All-
I am working on a Technics Equalizer model SH 8046. The power supply looks fried. There are 2 Zener diodes and some capacitors that are sitting on a heavily discolored patch on the board. See
below:
The shadows on the blue capacitors are actually soot.
Here is the back of the case.
Supposedly this equalizer was sitting on the shelf with the power button off. When it was turned on it was dead. He said he had it on a surge suppressor. So not sure what the cause was. I know that even with the power switch off on the unit, the transformer has power on it. Perhaps one of the power supply components simply failed open and caused the damage. I am pretty sure multiple components are affected. I have an ESR meter and will test the caps in-situ. I have been identifying the components and making a list of what needs to be replaced, an searching the regular sources.
The diodes (Panasonic) are obsolete. I find that I might be able to replace with with NOS, but I don't want to pay what could be collector prices. And if it is NOS, how good will they be? If I go to the usual sources, I will have to find a substitute. I'm assuming these are Zener diodes. If they are then I think I have found the datasheet them
The part number for the diodes is MAZ2150. Now the service manual calls out MA2150B, but I am pretty sure these are the same. Now for some questions:
John
I am working on a Technics Equalizer model SH 8046. The power supply looks fried. There are 2 Zener diodes and some capacitors that are sitting on a heavily discolored patch on the board. See
below:
The shadows on the blue capacitors are actually soot.
Here is the back of the case.
Supposedly this equalizer was sitting on the shelf with the power button off. When it was turned on it was dead. He said he had it on a surge suppressor. So not sure what the cause was. I know that even with the power switch off on the unit, the transformer has power on it. Perhaps one of the power supply components simply failed open and caused the damage. I am pretty sure multiple components are affected. I have an ESR meter and will test the caps in-situ. I have been identifying the components and making a list of what needs to be replaced, an searching the regular sources.
The diodes (Panasonic) are obsolete. I find that I might be able to replace with with NOS, but I don't want to pay what could be collector prices. And if it is NOS, how good will they be? If I go to the usual sources, I will have to find a substitute. I'm assuming these are Zener diodes. If they are then I think I have found the datasheet them
The part number for the diodes is MAZ2150. Now the service manual calls out MA2150B, but I am pretty sure these are the same. Now for some questions:
- Can I test the diodes in-situ or do they have to some out to test them?
- What are the general principles for diode substitution?
- I think I have found a substitute. https://ww1.microchip.com/downloads...Documents/DataSheets/1N4728AG_1N4764AG_e3.pdf
- I think its a toss-up between 1N4744A and the1N4743A. Can anyone advise me here?
John