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Messages - tonyharker

#136
What OpAmp are you using and with what supply voltages?

Tony
#137
Amplifier Discussion / Re: TDA2050 Pwr requirements
February 18, 2009, 05:30:08 AM
The data sheet I've got states - "Output peak Current (Internally limited) 5 A"
This is for a ST chip.


Edit..  The actual current drawn by the chip will be determined by the output (Watts) developed in the speaker.  By the way your Transformer voltage appears to be too High 48v CT = 24 + 24 vAC which will give you 24v * 1.414 = nearly +/-34v DC after rectification which will blow the chip :'(

A better transformer will be 32v CT ie 16 + 16 vAC which will give +/- 22.6v DC this will develop 32 watts rms @ 10% distortion into an 4 ohm speaker or 22 watts into 8 ohms. 
The current required will be approx 4A in 4 ohms or  2.5A in 8 ohms.

Hope this helps.

Tony.
#138
YouTube reproduction is such poor quality I'm surprised anyone could tell the difference.  :( :(
Also whatever recorded the sound - is going to have a big effect so don't go by that.
Get down your local store and try them out!   :tu:

Tony
#139
The Newcomer's Forum / Re: Loud hum and no sound output
October 19, 2008, 04:45:15 PM
As this is a transistor Amp I would think that the output has been shorted at some time and blown the output transistors - likely as the fuses have blown!

Tony 
#140
Amplifier Discussion / Re: LM386 based guitar amp
July 26, 2008, 08:15:59 AM
Hi ENGR BUGO,

Can you post the circuits/schematics of these please?

Regards Tony
#141
Definitely sounds to me like bad PS caps.  You'd get the pulsing effect with hum on the supply as the ripple beats with the input "hummmmm"

Tony :0)
#142
Amplifier Discussion / Re: Acoustic 150 Tremolo
May 18, 2008, 04:59:23 AM
Difficult to diagnose without the schematic.  Can you post it?
#143
Amplifier Discussion / Re: Tel-ray Supernova
May 08, 2008, 06:46:35 AM
Google MPSU57, or visit www.datasheet4u.com and search for the datasheet.
#144
Apparently ballasting the bootstrap capacitor with a resistor helps prevent turning on fully the NPN Driver transistor with large positive-going signals, which could cause this transistor to 'lock' hard on.  This of course would subsequently destroy the output transistors. 

Tony
#145
Amplifier Discussion / Re: Anybody use an OPA541
January 31, 2008, 04:47:49 AM
The only snag with these amps is that you lose high frequency response for gains over 30dB (about x13).

Tony
#146
It looks like you have missed the link between pin 1 of the Volume control and earth!

Tony
#147
If you don't know too much about the internals then take it to a professional repairer.  There are voltages inside this amp that will KILL you if you don't know what you are doing.  Even with it switched off!!

Don't risk your life it's not worth it!!!

Tony.
#148
With that large amount of hum, and the Caps getting hot it could be that the rectifier is (partly) shorted and you are getting a high ac ripple.  Check it out using the diode function on your DMM.
#149
Preamps and Effects / Re: tone frequencies
September 26, 2007, 02:30:18 PM
If you check out and download the Tone Stack Calculator on this page http://www.duncanamps.com/software.html It may give you some ideas.

Tony.
#150
Amplifier Discussion / Re: Crate GT212 Blowing Fuses
September 15, 2007, 02:31:39 PM
If its new send it back,  if you mess with it you will invalidate the warranty.

Don't whatever you do put a larger fuse in!

Tony