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Old 24th November 2011, 11:38 AM   #6931
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i have a problem. all circuits are fitted right. no grounded traces. all components are working. but when i turned it on, with protective resistor, these are the following problems.

1. protective resistors get hot after a minute or two.
2. my power transistor gets hot too.
3. output measures some DC. around 3volts

i don't hook up any load yet and the input is grounded as the procedure says.
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Old 24th November 2011, 12:03 PM   #6932
AndrewT is offline AndrewT  Scotland
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Power up via a bulb tester.
It will stop the devices becoming hot.
It will allow you to measure voltages without risk of the amp blowing up.
It will not prevent a slipped probe from blowing up the amplifier. The smoothing caps discharge through the accidental short and the magic smoke dissipates.
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Old 24th November 2011, 12:51 PM   #6933
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and one more thing. only A1943 is getting warmer but c5200 is cold. what is the problem? i check the voltage across the protective resistor and it reads 4.40v.
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Old 24th November 2011, 02:44 PM   #6934
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tight bass. pronounce mids and highs. DX amp is now working.
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Old 24th November 2011, 03:20 PM   #6935
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Quote:
Originally Posted by harmonicconverger View Post
tight bass. pronounce mids and highs. DX amp is now working.
What was the problem, and is it solved?
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Old 24th November 2011, 04:00 PM   #6936
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actually. it is now working. but it seems there are still problems like:

1.when i set my DMM to 200m and measure the output i have dc readings from hundreds then fluctuating slowly.

2. when i test the resistor protection i got my reading at 500+MV but when it is in the halfway, it reads 1400+MV.

now i don't know what to do.
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Old 24th November 2011, 06:23 PM   #6937
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Default There's a trimpot to adjust off set.

Is it assembled below (beneath) your pcboard.. is it in the copper side?

Is this trimpot adjusting?... when you turn the trimpot knob or the adjustment screw, is the off set changing?

Mistakes.... this is what you have... do not desperate..go searching because this is normal to happens..... **** happens as you know...yeah...i have typed this symbol (*) was not forum automatic correction.

Everybody makes mistakes.... even the one says that does not make mistake is doing a mistake..and his mistake is to say this foolish that cannot make mistakes...we are humans...we fail... search for your mistake dear Harmonic.

By the way..is the bias trimpot operating?

How is the sonics?...if not astounding and awesome..then you have mistakes..... everybody loves that sonics.

regards,

Carlos
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Dx Blame ST with a tube preamp. recorded with Xperia cell phone, https://www.youtube.com/watch?v=Qjs32J0gdj0; https://www.youtube.com/watch?v=nhrZ...vDnDhEpNv_XVxg

Last edited by destroyer X; 24th November 2011 at 06:32 PM.
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Old 25th November 2011, 02:05 AM   #6938
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here is my reading in output terminal.
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Old 25th November 2011, 12:53 PM   #6939
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Default Is this current scale or other scale?

Off set is Direct current... milivolts in DC...what is your measurement... the flash spot is covering the scale so i cannot know what scale you are using.

regards,

Carlos
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Dx Blame ST with a tube preamp. recorded with Xperia cell phone, https://www.youtube.com/watch?v=Qjs32J0gdj0; https://www.youtube.com/watch?v=nhrZ...vDnDhEpNv_XVxg
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Old 25th November 2011, 02:17 PM   #6940
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it was set to 200mV. and the reading was 4.7mV
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