Path: ...!s1-3.netnews.com!feeder.usenetexpress.com!tr2.iad1.usenetexpress.com!news-out.netnews.com!postmaster.netnews.com!eu1.netnews.com!not-for-mail
X-Trace: DXC=<Zf9;NmUS3ARkRm4=DZaWFU5[F2hIijDO7J470dMQQ7Ka`<]fY=Q9fA7AE3\kdmXc@h]J;WohKJ`Af@HSLgR[]oH7dKkgDfTEDLiJPUY0^i>7F
X-Complaints-To: support@frugalusenet.com
Date: Sun, 26 Jan 2025 02:45:10 -0500
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: Intermittent fault on Korg SDD 3300
Newsgroups: sci.electronics.repair
References: <67951f89$1$3620713$882e4bbb@reader.netnews.com> <vn3gki$31lh0$1@news.eternal-september.org>
Content-Language: en-US
From: bitrex <user@example.net>
In-Reply-To: <vn3gki$31lh0$1@news.eternal-september.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Antivirus: AVG (VPS 250125-4, 1/25/2025), Outbound message
X-Antivirus-Status: Clean
Lines: 44
Message-ID: <6795e805$0$13$882e4bbb@reader.netnews.com>
NNTP-Posting-Host: 127.0.0.1
X-Trace: 1737877509 reader.netnews.com 13 127.0.0.1:48455
Bytes: 3140

On 1/25/2025 3:13 PM, ehsjr wrote:
> On 1/25/2025 12:29 PM, bitrex wrote:
>> I have a Korg SDD 3300 triple digital delay rack unit that was a bit 
>> of a basket case when I got it. Someone had tried to "fix" it at some 
>> point and it had a number of issues including the wrong voltage 
>> regulator slapped in the negative rail, miswired output jacks, dead EL 
>> backlight, bad SRAM 2032...
>>
>> Fixed that up and I was able to get a copy of the service manual and 
>> use the three-finger-salute button combo to get its mind back after 
>> SRAM battery replacement as is common on units of this vintage, 
>> followed the adjustment procedure in the service manual and everything 
>> seems to work as it should now except one really irritating 
>> intermittent fault remains: the LCD will occasionally garble up at 
>> power-on or in use as so:
>>
>> <https://imgur.com/a/BjxoQDP>
>>
>> It's annoyingly unpredictable and seems somewhat related to how it's 
>> mounted? I can power it up 25 times on the bench and it works fine 
>> making me think I solved the problem, then slide it back in the rack 
>> and it starts acting up again. 
> 
> When the failure is position sensitive, look for a bad switch or cable 
> that causes a line to float between a logic 0 and 1.
> 
> War story: I had a bad ice maker in the freezer that failed only when it 
> was installed. Worked 100% on the bench and not possible to troubleshoot 
> when installed. Turned out to be a bad micro switch that failed (high 
> resistance instead of ~0 ohms when closed) only when I held the thing at 
> an angle.
> 
> Your problem looks like a tough one if it's a switch or cable. :-(
> 
> Ed

Thanks for your suggestions, I feel like there was some substance use 
going on when this unit was designed and servicing it makes me feel the 
same way so at least there is symmetry.. 
<https://youtu.be/BtMP2EiRH0Y?si=0klgHRWFFO8ybBiA&t=12>

-- 
This email has been checked for viruses by AVG antivirus software.
www.avg.com