Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

Ampli Technics SU-C03
Ampli Technics SU-C03
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 16th November 2013, 09:24 AM   #1
shintanjin is offline shintanjin  France
diyAudio Member
Join Date: Jun 2013
Default Ampli Technics SU-C03

When using the tuner or phono, few minutes after powering on the amp, there is a clack and the sound is cut. Then 10 or 15 seconds after the noise of a relay contact can be heard and sound comes back just. What could be the problem ?
  Reply With Quote
Old 16th November 2013, 09:40 AM   #2
Welcome is offline Welcome  France
diyAudio Member
Welcome's Avatar
Join Date: Mar 2013
Possibly the relay hold transistor, or the associated circuitry. Try replacing the electrolytic capacitors in that area, I've had a very similar problem before and that fixed it.

EDIT: Here's the schematic. Doesn't look promising. This thing is full of ICs. Might be a tough repair. Not being too knowledgeable in the field, I'd try replacing C408 with a 33F/16V cap... I've read multiple times that 6,3V capacitors (as found right there) can be flaky.

Click the image to open in full size.

Last edited by Welcome; 16th November 2013 at 09:46 AM.
  Reply With Quote
Old 16th November 2013, 10:06 AM   #3
KatieandDad is offline KatieandDad  United Kingdom
diyAudio Member
KatieandDad's Avatar
Join Date: Nov 2011
Location: UK
This might help you figure out what is going on.
Attached Files
File Type: pdf datasheet TA7317P.pdf (176.7 KB, 48 views)
  Reply With Quote
Old 16th November 2013, 10:56 AM   #4
east electronics is offline east electronics  Greece
diyAudio Member
east electronics's Avatar
Join Date: Jan 2006
Location: Athens GREECE
beyond the protection , functions and flaws of very low voltage electrolytics , you need to generally check for other leaking capacitors ( and if a few measure with a problem just replace them all )

Then you need to check things about soldering both in Power Ic but also in drive IC
Relays of protection click periodically in case of excessive Dc offset can be caused both from offset and soldering while the actual failure in the protection circuit it self is very low .

Finally check operating voltage of your area versus the amp ..If your voltage is 240 and amplifier is made for 220 these few volts more might cause some stress in the drive IC See if possible to adjust proper voltage from behind .

If there is no adjustment add a small heatsink to the drive IC ...it will help to long term stability ...

You also have a chance for a faulty drive IC if you need a new one proceed with caution there is plenty of fakes .

Kind regards
Sakis ...

Many IC and plenty of old transistors actually fail from mechanical reasons ...When you measure with a DVM all seems fine but under voltage the DUT fails ...Obviously if powered something goes wrong and most of the times this is mechanical where some heat expands the die and that looses contact from things that was supposed to be connected .Common failure in Vintage equipment
  Reply With Quote
Old 12th January 2014, 01:46 AM   #5
mikstick is offline mikstick  United Kingdom
diyAudio Member
Join Date: May 2011
Location: liverpool, UK
I had similar problems with this amp.
The relay clicks in and out if there is issues, it doesn't mean the relay is faulty necessarily.

Try removing SUP17231 board (the one with the voltage amp stk-3062 on it)
there are a couple of plastic pins holding it in, the board just slides up out off the pins it sits in (amp is off!)

If the relay clicks in without the board in place, then you may well say the fault is on that board.
I replaced all the lytics all over, there arent that many, but some are damn awkward, I found a leaky on down by the relay control ic.
I think there was a bit of a design fault on the board mentioned in so much as the 2 zeners, and 2sa794 and 2sc1567 and the stk 3062 give off heat constantly, whether the amp is idle or not and so the electrolytics around there suffer. Also I have read numerous cases of the stk 3062 packing up probably due to overheating (google it) as sanyo reckoned it didnt need heatsinking. I replaced all the electrolytics, I replaced 2sa794 and 2sc1567 with bd139-16 and bd140-16, and further when problems continued at a later date I replaced the stk 3062 with a NOS from Germany. I also saw people modding heatsinks for the stk module so have modded one from an old graphics card to fit into that very awkward space. I am running it right now after just finishing the heatsink today and tested all voltages and waveform in the oscilloscope.

There are blank spaces on the board in question for other caps and resistors, I haven't checked but it may be that you can put in a stk 3062 and 3082 version II or III which are cheaper but apparently these need caps and resistors across certain pins (google again) but like I said, it may be that the board already has these spaces ready on the board, I haven't verified.

p.s I have the service manual if you need a copy. I will be posting it up on a couple of sites soon aswell. I already posted a schematic up to hifiengine.
  Reply With Quote
Old 12th January 2014, 12:45 PM   #6
mikstick is offline mikstick  United Kingdom
diyAudio Member
Join Date: May 2011
Location: liverpool, UK
I just read OP point that it was happening on tuner and phone, no mention of tape and aux.
If the amp is fine on these 2 inputs, then ignore what I posted before.
  Reply With Quote


Ampli Technics SU-C03Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Panasonic SU-2700 Repair (Otherwise known as the Technics SU Z1) MChandler Solid State 22 11th April 2013 07:25 AM
Help with Technics SU-Z45! P3ta Solid State 10 27th October 2011 12:40 AM
Technics SU-Z400 ironfinger43 Solid State 2 26th June 2009 02:18 PM
Technics SU 7600 Ford_V6 Solid State 0 25th May 2004 02:28 PM

New To Site? Need Help?

All times are GMT. The time now is 12:24 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio