Neotek Elite PSU Help? Neotek PS-3

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outoftune

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Joined
Jul 14, 2007
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741
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canada
Hi everyone,

My first post on here.

I'm working on repairing a Neotek Elite power supply, the PS-3.

The client had the power supply go out on them during a session, heavily distorted audio. They have a spare supply and the console is currently running well with that one.

As for the defective supply, the +18V DC was giving 25V DC at it's output. The rest of the voltages test correctly.

I initially replaced the TIP36 transistor and the 5534 @ U1 and the supply was back to giving the +18V DC at the output.

When the unit was hooked back up to the console, it worked for about 3 minutes and the it popped again.

I'm going to have a second look at it this week and was planning to try replacing the TIP31 as well.

I had been working off a blurry copy of the schematic, but thanks to the Neotek User group I found a much clearer version with voltage probe notes...should be a huge help.

Does anyone have experience with this exact issue? Is it possible there is something I'm not thinking of that could be causing this issue? Something in the current or voltage limiting circuits shared between the two channels?

I'm wondering if it might be a good idea to fully rebuild the +/-18V DC supply, rectifier, caps and all the transistors / opamps...I've seen some others mention doing a full rebuild. Would it be necessary to replace all the diodes as well?

Thanks!

Tyler Crawford

neotek-ps3-schematic.jpg
 
Joined
Nov 16, 2008
Messages
15
radardoug said:
You could replace both transistors with more rugged parts. Those two parts are working very hard.

Why? I have consoles in LA with power supplies that have been working fine for the last 30+ years. Those transistors are perfectly fine.
 

Whoops

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Joined
May 9, 2008
Messages
5,720
Location
Portugal
One thing I would do for sure is to replace ALL the Electrolytic capacitors.

Thats what I can advise
 
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