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NAD 214 Troubleshooting

I'm hopeful that replacing R230 will resolve the issue.

diyaudio post has the relay as a 48V, 12mA item, so maybe IC pin 6 at 0.9V is a little high?
Let us know the outcome when R230 replaced.
 
kennycrippen said:
D210 coming in at .6v one way and 2.8v or so the other, I think that’s good? Measured D211 and get the same result.

Confirmed R229 value and it tests in spec.
Click to expand...
You need to measure D210 out of circuit, otherwise you are measuring across the relay coil. It's probably ok, though. If it was bad it would read a short.
 
The test on D210 was about testing the relay coil, making sure that it was not open. While I don't understand the 2.8V result it suggests the coil is not open, maybe we should dig deeper into the 2.8v result.

The relay appears to be 48V/12mA/4kohms

Maybe in circuit resistance check D210 then reverse probe orientation, do you get something approaching 4kohms?

Waiting at least 5 seconds after power up, measure dc voltage at D210 cathode (+49Vdc?) then repeat for D210 anode (+0.9Vdc)
 
Entirely possible the 2.8v measurement is user error on my part, I’m still getting the hang of my DMM. I can double check. Also hopeful R230 will resolve the issue though.
 
Parts arrived today and I quickly installed the new 18k resistor for R230. Some good news, some not so good. Noticed the soft clipping light was off on first power up after installing the new resistor. Flipped the switch and it was stuck on again, wiggled it around and it flickered, so I cleaned the heck out of it with Deoxit and the switch works as it should now. Soft clipping light goes on and off as it should. Some progress!

Still no relay click, however. Measurements on IC202 seem odd now, having trouble getting much of a reading on any pins. Pin 5 I did get to read .6v. I'll try probing them some more tomorrow to see if I can get any consistent readings. @mbz I also still need to measure D10 per your suggestion above, will get to that tomorrow.

I measured most every diode on the power supply and they all consistently seem to have that odd result in one direction, anywhere from 1.5 to 2.9v. Could be an in circuit thing?

I did order quite a few replacement diodes and some transistors as well to have on hand. Maybe I should've gone ahead and snagged some new output transistors while I was at it.

Thinking about testing Q201 and Q204 out of circuit next, I have replacements for those. However, that's just a gut instinct and I'm not sure if those relate directly to the relay or not. I'm still not great at reading schematics.
 
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You have some new diodes you ordered. Lets verify the operation of your meter with them. Measure one and see what you get. Should be .6V in forward direction and over range in the reverse direction. If not, your battery could be low or the meter is junk.
 
@dr*audio Meter is a Klein MM400, not top of the line for sure. Tested one of my new diodes, correctly measures .6V one direction and OL in the other. Last week I measured diodes on each driver board and they also measured correctly without the odd voltage in one direction that the power supply diodes have.

@mbz Here are the new measurements. I was able to get IC202 pins to measure some after all. R229 and D210 have strange measurements.

IC202
1: .668v
2: .16v
3: .16v
4: 0v
5: .651v
6: .03v
7: 0v
8: 0v
9: 0v

R229: Both sides 54.8v
D210: anode 52v, cathode 54.4v
R230: 54.4v one side, 3.1v other side
 
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Results indicate a step backward.
IC202 pin 9 (power supply) "can't" be 0V unless you have a burnt track/bad solder joint.

kennycrippen said:
R230: 54.4v one side, 3.1v other side
Click to expand...
Measure resistance between the "low" (3.1V) side of R230 and IC202 pin 9, expect less than 1 ohm.

kennycrippen said:
D210: anode 52v, cathode 54.4v
Click to expand...
kennycrippen said:
6: .03v
Click to expand...
D210 anode and pin 6 voltages should be the same unless TH101 or TH102 open

maybe MM issues as per dr*audio
 
Thanks @mbz I'll give those measurements a shot. At the very least I probably need to order some smaller leads for my DMM. Existing leads are just big enough that getting them onto the IC202 pins is difficult. Probably should just invest in a better DMM as well. I'll take another look at the bottom of the board and check for burnt tracks etc.
 
kennycrippen said:
Thanks @mbz I'll give those measurements a shot. At the very least I probably need to order some smaller leads for my DMM. Existing leads are just big enough that getting them onto the IC202 pins is difficult. Probably should just invest in a better DMM as well. I'll take another look at the bottom of the board and check for burnt tracks etc.
Click to expand...
If you have a bench grinder you can sharpen the leads.
 
Taking a break from this one while I work on a more straightforward rebuild for a bit. I’ll come back to this one eventually!
 
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