How to build the F5

[Bksabath]

The drain pin of the mosfet is conected to the metal tag and has very litle thermal impedance thath is to me the best place where to stick them adesive or tie wrap the key is low thermal impedence

 

[AndrewT]

The drain pin of the mosfet is connected to the metal tag and has very little thermal impedance that is to me the best place where to stick them, adhesive or tie wrap the key is low thermal impedance

Yes,
that's where the heat of the junction can be monitored fastest.

 

[6L6]

The drain pin of the mosfet is conected to the metal tag and has very litle thermal impedance thath is to me the best place where to stick them adesive or tie wrap the key is low thermal impedence

that's where the heat of the junction can be monitored fastest.

Aha!! That's why the thermistor is placed there on the factory-built F5! I have been scratching my head, wondering why the thermistor looks like it's too short...

Specifically, these are the photos that I am referencing -- (from 6moons.com)
http://www.6moons.com/audioreviews/firstwatt7/f5_2.html

Scroll down a little, you will see 2 pics with the output transistor and thermistor clearly visible.

 

[merlin2069er]

oh , I see the thermistor is glued right to the middle pin.

I also thought about using some heat shrink tubing to insulate the thermistors.

oh, the crazy glue didn't hold. I'll have to just float that board.

 

[Lerg]

If you need some form of glue to hold the standoff to the heatsink you might want to try metal epoxy.

 

[merlin2069er]

can you recommend an metal epoxy?

I was looking at j-b weld, but it's hard to find.

 

[JoMoCo]

can you recommend an metal epoxy?

I was looking at j-b weld, but it's hard to find.

Try a good auto parts store, if none local try online. That stuff has been very useful for a variety of apps and a lifesaver in others many times in the past; last time I looked they offered both a fast cure and slower cure version...

 

[Lerg]

LePage Epoxy Steel is what I have used before. It contains metal, it can be sanded/worked after setting and isn't supposed to expand or contract. It won't be as strong as having things screwed down, but for a single PCB standoff, it should be just fine.

Products - LePage for Canada
You can get it at most local hardware stores for less than $8, probably less than $7.

 

[labjr]

Arctic Silver has a couple products which are two part adhesives. They look interesting, although I haven't tried them.

Arctic Silver, Inc. - Arctic Alumina Thermal Adhesive

Arctic Silver, Inc. - Arctic Silver Thermal Adhesive

 

[Bksabath]

Me think that heath srink should do the trick
Metal poxi to glue a tiny tiny ini winy bead to a skiny therminal?

Catch my drift?
Not telling you what to do but be careful with metal poxi as it may be conductive.
Papa uses superglue or such I think.

 

[eyoung]

I was thinking epoxy to tranny body but middle pin makes more sense. I have switching p/s that have a thermistor on the heatsink glued to a small metal eyelet then screwed to the heatsink next to the trannies it looks at .
I would think either would be OK but faster response to the middle pin.

OIC,Elwood

 

[Lerg]

The suggestion for metal epoxy was for gluing a standoff to the heatsink, not for anything related to the thermistor.

 

[labjr]

How about mucilage. Remember that stuff? Glue everywhere. It was like rubbing a runny nose on the paper trying to get it to stick.

 

[Zen Mod]

RTV silicone

but - as you all can see from Papa's pics - you don't need to glue NTC ; just lean it next to mosfet case or leg

 

[merlin2069er]

By opening up a case with paypal, and applying a little bit of pressure, HIFI 2000 is sending out a new heat sink.

 

[AndrewT]

The Credit Card issuer has an enormous effect on the retailer's sales.
As soon as you have the Credit Card on your side, the retailer gives in.
Reporting through PayPal is the first warning that the retailer gets that you mean business and expected to be treated as a valued customer.

 

[Marra]

By opening up a case with paypal, and applying a little bit of pressure, HIFI 2000 is sending out a new heat sink.

Good result

 

[CanAm Man]

By opening up a case with paypal, and applying a little bit of pressure, HIFI 2000 is sending out a new heat sink.

Just out of curiosity, are they asking you to return the damaged one? (If not, it would be a great addition to your parts bin!)

 

[Bksabath]

Quote > By opening up a case with paypal, and applying a little bit of pressure, HIFI 2000 is sending out a new heat sink.

Realy made up for you

Got a few more pictures of my build.

A drill press would realy help but does not fit in the loft and to much noise.

The main frame is done so time to get started with the Circuit boards

Soft start and Aux suply From print to etched board in less than 30 minutes.

No picture for the back plate I got al the holes drilled and started to paint (mess it up I mean )
I realy realy hate painting

 

[6L6]

I realy realy hate painting

Everything is aluminum, isn't it? Have you considered anodizing it all?

That said, thanks so very much for posting more photos! Keep 'em coming!