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Viewing topic "S90 Power On Errors"

   
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Posted on: February 15, 2017 @ 04:58 PM
5pinDIN
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Total Posts:  9118
Joined  09-16-2010
status: Guru

I hope you get your S90 to behave. Let us know how it goes.

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Posted on: February 19, 2017 @ 03:36 AM
tertiumsquid
Total Posts:  8
Joined  02-04-2017
status: Newcomer
KSUS - 15 February 2017 05:42 AM

Hi 5Pin,
I’d love to see a reply from tertiumsquid also how he exactly found out what caused the problem, but I can imagine since his S90 is operational he won’t check the forum lately.

Haha yeah, I’m not much of a forum guy - I’m a member of probably a hundred forums out there, with probably an equal amount of total posts between them!  But yeah, my S90’s been behaving perfectly since I was last here, so I haven’t felt the need to be back.  Of course, I am subscribed to the thread (which doesn’t seem to email me all the time sadly).

I’ll actually probably be posting back here again, as a friend of mine also has a wonky S90 with the same problem - we got them from an audio engineering school who were selling off the working ones and tossing the bad ones (they had I think 18 total).

I found the problem by looking at the ripple voltage on an oscilloscope.  A really crappy one did the job - mine was a kit costing $60 (link), though it honestly is terrible even for occasional novice use.  I plan to get a MUCH better one when I have money to spare.

The points I checked and had problems at were at the caps 5pin and I mentioned - C9, C124, and C125.  As he mentioned, this might not fix your problem, as it could be something further upstream causing issues, all the way back to the +5v at the main power supply.

KSUS - 15 February 2017 05:42 AM

Is there a way to detect the ripple with that $10 tool you referred to?

The tool 5pin was referring to is one that will measure the ESR of the capacitor, but only once it’s removed from the circuit (presumably).  With the surface mount caps, you certainly don’t want to pull each off one by one to test them.

KSUS - 15 February 2017 07:51 AM

Thanks again 5Pin.
I will replace the the caps at IC46, IC47 and IC2. (after measuring them.)

I have a feeling it will fix it. I will replace them with radial lead capacitors if it got the space. If not, youtube is providing enough help to fix it this weekend.

Measuring the caps in and out of circuit didn’t do anything in my case - the ESR testing I tried didn’t show anything unusual at those caps, and even when I pulled them out they still measured 47-50uf.  Bad ripple voltage was the only indicator that something wasn’t working.

I replaced mine with regular radial caps after removing the bad ones.  I found the best way to remove the SMT caps was to wiggle them gently until the leads eventually broke, then I cleaned up the solder pads and “surface mounted” the radial caps. 

KSUS - 15 February 2017 03:34 AM

looks like you totally know what you’re talking about

Hahahahaha yeah I try my best!  I do have a certificate in electronics production and repair, though I certainly find a great many gaps in my knowledge.

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Posted on: February 21, 2017 @ 06:11 AM
KSUS
Total Posts:  6
Joined  02-15-2017
status: Newcomer

Hi Tertium,

Thanks for your reply :)

I’ll actually probably be posting back here again, as a friend of mine also has a wonky S90 with the same problem

I’m curious what the problem is at this unit, I’d like to know when you got it fixed and what caused the problem in this case.

The points I checked and had problems at were at the caps 5pin and I mentioned - C9, C124, and C125.  As he mentioned, this might not fix your problem, as it could be something further upstream causing issues, all the way back to the +5v at the main power supply.

Well, I guess I will just try to replace this ones first.
Did you order the caps online? What brand/type did you use?

Reg,

Kees

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Posted on: February 22, 2017 @ 02:59 AM
KSUS
Total Posts:  6
Joined  02-15-2017
status: Newcomer

I think we can delete the user with the ads here..

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Posted on: February 23, 2017 @ 03:34 AM
tertiumsquid
Total Posts:  8
Joined  02-04-2017
status: Newcomer
KSUS - 21 February 2017 06:11 AM

I’m curious what the problem is at this unit, I’d like to know when you got it fixed and what caused the problem in this case.

I’ll definitely keep this thread up to date when I get my hands on it.  That may take a while though, as my friend is coming up on the end of his school term and is quite busy.  He’ll get a break in about 3 weeks, so we’ll probably look at it then.

KSUS - 21 February 2017 06:11 AM

Well, I guess I will just try to replace this ones first.
Did you order the caps online? What brand/type did you use?

I just used cheapo caps I had kicking around here.  I think they were G-Luxon.  Admittedly they’re pretty crappy caps, but I did test them for ESR with my scope, and they are working right now.  I’ll get better caps in there when I do another Digikey order.

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Posted on: February 23, 2017 @ 07:06 AM
5pinDIN
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Total Posts:  9118
Joined  09-16-2010
status: Guru
tertiumsquid - 23 February 2017 03:34 AM

I just used cheapo caps I had kicking around here.  I think they were G-Luxon.  Admittedly they’re pretty crappy caps, but I did test them for ESR with my scope, and they are working right now.  I’ll get better caps in there when I do another Digikey order.

Even if the G-Luxon caps are OK now, I’d suggest not waiting too long to replace them. Many of that brand of caps were notorious for failure, although the problem was more prevalent several years ago.

http://www.google.com/search?q=g-luxon+bad+caps

As we previously discussed, Panasonic/Matsushita tend to be reliable. There are others, but Panasonic ones usually are readily available.

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Posted on: February 24, 2017 @ 01:24 AM
KSUS
Total Posts:  6
Joined  02-15-2017
status: Newcomer

Superb, thanks guys. Your help is great. I will solder some new pots in my ghost mixer this weekend and maybe I will open up the S90 to if I got some spare time.

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