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Old 2nd March 2006, 08:26 AM   #1
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Post problem with Technics SU-Z45 Power amplifier

Hi, need help!

This amp blew along with its speakers just recently with burning smells all over!

i've used it for 10 years now with no fuss.

can you tell me how to fix it?

Thanks.
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Old 17th November 2006, 08:01 AM   #2
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My SU-Z45 blew up recently too. It was only the filter capacitors. A lot of screws need to be taken out to get to the bottom of the main circuit board, but just de-solder the two main capacitors and replace them and the fuse. That fixed mine anyway, yours could be a different fault.
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Old 17th November 2006, 06:51 PM   #3
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The problem is probably not in filter capacitors, altough they should be
replaced because their lifespan is around 10 years.

If speakers blew as well, than output transistors (or IC) made burning smell.

Try to replace all active elements and see if would work.

This would probably save you time and nervs.
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Old 17th November 2006, 10:45 PM   #4
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Quote:
Originally posted by Mariodas
The problem is probably not in filter capacitors, altough they should be
replaced because their lifespan is around 10 years.

If speakers blew as well, than output transistors (or IC) made burning smell.

Try to replace all active elements and see if would work.

This would probably save you time and nervs.
This little "gem" of an amp has a STK module or something very similar attached to its heat sink. I had one many years ago and I miss that integrated amp. Crack it open and tell us the part number on that big IC in there.

Cheers,

Shawn.
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Old 6th February 2016, 09:00 AM   #5
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Hello all,
If you are repairing a SU-Z45 use the SU-Z22 schematics not the SU-Z55 schematics.
You can replace the STK2038 with a STK2038IV which is just a slightly improved version of the (mark I). But not with a STK2038 II as the pin outs are different.
You can also go one step further and replace it with a STK2048IV . The STK2048IV is the drop-in replacement for the STK2038IV.

If your amp is using a STK2038II you maybe able to replace it with a STK2048II but I have not tested this myself.

What you have to remember when buying STK's online is the old STK's were discontinued in the 1999's from what I can remember so we are now 17 years later and you are 90% of the time going to be getting a fake IC or a second hand one that has been stripped out of the amps that were returned to the manufacturers under warranty years ago chances are their outputs were blown that's why they were returned. So your best bet is to find a second hand working IC or find a repair shop that has been around for years and ask them to check in their old stuff.

In most cases the AN7060's will be undamaged by the STK blowing as they are protected by Q301 and Q302 which will need replacing.

If you are in a jam and only have AN7062's you could easily mod one and run wires to work in place of two AN7060's or use half of 2 AN7062's to replace 2 AN7060's be careful you need to match the pinouts and supply voltages.

Always test the AN7060's with the STK out just to make sure that they were not the cause of the STK blowing.

I have run these technics amps and the fisher amps at full volume for 10 hours straight with no amp problems I don't stack the components so the amp's have more ventilation.
I use old Sansui 3 way speakers with quality Sansui crossovers sometimes the subs blow.

If you are in a jam and have a working mark II it maybe possible to use the mark II by doing some mod to the extra pins I read some where that the extra pins are to set some control.

I will respond to the resistor burning Thread after checking my notes
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Old 6th February 2016, 09:08 AM   #6
Mooly is offline Mooly  United Kingdom
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Why are you repeatedly posting this information in old threads ?

Your latest post has not been approved.
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Old 6th February 2016, 08:07 PM   #7
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Grave digging isn't cool, man.
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Old 8th February 2016, 11:13 AM   #8
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Quote:
Originally Posted by Mooly View Post


Why are you repeatedly posting this information in old threads ?

Your latest post has not been approved.
Sorry may have clicked twice sometimes my Win10 hands.
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Old 8th February 2016, 11:16 AM   #9
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Originally Posted by Welcome View Post
Grave digging isn't cool, man.
It's fun resurrecting the dead
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Old 8th February 2016, 11:23 AM   #10
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by Mastertronics View Post
Sorry may have clicked twice sometimes my Win10 hands.
Not when you are looking up old threads to post this too
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