diff --git a/main.c b/main.c
index 62250fb..c5ca879 100644
--- a/main.c
+++ b/main.c
@@ -244,6 +244,7 @@ toggle_sweep(void)
 // Shell commands output
 int shell_printf(const char *fmt, ...)
 {
+  if (shell_stream == NULL) return 0;
   va_list ap;
   int formatted_bytes = 0;
   if (shell_stream) {
@@ -1888,7 +1889,7 @@ static void shell_init_connection(void){
 
 #else
 // Only USB console, shell_stream always on USB
-#define PREPARE_STREAM
+#define PREPARE_STREAM shell_stream = (BaseSequentialStream *)&SDU1;
 
 #if 0           // Not used
 // Check connection as Active, if no suspend input
@@ -1918,7 +1919,7 @@ static void shell_init_connection(void){
 /*
  *  Set I/O stream SDU1 for shell
  */
-  shell_stream = (BaseSequentialStream *)&SDU1;
+  PREPARE_STREAM;
 }
 #endif
 
@@ -2029,10 +2030,8 @@ void sd_card_load_config(char *filename){
 
   if (f_open(fs_file, filename, FA_OPEN_EXISTING | FA_READ) != FR_OK)
     return;
-
-  BaseSequentialStream *old_shell_stream = shell_stream;
-  shell_stream = (BaseSequentialStream *)NULL;
-
+  // Reset IO stream
+  shell_stream = NULL;
   char *buf = (char *)spi_buffer;
   UINT size = 0;
 
@@ -2061,7 +2060,8 @@ void sd_card_load_config(char *filename){
     }
   }
   f_close(fs_file);
-  shell_stream = old_shell_stream;
+  // Prepare I/O for shell_stream
+  PREPARE_STREAM;
   return;
 }
 #endif
@@ -2221,8 +2221,6 @@ int main(void)
 
   shell_init_connection();
 
-
-
   set_sweep_points(POINTS_COUNT);
 
   #ifdef __AUDIO__
@@ -2275,10 +2273,6 @@ int main(void)
     dacPutChannelX(&DACD2, 0, config.dac_value);
   #endif
   dacStart(&DACD1, &dac1cfg1);
-#ifdef TINYSA4
-  disk_initialize(0);
-//  SD_PowerOn();
-#endif
 
   chThdCreateStatic(waThread1, sizeof(waThread1), NORMALPRIO-1, Thread1, NULL);