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HELP! I think i blew my vitage sony stereo amplifier fh 15r

Muneeb

Muneeb

New Member
Ok so i just got this sony fh 15r. Paid 250 dollars. It came in from a foriegn country and i forgot to switch the thing on the back to 120v and it was at 240v. I plugged it in and saw a blueish spark. Turns out i blew the fuses. What happens next is even more retarded. The amplifier takes 1.25a fuses and i accidentally picked up a 10a fuse from my fuse box and put it in. I got it mixed up with the 1.25a fuse. I turn it on and see a medium sized fire ball looking spark come from somewhere near the transformer (the area where i am pointing the screw driver in the photo). The fuses werent blown so i think i really messed up this amplifier.... what do you guys think?
 

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Since it was originally used at 240 volts, when you didn't switch it to 120 volts while using the 120 volt input, it is just seeing half of the voltage so it wouldn't hurt anything. Something else was already wrong with it even if you accidentally put in a higher rated fuse. If it had no problems, a higher rated fuse would have worked fine with no issues as long as the unit itself was working properly.

It sounds like the normal rated fuse would have kept blowing and blowing until you found the problem.

I haven't looked but maybe go on Hi-Fi Engine and see if there is a schematic and service manual for that model.
 
Well the old fuses looked like they hadnt been changed forever which meant they couldnt have been changed recently unless the seller used really old fuses. However, a part of the transformer has screw driver pry marks and a tab is pryed up a bit. Might have had problems, i dont see why anyone would be messing with the transformer if it didnt. You think there is a way to replace the transformer? Im pretty good with soldering... think i could do it, except i just wouldnt know where to start since ive never repaced a tranformer before...
 
The transformer might not be bad. Have you ohmed it out with a meter? Even a novice in electronics needs a simple ohm meter. It is your best friend.

If you think there might be a problem with the transformer, simply remove or disconnect all secondary connections to the circuit and power up the power transformer all by itself. If the fuse blows and/or you see a spark in the same area, yup-transformer.

Just curious, is the fuse that blows connected to the wall socket side of the line?
 
Are you sure about the working properly part? Ive heard that putting in a fuse that has a higher ampere rating will do damage. I dont know why they said that it didnt make sense to me either... are fuses supposed to also act as resistors? Im 99.99% sure they arent.
 
are the fuses before or after the transformer ? i guess after being 2 of them . you might be lucky and only some rectifier diodes have gone shorted .
with this being a long way in the post check for cracked circuit boards .
 
Muneeb said:
Are you sure about the working properly part? Ive heard that putting in a fuse that has a higher ampere rating will do damage. I dont know why they said that it didnt make sense to me either... are fuses supposed to also act as resistors? Im 99.99% sure they arent.
Click to expand...

Won't know for sure until you either give some better pictures around the transformer area, or you troubleshoot it by using your ohm meter and/or disconnecting the secondary side. Its possible it the power transformer could have gotten damaged during shipping. :dunno:

You heard wrong about higher rated fuses unless there was damage already. Think about it, if it is/was working normally, a higher rated fuse would do no damage. Now if a short were to occur and it had a higher rated fuse inside, then poof, smoke, sparks - - and that's what you saw when you used that 10 amp fuse.

In other words, if there are no shorts or damage of any kind to begin with, A higher rated fuse will do no damage. Basically it is like having no fuse at all and we know all too well that a lot of stuff is not factory fused.
 
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Its hard to tell. Pretty sure its fuses first. Anyway, just discovered connectors that werent plugged in. Strange. I wonder why they were unplugged. I am so done with buying old audio equipment. Last tme i bought a yamaha cr 620 and opened it up to only find the entire thing molested by the idiot before me and had to scrap it... ugh.
 

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From what I can see on this end, it looks like that is the main line fuse. If it blows with an original rated fuse with nothing connected to the secondary, power transformer is then suspect. This would be the shotgun approach without using a meter. :eek:
 
one connector coming loose in transit is maybe excusable .i see 2 there without looking hard .. see if you can return it for full refund .
all i can guess now is seller genuine and it got damaged on the way .
or dodgy seller if said it was working .
it might have had 240v into it on 120v setting before you got it . hard to say but if its supposed to be working you are due a refund .
p.s welcome to AK
 
OH MY GOD. I OPENED IT UP AND SOMEONE DRILLED A HOLE THROUGH THE CAPACITOR. Anyway, i bought it for 200 shipping was 50. I saw one of these sell for 400 dollars before. I bought the entire boombox not just the thing i showed in the pictures. Anyway, why would someone drill a hole in the capacitor?
 

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Ooo another discovery. The trace on this part of the mobo is all sorts of ducked. Yup... time for a refund. Only if i wasnt banned on my ebay now for selling modified xbox 360 consoles... i guess ill ask for a refund thru paypal. This makes me very happy though, because originally i thought i messed something up.
 

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That disconnected look could be the green protective layer. I have been fooled in the past by what looks like cracks but when you carefully scrape off the green layer, the copper traces are totally intact.
 
No. you cant see it in the pic but the solder on the metal pin is higher than the trace on the pcb. They are not connected at all. Ill have to solder them together as well as replace the capicator with a hole drilled in it and hope that the fireball that i saw wasnt any permanant damage. But that part will have to wait until i get my new fuses in the mail.
 
Hello Muneeb. Welcome to AK. Saw the pic of the hole in the Nic cap, that would possibly short out the layers of the cap (Dead short?). The 120/240 switch changes the xformer windings from parallel ? (120) to series (240) to power the unit usually. But I would ask for a refund. Good luck.
 
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