Loved these mixer amps, used one for many years, 250 that is
Re: Roland PA-250 [guts]
Posted: 22 Oct 2016, 19:36
by mictester
karul wrote:Roland PA-250, powered mixer and the art of internal wiring from the early 80's
Those big electrolytics look to be a bit bulging! You might want to change those soon.
Re: Roland PA-250 [guts]
Posted: 22 Oct 2016, 21:23
by karul
mictester wrote:Those big electrolytics look to be a bit bulging! You might want to change those soon.
Power supply electrolytics are fine, just the plastic caps (covers) on top are deformed. Esr and capacitance are still in the range. No bulge on the caps themselves. However, considering the age of the amplifier, they will be changed soon.
Re: Roland PA-250 [guts]
Posted: 22 Oct 2016, 21:41
by karul
peterc wrote:Loved these mixer amps, used one for many years, 250 that is.
It sounds quite nice.
Re: Roland PA-250 [guts]
Posted: 22 Oct 2016, 22:11
by karul
Van Der Funk with Roland TR 808, TR 909 drum machine with RE-501 and PA-250
Re: Roland PA-250 [guts]
Posted: 22 Apr 2020, 20:05
by backlash
First of all, apologies for resurrecting this super-old thread. I just acquired a Roland PA-80 which needs some work, and shares a service manual with the PA-150 and PA-250. Unfortunately the links to the manual posted previously have expired. I wonder if anyone reading this has a copy they wouldn't mind making available.
Thank you.
Re: Roland PA-250 [guts]
Posted: 23 Apr 2020, 14:46
by backlash
Awesome, thank you!
Re: Roland PA-250 [guts]
Posted: 18 Jun 2022, 07:27
by wernersaurus
Seems I have to resurrect this thread again - because the Service Notes are not accessible on all 3 locations now.
Could someone please load them back up for me ? THANKS !!!
I got this PA-250 - worked a charm - put it away for 3 months - tried using and only getting very very faint signal from it. Headphone out is perfect. Using the 'finger humm test' on the signal connector into the power amp(s) gives full loud humm on the speaker(s) - so amp(s) are fine I think.
So - what's between the headphone take-off and the power amp in ??
ANSWER:
4 FETs stopping signal from mixer to both main out (and the main power amps) and monitor out if the input power is no good. Few components on the PSU board, ie a Diode, a cap 1uF/100V and two resistors and the cap went to 24nF hence the sense circuit never opened the FET's
Thanks so much, great thead Karul. Would just like to draw everybody's attention to the fact that you can edit your posts and the attachment limit has been expanded.
I also deleted some dead links and remarks about not being able to download etc from this thread to keep it readable. Keeping the mega links for now, but already re-attached the service notes to the first post.
operation manual - pa250.pdf