Technics SA-C07 display issue

[skippy1969]

Its a rectifier diode. Just use a 1N4001, or 2, or 3 and you'll be all set.

Hi Prime!
I got the display working,but now there is another unrelated problem with it.
The volume is screwed up. I mean there is a loud pulsing buzzing sound through the speakers or headphones it doesn't matter.
It is so bad it even blows the circuit breakers on the back of the speakers....
I don't know what happened,everything was fine except the display.
I thought maybe the new diode was wrong,so I tried it without it and it does the same thing.
Any ideas?

 

[baddboybill]

Its a rectifier diode. Just use a 1N4001, or 2, or 3 and you'll be all set.

Hi Prime!
I got the display working,but now there is another unrelated problem with it.
The volume is screwed up. I mean there is a loud pulsing buzzing sound through the speakers or headphones it doesn't matter.
It is so bad it even blows the circuit breakers on the back of the speakers....
I don't know what happened,everything was fine except the display.
I thought maybe the new diode was wrong,so I tried it without it and it does the same thing.
Any ideas?

Maybe a blown cap

 

[Prime]

well that always sucks....

The sound was fine before you got into it so something must have happened while you were in there.
To make matters worse, that particular power supply section supplies at least a half a dozen different voltages to the system.

Maybe you got a connector on wrong
or
by accident, bridged two spots with solder
or
shorted out a diode.

These are just three of many possibilities. For the last one, you could
check all remaining diodes on that board.
Using a meter with a diode checker function, each good diode (while in circuit) should read
about 500~600 mV one way and something much higher or off the scale the other way.
In most cases, a shorted diode will read zero in both directions.

It could be a capacitor issue as Bill suggested but having one fail because you were
in there seems unlikely.

 

[Superduper]

Just for the record skippy, the diode I sent you (if that's what you installed) was a 1N4007. Basically, the most robust in terms of voltage capacity of the 1N4001, 1N4002..... 1N4007 lineup.

The specs are the same for all in terms of current and other characteristics with the primary difference being voltage rating. 1,000 volts for the 1N4007 vs. 50 volts for the 1N4001.

 

[skippy1969]

Just for the record skippy, the diode I sent you (if that's what you installed) was a 1N4007. Basically, the most robust in terms of voltage capacity of the 1N4001, 1N4002..... 1N4007 lineup.

The specs are the same for all in terms of current and other characteristics with the primary difference being voltage rating. 1,000 volts for the 1N4007 vs. 50 volts for the 1N4001.

I forgot to thank you for the resistor Norm!

 

[skippy1969]

well that always sucks....

The sound was fine before you got into it so something must have happened while you were in there.
To make matters worse, that particular power supply section supplies at least a half a dozen different voltages to the system.

Maybe you got a connector on wrong
or
by accident, bridged two spots with solder
or
shorted out a diode.

These are just three of many possibilities. For the last one, you could
check all remaining diodes on that board.
Using a meter with a diode checker function, each good diode (while in circuit) should read
about 500~600 mV one way and something much higher or off the scale the other way.
In most cases, a shorted diode will read zero in both directions.

It could be a capacitor issue as Bill suggested but having one fail because you were
in there seems unlikely.

Thanks for your advice Prime,I checked the other diodes on that board and a few others as well like of the amp board and they tested good.
I checked and rechecked my connections,I'm pretty sure I have everything hooked up correctly.
I'm confused because everything seemed to be working fine before I replaced the diode,just the display was out.
once I soldered in the diode the display lit up so I reassembled it and plugged it in and the speakers were farting and buzzing.
You can hear the radio if you turn the volume very low,as soon as you turn up the volume the farting noise increases ind blows the circuit breakers on the speakers. It sounds the same in the headphones as well.....

 

[tshorba]

try tracing your ground's, this can sometimes be the issue.

 

[baddboybill]

well that always sucks....

The sound was fine before you got into it so something must have happened while you were in there.
To make matters worse, that particular power supply section supplies at least a half a dozen different voltages to the system.

Maybe you got a connector on wrong
or
by accident, bridged two spots with solder
or
shorted out a diode.

These are just three of many possibilities. For the last one, you could
check all remaining diodes on that board.
Using a meter with a diode checker function, each good diode (while in circuit) should read
about 500~600 mV one way and something much higher or off the scale the other way.
In most cases, a shorted diode will read zero in both directions.

It could be a capacitor issue as Bill suggested but having one fail because you were
in there seems unlikely.

Thanks for your advice Prime,I checked the other diodes on that board and a few others as well like of the amp board and they tested good.
I checked and rechecked my connections,I'm pretty sure I have everything hooked up correctly.
I'm confused because everything seemed to be working fine before I replaced the diode,just the display was out.
once I soldered in the diode the display lit up so I reassembled it and plugged it in and the speakers were farting and buzzing.
You can hear the radio if you turn the volume very low,as soon as you turn up the volume the farting noise increases ind blows the circuit breakers on the speakers. It sounds the same in the headphones as well.....

Scott come to think of it that does sound like a ground issue. Maybe when you were putting together you missed a ground wire

 

[floyd]

just put the old diode back in and see what happens .