Tuner Technics ST GT 550/650 has supercapacitors? - UK Vintage Radio Repair and Restoration Discussion Forum

promoter2000 · 23rd Aug 2019, 4:15 pm

Hello everyone. Please can someone who knows these two Technics tuners tell me if they have supercapacitors to store memories without an electrical supply? If they mount them where are they and what value do they have? Thank you all.

Jonster · 23rd Aug 2019, 5:19 pm

Yes I think they have got a supercapacitor rather than a backup battery. From memory it is near the front of the right hand side of the unit. I had one apart a while back to fit it onto a 19" rack tray and remember seeing it.

promoter2000 · 23rd Aug 2019, 5:59 pm

Thanks for the reply. I publish a photo of the interior: is it one of those circulated in yellow or blue? Remember the value in UF?

mhennessy · 23rd Aug 2019, 7:56 pm

If there is one, I haven't found it in the service manual. I could take the lid off mine if necessary, but I'd expect it to live on the front panel PCB where the microcontroller is located, so it might not be visible if just the top panel is removed....

But I don't quite understand the question: presumably the OP doesn't have the unit in front of them yet? If so, are they hoping for a simple fix based on a fault description? It certainly isn't any of those on the main PCB in post #3.

promoter2000 · 24th Aug 2019, 5:38 am

Well, it's finally a little clearer to me (this research is driving me crazy

). In fact, I also found nothing in the service manual that was soldered to the main PCB. Perhaps Matsushita has chosen another way to temporarily preserve the preselections. Thanks for the help mhennessy.

phut bang · 24th Aug 2019, 8:40 am

well i dont recognise this chassis but if its like technics other tuners i recall the value being around 3 farad yes thats right 3 farad not uf and about 3 volts even when they were oozing all their insides out they still can cause a big spark using soldering iron and i think they were supposed to be chopped out but you wont be able to get cutters in between cap and pcb i used to waggle them to and fro until they snapped if you still cant do that it is the soldering iron watch out though for the cap discharging very entertaining BANG!

promoter2000 · 24th Aug 2019, 10:20 am

Indeed. For example, in the ST-G7 model there are two 3.3 F / 2.3 V supercapacitors (placed side by side to each other) which, before being touched, should be unloaded with a 100 ohm resistor so as not to cause fireworks. . But in the two little brothers GT 550/650 it seems there are none

23rd Aug 2019, 4:15 pm	#1
promoter2000 Triode Join Date: Feb 2017 Location: Mantova, Italy. Posts: 18	Tuner Technics ST GT 550/650 has supercapacitors? Hello everyone. Please can someone who knows these two Technics tuners tell me if they have supercapacitors to store memories without an electrical supply? If they mount them where are they and what value do they have? Thank you all.

23rd Aug 2019, 5:19 pm	#2
Jonster Heptode Join Date: Apr 2008 Location: Eastbourne, East Sussex, UK. Posts: 671	Re: Tuner Technics ST GT 550/650 has supercapacitors? Yes I think they have got a supercapacitor rather than a backup battery. From memory it is near the front of the right hand side of the unit. I had one apart a while back to fit it onto a 19" rack tray and remember seeing it.

23rd Aug 2019, 7:56 pm	#4
mhennessy Dekatron Join Date: Jul 2007 Location: Evesham, Worcestershire, UK. Posts: 4,244	Re: Tuner Technics ST GT 550/650 has supercapacitors? If there is one, I haven't found it in the service manual. I could take the lid off mine if necessary, but I'd expect it to live on the front panel PCB where the microcontroller is located, so it might not be visible if just the top panel is removed.... But I don't quite understand the question: presumably the OP doesn't have the unit in front of them yet? If so, are they hoping for a simple fix based on a fault description? It certainly isn't any of those on the main PCB in post #3.

24th Aug 2019, 5:38 am	#5
promoter2000 Triode Join Date: Feb 2017 Location: Mantova, Italy. Posts: 18	Re: Tuner Technics ST GT 550/650 has supercapacitors? Well, it's finally a little clearer to me (this research is driving me crazy ). In fact, I also found nothing in the service manual that was soldered to the main PCB. Perhaps Matsushita has chosen another way to temporarily preserve the preselections. Thanks for the help mhennessy.

24th Aug 2019, 8:40 am	#6
phut bang Triode Join Date: Jan 2018 Location: Wrexham, Clwyd, Wales, UK. Posts: 47	Re: Tuner Technics ST GT 550/650 has supercapacitors? well i dont recognise this chassis but if its like technics other tuners i recall the value being around 3 farad yes thats right 3 farad not uf and about 3 volts even when they were oozing all their insides out they still can cause a big spark using soldering iron and i think they were supposed to be chopped out but you wont be able to get cutters in between cap and pcb i used to waggle them to and fro until they snapped if you still cant do that it is the soldering iron watch out though for the cap discharging very entertaining BANG! __________________ Adjust the volume for maximum smoke!

23rd Aug 2019, 5:59 pm	#3
promoter2000 Triode Join Date: Feb 2017 Location: Mantova, Italy. Posts: 18	Re: Tuner Technics ST GT 550/650 has supercapacitors? Thanks for the reply. I publish a photo of the interior: is it one of those circulated in yellow or blue? Remember the value in UF? Attached Thumbnails

24th Aug 2019, 10:20 am	#7
promoter2000 Triode Join Date: Feb 2017 Location: Mantova, Italy. Posts: 18	Re: Tuner Technics ST GT 550/650 has supercapacitors? Indeed. For example, in the ST-G7 model there are two 3.3 F / 2.3 V supercapacitors (placed side by side to each other) which, before being touched, should be unloaded with a 100 ohm resistor so as not to cause fireworks. . But in the two little brothers GT 550/650 it seems there are none