Hello.
NAD 214 power amplifier.
No power,fuse F501 blown.
Power on with bulb 60w but only soft clipping and bridge mode leds ok.
No red led,no green led.
Thanks
SM
https://www.google.com/url?sa=t&sou...FjAAegQIBBAC&usg=AOvVaw34Wviwvlzf4yxOvw4L-AUI
NAD 214 power amplifier.
No power,fuse F501 blown.
Power on with bulb 60w but only soft clipping and bridge mode leds ok.
No red led,no green led.
Thanks
SM
https://www.google.com/url?sa=t&sou...FjAAegQIBBAC&usg=AOvVaw34Wviwvlzf4yxOvw4L-AUI
With bulb limiter & fuse replaced, check for DC on speaker output. More than 200 mv, probably the output transistors are garbage.
If that is okay, checkthe power supplies at rating on the mains caps. Clip the meter negative to speaker gnd so you only use one hand power on probing. >24 vdc across your heart can stop it. Wear no jewelry on hands wrists or neck, 1 vdc at high current can burn your flesh to charcoal. Wear safety glasses, overstressed parts can exploded.
Next check +26 and +-38 v power supplies.
If that is okay, checkthe power supplies at rating on the mains caps. Clip the meter negative to speaker gnd so you only use one hand power on probing. >24 vdc across your heart can stop it. Wear no jewelry on hands wrists or neck, 1 vdc at high current can burn your flesh to charcoal. Wear safety glasses, overstressed parts can exploded.
Next check +26 and +-38 v power supplies.
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I don't understand why the red led do not light up,but soft clipping and bridge mode light up.........
So you replaced the fuse.
Do you own a variac or use the DBT (post 2) ?
Red LED is for protect mode.
Do you own a variac or use the DBT (post 2) ?
Red LED is for protect mode.
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The fuse blown direct.
I use a 60w bulb.
The red light need light up after pushing on off knob,but nothing
I use a 60w bulb.
The red light need light up after pushing on off knob,but nothing
+53.4v & -53.4v on c204 & C205 ok
+53.4v. &. -53.5v on +VR & -VR
+53.4v. &. -53.5v. on +VR. &. -VR
Where I need check +26. And +-38v?
+53.4v. &. -53.5v on +VR & -VR
+53.4v. &. -53.5v. on +VR. &. -VR
Where I need check +26. And +-38v?
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Since you have a 60 W bulb in series with the AC line, I'd replace the F501 with a 10 A, disconnect jp 201 & jp202, turn on & look for smoke or heat. If you see that where the smoke is the problem is downstream of that.
Of course when the unit is repaired, put the fuse back to the correct specified value.
If the light bulb is bright without the left or right power amp connected, the problem is on the power supply board.
If the fuse doesn't blow that way with both power amp boards disconnected, then I'd try jp201 connected alone to see if the 60 W bulb is brighter or dimmer. Bright bulb is bad sign, dimmer is better sign.
Then alternately disconnect jp201 and connect jp202.
Which ever side the light bulb is brighter, that is the side with a major problem.
Of course when the unit is repaired, put the fuse back to the correct specified value.
If the light bulb is bright without the left or right power amp connected, the problem is on the power supply board.
If the fuse doesn't blow that way with both power amp boards disconnected, then I'd try jp201 connected alone to see if the 60 W bulb is brighter or dimmer. Bright bulb is bad sign, dimmer is better sign.
Then alternately disconnect jp201 and connect jp202.
Which ever side the light bulb is brighter, that is the side with a major problem.
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The light bulb is bright dimmer without the left or right power amp connected.
the fuse F501 not blown
If I connect right of left power amplifier the bulb is brighter and fuse blown.
But I don't understand where is red light after power on,only soft clipping and bridge mode.
the fuse F501 not blown
If I connect right of left power amplifier the bulb is brighter and fuse blown.
But I don't understand where is red light after power on,only soft clipping and bridge mode.
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You need to put a big enough fuse in to take voltage measurements without it blowing again. 60 W bulb in series with AC plug should limit the AC current to something not too dangerous. Again watch for smoke, you don't need a fire on the board to burn pcb lands. Position of smoke matters.
You might check th101 for voltage if you can get the amp to sabilize with power on. It should have none, but if it has failed open could set the protection led on. Same with th102. Those wouldn't blow the fuse, though.
since the speaker relay is probably open, you need to check for >200 mv dc on o/p pin of each power amp. Output transistor failure is common, should be checked on right after the power supplies prove good. If ouput o/p is >200 mv, proceed to removing the output transistors q329, 331, 333, 335 or q330,332,334,336, which ever channel is bad.
You might check th101 for voltage if you can get the amp to sabilize with power on. It should have none, but if it has failed open could set the protection led on. Same with th102. Those wouldn't blow the fuse, though.
since the speaker relay is probably open, you need to check for >200 mv dc on o/p pin of each power amp. Output transistor failure is common, should be checked on right after the power supplies prove good. If ouput o/p is >200 mv, proceed to removing the output transistors q329, 331, 333, 335 or q330,332,334,336, which ever channel is bad.
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