Not sure where this response is going to end up, but ... I have seen
a lot of Yamaha 80's era stuff dying recently. In all cases so far
it's the switching power supply they use. In the luck cases I just
replaced all the electrolytics and cleaned the brown glue off the
board. In worse cases I had to replace other passives. In the worst
case there were other parts I could not find and had to make a
wholesale replacement of the power supply. Since yours is working, I
would suggest replacing all the electrolytics in the power supply.
It's inexpensive parts-wise (like, under $20USD). These supplies are
switch mode and they run very hot typically. I am NOT a pro-recap
person in the least, but in some cases it is required. So far I
think I've done a REV7, two SPX90's and a DX7S. I can't remember if
there are others or not.
GB
On 11/10/2020 12:46 PM, Gunter Weeks
via groups.io wrote:
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Good
Evening (Well it is here)
I have some issues with my 802, Some times it would boot and some
times I got a initial boot screen and then it would dim.? After a
power cycle it would work. However, two weeks ago it wouldn't pass
the boot screen.
The circuit diagram gives +5 and +15 however my power board gave
4.6 and 14.3. After tweaking the pot Im now back up to 5/15V
however, this took quite a turn.
So This brings on a question why did the voltage drop is it bad
caps? and how long can I use this before it start failing again
and I need a tweak to Max...
So I recon i have to recap the power supply and replace the large
1W power resistors. Any other pointers?
