Hi all, popped open the 1980 and took a close look at a few of the main NEC ouputs and was thinking to myself they could do with a fresh coat of grease, i can open them fine from the heatsink not a problem but just want to know what kind of thermal grease is the best, how much to apply ect any tips many thanks.

If you insist on digging in that deep, the old grease should be cleaned from the heatsink, the transistor, and (carefully) from the mica insulator. WD-40 works great for this.

As far as what to use, I have no idea of what you might have access to over the pond. This is what I use: http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=345-1007-ND&x=12&y=21

edit: EchoWars beat me, his stuff is NOT boutique computer grease..........

Don't go with boutique computer grease, check carefully that it is non-electrically conductive, silver = bad, ceramic = good... old school == better.

Thin application - should be almost no squeeze out - the idea is to fill thousandth of an inch gaps because the surfaces aren't flat.

I can't be more specific, that would involve USA sources.

http://www.mcmelectronics.com/search.aspx?C=&K=heat%20sink%20compound&T=

I never knew for sure about this but is the dried grease not as effective as it's proper pastiness? Intuition always told me to clean off the old stuff and apply fresh.

I never knew for sure about this but is the dried grease not as effective as it's proper pastiness? Intuition always told me to clean off the old stuff and apply fresh.

Absolutely correct.... when dried out after many many years, the gaps open back up... == less heat transfer, higher temperatures and eventual component failure.

Even inadequate torque (very loose) will cook transistors - I have seen MANY failures traceable to inadequate torquing, inadequate greasing and grease aging.

thanks guys, is there a dedicated site that shows all about applying thermal grease? i want to learn abit about it instead of just jumping in right away.

Should be able to get this over there..Dow-Corning 340
http://www.ellsworth.com/display/productdetail.html?productid=329&Tab=Vendors

thanks guys, is there a dedicated site that shows all about applying thermal grease? i want to learn abit about it instead of just jumping in right away.This ain't rocket science...put a thin coat on both sides of the mica insulator and put it all back together.

The thing that sorts the rookies from the pros here is the cleanliness of the reassembly job. Think ahead, have a few paper towels around to get rid of the excess from your fingers, and try not to smear the stuff all over creation.

ok so silican is the thing to go with then right, also can anyone recommend some type of heat resistent paint cos i want to re-do the heatsinks they are scratching away and could do with a touch up! this unit deserves it :)

This ain't rocket science...put a thin coat on both sides of the mica insulator and put it all back together.

The thing that sorts the rookies from the pros here is the cleanliness of the reassembly job. Think ahead, have a few paper towels around to get rid of the excess from your fingers, and try not to smear the stuff all over creation.

:lmao::lmao::lmao::lmao: :thmbsp:

Depending upon the situation I have a "dirty" acid brush loaded with grease, and a single edge razor blade I use as a trowel. The real accomplishment is not having to clean oneself up afterwards.... it CAN be done...

First I do the back of the transistor, holding it by the case or leads, depending...
then I lay on the insulator, and repeat on the back of the insulator.
Then install the stack.

Looking at pictures in the 1280 thread, with the oversize mica insulators, the mica insulator to heatsink side is completely coated, while the topside of the mica has a little bit of white exposed around the transistor body due to the transistor shifting slightly as things were settled in.

:lmao::lmao::lmao::lmao:

Ain't that the truth! :D

Scott

also can anyone recommend some type of heat resistent paint cos i want to re-do the heatsinks they are scratching away and could do with a touch up! this unit deserves it :)Heat resistant paint? How hot do you think those heatsinks get? ;)

Any-old satin-black paint will be fine. Do not paint the transistor side of the heatsinks...only the outer, finned side.