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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, 12:32 AM   #1
4V8s is offline 4V8s  United Kingdom
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Default Technics SU-V4X problem - no click from relay but indicator lights OK

Hi all,

Ive just joined up, seen some really useful stuff on here whilst Ive been trying to figure out what might be wrong with this Amp.

This amp means quite a lot to me as it was my late Father's and I remember him buying it (along with matching components) in around 1984/5. Ive been pestering my Mum for it and she finally agreed last week, so I collected it and eagerly set it up at home, connected to my newly installed cieling speakers and.....no sound!

Now I cant be sure the last time this was actually used, it has sat in my Mum's cupboard connected but switched off for many years now.

I always recalled that after a few seconds it would emit a click sound before the speakers would engage (a relay I guess).

It has never been messed with, never even opened up before and is clean and hardly any dust inside. Has the SVI 2004 A Amp IC

So when I switch it on, the amber light for the saftey operation flashes for about 5 seconds and then stays solid. According to the user manual this is normal, ie no fault detected.

about 5 seconds or so later, the green computer drive light goes green.

So it all looks like should be working, I know the input selectors seem working and I can pass the signal through the technics graphic equalizer as I can see the bars moving.

So there should be an output, but nothing from any of the 4 speaker ports regardless of any button settings.

Any ideas?

Im hoping it might be something simple, Id like to fix it or get it fixed if possible and if it's worth it, not just because I think it always was and probably still is a good amp, but also because it has sentimental value.

Any help would be much appreciated! I will attach a photo of it and the inside once ive downloaded the pics from my phone, as I opened it up to check for anything obvious. Both fuses are OK and I cant see any obvious signs of loose components or leaking capacitors.

thanks

Aaron
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Old 8th January 2019, 02:49 AM   #2
sgrossklass is offline sgrossklass  Germany
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No click = relays not engaging = no output. Since you say it sat unused for several years, it could be as simple as a dead electrolytic cap in the relay driver circuit... or just a bad solder joint that got upset when moving the unit. Further investigation with a multimeter and a keen eye will be required, as well as studying the service manual.

What's your experience level in terms of electronics DIY or repair? Do you have a decent smallish soldering iron or station and a multimeter? Can you read schematics?
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Old 8th January 2019, 03:22 AM   #3
adason is offline adason  United States
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There is service manual available for free download at hifiengine. Measure voltages on the amplifier output before and after the relay. If close to zero, relay is stuck, as it was not used for a while.

Or else...
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Old 8th January 2019, 03:41 AM   #4
SVI2004A is offline SVI2004A  New Zealand
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Technics SU-V4X problem - no click from relay but indicator lights OK
Bad relay... had this happen on 2 of mine...

Do check solder joints on relay coil connections in case it’s just a dry on it
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Last edited by SVI2004A; 8th January 2019 at 03:44 AM.
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Old 8th January 2019, 11:34 AM   #5
4V8s is offline 4V8s  United Kingdom
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Perfect, thanks I was hoping it might be something simpler like the relay it's self rather than the main IC.

thanks for the link to the service manual, I'll register on that site and download it

I do have a multimeter and am reasonably OK following schematics, I have a soldering iron but i'm not too good with it to be honest, it's quite a while since I did any neat soldering.

The Relay - seems like it has a top cover or something, is this removable? I can wiggle it but not seem to pull it off.

Im still figuring out how to insert an image, I guess they have to be hosted first in something like photobox?
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Old 8th January 2019, 11:46 AM   #6
4V8s is offline 4V8s  United Kingdom
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Click the image to open in full size.
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Old 8th January 2019, 11:49 AM   #7
SVI2004A is offline SVI2004A  New Zealand
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Technics SU-V4X problem - no click from relay but indicator lights OK
Power amp on.... see if gently pushing or wriggling relay makes it click

The top can come off, but it’s moot trying to mess w/ it....
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Old 8th January 2019, 11:52 AM   #8
SVI2004A is offline SVI2004A  New Zealand
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Technics SU-V4X problem - no click from relay but indicator lights OK
As for pictures click > go advanced <

Then manage attachments and upload there
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Old 8th January 2019, 11:54 AM   #9
adason is offline adason  United States
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No, no need to host photos on other server, that's not a good option. There is plenty of threads with blank photo as the hosting server no longer provides photo.
When you write post, insted of quick reply, hit go advanced, that will open window with attach images, browse from your computer, select, upload...its easy.

SVI beat me...
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Old 8th January 2019, 12:04 PM   #10
4V8s is offline 4V8s  United Kingdom
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OK thanks lets see if this works... 3 photos below, I circled in red the Relay I guess is the one in question?

technics 1.JPG

technics 2.JPG

technics 3.JPG
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