red hot transformer?

marko · 12th December 2007, 06:52 PM

what would cause this? a short i guess? the amp actually works for a bit untill my power supply trips out and the cables get warm too in the process!!

jol50 · 12th December 2007, 07:27 PM

Transformer shorted?

marko · 12th December 2007, 07:29 PM

i'll have a poke around, could be this as some of the anodising on the transfomer wiring is slightly scorched....

shagone · 12th December 2007, 08:13 PM

Quote:

Originally posted by marko
i'll have a poke around, could be this as some of the anodising on the transfomer wiring is slightly scorched....

try twisting with something while you play music and see if it comes and goes. look for a powdery substance between the shorted windings. they often short where the leads bend down to go into the board. if you can find the short you may be able to isolate it with kapton tape or new epoxy.

17DoubleE · 13th December 2007, 11:07 PM

Might your amp be suffering from simultaneous conduction in the transistors (FETs on my amps) that drive the transformer's primary? If so, this could be caused by a damaged gate drive circuit or by the use of replacement FETs having larger gate to source capacitances than the drive circuit was designed for.

marko · 15th December 2007, 03:25 PM

this is the amp, it's a bbg ryval by phoenix gold, it play fine for a few minutes then the transformer gets too hot to touch, i've ohmed all the devices out and they seam fine....

also the trasformer starts to very slightly smoke!!

Perry Babin · 15th December 2007, 10:02 PM

Pull the rectifiers out of the circuit. If the current draw remains high, you know the problem is in the supply. If the current draw goes down to ~1 amp, the problem is in the audio section.

After pulling the rectifiers, you need to put the board back in the sink and clamp the transistors down tightly. High current draw will destroy parts in seconds if they're not clamped to the sink.

marko · 22nd June 2008, 05:21 PM

hi all, i just got round to looking at this again as it's sunday and i'm board!

i pulled the rectifiers out and powered it up, within seconds the transformer was too hot to touch!! i didn't do a current draw check but i'm certain it would be high still...

do i have a shrorted transformer? i guess the only way to tell is to pull the transformer and do continuity tests..

12th December 2007, 06:52 PM	#1
marko diyAudio Member Join Date: May 2004 Location: donnyuk	red hot transformer? what would cause this? a short i guess? the amp actually works for a bit untill my power supply trips out and the cables get warm too in the process!!

15th December 2007, 10:02 PM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Pull the rectifiers out of the circuit. If the current draw remains high, you know the problem is in the supply. If the current draw goes down to ~1 amp, the problem is in the audio section. After pulling the rectifiers, you need to put the board back in the sink and clamp the transistors down tightly. High current draw will destroy parts in seconds if they're not clamped to the sink. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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12th December 2007, 07:27 PM	#2
jol50 diyAudio Member Join Date: Nov 2007	Transformer shorted?

12th December 2007, 07:29 PM	#3
marko diyAudio Member Join Date: May 2004 Location: donnyuk	i'll have a poke around, could be this as some of the anodising on the transfomer wiring is slightly scorched....

13th December 2007, 11:07 PM	#5
17DoubleE diyAudio Member Join Date: Nov 2007	Might your amp be suffering from simultaneous conduction in the transistors (FETs on my amps) that drive the transformer's primary? If so, this could be caused by a damaged gate drive circuit or by the use of replacement FETs having larger gate to source capacitances than the drive circuit was designed for.

22nd June 2008, 05:21 PM	#8
marko diyAudio Member Join Date: May 2004 Location: donnyuk	hi all, i just got round to looking at this again as it's sunday and i'm board! i pulled the rectifiers out and powered it up, within seconds the transformer was too hot to touch!! i didn't do a current draw check but i'm certain it would be high still... do i have a shrorted transformer? i guess the only way to tell is to pull the transformer and do continuity tests..

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