Category: Blog

Missing sound in left channel. Relay clicks .Bad contacts.Relays have limitations on the workability of their contacts, Relay replacement solved the problem.

Nice receiver . Build to last. Troubleshooting   –  Problem in Phono preamp board only. All other inputs working perfect. You have 6 transistors on phono preamp board . 3 – for left channel , 3 for right channel. While unit working  we touch plastic body all those transistors by hot soldering  iron tip  for 2-3 seconds. On one of them  sound distortion increase after touching – that is  indication that transistor is bad, even if it tested ok by tester . In this case was 2sa725 transistor with red dot on top. We use KSA992 instead original. Transistors pinout is different but parameters are  better for this specific use. It is always better to use same part if part available. We  support rule -minimum change to original schematic – that is repairman major goal. For good balance in two channels we changed same transistor in left channel. We guess these transistors are going bad  after   wrong input signal  connected to Phono input  1/ Phono input 2  ( from CD , cassette players, phone or Bluetooth .)c

Found shorted output transistors in right channel , left channel is ok. Original – SJ2517 and SJ2518 .   Installed NTE 180 and NTE181.  NTE 181 must be on top.  No modification or adjustments needed. Direct replacement.