low output in the right channel of a Sansui QRX 5001 when using QS SQ and Synth modes

[Roque]

Hello Sansui Gurus , my first time to post out here in this forum so please excuse if any errors cheers ... got a Sansui qrx 5001 on my bench and the issue i am facing is that the right channel when played through 2 channel direct and 4 channel direct sounds perfect but when i engage the synth or QS and SQ modes the volue drops drasctically ..have narrowed it down to the vario matrix board but tested most components on the board and they seem fine ...not sure if i am overlooking something simple??? any info or pointers would be much appreciated .thanks guys
Regards
Roque

 

[par4ken]

My first guess would be bad capacitors or a bad decoder chip. If the boards plug in as many Sansui's do you might have to deox/clean the board and connector contacts. Likewise clean any switch contacts.

 

[Sonik Wiz]

Hello Sansui Gurus , my first time to post out here in this forum so please excuse if any errors cheers ... got a Sansui qrx 5001 on my bench and the issue i am facing is that the right channel when played through 2 channel direct and 4 channel direct sounds perfect but when i engage the synth or QS and SQ modes the volue drops drasctically ..have narrowed it down to the vario matrix board but tested most components on the board and they seem fine ...not sure if i am overlooking something simple??? any info or pointers would be much appreciated .thanks guys
Regards
Roque

To Ken's suggestion I would also add check the power supply voltage to the decoder board. I am unfamiliar with your receivers parts layout but somewhere there should be a trim pot to adjust the decoder board voltage to 25 V. Below that & the decoding gets wonky anything can happen. Above that they go phhht!!. So adjust slowly & it's been recommended elsewhere to do this under load, that is while playing/decoding music. The FM will work fine.

 

[Roque]

My first guess would be bad capacitors or a bad decoder chip. If the boards plug in as many Sansui's do you might have to deox/clean the board and connector contacts. Likewise clean any switch contacts.

My first guess would be bad capacitors or a bad decoder chip. If the boards plug in as many Sansui's do you might have to deox/clean the board and connector contacts. Likewise clean any switch contacts.

My first guess would be bad capacitors or a bad decoder chip. If the boards plug in as many Sansui's do you might have to deox/clean the board and connector contacts. Likewise clean any switch contacts.

Hi Ken,
yes you were right about capacitors and the other deoxit options ...done the first part replaced all caps in the vario matrix board and voila!! the channel sounds good now also have deoxit all switches and pcb connectors too ...as Sonik Wiz mentioned about the 25 V i was getting the voltage around the range of 25v thank you to the two of you ....you guys are CHAMPS!!!! cheers.