Case for a ZM system

[Zed]

Here is the case I modified for my ZM system. I really like a big fan as you can see.
The fan runs on AC line voltage, and blows into the case over the hard drives and out through the back over the PV-155 and the video card.

Power input to the case is through the IEC connector on the back of the case itself, and then splits off to the fan and the short power cord that plugs into the back of the power supply.

The hard drive(s) are positioned so that they are in the donut shaped stream of air from the back of the fan (not mounted behind the center of the fan)

I reduced the fan speed by putting about 7 ufd of capacitors in series with fan power, these caps are out of view on the back side of the case. More capacitance makes for higher fan speed. At just the right cap value the fan will run faster than it does on the rated line voltage, a bad thing I think, so watch out for that if you try this. These caps need to be OK for AC use, rated for the peak AC voltage, (not the RMS) so solid film or oil filled motor running caps are OK, polarized or electrolytic caps are not. I would not use a motor starting cap either, they are rated for just a few seconds of duty cycle.

I use an AC fan because I want to reduce the load on the power supply, and also AC fans are easily available in large powerful versions. The fan is blowing into the system (instead of sucking air out of the system) because I do not want to fight against the power supply fan.

I cut the plastic of the case front with a router guided by a thin wooden (Masonite or pressboard) template with the right size round hole in it.

The power button, reset, USB have been remounted by cutting holes in a blank cover plate under the DVD writers.

The wiring is messy because I have been trying different installs on different hard drives. The ruler is in inches.

[curtishall]

Nice. With the large air flow and the heat sinks on the BT878 chips I bet they are nice and cool.

[Zed]

Thanks. I will look around in there with an IR temp detector when I get it processing frames..
The IR detector is not very accurate of course (only $29 at Harbor Freight on sale) but I can check the calibration of it against a hot block instrumented with a thermocouple. That is easier than gluing on a bunch of thermocouples to the chips themselves.

Then I can make a decision if the fan should run faster. Does Bluecherry have any data on the thermal conductivity of the double sided tape used on the heat sinks?

And if there is ever a respin of the board, some holes next to the BT878s would be nice for mounting heat sinks with pins and grease... Then Bluecherry could make extra money selling different heat sink solutions for the board.

[curtishall]

Thanks. I will look around in there with an IR temp detector when I get it processing frames..
The IR detector is not very accurate of course (only $29 at Harbor Freight on sale) but I can check the calibration of it against a hot block instrumented with a thermocouple. That is easier than gluing on a bunch of thermocouples to the chips themselves.

Then I can make a decision if the fan should run faster. Does Bluecherry have any data on the thermal conductivity of the double sided tape used on the heat sinks?

And if there is ever a respin of the board, some holes next to the BT878s would be nice for mounting heat sinks with pins and grease... Then Bluecherry could make extra money selling different heat sink solutions for the board.

I'll check on the data sheets. We just reworked our newest batch to be 3.3V compliant...so I doubt we'll have any new reworks anytime in the (near) future.

Thanks

[curtishall]

The datasheet is here:
http://www.bluecherry.net/specs/3m8815.pdf

[Zed]

Thank you for the datasheet. That tape is good stuff.

Can I assume that Bluecherry uses the 15 mil thickness since you linked to the 8815 part number? I would measure the tape on my heat sinks but I already put them on.

There is a lot of good info in the datasheet about cleaning the surface before application, perhaps at some point you could make a link to it on the website next to the heat sinks (if it is not already there) so customers can do the best possible job mounting them.

[curtishall]

Thank you for the datasheet. That tape is good stuff.

Can I assume that Bluecherry uses the 15 mil thickness since you linked to the 8815 part number? I would measure the tape on my heat sinks but I already put them on.

There is a lot of good info in the datasheet about cleaning the surface before application, perhaps at some point you could make a link to it on the website next to the heat sinks (if it is not already there) so customers can do the best possible job mounting them.

Yup...the tape is 15 mil. I've updated the website to reflect the manual and the prep work. (Click on the ?) button next to add heat sinks.

[Zed]

Thanks for doing that, it will help a lot of people. I notice the description is a bit at odds with the instructions on the data sheet though:

"This pure-copper heat-sink produced by Enzotech is easy to install. Just slap on the 3M thermal tape and install one heat sink for each chip on your capture card."

Perhaps "Follow the instructions in the 3M datasheet under the 'Technical Specs' tab for best best results when installing heat sinks" would be better, on the other hand you do not want to scare away customers who are too lazy to read a datasheet and apply the heat sinks properly.. and then again, the customers that mess up the heat sinks are more likely to burn up the card and create costs/problems for Bluecherry with returns due to overheated boards that are the customers fault..so maybe these are undesirable/unprofitable customers and you *want* to scare them away..a dilemma, and a reason why I don't work in sales.