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sony 700es repair advice

karma67

karma67

pfm Member
well just as i was happy with my set up the amp started to cause problems,it went off last night ,i opened her up and sure enough a fuse had blown,its 1 of 2 on a little circuit board near where the mains cable comes in.
i replaced the fuse today and it blows as soon as you push the power on button.
the amp is a sony ta-f 700es and id like to get it fixed if possible.
it appears it was the 4 ditton 44's stack that done it i had them through speakers A+B which states on the back of the amp impedance 8-16 ohms.
is there someome that can help me or know who i could take it too?
i have the wiring schematic if that helps.

regards.
j.
 
The output stage will be fried Jamie.

With the speakers wired like that its no surprised to be honest. The way speaker A/B selectors work you have effectively wired the speakers in parallel halving the impedance and your average Jap amp does not take kindly to it at all.
 
istari_knight said:
The output stage will be fried Jamie.

With the speakers wired like that its no surprised to be honest. The way speaker A/B selectors work you have effectively wired the speakers in parallel halving the impedance and your average Jap amp does not take kindly to it at all.
Click to expand...
yes i must admit i was ignorant to the fact,i know better now, they looked ridiculous too!
what would be helpful though is solutions and options james :)
thanks for your pm henry :)

20150802_121559_zpscy4dqlx6.jpg
 
I doubt very much that it's scrap, it all depends on how much the amp is worth to you. It's all discreet circuitry in there and the power amp section has its own board making it nice to work on.
 
thanks,well i suppose the other deciding factor is how much id have to pay to equal or better it as well.ive pm'd toprepairman for a ball park figure. it would be a shame to just give up on it as its a lovely sounding amp.

i wonder if anyone cant point me in the right area to check from the photos,
from left to right.

20150809_113149_zpsxpm6lz0e.jpg


20150809_113311_zpsquxge7pb.jpg


20150809_113333_zpsi4cnoakp.jpg


and full view,

20150809_113425_zps3q06f7nb.jpg
 
I don't see any burnt resistors, so probably not a full op stage failure. Need to see what the fuse is protecting really - do you have a cct diagram?. I assume you disconnected the speakers when replacing fuse the first time, and that the fuse is exactly the same type as originally in there?
 
yes to both questions,i also cant smell any burning odors. i do have a service manual which includes a wiring diagram,im not sure how i would post it here though,if you like you can pm me your email address and i'll send it over?

many thanks for everyone's input so far :)
 
Yours is the UK model? No voltage selector? One fuse protects the switched AC output, one the secondary windings - scan quality is really bad, so cannot see ref numbers. Which fuse is blowing? I assume F001 for secondary windings of transformer? If correct, it needs to go to a professional - could be output stage transistor short circuit, but could also be a bridge diode - worst case it could be a melted transformer. How long did you have it driving both sets of speakers, did it get hot? :)
 
Dowser said:
Yours is the UK model? No voltage selector? One fuse protects the switched AC output, one the secondary windings - scan quality is really bad, so cannot see ref numbers. Which fuse is blowing? I assume F001 for secondary windings of transformer? If correct, it needs to go to a professional - could be output stage transistor short circuit, but could also be a bridge diode - worst case it could be a melted transformer. How long did you have it driving both sets of speakers, did it get hot? :)
Click to expand...

its the top fuse in the photo,yes the manual isn't very clear but its all that's around on the net.
it is a uk model and was driving the speakers for about 15 mins at moderate volume before the protection kicked in,after that no power on.it didnt appear to be any hotter than normal.

20150809_133834_zpspil7ucd8.jpg
 
Strange that it didn't cope with 3 ohms of both Dittons, from specs that power stage looks quite capable and some 4 ohm speakers had much lower resistance on low frequencies. Also lot of fusible resistors used in power stage and power supply.
 
Sorry, I completely forgot about this thread.

Its one of those things that's near impossible to diagnose via photo's... It'll need those outputs pulling and testing, just because its not burnt/smelly doesn't mean its not "blown" - Though I do agree it doesn't appear to have been a catastrophic failure. I see it is the model I looked at last year as I had to recap the protection circuit which was taking a long time to engage.

Afraid I'm still between house move's and am in no position to look at it for you, there are some good amp repair guys on the forum though such as Witch hat audio, ClassA, henry toprepairman & Arkless (not sure if he's still here?) Or for someone more local I believe HifiHangar in Bordon have a repair workshop.
 
jamie123 said:
well just as i was happy with my set up the amp started to cause problems,it went off last night ,i opened her up and sure enough a fuse had blown,its 1 of 2 on a little circuit board near where the mains cable comes in.
i replaced the fuse today and it blows as soon as you push the power on button.
the amp is a sony ta-f 700es and id like to get it fixed if possible.
it appears it was the 4 ditton 44's stack that done it i had them through speakers A+B which states on the back of the amp impedance 8-16 ohms.
is there someome that can help me or know who i could take it too?
i have the wiring schematic if that helps.

regards.
j.
Click to expand...
I would go to a official Sony repair man Do not know where you are situated but there is one in Wembley, however get an estimate to find out if it is worth repairing. contact Sony for other addresses.
 
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