Pioneer SX 828 Switch Noises

[ttbccw]

Just tried with the filters. Same. There are 2 resistors on the switch & I don't know what they do. It just amazing to me that it could be disconnected from everything, unplugged, on, & only the tape out connected it still did it.

 

[ttbccw]

Well, I can say with some certainty that most of the signal noise is coming in from the Tape Out 1 connection connected to my computer. When the mini-jack is plugged into the computer the pop is much worse than if it is disconnected. And it eliminates the pops from the other switches. The pop is still in the input selector switch when the Tape Out is not connected, but much much lower volume. The FM thing is puzzling. It makes a loud pop and fades in when FM is selected, then if I switch back to AUX or MIC from FM the pop is louder for a couple seconds and then dissipates to the lower volume. I know, I didn't recap the FM board...partly because I can't realign it if that knocks it out of whack, but maybe I should. I think I will check the 2 resistors on the switch, and the ground connection on the switch. As for the computer connection...I don't think I can stop that. It's one of those connectors that "knows" when you plug something in. I'm sure that is the signal that is leaking in. The one that tests continuity so the PC knows you did something. Can anyone tell me by the pic, where these resistors connect to as far as the circuit? is one leg to ground on the switch terminal 3?? The other to the T1 & T2 on the Pre-Amp Board and another to the switch input on terminal 6. I guess...what is pin3? ground of the switch?

 

[fucanay]

Hi ttbccw,

Did you ever figure out the source of the popping on the input selector? I just did the same rebuild as you did and I am having this issue as well. I mean, exactly. The FM is loudest, etc.

 

[ttbccw]

Sorry, I didn't know you posed fucanay!
I found that somehow DC is leaking from the tape OUTPUT into the unit. I have the tape out RCA jacks connected to my PC sound card input to record my 78's. The card does that thing that I'm sure most cards do in that it detects a connection to the PC. I assume it uses a DC current to do so. If I have my PC off or unplug the mini jack from the PC the popping pretty much goes away. But it's really loud if I don't. I can also hear the volume pot "step" in volume too when it's connected. I am also assuming it is related. I would think that I could find a place to put a diode or something to stop it...but I don't know the "leak path" of the DC so I just unplug it from my PC. Look for sources of stray DC. I did the test and thought leaving the output connected would be ok....nope.

 

[mjantho]

Changing the 5 blue sanyo caps on the tuner board got rid of the pops for me