So basically I have a bunch of nakamichi receivers with nelson passes stasis topology.
First ta-4a had and issue when I was purchasing it. It had no power at all .even red indicator light was not lit. It occasionally did turn on but almost immediately started to gradually dimm.
I still bought the receiver at a huge discount"for parts" 80$+gas and and 20min of my time to chat around about everything the old seller had on his mind(psyhotherapy session for free)
When I got home I started tinkering around. Power button has a very good connection. On and off are working well. Tested with connectivity function of multimeter. Power button was disconnected from circuitry.
Had new spare power capacitors laying around. Soldered them on.. no positive results.
Sort of assumed that stand by pcb board is in the way between electric outlet and stasis.. took out this board from ta-4a with blown output transistors and put it into the just purchased ta-4a. I did try swapping black relay between boards . It didn't help. When swapping entire boards receiver turned on and worked fine
Everything works flawlessly for 5 months now.
So I also have ta-3a that started to have this issues. Occasionally turned off completely. Not protection mode . All lights turn off.
And another ta-4a that used to work fine has the same issue mentioned above
Attached are images of the board.. the key to issues is here
Not a lot of components. I don't have capacitor testers.
Is there another common component that goes bad. Is this a rectifier diode there? Black cylindrical semiconductor
First ta-4a had and issue when I was purchasing it. It had no power at all .even red indicator light was not lit. It occasionally did turn on but almost immediately started to gradually dimm.
I still bought the receiver at a huge discount"for parts" 80$+gas and and 20min of my time to chat around about everything the old seller had on his mind(psyhotherapy session for free)
When I got home I started tinkering around. Power button has a very good connection. On and off are working well. Tested with connectivity function of multimeter. Power button was disconnected from circuitry.
Had new spare power capacitors laying around. Soldered them on.. no positive results.
Sort of assumed that stand by pcb board is in the way between electric outlet and stasis.. took out this board from ta-4a with blown output transistors and put it into the just purchased ta-4a. I did try swapping black relay between boards . It didn't help. When swapping entire boards receiver turned on and worked fine
Everything works flawlessly for 5 months now.
So I also have ta-3a that started to have this issues. Occasionally turned off completely. Not protection mode . All lights turn off.
And another ta-4a that used to work fine has the same issue mentioned above
Attached are images of the board.. the key to issues is here
Not a lot of components. I don't have capacitor testers.
Is there another common component that goes bad. Is this a rectifier diode there? Black cylindrical semiconductor
Attachments
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not much to think
re-cap
test continuity of xformer windings
you can test diode bridge (that black thingy ) with diode test of your DMM , without desoldering
you can also test relay winding
if it clicks, and it doesn't power up receiver, relay contacts are shot
re-cap
test continuity of xformer windings
you can test diode bridge (that black thingy ) with diode test of your DMM , without desoldering
you can also test relay winding
if it clicks, and it doesn't power up receiver, relay contacts are shot