Tascam m-208 mixer with problem

[tmhobadcap]

I got this mixer for free and is trying to see if I can fix it.

The problem is when it is switched on, the lights just turn on for half a second and then nothing.

Instead of asking directly how to fix it, I would like to first try using my limited knowledge to fix it myself. Of course, I need your helps in some ways.

I suspect it is the power supply problem. Visually, there is nothing wrong on the power supply board. I am trying to find out which component is causing the problem. From the incoming AC power, I found that there is a component (as shown on photo) connecting between the black line and the line to the input of the transformer. According to the service manual, it is "Z001, CR, 0.033uF+120 125V". What exactly is this component? Can it be tested with a multimeter?

[petehall347]

Re: Tascam m-208 mixer with problem

safety capacitor .

[tmhobadcap]

Re: Tascam m-208 mixer with problem

safety capacitor .

Thank you! Should I just test it like a regular capacitor?

[petehall347]

Re: Tascam m-208 mixer with problem

it is not your problem .it goes across the power switch .
more likely a loose or corroded fuse or bad power switch . start by checking AC voltages at the fuses .
power for the lights and more comes from power supply pin 17 yellow wire .

[stj]

Re: Tascam m-208 mixer with problem

it's not exactly a capacitor,
it's a snubber - a capacitor and resistor in series.
but as said, it's not the problem.
maybe the switch has a bad contact, always good to start at the begining.

[tmhobadcap]

Re: Tascam m-208 mixer with problem

Thanks for petehall347 and stj's suggestions.

My checking results are as follows:
Power Switch - Checked and cleaned the contact.
Got input and output voltages from the transforma.
Fuses - checked and no problem
Checked the Power Supply PCB - no visible damaged components, re-weld some of the suspected poor welded joints, but problem still exist.
Output voltages from power supply board - Yellow wire (pin 17) is 6V, Blue wire (pin 16) is -15V, Red wire (pin 14) is 15V - all matching the voltages printed on the Meter PCB

Any more suggestions for me?

[petehall347]

Re: Tascam m-208 mixer with problem

have you checked to see if its actually working yet ?

[stj]

Re: Tascam m-208 mixer with problem

when you checked those voltages, where did you put the black wire - 0v, or ground?
you need to have it on 0v

[tmhobadcap]

Re: Tascam m-208 mixer with problem

have you checked to see if its actually working yet ?

I just checked that it is not working.

[tmhobadcap]

Re: Tascam m-208 mixer with problem

when you checked those voltages, where did you put the black wire - 0v, or ground?
you need to have it on 0v

Yes, when I checked those voltages, I put the black wire to the 0V.

[petehall347]

Re: Tascam m-208 mixer with problem

i would start pulling plugs and squirting contact cleaner in them .and looking for dry solder joints

[budwich]

Re: Tascam m-208 mixer with problem

Thanks for petehall347 and stj's suggestions.

My checking results are as follows:
Power Switch - Checked and cleaned the contact.
Got input and output voltages from the transforma.
Fuses - checked and no problem
Checked the Power Supply PCB - no visible damaged components, re-weld some of the suspected poor welded joints, but problem still exist.
Output voltages from power supply board - Yellow wire (pin 17) is 6V, Blue wire (pin 16) is -15V, Red wire (pin 14) is 15V - all matching the voltages printed on the Meter PCB

Any more suggestions for me?

Although you have checked the THREE voltages listed, you have not indicated what the voltages are back in the first post for FOUR fused positions / outputs in the first post. What is the "fourth"?

[petehall347]

Re: Tascam m-208 mixer with problem

pins 18 and 20 are the missing ones i reckon .. think that's headphone amp supply .
being as the lights are trying to give a clue maybe best see why they aren't working first .

[tmhobadcap]

Re: Tascam m-208 mixer with problem

Although you have checked the THREE voltages listed, you have not indicated what the voltages are back in the first post for FOUR fused positions / outputs in the first post. What is the "fourth"?

Pin 8 (F001) = 19.5V
Pin 9 (F002) = 19.5V
Pin 11 (F003) = 9.5V
Pin 12 (F004) = 9.5V

Sorry, I do not understand what do you mean by the "fourth".

[tmhobadcap]

Re: Tascam m-208 mixer with problem

pins 18 and 20 are the missing ones i reckon .. think that's headphone amp supply .
being as the lights are trying to give a clue maybe best see why they aren't working first .

Pin 18 = 11.4V
Pin 20 = -11.4V

[tmhobadcap]

Re: Tascam m-208 mixer with problem

i would start pulling plugs and squirting contact cleaner in them .and looking for dry solder joints

For me, this will take a lot of time, so I will leave this as the last job.