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Anyone have a Schematic for a Fender Acoustasonic 90?



 
 
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  #1  
Old August 1st 19, 02:30 AM posted to rec.audio.pro
Paul[_13_]
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Posts: 871
Default Anyone have a Schematic for a Fender Acoustasonic 90?

This one was not powering up, so I cracked it open.

The on-board fuse was still good. There was 120 AC,
and about 330 DC on the first rectifier. But
there were no DC voltages going to the next board.

So it's most likely a power supply issue, but as you
know, modern switching power supplies are very
complex, and are difficult to troubleshoot, especially
without a proper schematic.

Any advice is appreciated.
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  #2  
Old August 1st 19, 10:30 PM posted to rec.audio.pro
Scott Dorsey
external usenet poster
 
Posts: 16,655
Default Anyone have a Schematic for a Fender Acoustasonic 90?

In article >, Paul > wrote:
>This one was not powering up, so I cracked it open.
>
>The on-board fuse was still good. There was 120 AC,
>and about 330 DC on the first rectifier. But
>there were no DC voltages going to the next board.
>
>So it's most likely a power supply issue, but as you
>know, modern switching power supplies are very
>complex, and are difficult to troubleshoot, especially
>without a proper schematic.


Get the datasheet for the PWM controller. Likely most of the power supply
will be copied right off the datasheet, or at least enough for you to
figure out what is going on.

If the big switching fet isn't shorted, if there is power on the big
primary-side capacitor, and you don't see physical damage, and it's
not kicking on briefly or crowbarring, then change out the kickstart
capacitor (which will be one or two MFD and right near the PWM controller
chip). If it doesn't fix the problem, it's still the first step toward
diagnosing why the PWM oscillator won't come on.

I wrote an introduction to repairing switching supplies without the manual
in AudioXPress a couple years ago, and the article is probably worth digging
up.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #3  
Old August 1st 19, 11:32 PM posted to rec.audio.pro
Phil Allison[_4_]
external usenet poster
 
Posts: 457
Default Anyone have a Schematic for a Fender Acoustasonic 90?

Paul wrote:
>
> This one was not powering up, so I cracked it open.
>
> The on-board fuse was still good. There was 120 AC,
> and about 330 DC on the first rectifier. But
> there were no DC voltages going to the next board.
>
> So it's most likely a power supply issue, but as you
> know, modern switching power supplies are very
> complex, and are difficult to troubleshoot, especially
> without a proper schematic.
>
> Any advice is appreciated.
>



** Give the job to someone who knows what they are doing and has the needed safety and test equipment.

Yours is definitely a case of " fools rushing in where angels fear to tread".

FFS ignore Scott Dorsey, the guy is a dangerous idiot.



...... Phil



..... Phil
  #4  
Old August 2nd 19, 12:22 AM posted to rec.audio.pro
Paul[_13_]
external usenet poster
 
Posts: 871
Default Anyone have a Schematic for a Fender Acoustasonic 90?

On 8/1/2019 2:30 PM, Scott Dorsey wrote:
> In article >, Paul > wrote:
>> This one was not powering up, so I cracked it open.
>>
>> The on-board fuse was still good. There was 120 AC,
>> and about 330 DC on the first rectifier. But
>> there were no DC voltages going to the next board.
>>
>> So it's most likely a power supply issue, but as you
>> know, modern switching power supplies are very
>> complex, and are difficult to troubleshoot, especially
>> without a proper schematic.

>
> Get the datasheet for the PWM controller. Likely most of the power supply
> will be copied right off the datasheet, or at least enough for you to
> figure out what is going on.
>
> If the big switching fet isn't shorted, if there is power on the big
> primary-side capacitor, and you don't see physical damage, and it's
> not kicking on briefly or crowbarring, then change out the kickstart
> capacitor (which will be one or two MFD and right near the PWM controller
> chip). If it doesn't fix the problem, it's still the first step toward
> diagnosing why the PWM oscillator won't come on.
>
> I wrote an introduction to repairing switching supplies without the manual
> in AudioXPress a couple years ago, and the article is probably worth digging
> up.
> --scott
>


I found your article:


https://www.audioxpress.com/article/...power-supplies

Thanks much. I will read this and let you know what I find.

P
  #5  
Old August 2nd 19, 12:26 AM posted to rec.audio.pro
Paul[_13_]
external usenet poster
 
Posts: 871
Default Anyone have a Schematic for a Fender Acoustasonic 90?

On 8/1/2019 3:32 PM, Phil Allison wrote:
> Paul wrote:
>>
>> This one was not powering up, so I cracked it open.
>>
>> The on-board fuse was still good. There was 120 AC,
>> and about 330 DC on the first rectifier. But
>> there were no DC voltages going to the next board.
>>
>> So it's most likely a power supply issue, but as you
>> know, modern switching power supplies are very
>> complex, and are difficult to troubleshoot, especially
>> without a proper schematic.
>>
>> Any advice is appreciated.
>>

>
>
> ** Give the job to someone who knows what they are doing and has the needed safety and test equipment.
>


I have the test equipment....haven't you been paying attention to my
posts?

> Yours is definitely a case of " fools rushing in where angels fear to tread".


Yours is definitely a case of "I've got my head up my ass!"



>
> FFS ignore Scott Dorsey, the guy is a dangerous idiot.
>


Look in the mirror if you wanna see an idiot!


  #6  
Old August 2nd 19, 12:29 AM posted to rec.audio.pro
Phil Allison[_4_]
external usenet poster
 
Posts: 457
Default Anyone have a Schematic for a Fender Acoustasonic 90?

Paul wrote:

>
> I found your article:
>
>

( dangerous article link deliberately snipped )


> Thanks much. I will read this and let you know what I find.
>



** Better make sure your life insurance is paid up and you have updated your will.

Wot a ****ing idiot.


...... Phil



  #7  
Old August 2nd 19, 12:34 AM posted to rec.audio.pro
Paul[_13_]
external usenet poster
 
Posts: 871
Default Anyone have a Schematic for a Fender Acoustasonic 90?

On 8/1/2019 4:29 PM, Phil Allison wrote:
> Paul wrote:
>
>>
>> I found your article:
>>
>>

> ( dangerous article link deliberately snipped )
>
>
>> Thanks much. I will read this and let you know what I find.
>>

>
>
> ** Better make sure your life insurance is paid up and you have updated your will.
>


**** you, numbnuts. I've worked in the electronics field for
decades, so I know basic electronics safety.

Don't project your own ignorance and stupidity on others.

> Wot a ****ing idiot.
>


You're a ****wit! Go **** on your Momma's grave!



>
> ..... Phil
>
>
>


  #8  
Old August 2nd 19, 01:53 AM posted to rec.audio.pro
Paul[_13_]
external usenet poster
 
Posts: 871
Default Anyone have a Schematic for a Fender Acoustasonic 90?

On 8/1/2019 2:30 PM, Scott Dorsey wrote:
> In article >, Paul > wrote:
>> This one was not powering up, so I cracked it open.
>>
>> The on-board fuse was still good. There was 120 AC,
>> and about 330 DC on the first rectifier. But
>> there were no DC voltages going to the next board.
>>
>> So it's most likely a power supply issue, but as you
>> know, modern switching power supplies are very
>> complex, and are difficult to troubleshoot, especially
>> without a proper schematic.

>
> Get the datasheet for the PWM controller. Likely most of the power supply
> will be copied right off the datasheet, or at least enough for you to
> figure out what is going on.


I found the PWM chip. It's a 1271A, PTAC. So it's this one,
if I am not wrong:

pdf.datasheetcatalog.com/datasheet/on_semiconductor2/NCP1271-D.PDF

I have confirmed that I am getting AC and DC off the first main
rectifier, and there appears to be nothing on the secondary of the main
transformer.

I was NOT able to see a 65kHz driving signal on the driver pin 5,
but I assume this is because the oscillator is still off.

>
> If the big switching fet isn't shorted, if there is power on the big
> primary-side capacitor, and you don't see physical damage, and it's
> not kicking on briefly or crowbarring, then change out the kickstart
> capacitor (which will be one or two MFD and right near the PWM controller
> chip). If it doesn't fix the problem, it's still the first step toward
> diagnosing why the PWM oscillator won't come on.
>


Is the kickstart capacitor either C6 or C7 on page 18? One of the
1.2nF caps?


> I wrote an introduction to repairing switching supplies without the manual
> in AudioXPress a couple years ago, and the article is probably worth digging
> up.
> --scott
>


  #9  
Old August 2nd 19, 03:18 AM posted to rec.audio.pro
Phil Allison[_4_]
external usenet poster
 
Posts: 457
Default Anyone have a Schematic for a Fender Acoustasonic 90?

Paul wrote:

> On 8/1/2019 3:32 PM, Phil Allison wrote:
> > Paul wrote:
> >>
> >> This one was not powering up, so I cracked it open.
> >>
> >> The on-board fuse was still good. There was 120 AC,
> >> and about 330 DC on the first rectifier. But
> >> there were no DC voltages going to the next board.
> >>
> >> So it's most likely a power supply issue, but as you
> >> know, modern switching power supplies are very
> >> complex, and are difficult to troubleshoot, especially
> >> without a proper schematic.
> >>
> >> Any advice is appreciated.
> >>

> >
> >
> > ** Give the job to someone who knows what they are doing and has the needed safety and test equipment.
> >

>
> I have the test equipment....haven't you been paying attention to my
> posts?
>


** I bet you have not got a iso-transformer or any clue of how to use it.

Amateurs should NEVER touch a mains switcher supply.


> > Yours is definitely a case of " fools rushing in where angels fear to tread".

>
> Yours is definitely a case of "I've got my head up my ass!"
>
>




** You just proved beyond any doubt you are a bull****ting nut case and an asshole.

Make my day - go ahead, electrocute yourself.


  #10  
Old August 2nd 19, 03:23 AM posted to rec.audio.pro
Phil Allison[_4_]
external usenet poster
 
Posts: 457
Default Anyone have a Schematic for a Fender Acoustasonic 90?

Paul the Lunatic wrote:

-------------------------

> Phil Allison wrote:
> > Paul wrote:
> >
> >>
> >> I found your article:
> >>
> >>

> > ( dangerous article link deliberately snipped )
> >
> >
> >> Thanks much. I will read this and let you know what I find.
> >>

> >
> >
> > ** Better make sure your life insurance is paid up and you have updated your will.
> >

>
> **** you, numbnuts. I've worked in the electronics field for
> decades, so I know basic electronics safety.
>


** You made that bull**** claim before.

You know SFA about safety when working on live mains equipment.


>
> > Wot a ****ing idiot.
> >

>
> You're a ****wit!



** FYI to all:

This poster is clearly schizophrenic with a death wish.



> Go **** on your Momma's grave!
>


** Brainless POS like him would not be missed by anyone.



..... Phil
 




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