I'm dusting off this old project... I purchased the original Mnats rev D board back in 2007. My board is stuffed and I am partially through hooking up the wires in a Hairball case, which has brought me to a few questions.
1. On the original board there is no ground terminal next to pad 7, as shown on the current hook-up instructions provided by Mnats and Hairball Audio. I have found some old connection guides that suggest not bothering to connect the shield to ground from the main wire attached to pad 7. Another guide suggests connecting the shield from the wire at pad 7 to the shield/ground from the wire attached to pad 22. However, I would think connecting it to the non-connected shield from the input transformer may be easier (as it's closer), if that would work. Or is there any real trade-off to leaving the pad 7 shield not connected to ground?
2. I am using the Cinemag CM-96731 output transformer. As stated on Mnats guide about halfway down the following link in the section marked "Output transformer options:"
http://mnats.net/1176_revision_d.html
the output of the transformer can be terminated into a 619ohm resistor. Where exactly do I place the resistor in terms of the circuit (between ? and ?). Also, I read that some folks put this resistor on a switch as mentioned in the second to last post in the following link:
http://groupdiy.com/index.php?topic=18209.msg212586;topicseen#msg212586
How exactly can I wire the resistor on a switch. Meaning, what kind of toggle switch do I need to buy (number of poles?, etc.), and any specifics on the wiring of the switch/resistor would be greatly appreciated.
3. Finally, when I started this project there was no Hairball Audio to make this process, especially the sourcing, much easier. I bought expensive push-button assemblies directly from UA. Mike at Hairball has a post here:
http://groupdiy.com/index.php?topic=26998.msg326843#msg326843
where he very clearly explains the connections from the UA ratio board. He attempts to explain the meter board hookup in the next few posts, but I don't follow. There are 7 terminals on the UA meter board rather than the 6 found on every diagram I can find (new or old) from Hairball's push-button boards or those old green ones from Mnats (I actually have a set of those, too). The 7th is for +8 metering? If this is the case, what does the +8 button do on the modern Hairball/Mnats units? If someone is able to refer me to a diagram or simply tell me which connections to make from the UA meter board to the Mnats board, that would be great. Or would I be better off biting the bullet and just buying new meter boards and push-button assemblies from Hairball to make it easier to follow the current wiring diagrams? Any links, diagrams, insight, etc. would be greatly appreciated.
Thank you!
