Sansui Quad qrx6500 receiver

[Tunedup55]

Re-caping. Was wondering what the pwr supply voltage is and where to connect DMD to adjust voltage? On pwr supply board

 

[par4ken]

You should be able to find the information in the service manual.

https://www.hifiengine.com/manual_library/sansui/qrx-6500.shtml

 

[Tunedup55]

Ty for welcoming me to quad. Currently working on Sansui qrx 6500, r&r the main caps and power supply caps, Read the service manual top to bottom. Nothing. I do have glasses, no I read on line a guy who had the same issue and said it was 25 v, which seems a little low, this is my 1st Sansui quad Ive had the pleasure as my hobby. Worked on a few Marantz’es. They were 35v pwr supply output. So I set the pot on pwr supply board to 25v out. Seems low when I run it, comes on slow, fades in and out. Any help would be appreciated! Ty

 

[par4ken]

Ty for welcoming me to quad. Currently working on Sansui qrx 6500, r&r the main caps and power supply caps, Read the service manual top to bottom. Nothing. I do have glasses, no I read on line a guy who had the same issue and said it was 25 v, which seems a little low, this is my 1st Sansui quad Ive had the pleasure as my hobby. Worked on a few Marantz’es. They were 35v pwr supply output. So I set the pot on pwr supply board to 25v out. Seems low when I run it, comes on slow, fades in and out. Any help would be appreciated! Ty

Vario Matrix decoders using the Sansui chips require 25 volts if that's what you are asking.

 

[Tunedup55]

The pwr supply for the whole Sansui qrx 6500. Don’t know the operating voltage? There’s a pot on the pwr supply board. That’s all I know. Sansui service manual has nothing on what to set it too.

 

[Sonik Wiz]

The pwr supply for the whole Sansui qrx 6500. Don’t know the operating voltage? There’s a pot on the pwr supply board. That’s all I know. Sansui service manual has nothing on what to set it too.

There will be multiple different voltages in a product like this. Probably higher voltages for the amps, lowest voltages for the pilot lights, and 25V which is for the decoder boards. Adjust this too low & the decoding gets very wonky. Too high & the Variomatrix chips go pffft. This isn't your particular model but it might be of assistance:

http://www.4channelsound.com/sansui.htm

 

[par4ken]

The pwr supply for the whole Sansui qrx 6500. Don’t know the operating voltage? There’s a pot on the pwr supply board. That’s all I know. Sansui service manual has nothing on what to set it too.

I would think that the pot is to adjust the voltage to the decoder board. Usually the voltage to the power amps is unregulated. Sad that the voltages aren't shown more clearly in the manual.

 

[skywaveTDR]

I have a couple of these Quad receivers and will one day have to recap them too. If I had Technical question I would get in touch with people who restore them all the time and I think that is QRXRestore in the Oregon area. I will confur with other technical people who work on a given product such as those that call me for help with Teac and Tascam decks. Be advised I do not have any connection with this guy but from what I read it seems to be above those that are boneheads. See for yourself-http://www.qrxrestore.com/services/
This might also help further-
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