diff --git a/drivers/media/dvb/frontends/isl6423.c b/drivers/media/dvb/frontends/isl6423.c
index c1943dcb8db6..dca5bebfeeb5 100644
--- a/drivers/media/dvb/frontends/isl6423.c
+++ b/drivers/media/dvb/frontends/isl6423.c
@@ -73,6 +73,7 @@ static int isl6423_write(struct isl6423_dev *isl6423, u8 reg)
 
 	struct i2c_msg msg = { .addr = addr, .flags = 0, .buf = &reg, .len = 1 };
 
+	dprintk(FE_DEBUG, 1, "write reg %02X", reg);
 	err = i2c_transfer(i2c, &msg, 1);
 	if (err < 0)
 		goto exit;
@@ -133,6 +134,9 @@ static int isl6423_voltage_boost(struct dvb_frontend *fe, long arg)
 	if (err < 0)
 		goto exit;
 
+	isl6423->reg_3 = reg_3;
+	isl6423->reg_4 = reg_4;
+
 	return 0;
 exit:
 	dprintk(FE_ERROR, 1, "I/O error <%d>", err);
@@ -144,12 +148,10 @@ static int isl6423_set_voltage(struct dvb_frontend *fe,
 			       enum fe_sec_voltage voltage)
 {
 	struct isl6423_dev *isl6423 = (struct isl6423_dev *) fe->sec_priv;
+	u8 reg_3 = isl6423->reg_3;
 	u8 reg_4 = isl6423->reg_4;
 	int err = 0;
 
-	/* SR4H = 0, SR4M = 1, SR4L = 1 */
-	reg_4 = 0x03 << 5;
-
 	switch (voltage) {
 	case SEC_VOLTAGE_OFF:
 		/* EN = 0 */
@@ -160,6 +162,7 @@ static int isl6423_set_voltage(struct dvb_frontend *fe,
 		/* EN = 1, VSPEN = 1, VTOP = 0, VBOT = 0 */
 		reg_4 |= (1 << 4);
 		reg_4 &= ~0x3;
+		reg_3 |= (1 << 3);
 		break;
 
 	case SEC_VOLTAGE_18:
@@ -167,15 +170,23 @@ static int isl6423_set_voltage(struct dvb_frontend *fe,
 		reg_4 |= (1 << 4);
 		reg_4 |=  0x2;
 		reg_4 &= ~0x1;
+		reg_3 |= (1 << 3);
 		break;
 
 	default:
 		break;
 	}
+	err = isl6423_write(isl6423, reg_3);
+	if (err < 0)
+		goto exit;
+
 	err = isl6423_write(isl6423, reg_4);
 	if (err < 0)
 		goto exit;
 
+	isl6423->reg_3 = reg_3;
+	isl6423->reg_4 = reg_4;
+
 	return 0;
 exit:
 	dprintk(FE_ERROR, 1, "I/O error <%d>", err);
@@ -189,9 +200,6 @@ static int isl6423_set_current(struct dvb_frontend *fe)
 	const struct isl6423_config *config	= isl6423->config;
 	int err = 0;
 
-	/* SR3H = 0, SR3M = 1, SR3L = 0 */
-	reg_3 = 0x02 << 5;
-
 	switch (config->current_max) {
 	case SEC_CURRENT_275m:
 		/* 275mA */
@@ -226,13 +234,13 @@ static int isl6423_set_current(struct dvb_frontend *fe)
 
 	switch (config->curlim) {
 	case SEC_CURRENT_LIM_ON:
-		/* DCL = 1 */
-		reg_3 |= 0x10;
+		/* DCL = 0 */
+		reg_3 &= ~0x10;
 		break;
 
 	case SEC_CURRENT_LIM_OFF:
-		/* DCL = 0 */
-		reg_3 &= ~0x10;
+		/* DCL = 1 */
+		reg_3 |= 0x10;
 		break;
 	}
 
@@ -240,6 +248,8 @@ static int isl6423_set_current(struct dvb_frontend *fe)
 	if (err < 0)
 		goto exit;
 
+	isl6423->reg_3 = reg_3;
+
 	return 0;
 exit:
 	dprintk(FE_ERROR, 1, "I/O error <%d>", err);
@@ -268,6 +278,11 @@ struct dvb_frontend *isl6423_attach(struct dvb_frontend *fe,
 	isl6423->i2c	= i2c;
 	fe->sec_priv	= isl6423;
 
+	/* SR3H = 0, SR3M = 1, SR3L = 0 */
+	isl6423->reg_3 = 0x02 << 5;
+	/* SR4H = 0, SR4M = 1, SR4L = 1 */
+	isl6423->reg_4 = 0x03 << 5;
+
 	if (isl6423_set_current(fe))
 		goto exit;
 
diff --git a/drivers/media/dvb/ttpci/budget-ci.c b/drivers/media/dvb/ttpci/budget-ci.c
index dbdc7953c6a1..e1c83c513f3c 100644
--- a/drivers/media/dvb/ttpci/budget-ci.c
+++ b/drivers/media/dvb/ttpci/budget-ci.c
@@ -1383,6 +1383,7 @@ static struct stv6110x_config tt1600_stv6110x_config = {
 static struct isl6423_config tt1600_isl6423_config = {
 	.current_max		= SEC_CURRENT_515m,
 	.curlim			= SEC_CURRENT_LIM_ON,
+	.mod_extern		= 1,
 	.addr			= 0x08,
 };