Sony TA-FE230 Amplifier 120W

Thread Starter

spike1947

Joined Feb 4, 2016
496
Look at page 10 of the manual. Top right hand corner. Note the text seems to be a mirror image on that drawing.

Les.
Is it the DC sub board ?, will have to remove transformer to get at the underside of the DC sub board, the Amp switches on and the dials luminate so there is DC power to the board !.
 

MisterBill2

Joined Jan 23, 2018
18,176
Looking at the speaker connection terminals would have been safer. That was what I thought was suggested. The protection circuit is there to save the speakers if the amp develops a DC voltage on the output, in addition to preventing "turn on thumps."
 

Thread Starter

spike1947

Joined Feb 4, 2016
496
I think I will get a new STK4192II, it will probably get me back to were I was this morning, but will have to try, don't want it going to the tip !.
 

MisterBill2

Joined Jan 23, 2018
18,176
A much safer way to measure that pin 12 voltage is at that series coil connected to pin 12. That is the copper coil near the module in the one photo. Just a bit of insulation scraped off the top so the probe can touch the copper, and nothing nearby to accidentally touch. Much safer and easier to probe.
And hope that the module was not damaged, they were rather expensive 20 years ago,
 

LesJones

Joined Jan 8, 2017
4,174
Hi MisterBill, At first I was going to suggest suggest doing the test at the speaker terminals but realised that that they would only be connected until the relay contacts opened. With only one speaker connected I wondered if any offset on the other channel increased without the load of a speaker and that was enough to trip the protection circuit.
If I was looking at the fault I would now follow the signal from the turntable input to the input of the power amp before replacing the power amp IC to find the origin problem.

Les.
 

Thread Starter

spike1947

Joined Feb 4, 2016
496
A much safer way to measure that pin 12 voltage is at that series coil connected to pin 12. That is the copper coil near the module in the one photo. Just a bit of insulation scraped off the top so the probe can touch the copper, and nothing nearby to accidentally touch. Much safer and easier to probe.
And hope that the module was not damaged, they were rather expensive 20 years ago,
Hi
Thanks for your reply, I am not sure now what I have blown or damaged fir the speaker relay to not operate at all now, I am thinking to order the STK4192II , they are not a bad price at the moment, I just hope that I haven't damaged anything else, but am going to replace the STK4192II power amplifier ic, and see if I can get back to this morning and do the testing in a safer way .
Spike
 

MisterBill2

Joined Jan 23, 2018
18,176
The connection at the choke coil is right after the amplifier module, tied to pin 12, the output. So probing that point will let you know if the amplifier is working or not. It should be very close to zero DC volts, especially with no signal.
 

Thread Starter

spike1947

Joined Feb 4, 2016
496
Hi Guys
Thanks again for all your help n time, just a note, when I manage to fit a new "IC301", when I come to testing the unit again, is it best to have the speakers connected ?.

Cheers
Spike
 

MisterBill2

Joined Jan 23, 2018
18,176
Until you can verify that the speaker protection system is functioning correctly I suggest not connecting any speakers worth protecting.
The voltage and current available in that amplifier are capable of damaging a speaker if there is a serious amplifier malfunction and the protection system is not working correctly. So connecting good speakers for the very first check is not a good idea. A 4.7ohm small (1/4 watt) resistor across the output,or whatever low value low power resistor is on hand, will be OK for the initial checking, which will not include running any signals thru the system. The resistor will be a no-signal load to verify that with no input there is no output, AC or DC.
After verifying that the protection circuit functions and the relay pulls in and does not drop out, but stays operated, and you can measure the voltage at the speaker terminals and it is very close to zero, AC and DC, then it should be safe to connect good speakers.
 

Thread Starter

spike1947

Joined Feb 4, 2016
496
Until you can verify that the speaker protection system is functioning correctly I suggest not connecting any speakers worth protecting.
The voltage and current available in that amplifier are capable of damaging a speaker if there is a serious amplifier malfunction and the protection system is not working correctly. So connecting good speakers for the very first check is not a good idea. A 4.7ohm small (1/4 watt) resistor across the output,or whatever low value low power resistor is on hand, will be OK for the initial checking, which will not include running any signals thru the system. The resistor will be a no-signal load to verify that with no input there is no output, AC or DC.
After verifying that the protection circuit functions and the relay pulls in and does not drop out, but stays operated, and you can measure the voltage at the speaker terminals and it is very close to zero, AC and DC, then it should be safe to connect good speakers.
Thanks for that.
Cheers
Spike
 

Thread Starter

spike1947

Joined Feb 4, 2016
496
The connection at the choke coil is right after the amplifier module, tied to pin 12, the output. So probing that point will let you know if the amplifier is working or not. It should be very close to zero DC volts, especially with no signal.
Hi again
Have fitted a new IC 301, but still the relay is not pulling in, checked the voltage at pin 12 just a few mV .
Spike
 

LesJones

Joined Jan 8, 2017
4,174
I was looking back though the post to see if you had checked the + and - 49 volt rails. I found that you partly answered the question in post #24 where you say you 47 volts. connector CN951 is a 3 pin. one pin is ground, one +49 volts and one -49 volts. Can you clarify your answer. I would NOT have risked replacing IC901 before doing some more testing. (I imagine it is quite expensive.) The protection IC (IC601) checks a number of things before energising the relay coil. (NOTE there is also a speaker switch between the output of IC601 and the relay coil.) If you can safely check the voltages on the pins of IC601. (By following the schematic to components whose pins are not close to anything that test prods will NOT short to.)

Les.
 

Thread Starter

spike1947

Joined Feb 4, 2016
496
I think that this is a stereo amplifier and so you will need to check both output sections . And certainly a bad or failed capacitor will cause problems.
Hi
Thanks for that, yes it is a integrated stereo amplifier, what readings am I supposed to get ?, and where are the output points to measure ?.
Sorry for all the questions, I purchased this new quite awhile go, along with my Sony turntable it had not had a lot of use over time, I really don't want to bin it, will try my hardest to try and fix it !.
Regards
Spike
 

Thread Starter

spike1947

Joined Feb 4, 2016
496
I was looking back though the post to see if you had checked the + and - 49 volt rails. I found that you partly answered the question in post #24 where you say you 47 volts. connector CN951 is a 3 pin. one pin is ground, one +49 volts and one -49 volts. Can you clarify your answer. I would NOT have risked replacing IC901 before doing some more testing. (I imagine it is quite expensive.) The protection IC (IC601) checks a number of things before energising the relay coil. (NOTE there is also a speaker switch between the output of IC601 and the relay coil.) If you can safely check the voltages on the pins of IC601. (By following the schematic to components whose pins are not close to anything that test prods will NOT short to.)

Les.
Hi
Thanks for that, ok will re group my brain and do them tests and come back to you.
Regards
Spike
 

Thread Starter

spike1947

Joined Feb 4, 2016
496
I was looking back though the post to see if you had checked the + and - 49 volt rails. I found that you partly answered the question in post #24 where you say you 47 volts. connector CN951 is a 3 pin. one pin is ground, one +49 volts and one -49 volts. Can you clarify your answer. I would NOT have risked replacing IC901 before doing some more testing. (I imagine it is quite expensive.) The protection IC (IC601) checks a number of things before energising the relay coil. (NOTE there is also a speaker switch between the output of IC601 and the relay coil.) If you can safely check the voltages on the pins of IC601. (By following the schematic to components whose pins are not close to anything that test prods will NOT short to.)

Les.
Hi
Here goes, I think I got the correct test points !.
CN951, yes getting - 47.2v nand +47.2v.

IC901
1:---1.2mV (R603)
2:---0 to 12 mV (R604)
3:---0 (chassis)
4:---2.2v and 30mV ( C916)
5:---0 ( chssis)
6:---+47.2 (R608)
7:---10mV and 3.3v ( R605)
8:---3.3v and 47.2v ( R606)

PS: Speaker Switch is on the front panel
Regards
Spike
 
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MisterBill2

Joined Jan 23, 2018
18,176
OK, and as for the test points that I suggested, they are the bare copper coils that show in the photos posted back a ways. You will need to either probe at the end of the coil or scrape off a patch of the clear insulation coating to get a good connection.
The voltage at the output of a correctly operating amplifier module is very close to zero once it has stabilized after switch-on.
If you examine the circuit schematic you will see that the coil is connected directly to the module output on pin 12. This makes the coil a safer point to probe the output of the IC than probing pin #12 AT THE PIN.
 
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