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Author Topic: Quantec Power Supply and Heatsink questions  (Read 1546 times)

River

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Quantec Power Supply and Heatsink questions
« on: February 06, 2006, 05:01:01 AM »

I've got a QRS here that apparently had some problem with the power supply, which is pretty common.  

I say apparently because it came to me after having been worked on by some other tech, who pulled the toasted regulator but never bothered to replace the heatsink.

So, I did manage to find the regulator - no small feat in the US - but because of the way that things fit together with the regulator heatsink bolting to the front panel for additional heat dissipation, I'm still hung up because of a lack of a heatsink.

Has anyone ever worked on one of these before that can add any insight?

I think that I've come up with a pretty good idea of what the dimensions must be, but I don't think that I'll find anything like it off the shelf.

Has anyone ever had a heatsink machined for them?

Tim
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Jolly Ted

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Re: Quantec Power Supply and Heatsink questions
« Reply #1 on: February 06, 2006, 05:29:47 AM »

Hello Tim,

Our shop has worked on these before. It does take some time to  get to the actual PSU ! And you HAVE to follow the correct proceedure.

Here a link to the 'blow by blow' steps to take from the Quantec site...

http://www.quantec.de/docs_e/fix_qrsps_doc.shtml

Good luck on this. Let us know how you progress.

Regards,

TWJ
GRS Systems

River

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Re: Quantec Power Supply and Heatsink questions
« Reply #2 on: February 06, 2006, 07:02:11 AM »

Thanks for the response!

I've done some checking around and it looks like the heatsink can probably be fashioned out of a piece of 1" channel extrusion cut down to length and drilled for the 4 pin TO-66 package.  Any memories on what that heatsink looks like?

I forgot to mention that the same tech that pulled the heatsink also pulled the molex connectors from both the PS and the MB - I'm guessing to test it with an external PS.  For some reason I'm having a hard time finding those connectors with a .2" spacing.

I really hate seeing such a great reverb sitting dead because of what probably amounts to about $4 worth of parts.

One question - do you remember how the transformer was mounted in the unit?  On this one the transformer is attached to the PCB with some kind of adhesive and there is a rubber gasket bolted to the side of the chassis between the chassis and the transformer.

It really looks like the transformer should be bolted to the chassis side somehow.  Is that how it came from the factory.

Thanks again!


Tim
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Jolly Ted

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Re: Quantec Power Supply and Heatsink questions
« Reply #3 on: February 06, 2006, 08:06:16 AM »

Hi Tim,

(Updated after my initial post)
Check this diagram of the PS board with the details of the transformer, Q1, etc.

http://www.quantec.de/graph/fix_qrs10.gif

If you look at the diagram (below), you will see item 34, which is the screw that attaches the PS board to the T1 transformer, which is then itself attached to the side of the chassis unit. This was the case in the last unit we worked on, IIRC. This is as it comes from the factory.

http://www.quantec.de/graph/fix_qrs3.gif

The molex connectors on these units were problematicand caused power supply problems. There were issues with the metal used in the contacts and they would go bad in short order. See the notes on the Quantec web link. There is a good diagram relating to this.

The regulator attaches to a small heatsink. And as I recall was in turn bolted to the front panel to further aid in disapating heat from Q1. You can somewhat see this in the diagram above,  item location #29 and in the diagram at the top of this post.

So I gather you are missing the heatsink, obviously...after re-reading your post. I don't recall the exact size or shape of the heatsink. It's been a long time since working on that particular unit. But should not be too difficult to fab either a piece of aluminum stock or channel, adapted to attach to both the regulator and the front panel.

Here is a link to the QRS PS Schematic (it's too big to post here):

http://www.quantec.de/docs_e/fix_qrsps_sch.html


If you can post a pic of the inside area of the PS, that may help jolt my brain cells to recollection.

Regards,

TWJ
GRS Systems

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