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yamaha cr620 problem

M

Mark.Cass

Member
Hi everyone I am having trouble with my yamaha CR620. Can not figure it out. when i turn the volume up. as soon as any low signals hit. the speakers crackle. and its both channels. more bass worse it gets. and when it hits a bass signal the lights dim and it crackles. I changed filter caps and powresupply caps and it still happens. I checked all fuses, I checked all output transistors, checked all diodes on power supply. Everything is testing good. All switches and buttons deoxed. Oh ya and at 3/4 volume it sounds beautifull . Any higher it will start crackleing. Anyway thats the best i can describe it. If anyone has any thoghts please help. Im not a pro Im a hobbiest Who Is just learning how to Love these things correctly .... Thanks Mark
 
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Binkman said:
G'day:
Sounds like you did a good job on p.s. caps and cleaning. At 3/4 vol. is probably a limit per say. Even at 35w it's not a block party unit but Yammies are noted for the quality of sound and this has pretty good specs.
https://www.hifiengine.com/manual_library/yamaha/cr-620.shtml
Might read the user manual to acquaint yourself with the filters, loudness etc.
noted:
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I apologize that was supposed to be a 1/4 volume not 3/4 lol. Thanks. Mark
 
Mark.Cass said:
1/4 volume not 3/4 lol.
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Crackling usually hints at transistors even though they test okay.
Take a look at the service bulletins.. one does refer to transistor replacements but no symptom so tech info. but good info.
The unit may require further electrolytic recaps beyond the Power supply. (Also look for cold or aged solder joints as well.)
 
mbz said:
Oscilloscope would be helpful, consider building an audio probe. Freeze spraying transistors may give quick results
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ok so this is weird when i go to my main system the speakers crackle at just under half volume but on my test speakers it sounds perfect on any volume i have tried 3 diffreint speakers to make sure it was not the speakers
 
it has had this issue since i got it i have changed the amp and power supply caps i have changed most transistors in both aswell i tested the output transistors they all test good im very stummped
 
Welcome aboard Mark....
Have you changed out the two large power supply capacitors ?

Kind of sounds like " clipping " ie. Running out of available power supply voltage & current.

Both channels is indicative of a power supply problem...
 
yes i agree on it being the powersupply board i did change the big caps. ive tried solder cracks there are none that i can see with magnifing glass but there are a couple of transistors i dont have in my stock they are d438 - b560 i guess i will order them and go from there. Still why dose it work on my test speakers just fine . arggggg!! Thank you for trying to help
 
Yes my test speakers are like 8 ohms my main speakers are 8 also I tried my klipsch chorus my focal cobalt and my b&w 603. My test speakers are axioms.
 
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