Technics SUV4X new class A Amp - 20 odd years old but lovely sound !!
Amp gone into "safety operation" mode - flashing amber light+no output.
Amp is connected to 1pr. 8ohm KEFS + 1pr. 8ohm CELESTIONS(correct impedance selected on amp). I had it on 3 of 10 ( loud amp - 65wpc ) and the output suddenly stopped and amp went to above mode. i switched it off and noticed the transformer was hot - although well ventilated. ive taken cover off and checked the 2 fuses i could see ( both ok ) + can see no toasted components.Do you think ive cooked the transformer or possibly the output IC?. As the unit will power up i dont think the Transf. is the problem - hopefully it could be other components that are standard service items - cheaper ones??!. Thank you if you can help me. A fellow Biker !!!!!!.
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Re: Technics SUV4X new class A Amp - 20 odd years old but...
Quick check... If the amp still stays in safety mode with the vol turned down and the speakers disconnected, it will have failed in some way. Since you have the safety operation light ON, you can expect that the power transformer is OK. I would expect that you have a DC offset condition on one channel. The most common problems you may have are
dry solder joints about the power stages such as regulators, and output/driver transistors/IC's.
blown output transistors/output IC with possible fusible resistor failures, and or sometimes burnt up printed circuit tracks.
a voltage rail failure from a burnt fusible or power supply component.
If you are up with electronic fault finding, soldering and have the tools, have a go yourself, I could talk you through it. If not, I would suggest you contact you local HiFi specialist and find who can repair it or at least check to see what has failed for you. Good Luck. If you cannot find someone, hit me back and I will try to find someone for you. Cheers
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Do you use the phono input or do you have line output . If you have a line output it's possible that for example your technics has a very high impendance, but with technics amp do you use and which phono amp and you cleaned your needle very good ... Does it work good using a cd player .... it can be a lot, so you need to tell your whole system , cleaned the amp inside, especially the potentiometres??????. Gr richard
Hello Your Tchnics is too old model and it has power transistors are used in output section. The output power is rated as 50Watts/channel/4Ohms. You can connect extra speakers to this left and right outputs, such a sway that the impedence should not go bellow 4 Ohms. Its repair book informs me that if any of the output transistors has gone out, it will not be available any more, and no substitutions cam be done. So be care when connecting more speakers. OK.
Check for dry solder joints especially on the main power output transistor. A
blown power transistor will stop the 'Current Drive' from engaging so
if the problem you have is intermittent then it is most likely dry
It sounds like yo shorted the speaker wires together for a short time and smoked the output section of the amp. The amber light is an indication that the amp is in protect mode. If you attempt to power up the amp and still have the amber light even with all speaker wires disconnected, the amp needs repair. The output transistors for that side will need to be replaced.
Blingking Light usually means that there is DC appearing in output stage and is protecting Connected Speakers.
It can be faulty Output Stage (Bad ICs/Transistors/Resistors/Capacitors) or Faulty Power Supply.
Working on These types of Problem is not user friendly at all.
check volume balance between right and left-then change inter connection between sound source and amplifier with new cabel(i prefer gold plated type connectors)(see radio shack). after that if the problem excit your fault in output transistors or output stereo ic depend on circuit design.