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YAMAHA CR-620 receiver not enough base, any suggestions.

Visual is always a good place to start, but probably a waste of time in this case. My belief is that Yamaha either bought short life caps, or they possibly cleaned the boards with something that got past the seals and degraded the caps sooner than you'd expect. I've worked on several of these now and every one was a capacitor disaster. No bulges and esr was fine, but the values were way low. They also tend to have some small signal transistor problems. You need a full service. When that's done, it's a fantastic receiver, when used within its capabilities.
 
My observation on that age caps is that the blue Elna caps used by Kenwood and others are at the limit of their functional life, most likely due to seal deterioration and drying electrolyte. The earlier gray Elna caps are almost certainly dead.

Quality seems to have improved somewhat after about 1982 or so, as I find far fewer dead caps even in equipment with blown outputs and signs of hard usage. Could just be that they haven't hit the magic age limit though.

And as I noted, those 6.3V caps always seem to be way off in value.

The exception to that rule is the later equipment with remote controls. In that equipment at least the 5V power supply is always powered up to allow remote switching, and in many cases the main PS is also powered, and the caps die.
 
I don't know anything about modern 6.3 volt aluminum electrolytics, but back when Sprague published detailed test results the 6.3 volt parts were always inferior to the higher voltage parts. In my experience they fail in expensive test equipment, cheap consumer products and anywhere else you find them. If space permits, and it almost always does, I never use anything less then 25 volts.
 
plugto said:
Thought you might like this short vid. Very simple fix, first just observation of distorted cap. I am sure this guy as some experience, but none the same a simple fix. You should pull the cover off of your receiver and give it a visual. Usually you can discharge the caps by unplugging the unit and then engaging the power button. Who knows you might get lucky.
Nothing to lose.

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Thanks for suggestion. I did unplugged it and pressed power button, nothing changed, still have to keep bass at 4 or max 5. Looks like it's time to do a service.
 
The suggestion to unplug and press the power button was to uncharge a few caps to protect you from a shock. Not as a fix.
Only experience I have with Yamaha is an integrated amp back in the mid 80s A-1000. It was very quiet, SN noise floor was dead silent. Had decent power, and many good features like MM and MC choices for your cartridge. And I still have it and it works fine. It does have scratchy pots. One weakness it showed was oscillation when I ran high frequency log sweeps from low to high. Other than that it was a fine piece of gear.
Make sure you post what you do for a fix, and get the bad parts from the tech if you go that way. Good luck!!
 
plugto said:
The suggestion to unplug and press the power button was to uncharge a few caps to protect you from a shock. Not as a fix.
Only experience I have with Yamaha is an integrated amp back in the mid 80s A-1000. It was very quiet, SN noise floor was dead silent. Had decent power, and many good features like MM and MC choices for your cartridge. And I still have it and it works fine. It does have scratchy pots. One weakness it showed was oscillation when I ran high frequency log sweeps from low to high. Other than that it was a fine piece of gear.
Make sure you post what you do for a fix, and get the bad parts from the tech if you go that way. Good luck!!
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I might stay with it the way it is keeping bass at 4 or 5, mids and highs are very pleasing. I really don't want to invest another $300-$500 into this unit doing recap. I bought it for $180 and paid $150 to install lights. But if I do something I will post it here for sure.

 
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eev776 said:
I might stay with it the way it is keeping bass at 4 or 5, mids and highs are very pleasing. I really don't want to invest another $300-$500 into this unit doing recap. I bought it for $180 and paid $150 to install lights. But if I do something I will post it here for sure.

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Recapping was suggested to keep this unit functioning long term, otherwise no capacitor in the world is going to give you the kind of bass response you’re expecting out of this unit. Also please keep in mind that constantly running the amp at highly inflated bass and treble settings will put a lot of stress on the speakers and may even cause irreversible damage. Yamaha gear are renowned for their tight and controlled bass response, the kind you hear in a concert hall.
Good luck.
 
Sparkplug said:
Recapping was suggested to keep this unit functioning long term, otherwise no capacitor in the world is going to give you the kind of bass response you’re expecting out of this unit. Also please keep in mind that constantly running the amp at highly inflated bass and treble settings will put a lot of stress on the speakers and may even cause irreversible damage. Yamaha gear are renowned for their tight and controlled bass response, the kind you hear in a concert hall.
Good luck.
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Thank you. I appreciate your suggestion! :beerchug:
 
I have good news!!!
As mentioned earlier I was waiting to receive a new pair of JBL L-100 speakers to see how it works with them. Originally I tested my Yamaha CR-620 with speakers: Kenwood JL-701 and JBL L-20T, was not satisfied with Kenwood, JBL L-20T was better, but 6" woofer is too small for my room.
JBL L-100 was complete game changer, with a spectacular sound, full and rich bass, incredibly detailed highs and great minds. I listened same songs that I tested before and now setting Bass to 2-3, Treble to Flat, Loudness to Flat or 3 worked fantastic, Volume at 2. There is also controls on speakers itself to adjust highs and lows, I just kept them at Flat.
So apparently problem was with speakers, somehow Yamaha CR-620 works very well with 4 Ohm JBL that have 12" woofers, it makes you feel present right at the music stage.
I'm very happy after all, great experience speaking in this forum I have learned a lot from everybody here.
Thanks!

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eev776 said:
I have good news!!!
As mentioned earlier I was waiting to receive a new pair of JBL L-100 speakers to see how it works with them. Originally I tested my Yamaha CR-620 with speakers: Kenwood JL-701 and JBL L-20T, was not satisfied with Kenwood, JBL L-20T was better, but 6" woofer is too small for my room.
JBL L-100 was complete game changer, with a spectacular sound, full and rich bass, incredibly detailed highs and great minds. I listened same songs that I tested before and now setting Bass to 2-3, Treble to Flat, Loudness to Flat or 3 worked fantastic, Volume at 2. There is also controls on speakers itself to adjust highs and lows, I just kept them at Flat.
So apparently problem was with speakers, somehow Yamaha CR-620 works very well with 4 Ohm JBL that have 12" woofers, it makes you feel present right at the music stage.
I'm very happy after all, great experience speaking in this forum I have learned a lot from everybody here.
Thanks!

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:thumbsup:

Very nice looking speakers, well done. You might want to try various speaker cables as well, they do make very discernible difference though not as much as the speakers themselves of course. One of my favorites is Furutech FS-301, don’t know whether it’s available where you are or not but at any rate … enjoy.
 
As I promised to follow up, here is finally what has happened with my Yamaha CR-620. I was never happy with sound of it, especially comparing with my other amps and I decided to get it recapped. It's all works perfect now, I can keep my bass at 0, sound overall improved a lot, strenght of the radio signal is so much better, repair guy told me there was power source problems and also dying transformer. I changed all lights to LED, green one VUE meters and white on radio dial, we also installed internal Bluetooth.
After all I'm super happy with performance of this unit! Checkout some photos below and link to my Yelp review of 'Stone Electronics" where I got it repaired in Hollywood, I highly recommend Joe if you located in Los Angeles, I hope he is not going to retire anytime soon.

https://www.yelp.com/biz/stone-elec...opup&utm_medium=copy_link&utm_source=(direct)

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Cool receiver and nice photos! Sometimes the speakers can really fine tune the sound and getting base out of the little guys can be frustrating especially if they haven't been touch inside. I got curious with my little AIWA 22 and just put on some LL Cool J "I'm Bad" and it's barely breaking a sweat.

The music your playing can also make a difference, late 70's rock is usually bass-shy and it sounds good even on low watt units but early 80's rap is in your face and might need some help to shake the walls.
 
Bone Yard said:
Cool receiver and nice photos! Sometimes the speakers can really fine tune the sound and getting base out of the little guys can be frustrating especially if they haven't been touch inside. I got curious with my little AIWA 22 and just put on some LL Cool J "I'm Bad" and it's barely breaking a sweat.

The music your playing can also make a difference, late 70's rock is usually bass-shy and it sounds good even on low watt units but early 80's rap is in your face and might need some help to shake the walls.
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Thank you!
After servicing and recapping I see how much difference it makes. Now I know that it’s essential to do for units that you love..
 
Very nice looking amp with those green lights. I have a CR-600 and CR-2040. The bass on the 600 is deep and pronounced vs the 2040. I thought when I first hooked it up the bass knob was up but all the levels where flat. I thought the receiver was malfunctioning. I tried it on 3 sets of speakers with the same results. I have to turn the bass down.
 
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