Saved by Heat Sink Compound

Another manufacturing defect I guess. Should have been Lionel warranty.

Rod

I have had the engine since 2013 and it had run perfectly until last weekend.

Lonnie posted:

I have had the engine since 2013 and it had run perfectly until last weekend.

Interesting. I wonder what changed?

Rod

I've had several engines that have the voltage regulator module.  For Legacy, Lionel exposed the triac so it could be bolted to the chassis to dissipate the heat.  However, they have it perched on a fiber post in these engines, not much heat going down that!  Needless to say, I change that to be on the chassis with HS compound and an insulating wafer.

NOT ALL HEAT SINK COMPOUND CREATED EQUAL.  I have been using TechSpray  silicone free HSC for years and about a year ago I ran across a shoot-out of 85 different different compounds on Tom's Computer Hardware site.   TechSpray was not on the list. I think that some of these high performance compounds may be of benefit when space does not allow a properly sized sink.  By the way, Tooth Paste is on the list. Though they did not test the brand I use.   Also take note some of these thermal compounds are electrically conductive.    My link is to page 8 though you can back track should you want to read the entire article.                  j

  https://www.tomshardware.com/r...mparison,5108-8.html

John, I have some minimal experience with heatsinks and thermal compound.   FWIW, the thermal compound is only one part of the picture, whatever it's attached to has to have the thermal mass to actually do something with the heat you conduct through the thermal compound.

One heatsink compound that I have had great performance with for cooling processors in computers and servers is called Arctic Silver. Not cheap though. A 30 ml hypodermic type dispenser costs around 25 bucks, but will last for many many installations. 

Rod

gunrunnerjohn posted:

John, I have some minimal experience with heatsinks and thermal compound.   FWIW, the thermal compound is only one part of the picture, whatever it's attached to has to have the thermal mass to actually do something with the heat you conduct through the thermal compound.

Who could argue with that.  As the temperature within the sink goes up relative to ambient it's efficiency also goes up and a poor transfer through the compound bottles up the heat in the joint.  And then there is surface area. A sink of relatively low mass can make up for lack of mass through surface/air interface efficiency but all this heat must first pass through a relatively small contact patch between the electrical device and the sink and a more efficient thermal compound certainly ain't gonna hurt. To that I have yet seen a sink on a Lionel motor driver that was optimal for it's task.  I mentioned lately that I want to drive four motors with a Train America Studios cruise board and plan to swap Teccor 4008 triacs with 4015 fifteen amp triacs.  The TAS sink comes out of the box considerably better that any of the Lionel sinks that I have seen but I plan to replace their sink with one cut from this finned copper I bought off eBay should be here early Jan.  Might look for some of that new fangled thermo compound also.      j

How will you attach that heatsink to the triacs on the TAS board?

Rod Stewart posted:

One heatsink compound that I have had great performance with for cooling processors in computers and servers is called Arctic Silver. Not cheap though. A 30 ml hypodermic type dispenser costs around 25 bucks, but will last for many many installations.

I used that a lot in past years when I was assembling lots of computers from parts, it is a very good thermal compound.

gunrunnerjohn posted:

How will you attach that heatsink to the triacs on the TAS board?

Been a long day finally got to sit down.   The factory sink on the TAS board is 32mm X 100mm.  The plan is to cut a strip down the length of the copper sink to get a 32 X 100mm strip then use the holes in the original sink as a template for drilling the holes for the triac screws in the bottom of the copper sink.  If a fin should get in the way I'll use the holes in the bottom as a registration guide to run an end mill down the fin to the bottom and clear out enough fin to get the screws in.  The 18mm X 100mm strip that is left over I plan to cut down small pieces and attach to some stock Lionel sinks.  Or,  if I think on it long enough I may talk myself into making the strips 25 X 100mm as I do have two 4 motor locos the centipede and a MTH 4 motor F3. 25mm strips would be just wide enough to overhang the triacs by 1mm on each side.  I have enough need for better sinks that I would have ordered three of the finned copper but they are $20 each and I won't spend $60 on the first transaction with someone in china.  BTW this same seller has several different size finned copper sinks here is a link should you be interested.     j

https://www.ebay.com/sch/m.htm...eatsink&_sacat=0

gunrunnerjohn posted:

 

Rod Stewart posted:

One heatsink compound that I have had great performance with for cooling processors in computers and servers is called Arctic Silver. Not cheap though. A 30 ml hypodermic type dispenser costs around 25 bucks, but will last for many many installations.

I used that a lot in past years when I was assembling lots of computers from parts, it is a very good thermal compound.

According to Toms Hardware Arctic Silver is a rather middling thermal compound by todays standards though I would think that as long as your keeping your jobs stock factory components it is more than fine.  The TECHSPRAY COMPOUND I have been using is not even middling by todays standards.  I was comparing two of the non metallic compounds for my hopped up TAS board and on a cost performance basis    "Innovation Cooling Diamond 24"  is one of the better products for the prices on eBay.  "Thermal Grizzly Kryonaut" is a very small bit better but a lot more expensive.  You have to be careful many of the sellers don't mention what size / weight  package they are selling for their price.  However IF you are brave soldering the device to the sink affords the best heat transfer. I'm just not that brave or good to pull that off.   j

I haven't tracked HS compound lately as I haven't been pushing the envelope.  However, the heatsink is still the long pole in the tent, so the better that is, the better your cooling solution will be.

I don't think I'll be soldering to my chips anytime soon.

Best oil, best grease, best battery, now best heat sink thermal compound...?  What is the best aluminum to use for a heat sink?    G

The size of the heatsink is important as well as the material: copper, then aluminum, then steel etc.  The surface area provided by the heatsink fins and the mechanical heatflow within the heatsink are also important.  The surface of the heatsink should be as large as possible.  You can increase the surface area by bead blasting the heatsink fin surfaces.  The heatsink contact surface can be polished to improve the surface contact area (use #0000 steel wool and clean afterward very well).  The color of the heatsink should be black for best emissivity.  Use as small a quantity of thermal compound as possible (smear it lightly with your finger).  You only need it to fill in the micro voids in the metal surfaces.  Metal to metal pressure contact is the best transfer medium.  Airflow with a fan can allow the use of a smaller heatsink or compensate for shortcomings in other areas.  In using a fan, the risk is a possible catastrophic component failure if the fan air flow stops.  The use of a fan is usually not possible inside train engines and the cost wouldnt be tolerated I'm sure.

I was being sarcastic...the rectifier does not generate the type of heat at the limit of the component.  Just teasing the debate about what is best....

GGG posted:

Best oil, best grease, best battery, now best heat sink thermal compound...?  What is the best aluminum to use for a heat sink?    G

The absolute best aluminum is the sheet stock I bought for making heatsinks.  It must be the best as it's the stuff as I use whenever I have to make one!

aussteve posted:

The size of the heatsink is important as well as the material: copper, then aluminum, then steel etc.  The surface area provided by the heatsink fins and the mechanical heatflow within the haysink are also important.  The surface of the heatsink should be as large as possible.  You can increase the surface area by bead blasting the heatsink fin surfaces. 

Steve,  I have a stiff wire wheel that when possible I run across the fins on heatsinks it leaves a lot of nice ridges and valleys.  I then dip it in Aluminum Black.  Never tried to run any test as to how much more effective this makes the sink but keep reading that it does so.  The first article I read on blackened aluminum's heat dissipation  was in a motorcycle magazine probably in the late 60s where Suzuki or Yamaha had found on their racing bikes that cooling fins could be 15-20% smaller if blackened.   J

gunrunnerjohn posted:

I haven't tracked HS compound lately as I haven't been pushing the envelope.  However, the heatsink is still the long pole in the tent, so the better that is, the better your cooling solution will be.

I don't think I'll be soldering to my chips anytime soon.   Not to mention, the flux really makes them soggy !  j

Or is it the long chimney and the compound is the flue damper ?         j

Noctua NT-H1 is what I use under MacBook Pro processors and heat sink assemblies.  It is great stuff and lasts a LOOOOONG time.  Expensive, yes.  Worth it, bigger yes.

Liquid metal is fantastic for heat transfer but it goes on very thin and is very conductive.

JohnActon posted:

aussteve posted:

The size of the heatsink is important as well as the material: copper, then aluminum, then steel etc.  The surface area provided by the heatsink fins and the mechanical heatflow within the haysink are also important.  The surface of the heatsink should be as large as possible.  You can increase the surface area by bead blasting the heatsink fin surfaces. 

Steve,  I have a stiff wire wheel that when possible I run across the fins on heatsinks it leaves a lot of nice ridges and valleys.  I then dip it in Aluminum Black.  Never tried to run any test as to how much more effective this makes the sink but keep reading that it does so.  The first article I read on blackened aluminum's heat dissipation  was in a motorcycle magazine probably in the late 60s where Suzuki or Yamaha had found on their racing bikes that cooling fins could be 15-20% smaller if blackened.   J

I had to take a course in heat and thermodynamics in the late 70s.  Afterwards i understood why radiators on cars, refrigerators, etc were painted black and why desert nomads wear white clothes.

I have always used Arctic Silver 5 on processors for computers and sometimes video cards in laptops. It has to have something to bind it together which the heat eventually cooks out. 

I have seen all the types /colors of paste and they all lose thickness and flexibility and, with that, contact with the sink and device.

Good save on the engine, Lonnie. It never hurts to post a problem and the solution. It provides more chances for someone to find it.

Thanks, Carl.  I like to think that any money saved on repairs is money that can go towards getting something new!