• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Yamaha CR-2040 Shorted During DC/Bias/Voltage Adjustment

avionic said:
6 ea. KSC1815
4 ea. KSA1015


2 ea 4558 opamps --- > https://www.mouser.com/ProductDetail/NJR/NJM4558D?qs=uTtZEXA6qg82qae6cdQ0Qw==


2 ea HA1457 opamps ------> option 3---->https://www.cimarrontechnology.com/product/browndog-140901-ha1457-upgrade-adapter
Click to expand...

Alright, I'll order and ask questions later. Thanks for the help.

With the level of disassembly, sitting for 6 months, and now trying to put it back together I feel like I should see if I can even get the damn thing to power up after reassembly before putting more money into it, but screw that, go big or go home. The time lag has me very nervous on this one though, feel like there's going to be something I forgot or reconnected incorrectly.
 
avionic said:
Those will due.
Click to expand...
Alright. Got this all put back together before replacing the recent order of transistors and op amps (still waiting on the HA1457's), basically wanted to test functionality for any mistakes I may have made during the 6 month wait and then re-assembly. I was pretty diligent in double checking notes/pics/schematic to avoid mistakes and luckily it powered up with no fireworks, smoke, or blown fuses.

Both channels produced sound but that damn presence pot is the same symptom as before where there is loud distortion/popping...this is the replacement presence pot so the pot is ruled out unless it's just dumb luck to have a bad original and replacement. Also, with volume at minimum, there is low level noise (like a gurgling/bubbling static, dont know how else to describe it).

So I replaced all the KSC1815 and KSA1015 small transistors on the tone board. Same issues still exist. So now on to the OpAmps, I have the 4558's but going to be next week before the HA1457's arrive. Do these need to go in at the same time or is it fine to put the 4558's in now? The little that I know about standard discrete components, I know way less about IC's and OpAmps so I dont want to put those 4558's in if something bad elsewhere in the circuit could damage them.
 
Dead quiet! Alright, so how the hell would you personally diagnose an issue like this? Do you just have to pull and replace parts until you find it or is there a tell tale sign to look at IC's, another sign for transistors, another sign for caps or resistors?
 
I had a 2040 here a few years ago with the same issues.The 4558's remedied the problem.
 
Pops and crackles are usually always and active device. Transistor,diode ,opamp etc.
 
avionic said:
Pops and crackles are usually always and active device. Transistor,diode ,opamp etc.
Click to expand...
Same with that gurgle/static at no volume? I had thought through the reading/research of many past forums that that would indicate a capacitor getting ready to hang it up...or maybe it's my own way of reasoning through it because the gurgle literally sounds like I would envision a drying out electrolytic cap boiling out it's remaining liquid (I know that's not how these devices work but that is pretty much what I picture in my head on old electrolytics... I'm an ME not an EE, and think in physical material interactions and not down to the electron level).
 
I should have recorded it. However, I've got an HK 930 that was doing a good impersonation of it...this is through the speakers by the way, not the actual cap boiling/gurgling if you thought I was saying that...I actually have heard a receiver sizzle/gurgle and I believe it was something with the power switch on a pioneer SX-750 if I recall correctly, straight up sounded like bacon in a pan.

Different way of describing the static gurgle....a low steady static that lightly spikes up similar to how some receivers will send a "whoomp" type sound through the speakers when powering off if something is not right. Was very low level on the Yamaha, the HK 930 was more pronounced so it'll be coming to the bench soon.
 
Beavs said:
Do you just have to pull and replace parts until you find it or is there a tell tale sign to look at IC's
Click to expand...
Sometimes you can spray the components with some type of freeze spray and the faulty component will settle down until it warms up.
 
avionic said:
Sometimes you can spray the components with some type of freeze spray and the faulty component will settle down until it warms up.
Click to expand...
I should get a can of that, a lot easier than removing, testing, then putting back in. IC's and OpAmps, are those even testable?

On another more specific note, I replaced the trimmers for DC and idling current adjustment to more accurately adjust each of these (which was how I got into this in the first place!..no more alligator clips). However, DC seems to cycle up and down about 15-20mv on both channels. In your experience with the CR-2040, is that normal?
 
Last edited:
avionic said:
15-20 mv is not worth bothering with.
Click to expand...
I was just surprised to sit there and watch it cycle up and down consistently. I'll have it playing regularly for the next week until those last two OpAmps come in and monitor to see if it tries to run away at all.
 
You must log in or register to reply here.
Back
Top Bottom