So if your measuring is correct your problem lays elsewhere
protection in this amplifier might be tripped from any mistake in secondary power supply DC in the outputs ( that you already measured ) over load in the output ( clearly not your case ) and excessive temperature also clearly not your case .
So if you measured correct your fault lays else where Sony likes to use fusible resistors here and there in many points of the amplifier Usually these are small resistors of 1/8W 4.7 ...any of them open might make the protection trip but from power supply issues .
Please notice that most Sony of that era suffers from poor soldering down under the main board disassembly , visual inspection and a resolder might be in order There is many Sony of that era had issues like that and cured with a simple resoldering on the IC that drive the outputs Work that need to be done with caution .
Lets do something useful ....
A curve tracer is an instrument that is used to verify the performance of a semiconductor ...This is a critical feature to any circuit that requires precision but also in audio devices that require matching IE to make sure that the transistors of ch R have equal performance with transistors of ch L That will make a very good amplifier but obviously a curve tracer will never be used as a fault finding device .
Farther more one oscilloscope will actually convert the audio signal to a visual form and through that you might understand things about the performance and operation on a working amplifier Still and at this level there is no use for an oscilloscope as a fault finding device .
Understanding the basics of electronics , verify all voltage present according the schematic using a method and a procedure will get your amplifier fixed. Urban legends and random measuring will not ...
I asked your occupation since this story smells a student that got messed up by a school teacher that uses fancy words like curve tracer and oscilloscope to hide that he has zero practical experience and a Sony amplifier of that simplicity is a nightmare for him to troubleshoot so he is making this way more difficult than it is in reality ( it could be as well just a simple fuse blown )
Trust me on this been there several times ....
Kindest regards
Sakis
protection in this amplifier might be tripped from any mistake in secondary power supply DC in the outputs ( that you already measured ) over load in the output ( clearly not your case ) and excessive temperature also clearly not your case .
So if you measured correct your fault lays else where Sony likes to use fusible resistors here and there in many points of the amplifier Usually these are small resistors of 1/8W 4.7 ...any of them open might make the protection trip but from power supply issues .
Please notice that most Sony of that era suffers from poor soldering down under the main board disassembly , visual inspection and a resolder might be in order There is many Sony of that era had issues like that and cured with a simple resoldering on the IC that drive the outputs Work that need to be done with caution .
Lets do something useful ....
A curve tracer is an instrument that is used to verify the performance of a semiconductor ...This is a critical feature to any circuit that requires precision but also in audio devices that require matching IE to make sure that the transistors of ch R have equal performance with transistors of ch L That will make a very good amplifier but obviously a curve tracer will never be used as a fault finding device .
Farther more one oscilloscope will actually convert the audio signal to a visual form and through that you might understand things about the performance and operation on a working amplifier Still and at this level there is no use for an oscilloscope as a fault finding device .
Understanding the basics of electronics , verify all voltage present according the schematic using a method and a procedure will get your amplifier fixed. Urban legends and random measuring will not ...
I asked your occupation since this story smells a student that got messed up by a school teacher that uses fancy words like curve tracer and oscilloscope to hide that he has zero practical experience and a Sony amplifier of that simplicity is a nightmare for him to troubleshoot so he is making this way more difficult than it is in reality ( it could be as well just a simple fuse blown )
Trust me on this been there several times ....
Kindest regards
Sakis
I do not want to frustrate you any more by my brutal, fuzzy findings, but since you have asked about the noise, here is a record of it:
Interesting. Thanks 
and not what I was expecting to see really.
OK, so this is broadband noise generated 'electronically' for want of a better word... and that makes this look like quite a deep seated fault. My initial feeling is that while its certainly fixable, its not going to be an easy fix and it would more than likely require part/s unique to this model.
You would need an oscilloscope to delve into this in order to get some idea of what and where things were falling apart.
All that said, one check that should always be done on ANY unit is a check and confirmation that ALL the DC voltage rails are correct. There will be several in a unit like this with dedicated low voltage supplies feeding the various signal processing sections.
This shows the noise, how it rises and its frequency make up (wideband noise)
and not what I was expecting to see really.OK, so this is broadband noise generated 'electronically' for want of a better word... and that makes this look like quite a deep seated fault. My initial feeling is that while its certainly fixable, its not going to be an easy fix and it would more than likely require part/s unique to this model.
You would need an oscilloscope to delve into this in order to get some idea of what and where things were falling apart.
All that said, one check that should always be done on ANY unit is a check and confirmation that ALL the DC voltage rails are correct. There will be several in a unit like this with dedicated low voltage supplies feeding the various signal processing sections.
This shows the noise, how it rises and its frequency make up (wideband noise)
Attachments
Another crazy/mad thought to be done at your own risk
The unit may well use a 'supercap' in place of a battery backup for all the system memory functions. If so, then it might be worth disconnecting that to reset everything. Logic circuits can do strange things sometimes and if they get stuck in a loop, they don't always reset. Its a long shot but maybe worth trying.
I'll have a think about that...
The unit may well use a 'supercap' in place of a battery backup for all the system memory functions. If so, then it might be worth disconnecting that to reset everything. Logic circuits can do strange things sometimes and if they get stuck in a loop, they don't always reset. Its a long shot but maybe worth trying.
I'll have a think about that...
Thanks Mooly, this moves my thoughts again in the space of searching for a new machine.
This is an important progress.
I have used at the very beginning of fail the "clearing" function, but no results. Service manual shows also a protection mode on/off function.
I remind you the fact is that this fail happened when the ups was turned off. Then opening it again it had failed again. But, using the UPS only in battery mode (unplugging mains), it started to work again. Then again plugging it in the main power it worked for about a week. Then this happened again and the brutal ups battery trick did not work.
This "logic thing" stuck may had happened to me once on an external pro grade sound card, it forced it to show dead outputs (non amplified signal), all of them!. Drivers re-installation fixed it, and only this could fix it! But now it is different.
This is an important progress.
I have used at the very beginning of fail the "clearing" function, but no results. Service manual shows also a protection mode on/off function.
I remind you the fact is that this fail happened when the ups was turned off. Then opening it again it had failed again. But, using the UPS only in battery mode (unplugging mains), it started to work again. Then again plugging it in the main power it worked for about a week. Then this happened again and the brutal ups battery trick did not work.
This "logic thing" stuck may had happened to me once on an external pro grade sound card, it forced it to show dead outputs (non amplified signal), all of them!. Drivers re-installation fixed it, and only this could fix it! But now it is different.
Last edited:
I've had a really good look at the circuit diagrams and my instincts tell me that this one is not going to be diy friendly. I didn't see a backup cap anywhere so it looks like this one uses what's known as NVM or non-volatile-memory.
Having said that, and considering your comments on the UPS issue, I would try two things. If its a case of binning the unit anyway then there is nothing lost...
1/ Measure the important supply voltages beginning with those on the DIR processor. The two supply voltages should be minus and plus 7 volts -/+ 5%. This DIR chip (80 leg SMD or surface mount device) seems to handle most of the processing and if that is suspect then replacement is the only way to prove it. That's not a diy friendly job, you would need to be experienced in working with SMD to successfully swap it.
2/ Years of experience tell me 'its never the big chip' and 95% of the time that's true. Something you could try... again this is risky. Leave the unit unplugged for several hours and then press some tinfoil over all the pins of that IC so that you are shorting them all out. That will remove any remaining charge and may allow a 'stuck' chip to reset when its powered back up. A chance in a hundred but it would be something I would do if it were on the bench in front of me.
Having said that, and considering your comments on the UPS issue, I would try two things. If its a case of binning the unit anyway then there is nothing lost...
1/ Measure the important supply voltages beginning with those on the DIR processor. The two supply voltages should be minus and plus 7 volts -/+ 5%. This DIR chip (80 leg SMD or surface mount device) seems to handle most of the processing and if that is suspect then replacement is the only way to prove it. That's not a diy friendly job, you would need to be experienced in working with SMD to successfully swap it.
2/ Years of experience tell me 'its never the big chip' and 95% of the time that's true. Something you could try... again this is risky. Leave the unit unplugged for several hours and then press some tinfoil over all the pins of that IC so that you are shorting them all out. That will remove any remaining charge and may allow a 'stuck' chip to reset when its powered back up. A chance in a hundred but it would be something I would do if it were on the bench in front of me.
Attachments
Realistically its probably the end. To go further (with no guarantee of immediate success) would involve literally going around all the pins on the processor with a scope checking and looking for anomalies. You have to rule everything possible out first before condemning the chip.
And any parts like the DIR chip would have to come from Sony which could be problematic for non account holders.
I think in this instance we have to be realistic and say its not a diy proposition without all the necessary test gear and experience.
And any parts like the DIR chip would have to come from Sony which could be problematic for non account holders.
I think in this instance we have to be realistic and say its not a diy proposition without all the necessary test gear and experience.
Sorry to open this up again, I have a question for you. Months ago, I gave this unit for repair and none of the services I had visited did not found an obvious/common problem so they pointed maybe in an integrated circuit that might be the case, so it might be very difficult to fix or not worth the repair.
After 6 months I have switched the unit again. This time there was a mixed behavior of doing the same thing as mentioned above, but there were on/off cases where the "protect mode" did not engage. So, I have switched the headphones again and realized that then, the noise came out only from 1 channel and it was constant, not increasing. So the unit remained on...
So what I have just observed is this:
After 5-10 minutes of operation,
Almost all components are cold, including all power transistors, power supply is barely warm,
The only parts that are "very hot" and I mean untouchable are:
IC700: sony part: 6-710-828-01 description: IC STK350-530T-E
IC604: sony part: 6-705-468-01 description: IC BA33BC0FP-E2
The first one is an IC VOLTAGE AMPLIFIER
and the second, is a Linear Voltage Regulator IC Positive Fixed 1 Output 3.3V 1A TO-252-3
Just by instinct, there might be a chance that this IC700 could be the problem (this one also includes the protection circuit).
After a quick search I have found that this is an almost obsolete part but there might be some parts here:
EET Europarts: Sony IC STK350-530T-E
or a cheaper copy maybe?
http://www.ebay.com/itm/1PCS-STK350...2-Channel-AF-Voltage-Amplifier2-/131830318043
You can see that those Sony amps below use the same IC:
DH700STR, DH100STR, DG520STR, DE400STR, K785STR, DA1500ESSTR, DH500STR, K790
and this one for reference: http://www.diyaudio.com/forums/solid-state/98298-data-needed-stk350-530-sip-ic.html
What do you think?
After 6 months I have switched the unit again. This time there was a mixed behavior of doing the same thing as mentioned above, but there were on/off cases where the "protect mode" did not engage. So, I have switched the headphones again and realized that then, the noise came out only from 1 channel and it was constant, not increasing. So the unit remained on...
So what I have just observed is this:
After 5-10 minutes of operation,
Almost all components are cold, including all power transistors, power supply is barely warm,
The only parts that are "very hot" and I mean untouchable are:
IC700: sony part: 6-710-828-01 description: IC STK350-530T-E
IC604: sony part: 6-705-468-01 description: IC BA33BC0FP-E2
The first one is an IC VOLTAGE AMPLIFIER
and the second, is a Linear Voltage Regulator IC Positive Fixed 1 Output 3.3V 1A TO-252-3
Just by instinct, there might be a chance that this IC700 could be the problem (this one also includes the protection circuit).
After a quick search I have found that this is an almost obsolete part but there might be some parts here:
EET Europarts: Sony IC STK350-530T-E
or a cheaper copy maybe?
http://www.ebay.com/itm/1PCS-STK350...2-Channel-AF-Voltage-Amplifier2-/131830318043
You can see that those Sony amps below use the same IC:
DH700STR, DH100STR, DG520STR, DE400STR, K785STR, DA1500ESSTR, DH500STR, K790
and this one for reference: http://www.diyaudio.com/forums/solid-state/98298-data-needed-stk350-530-sip-ic.html
What do you think?
Attachments
![2016-10-11 19_00_09-sony_str-da1500es_ver-1.0_sm.pdf - [00_01-04_STRDA1500_02.indd].jpg](/community/data/attachments/525/525623-badb4a031db8bd225730ad0d7db84768.jpg)
Last edited:
PENTAJAZZ ....it seems that you have a Greek flag ...So if you are greek send the amplifier to us and we will fix it for you
Since this is an offer through the forum we might as well fix it for free and secondly let you know what was the problem exactly ....
It seems to me that you are continuously focusing on the wrong target ...Both of these IC are supposed to produce some heat Actually every part inside the amplifier is producing some heat the question is how much .....
Kind regards
Sakis
Since this is an offer through the forum we might as well fix it for free and secondly let you know what was the problem exactly ....
It seems to me that you are continuously focusing on the wrong target ...Both of these IC are supposed to produce some heat Actually every part inside the amplifier is producing some heat the question is how much .....
Kind regards
Sakis
That's a great offer from Sakis and probably the most realistic chance of you getting it fixed.
Parts can run hot but they shouldn't be able to sizzle water as a general guide. If a voltage regulator is producing the correct output (and is also clean viewed on a scope) then it probably wont be faulty as such and its the current drawn from the following circuitry that is heating it.
Parts can run hot but they shouldn't be able to sizzle water as a general guide. If a voltage regulator is producing the correct output (and is also clean viewed on a scope) then it probably wont be faulty as such and its the current drawn from the following circuitry that is heating it.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.