Discussion in 'Yamaha' started by mr_light, Jan 8, 2013.
Thanks, I will post the results.
Were you able to you solve the problem?
give the man some time to get the part from mouser man Although, I am anxious to hear the results as well :yes:
I installed the "C5: OKAYA 0.2uF 120 Ohm 250V CAPACITORS-SPARK QUENCHER", but no change....
None of the filters, loudness, adapter switch, etc. seem to make any difference in the volume of the pop.
I just noticed that in the SM they say to adjusted idle current to -10mV +/-2mV (note the negative sign in front of the 10). I had adjusted the idle current to +10mV based on postings by the great Merrylander and others. Since I have nothing to lose I will try the -10mV setting and see what happens (and post results).
No ,dont mess with it or you'll end up frying your outputs trying!!! ---- If you don't like the +10mv swap your test leads around. Absolute values!!! 10mv!!!!! Your actually adjusting the bias current ie milliamps that flow from the collector to the emitter of you output transistors at rest or idle.(quiescent) -- current is current +/- Macht Nichts !
Idle current (bias) has nothing to do with your popping. DC offset however might be and issue.
I can't believe you even made that statement with a 2040
Pardon my ignorance.... Another example of not knowing what I don't know. I'm not sure why the SM specifies "-10mV"? Sorry about the nothing to lose comment, this is a sacred object I have been entrusted with! I shall wait for a suggestion from someone that knows what they are doing (not me!) before I continue my diagnosis/repair.
These procedures were most likely written for analog voltmeters- where test lead polarity would need to be correct for the correct pointer movement on the meter.Yamaha manuals have a lot of typo's as well.
Did you recap the power supply?
Any threads around with a Recap shopping list for a CR-2040?
No.. The pre-amp out is tapped off the same place as the headphones and speaker out ie. from the 2040's amplifiers outputs - then routed through 10kΩ dropping resistors.
Curious if you tried turning unit on/off with powerstrip and just leaving the on switch always on.
I make my own lists..The last 2040 I did was and entire 100% recap.
That would eliminate the switch. The past two 2040's I've done, both had fouled up protect circuits.Causing power on and/or power off pops. Shorted relay driver transistors and/or protect circuit capacitors.
Just noticed the following comments in previous 2040 threads:
Just following up on this theory about new bulbs curing the power-off thump. I acquired a CR-2040 in nice shape except all the bulbs were out, and it made a LOUD pop/crack when the power was turned off, even with volume down. As suggested in this thread, replacing all the bulbs with the great dgwojo lamp kit fixed the pop! Did it fix your problem?
Comment by Merrylander
"The lamps are on the same supply as the protection relay and it is a filtered supply (in fact try using a diode to rectify AC and don't put a cap on its output, you will see some strange voltage). So without the load from the lamps to pull the power supply voltage to zero the protection relay has a tendency to hang up rather than do a fast release. This is why you get the pop on power off. "
All my bulbs are out, so I'm going to try hooking up some bulbs to test this theory.
Recap on hold...
dgwojo.com has all the lamps required even the little plastic twist-loc bulbs for the tuning dial plate.
I hooked up 9 LEDs in series with a 100 Ohm resistor (what I have in my fully functional CR-2040), and no change in the POP... I'm sure I can find 9 working bulbs in my pile of Yamaha parts, if anyone think that might work. Otherwise I will start preparing for ReCap. I have a couple of matching speaker relays from CR-840s if anyone thinks that might be the problem. I have also tried using a power strip for power off with the same pop.
led lamps wont be pulling the same current as regular lamps .plus they are diodes . get the proper lamps .
I will scrounge up ten bulbs and hook up 5 pairs and see what happens.
Connecting the five pairs of bulbs fixed the POP!!!!!!! I admit I was a little skeptical since I have had a variety of xx40 Yamaha Receivers with no functional bulbs and no pop, but this worked. I would like to replace the bulbs with LEDs. So I am now wondering what components I can substitute for the bulbs (resistors?) to dissipate this charge. Thanks for everyone's help so far.
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