I'm contending that's highly unlikely. Say the resistor is rated 1/8 Watt. To dissipate 125mW (not even smoking) in a 382K resistor requires about 219VDC. I don't believe that's even available anywhere in the amp. This needs to be sorted out.
Would you describe particulars of the resistor--- power rating, color code/numeric code?
Would you describe particulars of the resistor--- power rating, color code/numeric code?
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Honestly Im not good with color codes. I'm not totally color blind but dont see them as well as most people. I rely on meter. The resistor is same physical size as other one it replaced. I think its a 1/8 or 1/4 watt. Its from a resistor kit i bought from radio shack before they went out of business.
I just retested. The resistor burned but is still good. Shows 378k now. Its still further burning everytime i cut on but im powering off pretty soon. I made measurement of voltage in this state and one side is 35v and other side is 1.5. It is pulling the relay still.
Could you suggest a possible path for this load current? It would have to somehow deliver 219 V to R816. I can't conceive how this could occur.
I suspect the resistor installed at R816 is much smaller than 382K. Didn't you measure the observed voltage as 50V? Try again and touch resistor. It ought to be barely warm if it's 390K with applied 50V.
I suspect the resistor installed at R816 is much smaller than 382K. Didn't you measure the observed voltage as 50V? Try again and touch resistor. It ought to be barely warm if it's 390K with applied 50V.
You are right. I could have swore it had a k after it. I hope I got a 390k somewhere. Sorry for the misinfo.
I've got a 333k in same wattage and a 470k in the next size higher wattage. Would either of those be safe to use?
for me, i will replace the input differential H701/H702 with new pair even if the old ones tested good, replace with high Hfe types and checked for very good matching...
The originals are definately not available. I had purchased some ksa992 which many say are good replacement to try and resolve the unstable dc but my meter does not have a hfe to do any matching. After hearing everyone say they need to be matched Im hesitant about putting in until I can find a meter with that function. In your opinion are KSA992's OK?
I put in the one that measured 333k (probably a high tolerance 330k). It works and has 42.8v on one side and 1.3 volts on the other. Is that safe for the circuit or do I need to order up a 390k?
That should be fine. Note that R816 and R815 form a voltage divider; in concert with C813, I believe they set turn-on delay for speaker activation. 333K will probably speed turn on slightly.
If you continue to see erratic output offset, H701/H702 are best guess for culprits. I think you'll continue to find poor adjustment range with R713. I suggest changing R712 to 7.5K.
ok, R816 in series with the C813 sets the time delay, so 390k is about right, lower it and the delay is shorter and increasing it delay is longer, R815 discharges the C813 faster and ensures that the H806/H807 did not saturate hard so that fast disengagement is possible...
i doubt that there is problem here, so that the input voltage of 0.4/0.5 vdc is enough to trigger protection on the positive side, the negative offset is fed to the H806/H807 directly turning it off quickly...
very sweet and simple tact...