RFmaster
Member
Working on another SX-780 that came in with blown 1 AMP fuses. After checking the +/- 39.5 supply rail is dead. Replaced both Q19/20 (KSC2073/KSA940) but it clear that positive side will not start. After probing around - Q23 (2SK34) appears to have shorted internally. Well, what to do??
2SK34 is a JFET that has been been long discontinued. There are no exact replacements for this device. Originally this part was designed as VHF LNA. Pioneer used this part all over the place as well as using as a current source in the pass through regulator of SX-780 (and others as well) PSU. Search of ebay result in couple of hits, but I am not in a mood to pay $14 for pair of 2SK34's. A modern alternative is a bit more desirable!
A while back Mark posted a recommendation - CRD E202 - here the thread.
http://www.audiokarma.org/forums/index.php?threads/sx-d7000-poppity-pop-up-in-smoke.453275/page-4
But OP did not go forward with CRD E202 installation. l willing to go through and document this retrofit. From Semitec data sheet it would appear that Anode (the marked end) of E202 should be coupled the base of Q19 (+39.5V rail), same for the negative rail (-39.5V) the Anode should be coupled to the base //RF
2SK34 is a JFET that has been been long discontinued. There are no exact replacements for this device. Originally this part was designed as VHF LNA. Pioneer used this part all over the place as well as using as a current source in the pass through regulator of SX-780 (and others as well) PSU. Search of ebay result in couple of hits, but I am not in a mood to pay $14 for pair of 2SK34's. A modern alternative is a bit more desirable!
A while back Mark posted a recommendation - CRD E202 - here the thread.
http://www.audiokarma.org/forums/index.php?threads/sx-d7000-poppity-pop-up-in-smoke.453275/page-4
But OP did not go forward with CRD E202 installation. l willing to go through and document this retrofit. From Semitec data sheet it would appear that Anode (the marked end) of E202 should be coupled the base of Q19 (+39.5V rail), same for the negative rail (-39.5V) the Anode should be coupled to the base //RF