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Title: Vox DA5 Battery Problem
Post by: Carl on February 07, 2010, 10:11:43 AM

I have a Vox DA5 with the battery power out of service. I thought it was just a bad connection but that does not seem to be true. I had a good amp tech look at it. He said that he thinks there is a transistor out. He can jump it so the battery works but then the on/off switch does not work. He needs a schematic to get any further.

Does anyone have any ideas?

Thanks,

Carl

Title: Re: Vox DA5 Battery Problem
Post by: lemaroille on January 09, 2014, 08:31:15 AM

hi,

here is the schematic of the supply part I get opening my amp.

hope it helps.

Can anyone tell me what is the aim of the KTC2026 transistor and the big 1 or 2W resistor ?

thx

(http://img.imagesia.com/fichiers/f2/da5-bat_imagesia-com_f2lu_large.jpg) (http://imagesia.com/da5-bat_f2lu)

Title: Re: Vox DA5 Battery Problem
Post by: Roly on January 12, 2014, 05:33:29 AM

Hi lemaroille, welcome!

Quote from: lemaroilleCan anyone tell me what is the aim of the KTC2026 transistor and the big 1 or 2W resistor ?

It's a voltage regulator.

The "diode" connected to the 47 ohm and transistor Base will actually be a zener diode. This provides a voltage reference for the transistor which does the actual voltage regulating, the Emitter being about half a volt lower than the zener voltage on the base.

HTH

Title: Re: Vox DA5 Battery Problem
Post by: J M Fahey on January 12, 2014, 07:32:16 AM

Agree.
The schematic shows 2 alternative power supplies.
The batteries provide straight 9V; the regulated one turns raw 12V (which in cheap wall adapters may be as high as 16 or 17V :duh ) into stable 9V.
The Zener will be a 9.5V to 10V one.

Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: Carl on February 07, 2010, 10:11:43 AM