Archive of the former Yahoo!Groups mailing list: Korg DW8000, Mono/Poly, MS-20...

Hi John,

----- Original Message -----
From: 'John Rose' johnhenryrose@... [DW8000] <DW8000@yahoogroups.com>
To: DW8000@yahoogroups.com
Sent: Thu, 04 Apr 2019 12:45:34 -0400 (EDT)
Subject: RE: [DW8000] Korg EX-8000 display flashes once, then nothing! Please help!

If you still have the original IC’s have a look at them carefully as the do come in different variant with varies current capabilities and it could be possible that when you replaced IC3 that the version used was not a high enough current model.
As far as the voltage drop on these most are rated up to 30V or higher on the input so the volt drop should not be a problem, they can be run quite hot around 80 degrees but if you could use a higher current rated part this would bring the operating temp down a bit.

This is a link to a datasheet for a version of the 7805 with a 2.5A capability, having a look at this may also help with understanding what is going on and why you got the shutdown condition before.
http://www.farnell...com/datasheets/1904473.pdf?_ga=2.50632617.1652918337.1554395948-985662631.1433240701 <http://www.farnell.com/datasheets/1904473.pdf?_ga=2.50632617.1652918337.1554395948-985662631.1433240701&_gac=1.12305152.1554395948.EAIaIQobChMI2ODIiPC24QIVDZztCh0SIgJKEAAYASAAEgIbWfD_BwE> &_gac=1.12305152.1554395948.EAIaIQobChMI2ODIiPC24QIVDZztCh0SIgJKEAAYASAAEgIbWfD_BwE Many thanks John Rose (www.astrodevelopments.com)

From: DW8000@yahoogroups.com [mailto:DW8000@yahoogroups.com]
Sent: 03 April 2019 18:46 To: DW8000@yahoogroups.com
Subject: RE: [DW8000] Korg EX-8000 display flashes once, then nothing! Please help!
Thanks John! I really appreciate your reply.
You were dead right. It was IC3 that was preventing the synth from firing up.
I replaced it with a cheap 7805 from altronics and the unit is working fine.
Do you think it would be wise to replace all of the 7805's and also the 7905 as well - so that they're all new - or is it likely that IC3 only failed due to something further down (do you mean just within the power supply?) drawing too much current (I assume this equates to a failed component).

Is it normal (safe) for the 7805's to be dropping 7v and the 7905 to be dropping just over 8v? Even after replacing IC3 IC's 2-4 especially are super red hot, despite a rather large heatsink being attached.
Someone mentioned to me that the 7805's and 7905 might be being used for current limiting rather than voltage regulation.

Does this make sense? How do i know what the 7x05's are being used for?

Thanks again,
Waz