Technics SU-Z400 problem

exzlr8 · 2nd November 2009, 03:45 AM

My uncle recently gave me this amp because he had it in storage for ages and was going to throw it out.
When it was put into storage it worked, but now (about 5 years on) it doesn't work.
When plugged in and turned on it does nothing; no lights, sounds anything.

Does anyone know what could be wrong?
Any help is appreciated.

jaycee · 2nd November 2009, 06:47 AM

Check primary side fuse, these sometimes just blow from old age

exzlr8 · 2nd November 2009, 07:39 AM

sorry, forgot to add that i checked the fuse and its fine (think there's only one).
also i though maybe the switch could be broken (unlikely but hey) so i used screwdriver to bridge across it but made no difference.

exzlr8 · 2nd November 2009, 07:57 AM

ahh, think i ma have just figured it out. I "carefully" connected a 240v light globe inside the amp where the 2 power wires are soldered to a small board, plugged it in and no light.
Never really thought the cord could be bad as it looks in perfect condition, guess i'll swap it out and see what happens.

exzlr8 · 2nd November 2009, 11:15 AM

never mind, checked with multimeter and there was power.
any other thought?

Pedrotech · 22nd April 2010, 08:42 AM

Have just picked up on these posts while looking for info on this model I'm looking at for a friend. If you are still interested, i have diagnosed on this one what may be your problem. On my friend's amp's transformer the primary winding that is being used is open circuit. This gives symptoms identical to yours. Hope this helps - there could be a batch issue with these transformers, who knows ?? [This one has the Matsushita logo on it.]
I think a cheap second-hand amp would be the only shot at a result for me.
P.

sheldonstv · 22nd April 2010, 10:49 AM

get yrself a multimeter,set it to read ac volts -set it to a high range if it isnt auto ranging and check the ac supply going directly to the mains transformer primary,then check the ac supply from the transformer secondary-if it is present yr transformer is ok if not-some transformers have an internal temp.fuse which simply could have failed due to old age.
if you are unlucky the transformer primary may be faulty but doubtfull or yr secondary may be oc....you should be able to dissassemble the transformer to get to the fuse ...

sakis · 22nd April 2010, 10:53 AM

Quote:

Originally Posted by sheldonstv

get yrself a multimeter,set it to read ac volts -set it to a high range if it isnt auto ranging and check the ac supply going directly to the mains transformer primary,then check the ac supply from the transformer secondary-if it is present yr transformer is ok if not-some transformers have an internal temp.fuse which simply could have failed due to old age.
if you are unlucky the transformer primary may be faulty but doubtfull or yr secondary may be oc....you should be able to dissassemble the transformer to get to the fuse ...

KEEP IN MIND ....that some of these trafos feature windings for other voltage also and this might be a complication

Pedrotech · 23rd April 2010, 07:44 AM

Thanks - I'll dig in a bit. Also the unused primary winding reads ok - but of course it would be .... (This is wired as a 240v version.)
Keep you posted.

2nd November 2009, 03:45 AM	#1
exzlr8 diyAudio Member Join Date: Nov 2009	Technics SU-Z400 problem My uncle recently gave me this amp because he had it in storage for ages and was going to throw it out. When it was put into storage it worked, but now (about 5 years on) it doesn't work. When plugged in and turned on it does nothing; no lights, sounds anything. Does anyone know what could be wrong? Any help is appreciated.

22nd April 2010, 08:42 AM	#6
Pedrotech diyAudio Member Join Date: Apr 2010	Re: Technics SU-Z400 problem Have just picked up on these posts while looking for info on this model I'm looking at for a friend. If you are still interested, i have diagnosed on this one what may be your problem. On my friend's amp's transformer the primary winding that is being used is open circuit. This gives symptoms identical to yours. Hope this helps - there could be a batch issue with these transformers, who knows ?? [This one has the Matsushita logo on it.] I think a cheap second-hand amp would be the only shot at a result for me. P.

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2nd November 2009, 06:47 AM	#2
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Check primary side fuse, these sometimes just blow from old age

2nd November 2009, 07:39 AM	#3
exzlr8 diyAudio Member Join Date: Nov 2009	sorry, forgot to add that i checked the fuse and its fine (think there's only one). also i though maybe the switch could be broken (unlikely but hey) so i used screwdriver to bridge across it but made no difference.

2nd November 2009, 07:57 AM	#4
exzlr8 diyAudio Member Join Date: Nov 2009	ahh, think i ma have just figured it out. I "carefully" connected a 240v light globe inside the amp where the 2 power wires are soldered to a small board, plugged it in and no light. Never really thought the cord could be bad as it looks in perfect condition, guess i'll swap it out and see what happens.

2nd November 2009, 11:15 AM	#5
exzlr8 diyAudio Member Join Date: Nov 2009	never mind, checked with multimeter and there was power. any other thought?

22nd April 2010, 10:49 AM	#7
sheldonstv diyAudio Member Join Date: May 2005 Location: united kingdom	get yrself a multimeter,set it to read ac volts -set it to a high range if it isnt auto ranging and check the ac supply going directly to the mains transformer primary,then check the ac supply from the transformer secondary-if it is present yr transformer is ok if not-some transformers have an internal temp.fuse which simply could have failed due to old age. if you are unlucky the transformer primary may be faulty but doubtfull or yr secondary may be oc....you should be able to dissassemble the transformer to get to the fuse ...

23rd April 2010, 07:44 AM	#9
Pedrotech diyAudio Member Join Date: Apr 2010	Thanks - I'll dig in a bit. Also the unused primary winding reads ok - but of course it would be .... (This is wired as a 240v version.) Keep you posted.

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