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Old 5th May 2007, 02:07 PM   #1181
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Default Try 1K8 man...in the place of the resistance you have from base to colector

Also you can try to install...under the board...a parallel one, that will reduce the resulting ohmic value be carefull.

Let's imagine 10000 ohms (10K) in parallell with 2200 ohms (2k2)

10000 multiplied by 2200 22000000
-------------------------------------------------- = ------------------- =
10000 added to 2200 12200

The result is 1803 ohms...near the 1K8....this may fit your needs dear Nordic.

This is NOT in parallel with the trimpot...it must be over (or under) the 2K2 fixed resistance already in place.

What is your trimpot value..is it 1000 ohms?

regards,

Carlos
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg
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Old 5th May 2007, 02:09 PM   #1182
Nordic is offline Nordic  South Africa
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Thanks uncle Charly will look now... quickly makeing a short signal cable with a 3.5mm jack to use ipod for testing... will use old speaker first... only to listen softly....

I have 1k8 resistors thanks will be easier to swap out than solder on extra one... safer in long run... don't want tracks to touch heatsink.

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Old 5th May 2007, 02:11 PM   #1183
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Default Nordic..good idea to place a fuse..at least in the output.


Some bad solder joint can create huge problems related the outpud DC voltage... it can may jump to stratosphere.

hehe.. within the supply voltage limits of course....supplie's Stratosphere.

Cold solder joints happens....yeah...it is not too much hard to find those cold solder joints.

I am excited (the image) as we gonna listen this amplifier today.

Speaker inside the enclosure...please!!!!

regards,

Carlos
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Old 5th May 2007, 02:19 PM   #1184
Nordic is offline Nordic  South Africa
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nope first speaker will be in my hands... lol don't worry I always test amps this way... I know its sound, and I adjust the bass by changeing distance to floor, holding it up towards my face... then I will leave it to play at least an hour before I let it touch my good speakers... will out 5A fuse on output...
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Old 5th May 2007, 02:24 PM   #1185
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Default Bah...not a good sonic this way..you will perceive amplifier week


Bah!...pooh!.... buuŠaaaa!

Oh day..oh life...not fair...not fair....i do not deserve..this is too bad..oh pain...oh..oh..oh!

regards,

Carlos
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Old 5th May 2007, 02:45 PM   #1186
kvholio is offline kvholio  Netherlands
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Nordic, your bias should be adjustable from below 10 mA minimum.
1.4A rail-current is huge !

DON'T attach your main loudspeaker(s) before this works properly.


Did you connect the vbe-multiplier from A to C as shown on Greg's website ?
Did you omit r14 an vr2 ? you should.

Best regards,

Klaas
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Old 5th May 2007, 02:48 PM   #1187
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Default I think he had already fixed this Klaas



The last inform i had was 3 milivolts off set...33 Vdc supply and 135 miliamps each rail.

I suppose he could reduce and may be listening...and dancing..for sure..so happy that will not remember to come here to tell us some news.

Hello Klaas...happy to have you once again.

take your seat...today we gonna have a party here..

BTW..i am waiting for the lunch time..and observing this lamp....remembers me something..hehe..i do not know what?

regards,

Carlos
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Old 5th May 2007, 02:55 PM   #1188
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Default I was wondering if i can use those transistors as VAS


They are oscilating, well, working as oscilator to increase voltage into a toroidal transformer...and are holding DC Voltages bigger than 300 volts DC...hummmm...this one may be interesting.

regards,

Carlos
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Old 5th May 2007, 02:58 PM   #1189
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Default I am thinking....EVA!....what do you think?


I hope Eva has patience to track this thread...hummm..i do not know...she is in a higher level of knowledge.

Oh!..she is not on line.

But i may be lucky latter.

regards,

Carlos
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Old 5th May 2007, 03:35 PM   #1190
Nordic is offline Nordic  South Africa
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baah,,, ok i broke something... on replaceing the 2k2 resistor with 1k8, I soldered badly and there was no connection to VBE base...

I did not see it, was like a microfracture.. looked perfect.

Anyhow on powerup the 10R resistors started to smoke... DMM was on 20V range.. and voltage was above that scale...i.e. showing 1.

I then found the mistake on the solderjoint with continuity tester...

Now on power up the resistors only carry 15mA and it does not change with turning the trimpot... I assume the bd139 is dead and the trimpot too probably... will test em later... anything else likely to have died... nothing smells...yet

Yes, Klaas, VBE circuit is correct according to scematic... and needed components omitted..

I have spare transistors, tell me where to start looking...
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