So, my beloved SU-V4X has died. No more of that Iovely great sound coming out of my speakers. No sound comes out of sthe headphone jack either.
Now, when I turn the unit on, first the class A logo light up and the the right orange "safety operation" light starts to flash, then after around 5 seconds or so it stays on. After about 30 seconds, the left "auto computer drive" light (green) turns on, but I do not get a click from the relay.
Previous to that, I would sometimes get a louder crackle whilst playing music (one only, like when you connect a speaker wire and the unit was on), through the speakers, but it would either
a: continue playing, or
b: it would shut itself off.
If case b, then I could turn off the amp, wait a couple of seconds, then restart it normally and it would continue to play as if nothing had happened. Alas, this is no longer the case.
I bought the unit off the bay from th UK around 4-5 years ago, after getting more than one recommendation for this unit on this site. It replaced my busted SU-V4K and I really loved the V4X 's performance. Much better than the old V4K.
I'm not much of an electronics guy, though I do have a good soldering iron and meter.
Can anyone help me out and give me a couple of pointers as to where to look?
Thanks
Now, when I turn the unit on, first the class A logo light up and the the right orange "safety operation" light starts to flash, then after around 5 seconds or so it stays on. After about 30 seconds, the left "auto computer drive" light (green) turns on, but I do not get a click from the relay.
Previous to that, I would sometimes get a louder crackle whilst playing music (one only, like when you connect a speaker wire and the unit was on), through the speakers, but it would either
a: continue playing, or
b: it would shut itself off.
If case b, then I could turn off the amp, wait a couple of seconds, then restart it normally and it would continue to play as if nothing had happened. Alas, this is no longer the case.
I bought the unit off the bay from th UK around 4-5 years ago, after getting more than one recommendation for this unit on this site. It replaced my busted SU-V4K and I really loved the V4X 's performance. Much better than the old V4K.
I'm not much of an electronics guy, though I do have a good soldering iron and meter.
Can anyone help me out and give me a couple of pointers as to where to look?
Thanks
STK inside, either pre or final stage.
Get the service manual.
Check the supply volts.
STK modules do fail, others do as well.
The crackling was a warning, be thankful if the speakers and power supply are not damaged...check those as well.
STK modules are out of production since the mid 90s, what is available is mostly fake.
Option 1:
Replace with a TDA 7293 two channel module, or a populated transistor PCB, which matches your supply.
Option 2: They are about 90 Euros on Europe fleabay. Buy another.
Option 3: Build a new one from scratch, this is after all a DIY site!
Plenty of choices, limited by your ability, and budget in time and money.
Get the service manual.
Check the supply volts.
STK modules do fail, others do as well.
The crackling was a warning, be thankful if the speakers and power supply are not damaged...check those as well.
STK modules are out of production since the mid 90s, what is available is mostly fake.
Option 1:
Replace with a TDA 7293 two channel module, or a populated transistor PCB, which matches your supply.
Option 2: They are about 90 Euros on Europe fleabay. Buy another.
Option 3: Build a new one from scratch, this is after all a DIY site!
Plenty of choices, limited by your ability, and budget in time and money.
Hello,
Start by checking for cold solder joints or, better, re-do all of them carefully (the pcb isn't the toughest one). You'll have to make sure that main filter capacitors are discharged. Also, there are 2 super-capacitors in series somewhere on the same main pcb, avoid any shortcircuits...
I used to play with such an amp a few years ago and I was left with the impression that the main IC - SVI2004 - is pretty resilient.
Keep this topic alive with updates.
Regards, good luck,
Cosmin
Start by checking for cold solder joints or, better, re-do all of them carefully (the pcb isn't the toughest one). You'll have to make sure that main filter capacitors are discharged. Also, there are 2 super-capacitors in series somewhere on the same main pcb, avoid any shortcircuits...
I used to play with such an amp a few years ago and I was left with the impression that the main IC - SVI2004 - is pretty resilient.
Keep this topic alive with updates.
Regards, good luck,
Cosmin
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Go over with a magnifier the whole board(s) and inspect for solder cracks - mostly around heavy or heatsinked parts.
Also any inter-board connectors.
Then report back.
I would flow the solder again around the heavy parts just as a precaution, after checking the supply and the speakers.
It should be leaded solder, and it is Technics, unlikely, but Wise has decades of experience.
Look for dulled joints, that indicates corrosion.
You are in a coastal or humid area?
It should be leaded solder, and it is Technics, unlikely, but Wise has decades of experience.
Look for dulled joints, that indicates corrosion.
You are in a coastal or humid area?
Thanks guys.
Yes, this unit has the SVI2004 chip in it. Will open it up to check which version it has and then check the relay / look for solder problems.
BTW- it turned on again earlier this evening and ran as if nothing had happened. Strange, as it hasn't started up for like 2 months... it probably knew that I needed my Floyd fixxx...
Yes, this unit has the SVI2004 chip in it. Will open it up to check which version it has and then check the relay / look for solder problems.
BTW- it turned on again earlier this evening and ran as if nothing had happened. Strange, as it hasn't started up for like 2 months... it probably knew that I needed my Floyd fixxx...
That would help a lot but........I don't know:
https://audiokarma.org/forums/index.php?search/84540282/&q=Technics+SU-V4X&o=date
Good luck.
That module might be the brother in law version of the STK by Panasonic (Sanyo was founded by Mr. Matsushita's brother - in - law), and usually a reliable version.
But it was not in production for a long time, IIRC.
Do check the soldering, and heat sink, like we said above.
It is even more rare than STKs. Be very careful.
Erratic failure or shutdown will be mostly caused by capacitors in the power supply, and the regulator circuit values would need checking with a reliable meter. Zener voltages, and small filter caps for the main section also would need checking...
Usually a higher secondary voltage for the power section is used, and a 12-18V supply, less current is used for the pre amp and selector side, so expect at least two secondary voltages, and two sets of regulation to be checked.
But it was not in production for a long time, IIRC.
Do check the soldering, and heat sink, like we said above.
It is even more rare than STKs. Be very careful.
Erratic failure or shutdown will be mostly caused by capacitors in the power supply, and the regulator circuit values would need checking with a reliable meter. Zener voltages, and small filter caps for the main section also would need checking...
Usually a higher secondary voltage for the power section is used, and a 12-18V supply, less current is used for the pre amp and selector side, so expect at least two secondary voltages, and two sets of regulation to be checked.
Downloading the schematic or service manual for this would be a good place to start as well. That'll allow you to see which things the protection circuit cares about and go through those one by one.
Tom
Tom
I'm nowhere near the coast (in fact, we have a preasonably dry climate), but, I bought the unit used from the UK a few years back, so I presume it's seen a wetter climate most of its' life.
Manuals downloaded. Yes on the reflowing of solder, as much as I can.
Certainly don't want to repeat the mistake I made with my SU-V4K - where I slipped with my probe and fried the STK8050 whilst checking voltages... that was not a good day.
Manuals downloaded. Yes on the reflowing of solder, as much as I can.
Certainly don't want to repeat the mistake I made with my SU-V4K - where I slipped with my probe and fried the STK8050 whilst checking voltages... that was not a good day.
If checking voltages, etc, in a confined and critical area, I look for a nearby component (resistor, tie point, capacitor) on the same foil/trace of the IC pin I want to measure, and use a mini-clip-on test lead there.
Find a surface-mount resistor for instance, and clip the probe on it's lead.
Find a surface-mount resistor for instance, and clip the probe on it's lead.
I have a probe set with different ends, that can be handy.
It has standard, pins, alligator, and round lugs, which I can use on the threaded ends of the leads.
In this case, alligator clip to negative rail, or lug if a screw can be found.
A sleeve can be put, so only the probe tip is exposed, less chance of short circuits and accidents.
Always use good lighting, and take basic precautions for electrical leakage.
A jolt through your arms, as low as 24V DC, can cause your heart to stop, or upset the heart rhythms...not a good thing if you are alone, you are brain dead after 6 minutes of heart stoppage.
So, if possible, keep one hand away from the circuit, and do not have any metal on your hands and wrists.
It has standard, pins, alligator, and round lugs, which I can use on the threaded ends of the leads.
In this case, alligator clip to negative rail, or lug if a screw can be found.
A sleeve can be put, so only the probe tip is exposed, less chance of short circuits and accidents.
Always use good lighting, and take basic precautions for electrical leakage.
A jolt through your arms, as low as 24V DC, can cause your heart to stop, or upset the heart rhythms...not a good thing if you are alone, you are brain dead after 6 minutes of heart stoppage.
So, if possible, keep one hand away from the circuit, and do not have any metal on your hands and wrists.
Thanks guys. I have a Fluke27, with regular and mini alligator clips, the std test probes and those little mini-hook retractable clamps. Hoping that this selection is sufficient.
Yup, even a 9v battery can kill you, if applied at the correct location....
Yup, even a 9v battery can kill you, if applied at the correct location....
Indeed, I have a stun gun and a nite-stick/cattle prod stun and both run on 9 volt batteries.
Pity anyone on the 'business end' of those devices!
Pity anyone on the 'business end' of those devices!