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Technics SU-V4X problem - no click from relay but indicator lights OK
Technics SU-V4X problem - no click from relay but indicator lights OK
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Old 8th January 2019, 12:41 PM   #11
SVI2004A is offline SVI2004A  New Zealand
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Technics SU-V4X problem - no click from relay but indicator lights OK
Yes that is the relay
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Old 8th January 2019, 12:45 PM   #12
SVI2004A is offline SVI2004A  New Zealand
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Technics SU-V4X problem - no click from relay but indicator lights OK
Out of curiosity - on the pcb next to the SVI is it labelled 16 or 17 - and what serial # is the amp?
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Old 8th January 2019, 01:35 PM   #13
4V8s is offline 4V8s  United Kingdom
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I'll have a look and let you know.

is there any way for me to get at the relay internals without taking the whole unit apart and taking out that bottom circuit board and desoldering it?

but I'll do the measurment checks beforehand as suggested in the thread.

I have tried tapping last night but it had no effect.

thanks

Aaron
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Old 8th January 2019, 02:24 PM   #14
SVI2004A is offline SVI2004A  New Zealand
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Technics SU-V4X problem - no click from relay but indicator lights OK
Opening the relay wonít achieve a lot as itís most likely the coil wire broken at the terminal... you can squeeze firmly at the corners and it will unclip on the long sides.

Donít need to pull main board out as such - undo screw at front corner of main board, and the screw at heatsink support (see pic) then the 4 screws under bottom panel

Do also check joints on Q608 (relay drive)
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Old 8th January 2019, 03:07 PM   #15
4V8s is offline 4V8s  United Kingdom
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Great! thanks, I also have the service manual downloaded and that's a massive help!

Im not with the unit at the moment, so I'll have a fiddle this evening.

Just one more question though - if I were to plug some headphones into the jack, would I expect to get sound even if the relay wasnt working? or does that control the output to headphones also?

cheers

Aaron
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Old 8th January 2019, 03:31 PM   #16
SVI2004A is offline SVI2004A  New Zealand
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Technics SU-V4X problem - no click from relay but indicator lights OK
Headphones is also fed from relay
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Old 8th January 2019, 06:23 PM   #17
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Hi, I have exactly the same problem, plus, probably, several more. Green liight is on, relay is not. I have changed several electrolyths, as well both 3,3 25v, which actually were 2,5v. C710 c709, then changed ic701, as it was not providing stable 5v. Still something wrong. Removed the cap of relay, tested it, as far i remember it works from something ~115v. Still nothing. One thing which is strange on ic502 leg 7-10 is constant -52 volts. That forced me to change q606 without results. I am now concerned if i have not burned ic502.. any coments?
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Old 9th January 2019, 03:31 AM   #18
SVI2004A is offline SVI2004A  New Zealand
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Technics SU-V4X problem - no click from relay but indicator lights OK
If [Safety Operation] is steady and [Auto/computer drive] is lit - there is no overload or fault.

IC 601 pin 12 should be 2.8V or higher, which feeds Q608 that turns relay on.

R630 (2W 560 ohm) supplies power to relay
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Old 9th January 2019, 03:19 PM   #19
SVI2004A is offline SVI2004A  New Zealand
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Technics SU-V4X problem - no click from relay but indicator lights OK
Quote:
Originally Posted by Briedonis View Post
One thing which is strange on ic502 leg 7-10 is constant -52 volts. That forced me to change q606 without results. I am now concerned if i have not burned ic502.. any coments?
In this amp the manual is incorrect... near on -50 or -43v is no load condition

The -V is fed from a digital transistor UN4211 (Q606) under overload, the SVI will pull up the -V towards ground, which turns on Q606, triggering overload detector feed to IC601
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Old 9th January 2019, 04:02 PM   #20
Briedonis is offline Briedonis
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Quote:
Originally Posted by SVI2004A View Post
If [Safety Operation] is steady and [Auto/computer drive] is lit - there is no overload or fault.

IC 601 pin 12 should be 2.8V or higher, which feeds Q608 that turns relay on.

R630 (2W 560 ohm) supplies power to relay
Thank you for response. As far as i remember all pins on ic601 are more or less correct voltage, will check pin 12 valtage one more time. As well as R630.

Last edited by Briedonis; 9th January 2019 at 04:15 PM.
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