch to 35w/ch - its simply a doubling of power, not volume.
Usually you have to jump to a lot more power (say, 4 times the power - 70w/ch or better) to hear any appreciable difference.

You might want to look for a CR800 or CR1000 to get a real jump in power ...

If you get an account at HiFi Engine you can get a copy of the Owners Manual for the CR400 -
http://www.hifiengine.com/library/yamaha/cr-400.shtml - which shows these specs

Frequency response: 20Hz to 50kHz
Total harmonic distortion: 0.5%
Damping factor: 40
Input sensitivity: 3mV (mic), 3mV (MM), 150mV (line)
Signal to noise ratio: 65dB (mic), 72dB (MM), 85dB (line)
Channel separation: 50dB (MM), 50dB (line)
Output: 150mV (line), 0.2V (Pre out)
Dimensions: 444 x 158 x 300mm



They also have the CR620 Owners AND Service manual available for free download there -
http://www.hifiengine.com/library/yamaha/cr-620.shtml

Frequency response: 20Hz to 20kHz
Total harmonic distortion: 0.05%
Damping factor: 40
Input sensitivity: 2mV (MM), 120mV (line)
Signal to noise ratio: 92dB (MM), 97dB (line)
Output: 120mV (line)
Speaker load impedance: 4Ω (minimum)
Dimensions: 508 x 167 x 395mm


That said, I'd still go for the more powerful CR1000 (70w/ch).

FWIW, the CR800 at 45w/ch doesn't gain you much over the CR400
 
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Again, as I mentioned in that other thread, you need to check the idle current. Too low, you'll get distortion. Too high, you'll get distortion. Just right, and you won't get distortion.

Distortion pretty much sucks.
 
Thanks for your replies.

I don't know if I could check the idle current.
Maybe I should just try to find another CR 400, or some other Yamaha.

I like my SX 780 Pioneer more than this CR 620 - at least right now in the state the 620 is in. It seems to have a lot more power. I have to run the CR 620 at 11 or even 12 o'clock. It's like the mute button is on, but it doesn't have a mute button.

The only drawback with swapping with this guy is that sometimes he doesn't use any of the units he acquires long enough to really see how they perform, so the real test they get is when someone like me barters with him and acquires it. I'm swapping it based on it's very good to great physical appearance but that's no guarantee it's innards are balanced.

About the only thing I can do with it is drive it one hour from here to a vintage audio repair person and that would cost me 2-3x what I have into it. I might as well just see what other receivers I can swap him for and hope they sound good, and let this one go for $50.

Actually the tuner in this CR 620 is OK, it just doesn't seem to get a strong signal from WETS for some reason but picks up other stations well.
 
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I think the other poster is right -
go ahead and set the idle current and that may improve things!
You certainly have little to lose ...
 
Get some mini-grabbbers not alligator clips and follow the attached adjustment for the idle current. The attachment is for the CR-820 but the procedure is identical for the CR-620. Yamah built the CR-629 and 820 on the saame chassis.
 
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Thank you.

I have my DMM ready to use. I'm going to try it tomorrow when I have more light.

I'll look this over.
Someone at the Vintage Solid State section referred me to a manual at hifiengine.com

Joe
 
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Hi-

When looking at this diagram, which side is which?
Are these points visible from the top?

I'm going to have a look in it Friday.
 
The top of the diagram is thr front of the 620, TP3 and TP4 are the legs of the two front output transistors. TP1 and TP2 are connected to the rear pair of output transistors because they are hidden by the transformer. Be careful with your teat leads that they do not touch anything but the test points (TP)
 
I will, and thanks again.
I'm going to get me a pair of mini grabbers as you suggested.
Seems like the mini grabbers will help prevent accidental contact with other parts of the unit.
 
I got :

8 mV on L channel
5.7 mV on R channel

I now have them set to 7.8 mV in one channel and 7.7 mV in the other channel.

Is that OK? That's about as close as I can get them.

I have a feeling this will help, due to the 5.7 reading it was set at before I changed it.
 
Let us know. I have a CR-420 that I love, also a CR-240. Both are great receivers. The CR-420 is one of my favorite vintage pieces I own...she's one I would invest in to keep running well for a long time...
 
J English said:
Let us know. I have a CR-420 that I love, also a CR-240. Both are great receivers. The CR-420 is one of my favorite vintage pieces I own...she's one I would invest in to keep running well for a long time...
Click to expand...


I don't blame you.

I love my little CR 400 that I got for $25. I love the Natural Sound of this Yamaha and I'm hoping to get my newly acquired CR 620 sounding just as good, if not better.

Doing this procedure myself saved me 4 hours of driving and $50-$100, plus I can now perform it on other vintage receivers.
 
J English said:
Let us know. I have a CR-420 that I love, also a CR-240. Both are great receivers. The CR-420 is one of my favorite vintage pieces I own...she's one I would invest in to keep running well for a long time...
Click to expand...

See my new post about my CR 620. I cannot seem to appreciate the sound of this CR 620. It's nowhere near as good sounding as my CR 400.

I have a hunch I wouldn't like the CR 420 or CR 440 any more than I like the CR 620 because they all are newer models than my CR 400.
 
I'm liking the CR 620 more today, but my CR 400 is still my favorite receiver.

I kind of think I like the CR 620 more than my SX 780 now, at least until I run my SX 780 again and change my mind, again. I'm noticing the good S/N ratio and low THD and I have to say that it is impressive.
 
merrylander said:
The top of the diagram is thr front of the 620, TP3 and TP4 are the legs of the two front output transistors. TP1 and TP2 are connected to the rear pair of output transistors because they are hidden by the transformer. Be careful with your teat leads that they do not touch anything but the test points (TP)
Click to expand...

The tuner in this CR 620 seems kind of weird and seems like it could tune better. Is it hard to tune the tuner?

I saw the instructions in the manual but it looks kind of confusing.

It said something about "set the tuner at SG" and I wasn't sure how to do that.
 
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