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Sharp gf 8989 power supply


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#1 Guest_Dave1342_*

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Posted 22 November 2018 - 07:29 PM

Hi has anyone got a power supply for a sharp gf 8989, or something compatible?

#2 Guest_Dave1342_*

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Posted 16 December 2018 - 04:10 PM

Still looking 🙏

#3 Superduper

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Posted 16 December 2018 - 04:30 PM

What is wrong with yours and can’t it be fixed?

#4 Guest_Dave1342_*

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Posted 26 December 2018 - 03:48 AM

I think the transformer is gone, I have no clue what should be the correct one to fit, I’m not big on electronics so not 100% sure if that’s the issue, I know it works on battery’s and the 12volt plug but not on 240v, and can solder and if I knew the components to change I’m confident I could do it but don’t wanna screw it up and break it, any ideas are welcome

#5 Superduper

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Posted 26 December 2018 - 02:02 PM

Testing the transformer to see whether it's failed is relatively easy, just check the primary and secondary coils for continuity.  In fact, power supplies are one of the easiest repairs to effect in boomboxes.  That does not mean that the exact same component in every power supply is the same or always fail.  So when you say my PS doesn't work, tell me what part to change, the only possible answer is "everything."  Only if you are capable of performing some tests and measurements are we able to help you diagnose it, and only if you own an electronics soldering iron will I even consider any suggestions.  I'm saying electronics soldering iron as opposed to one intended for automotive, plumbing or soldering guns.

 

Lastly, you might get more responses if you include information such as location in your profile.



#6 Guest_Dave1342_*

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Posted 26 December 2018 - 08:46 PM

Thanks for that I used to work in a pcb factory and can solder components all day, I tested the transformer with a voltmeter a while ago now, and I know it’s faulty, I don’t really want to spend the time repairing something I can replace if I can get hold of the part really. That said if I can’t then I guess that’s what I need to do, unfortunately I have no idea what transformer is on the board

#7 Superduper

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Posted 26 December 2018 - 10:01 PM

It's far easier to repair the PS than to find someone to part out their unit for you.  You know they don't make them anymore right?  Let me ask you something, you said you tested the transformer with a voltmeter and you know it's faulty.  May I ask how exactly did you do that or how you came to that conclusion?  That is important to know.  Just because you don't get 12V at the secondary power supply output doesn't mean the transformer is bad unless you have measured Ω continuity at the actual coils or V output at the actual output terminals.  Blown fuses, dirty or broken AC/DC switch or blown rectifier all could translate to no output yet transformer could be fine.

 

I just now looked at the service manual and on this model, looks like both primary and secondary windings are protected.  The primary by thermal cutoff and secondary by a fuse.  If the primary thermal cutoff is blown, it might not be serviceable but the secondary fuse certainly can.  And when you say tested it with a voltmeter, then did you test it at the PS pcb?  If so, you must be looking at the transformer, correct?  If the fuse is not blown and you are certain that the transformer is bad, then just go to Digi-key or mouser and browse the transformers for one that will physically fit, has 12 or 12.6v secondary and center tapped primary (if you want to retain 120/240v) or a plain single primary coil if single voltage 120 or 240 is all you need.  It looks like you will need a PCB mount transformer.  I'm guessing that a 30va transformer or thereabouts will work just fine.

 

Or maybe you really don't want to spend any time to repair it, in which case, I guess then just keep checking back.  Somebody someday might part out their box, or check eBay.  I see parts occasionally being offered, although most from overseas (to me) sellers.



#8 Guest_Dave1342_*

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Posted 27 December 2018 - 04:15 AM

I’m happy to replace all the components on the board to be honest that’s no drama really, the fuse is good, sorry I meant a multimeter, I tested the resistance across both the windings one of them had an open cercuit, thanks for the advice about the web site, if I can’t find the components I think I might just change everything there’s not much on it