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Old 19th Sep 2019, 3:03 pm   #1
Dorian27
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Default Sony TA-EX10 amplifier

Can any one tell me where I can get repair help for this model please there is no sound output at all all front lights up and buttons change to various usage but nothing out of speakers at all if some one could help or point me to a place forum that might thanks
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Old 19th Sep 2019, 3:24 pm   #2
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Default Re: Sony TA-EX10 AMPLIFIER

Service manual can be had from Elektrotanya.



This beast is full of ICs and uses STK Power Amp modules. Could be a right PITA to fix- parts availability/cost!
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Old 20th Sep 2019, 2:31 am   #3
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Default Re: Sony TA-EX10 amplifier

I'm sorry to say that I agree with Chris on this one and I'd just dump it. I probably wouldn't even bother to take the covers off as those output modules will likely be blown into the next decade. You could check for a blown fuse and check for voltage from the power supply, but other than that you'd be wasting your time. It might be worth removing and keeping the transformer before you drop the rest into the nearest bin!
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Old 20th Sep 2019, 8:49 am   #4
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Default Re: Sony TA-EX10 amplifier

When presented with that type of thing I generally dismantle all the various bits and pieces.

This usually yields all sorts of useful nuts, bolts, screws, metal chassis work pieces, a transformer, metal brackets, potentiometers etc.

All may come in useful for electronic repair / construction projects

Then bin all the unrepairable stuff.
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Old 20th Sep 2019, 9:12 am   #5
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Default Re: Sony TA-EX10 amplifier

I'm afraid I agree with the others. Home cinema amps are a pig to fix. Unlike hifi audio amps where simple discrete component construction helps sales, AV amps use all sorts of obscure modules and ICs to keep costs and weight down. This makes them difficult to fault find, and parts will be difficult and expensive to source.

By all means take the cover off and look for something obvious, but don't spend a lot of time and money on it.
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Old 21st Sep 2019, 11:39 am   #6
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Default Re: Sony TA-EX10 amplifier

Thank you all for info
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Old 21st Sep 2019, 2:47 pm   #7
Edward Huggins
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Default Re: Sony TA-EX10 amplifier

Quote:
Originally Posted by paulsherwin View Post
I'm afraid I agree with the others. Home cinema amps are a pig to fix. Unlike hifi audio amps where simple discrete component construction helps sales, AV amps use all sorts of obscure modules and ICs to keep costs and weight down. This makes them difficult to fault find, and parts will be difficult and expensive to source.

By all means take the cover off and look for something obvious, but don't spend a lot of time and money on it.
From what I've read over the years, these AV amps, especially those in the £175-300 price range, make for rather poor souning 2 channel stereo.
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Old 21st Sep 2019, 3:24 pm   #8
Chris55000
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Default Re: Sony TA-EX10 amplifier

Hi!

The Service Manual is a good one and it's clearly readable, so before you follow the suggestion
from other friendly members to dump the thing, first of all see if the speaker protection relay clicks in a few seconds after you switch it on – if it does, then the STK4122 o/p modules may well be serviceable as the outputs from both of them are checked by the protection circuits.

If there is no click, then there's either one or more blown fuses or possibly a defective module – the loudspeaker outputs are on pin 13 and are nominally zero volts DC, and any voltage sensed by the protection circuitry will prevent the relay coming on to connect the speakers!

However whilst these modules aren't excessively expensive, about £15 each, it can be a pita to dismantle the main–board assembly from the heatsink to replace them, and you also need a good quality desoldering tool, altho' you can get away with cutting the leads and then removing the stumps one at a time by heating the joint with an iron and then pulling the lead out with fine needle–nose pliers.

If you really are a glutton for punishment and would prefer to repair the thing, let us know what tools and meters, etc., you have, and I'll be happy to go through it all and help you get it working again!

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Old 21st Sep 2019, 5:03 pm   #9
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Default Re: Sony TA-EX10 amplifier

Thank you Chris55000 for replying when I am ready to tackle it can I get in touch with you for help please .and. Yes it does click when switching on and all buttons work on the led panel ok just no output on any speaker outlets Thanks again
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Old 21st Sep 2019, 5:37 pm   #10
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Default Re: Sony TA-EX10 amplifier

Hi!

Just let us know when you want to begin and I'll be going thro' a fault-location procedure on this thread as further replies, with suitable pauses for you to reply with your findings from the tests I suggest!

I do recommend you use a cheap or disposable pair of loudspeakers for test purposes, as you don't need to run the amplifier anywhere near maximum output for fault finding purposes!

You will also need two 1K resistors and two 1uF axial capacitors about 160V working, and a good quality Digital Multimeter, plus a 3.5mm plug fitted with pieces of wire for left ch output, common and right ch. output. An oscilloscope will make fault location much more straightforward but it's not absolutely necessary!

To begin with, the first test you need to make is to connect one 1K resistor to each pair of speaker terminals, switch the unit on, wait for the relay to click, then measure the d.c. voltage across each resistor with your D.M.M., there should be no more than ±0.25V across each resistor if the STK4122 modules aren't duffy!

If this voltage is very low or zero it should be safe to connect a pair of loudspeakers to the unit.

Carry out this loudspeaker safety test first, then I'll go on from there!

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Old 21st Sep 2019, 6:19 pm   #11
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Default Re: Sony TA-EX10 amplifier

Hi!

I've just studied the service manual more carefully and realised your unit has no front speaker power amplification as it's intended for use with Sony's SA-EX100 powered front sub-woofers, however, if you have a pair of powered PC speakers, etc., with phono-plug input, you can try these in the front speaker sockets!

The EX10 still has power amplifiers for the centre & rear speakers - have you tried these?

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Old 21st Sep 2019, 6:33 pm   #12
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Default Re: Sony TA-EX10 amplifier

Yes I have tried speakers in all outlets nothing at all not a click or crackle it does click a few seconds after switch on by the way
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Old 22nd Sep 2019, 12:00 pm   #13
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Default Re: Sony TA-EX10 amplifier

Hi!

That's fair enough - now we need to make up a simple signal source, and this is where the 3.5mm plug with leads I suggested comes into play!

Solder a 1uF 160V capacitor to each LH and RH output lead from the jack plug, connect the free end of each capacitor to CN205 on the Audio PCB (see Audio Board Layout Diagram) pin 11 for the LH capacitor output, pin 10 for the earthy/common lead and pin 9 for the RH ch capacitor output, insert the plug into your 'phone with the phone's volume at min, play some audio from your phone and gradually increase the phone's volume.

Can you get any output from the speakers by trying a phone signal at CN205 pins 9 & 11 as I describe above?

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Old 22nd Sep 2019, 12:29 pm   #14
Dorian27
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Default Re: Sony TA-EX10 amplifier

Sorry Chris but there is no click when or after switching on I was mistaken so does that mean it is stk4122 faulty
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Old 22nd Sep 2019, 4:58 pm   #15
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Default Re: Sony TA-EX10 amplifier

Hi!

Not necessarily! You will need a good D.M.M. for the following:-

Begin by checking all the power supply voltages on the main PCB:–

These are:–

+B1 & –B1 (23.5V and –23.5V) each feeding the STK 4122 – these are simple smoothed unregulated supplies from the "AC2" taps of the mains transformer (18–0–18 VAC) – there are two fuses (F911 & F912) on the main pcb for each supply – if either or both are blown, the bridge rectifier diodes (or more likely!) one of the '4122s is faulty!

If both the +23.5V and –23.5V are present, check pin 10 and pin 13 of the STK4122 for zero volts DC with respect to chassis–earth/0V – anything more than ±0.5V will prevent the speaker protection relay RY701 coming on, and in such a case the device showing a voltage at pin 10 or pin 13 more than ±0.5V should be replaced.

The STK4122 also has a driver/preamplifier supply (both +ve & –ve) fed by 100Ω fusible resistors R400/R701 fed from the main supplies, if either of these resistors is o/c., the device is suspect.

Replacement STK4122IIs are about £15 each and fairly readily available on ebay, etc!

If pins 10 & 13 of the '4122 are both at zero volts and none of the fusible 100Ω resistors have failed, the device is probably OK, so turn your attention to the +5V, +10V and the +8V/–8V supplies, all three of these come from three–terminal i.c. regulators (IC911 +8V, IC912 -8V and IC913 +10V) on the main p.c.b. with small fusible resistors (R911 to R915) in their input leads.

If one of the fusible resistors feeding the auxiliary i.c. regulators has failed you can probably use an ordinary ¼W film resistor temporarily for test purposes whilst you're ordering fusible replacement types from RS, Farnell or Mouser etc!

The other two supplies provided by the main P.C.B. are +5V from IC951 and -34.5V from Q961, but as your initial post said all the displays, etc., are alight and working, we can discount these last two voltage rails!
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Old 26th Sep 2019, 3:30 pm   #16
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Default Re: Sony TA-EX10 amplifier

Ive decided to give up on it and scrap it thanks for all your help Chris
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