SX-650 post-recap--pops and static/noise issues w/ phono input

[malcmcm]

Hi all, I need some help

I recently acquired a sx-650 from ebay, this is the 220/240V international version. Original owner kept it in very good condition minus the saw dust on the inside.

I cleaned it up/ deoxed everything and recapped re-transistored, minus most of the tuner board.

The Aux input works and sounds great, and I get a few clear stations with the tuner. However, I was testing out the phono input tonight and noticed an extremely loud pop when switching to phono that trips the relay, everything then seems ok except when I change the volume there is very high levels of white noise/static only while adjusting the knobs, at a certain point the noise gets loud enough to trip the realy. flipping on various things while in the phono function, like the 'loudness' and 'stereo or mono' and tape monitors also cause this loud pop that trips the relay too.

If I don't touch anything while in phono, it is quiet, everything seems ok, it is only if I move the volume knob and or flip a switch.

Keep in mind this is while nothing is plugged into the phono input.

To make things more difficult, I've replaced all of the transistors and electrolytic capacitors on the EQ board, which seems to be the usual solution, I'll list below everything I've replaced. This unit has 2 EQ amp (awk-065) boards. I have not replaced the 2 cereamic capacitors or tested any of the resistors on the boards.

I'm not versed in electronics and I've been teaching myself through this whole process so please explain things in very simple terms

Cheers and thanks for the help


Replaced:
Original Part Replacement part values Mauser #

EQ Amp
awk-065 c3 100uF 10V cea x2 100uf 10v x2 647-UPW1A101MDD
awk-065 q1 2sa725-g x2 KSA992 x2 512-KSA992FBU
awk-065 q2 2sa725-g x2 KSA992 x2 512-KSA992FBU
awk-065 q3 2sc1313-g x2 KSC1845 x2 512-KSC1845FTA
awk-065 q4 2sa726-g x2 KSA992 x2 512-KSA992FBU

Tone Control
AWG-049 C1 .47uF 35V csza 0.47uf 50v 647-UKL1HR47KDDANA
AWG-049 C2 .47uF 35V csza 0.47uf 50v 647-UKL1HR47KDDANA
AWG-049 C5 220uF 25V cea 220uf 25v 647-UPW1E221MPD1TD
AWG-049 C6 220uF 25V cea 220uf 25v 647-UPW1E221MPD1TD
AWG-049 C9 47uF 6V cea 47uf 10v 647-UPW1A470MDD
AWG-049 C10 47uF 6V cea 47uf 10v 647-UPW1A470MDD
AWG-049 C13 4.7uF 25V ceanl 4.7uf 25v 647-UKL1E4R7KDDANA
AWG-049 C14 4.7uF 25V ceanl 4.7uf 25v 647-UKL1E4R7KDDANA

Tuner
AWE-075 C84 100u 6v cea 100uf 10v 647-UVR1A101MDD
AWE-075 C85 100u 6v cea 100uf 10v 647-UVR1A101MDD
AWE-075 C94 220uf 25v cea 220uf 25v 647-UPW1E221MPD1TD
AWE-075 C95 220uf 25v cea 220uf 25v 647-UPW1E221MPD1TD
AWE-075 C101 47uf 10v cea 47uf 10v 647-UPW1A470MDD
AWE-075 C105 100uf 35v cea v 647-UPW1H101MPD

Power Amp 1
GWH-101 Q1 2SA798-F KSA992 x2 backs 512-KSA992FBU (replaced Q1, not Q2)
GWH-101 Q2 2SA798-F KSA992 x2 backs 512-KSA992FBU (Parts ordered, have not replaced yet)


GWH-101 C1 1uF 25V csza 1uf 50v 647-USR1H010MDD
GWH-101 C2 1uF 25V csza 1uf 50v 647-USR1H010MDD
GWH-101 C7 220uF 6V cea 220uf 16v 647-UPW1C221MPD
GWH-101 C8 220uF 6V cea 220uf 16v 647-UPW1C221MPD
GWH-101 C9 47uF 35V cea 47u 35v 647-UPW1V470MED
GWH-101 C10 47uF 35V cea 47u 35v 647-UPW1V470MED
GWH-101 C13 220uF 6V cea 220uf 16v 647-UPW1C221MPD
GWH-101 C14 220uF 6V cea 220uf 16v 647-UPW1C221MPD

Power Amp 2
GWR-101 Q9 2SC945A KSC2383YTA 512-KSC2383YTA
GWR-101 Q11 2SC1647 KSC2383YTA 512-KSC2383YTA
GWR-101 Q14 2SC1647 KSC2383YTA 512-KSC2383YTA
GWR-101 Q15 2SC1384 KSC2690AYS 512-KSC2690AYS
GWR-101 C21 .22uF 10V cssa 0.22uf 250vdc 667-ECQ-E2224JF
GWR-101 C22 .22uF 10V cssa 0.22uf 250vdc 667-ECQ-E2224JF
GWR-101 C23 220uF 16V cea 220uf 16v 647-UPW1C221MPD
GWR-101 C24 100uF 35V cea 100uf 50v 647-UPW1H101MPD
GWR-101 C25 100uF 35V cea 100uf 50v 647-UPW1H101MPD
GWR-101 C26 330uF 6V cea 330uf 25v 647-UVZ1E331MPD1TD
GWR-101 C27 330uF 6V cea 330uf 25v 647-UVZ1E331MPD1TD
GWR-101 C28 4.7uF 35V cea 4.7uf 35v 647-UPW1V4R7MDD
GWR-101 C29 220uF 16V cea 220uf 16v 647-UPW1C221MPD
GWR-101 C30 100uF 35V cea 100uf 50v 647-UPW1H101MPD
GWR-101 C31 100uF 50V cea 100uf 50v 647-UPW1H101MPD
GWR-101 C33 3.3uF 50V cea 3.3uf 50v 647-UPW1H3R3MDD
GWR-101 C34 100uF 50V cea 100uf 50v 647-UPW1H101MPD
GWR-101 C35 100uF 50V cea 100uf 50v 647-UPW1H101MPD
GWR-101 C36 220uF 16V cea 220uf 16v 647-UPW1C221MPD
GWR-101 C37 220uF 50V cea 220uf 50v 647-UPW1H221MPD6
GWR-101 C38 220uF 50V cea 220uf 50v 647-UPW1H221MPD6

 

[malcmcm]

And I've also checked and double checked I put everything in the correct way on the EQ Amp board

 

[savatage1973]

Before digging too much deeper, since all of your noises are related to switch and knob operations, I'd start with another thorough DeOxit bath.

 

[malcmcm]

Before digging too much deeper, since all of your noises are related to switch and knob operations, I'd start with another thorough DeOxit bath.

Tried this right before posting drowned it with deOxit and let it dry for a good 30mins. Wouldn't this have a similar effect to the other inputs (AM, FM, Aux) if it were a dirty knob?

 

[savatage1973]

Tried this right before posting drowned it with deOxit and let it dry for a good 30mins. Wouldn't this have a similar effect to the other inputs (AM, FM, Aux) if it were a dirty knob?

Possibly, but not necessarily. You do know that you have the work the hell out of the knobs and switches while they'red still soaked with DeOxit? Just hosing it down and letting it sit won't do much--you have to physically work the controls while wet.

 

[malcmcm]

Ya I did, worked the knobs for about 5 min, there was no noticeable improvement

 

[malcmcm]

Ok I found out what I did .. whoops!

I made a noob mistake and assumed all the replacement transistors would follow the same layout as the old transistors. Although I did recheck the placement I made, I confused myself when comparing the drawing from the service manual (backside of PCB) with what I was looking at (front of PCB). I found this out when I removed the boards and looked closely at the markings on the pcb and the datasheet for the replaced transistors.

For someones` future reference, dont do what I did! compare the layout from the service manual or older datasheet for all old/new transistors.

Seems like in this case, the ones I screwed up were the:

awk-065 2sa725-g BCE replacement: 512-KSA992FBU ECB
awk-065 2sa726-g BCE replacement: 512-KSA992FBU ECB
awk-065 2sc1313-g BCE replacement: 512-KSC1845FTA ECB