Technics SU-G90 amp

R2E2

Nuclear Physicist
Technics SU-G90 amp, powers up, switches through inputs, shows level increase with rotation of the big knob. Has no output. from what Ive read it leans towards BC Power Module SVI 3206 C (IC601) being FUBAR. I cant find the EXACT replacement, I have found a 3206 D module through an internet supplier. I dont know the cross-compatibility of the components yet, but I emailed the retailer today. The part sells for less than $50 shipped. Is this an acceptable gamble? I do NOT have a service manual for this amp, and Im not sure its worth the $20 I would have to pay on E-SCAM for a repro.

Any input is appreciated.
Rob
 
Rob, I had the same problem with an SU-G75, thought it was the module, took a shot at the volume control as it was cheaper and in stock. Has been working great for 8 months. I gave it to a friend as part of a housewarming gift and he loves it. Might be worth it, was easy & cheap. Just like me. :)
 
I have two SU-G90's both with the same problem. When they warm up the whole front display dies! You can tap on the case or wiggle the front section with the case top removed and it will work again! Sounds like a design issue since both amplifiers have the same problem! Anyone out there with ideas?
 
Usually if you can tap on the case or give it the wiggle treatment it is a bad connection. I usually clear these problems by checking for bad solder connections that over time have managed to go bad. Takes a little patience but usually you will find the problem and by resoldering will make it "happy" again.
 
The regulators in those amps run pretty hot and cause bad solder joints around them and around the output module. The last 5 out of 6 of those I worked on all had the same problem, and were cured by re-soldering all of the bad joints. You have to pull the whole board out, as there is no bottom access panel. Not a job for the novice.
So far, none of those amps that I have seen have had a bad output module.
 
Are the BC modules proprietary & manufactured by Panasonic? I came across an SU-CH7 integrated and it has one version of the BC module in it. I'd never come across these before and could find no cross or datasheet for it.
 
Technics SU-G90 amp, powers up, switches through inputs, shows level increase with rotation of the big knob. Has no output. from what Ive read it leans towards BC Power Module SVI 3206 C (IC601) being FUBAR. I cant find the EXACT replacement, I have found a 3206 D module through an internet supplier. I dont know the cross-compatibility of the components yet, but I emailed the retailer today. The part sells for less than $50 shipped. Is this an acceptable gamble? I do NOT have a service manual for this amp, and Im not sure its worth the $20 I would have to pay on E-SCAM for a repro.

Any input is appreciated.
Rob
 
ressurection alert: there are to-220 devices for the various voltages it needs, to the left and right of the main amp on the large heat sink. They desolder themselves. reflow them and add more solder. also, consider having the fan on all the time. it only comes on when a) very hot or b) when at louder volume setting with the surround engaged.

these will last longer (if they are even still alive) if cooler and since they breath out back....
 
hi!

first of all, I'm from Bahía Blanca, Argentina, and we don't have good and capable technical services here, with expertise with this amps, so I'm doing some research to solve this...or at least to find the cause

I own a SU-G90 amp, and after running some time, and more quickier as higher is the volume level, you hear some "electrical" sound, and then the amplifier goes to a "freeze status", turning off the following, for example: the sorrund (lowering the rear level), the superbass, the dat/vcr input...

After that happens, you can manually turn on everything again, and works properly for a few more minutes, and then "fails" again...

What do yo think it could be?
is that an overload issue?
is that a high temp issue?
is that a bad solder issue?

when the amp does that, i feel it hot. the fan works, and fan's speed is related which amp "charge"...higher volume, higher speed

Any advice or suggestions are welcomed.

Thanks in advance.

Regards!
 
Knowing those amps, the first thing I would do is check the amp board for cracked solder joints. I'd bet that you'll find plenty. While you have it apart, pull the amp modules from the heatsinks, clean them, and apply new thermal paste.
After fixing the cracked solder joints, and re-assembly, insure that the fan is working. It is controlled by the current draw of the amplifier, so you have to turn it up for the fan to come on.
Also, check your speaker connections and the speakers themselves.
 
Knowing those amps, the first thing I would do is check the amp board for cracked solder joints. I'd bet that you'll find plenty. While you have it apart, pull the amp modules from the heatsinks, clean them, and apply new thermal paste.
After fixing the cracked solder joints, and re-assembly, insure that the fan is working. It is controlled by the current draw of the amplifier, so you have to turn it up for the fan to come on.
Also, check your speaker connections and the speakers themselves.
Thanks a lot for your reply!

I will do that.
The fun is working, I have checked it, but the doubt if it is enough...

Will keep you informed

Thanks
 
in which areas of the main PCB should I found cracked solder joints?

i'm not an expert in those tasks...my brother had lots of experiencie in electronics, but he passed away last July, due to CoVid...so I'm facing this project by myself,,,great challenge...

thanks!
 
ressurection alert: there are to-220 devices for the various voltages it needs, to the left and right of the main amp on the large heat sink. They desolder themselves. reflow them and add more solder.

please, can you give me more info about this?
photos?

I'm still having the issue, and want to sold them again, and also want to add an extra fan, but need t found the way to get 12V...
 
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