I was in danger of hijacking the Restim thread, so I've opened a new one here.
@diglet, @Kelvinator and @47dahc: I checked all the possible connections with the continuity check feature on my multimeter. The only notable reading came from the input connections, ie, the black and red channels going into the transformers. This is either expected behavior, or I have really screwed something up.
Any thoughts?
Thanks.
lorada wrote: ↑Mon Mar 04, 2024 12:00 am
I am not very experienced with electronics. I was lucky to be able to build this thing in the first place. I really don't know where to look.
I don't see anything obvious. Could the hexnuts securing the purple and green outputs somehow cause a short? I had a mishap while drilling the holes in the faceplates, so those two sockets are close enough that the hexnuts are in contact. I used sockets that don't have any gap in the plastic housing to avoid making contact with the aluminum case.
The only other thing I can think of is that I crammed the components in to a case that's too small (you can see my initial screwholes for an arrangement of the resistors that didn't fit). Could the housing of the resistors making contact cause a short? Am I just an idiot for using a metal case in the first place?
47dahc wrote: ↑Mon Mar 04, 2024 1:38 am
I think this might be better suited in the hardware thread. However, to answer your questions:
I used sockets that don't have any gap in the plastic housing to avoid making contact with the aluminum case.
If your sockets are shorted out against the case, then yes, this will short out that channel.
Could the hexnuts securing the purple and green outputs somehow cause a short? I had a mishap while drilling the holes in the faceplates, so those two sockets are close enough that the hexnuts are in contact.
Yes. The hex nuts are metal, so if they are touching, that will cause a short.
Could the housing of the resistors making contact cause a short?
No. The housings are nothing more than heat sinks. The heatsinks have no effect on the resistor value unless somehow the leads are in contact with them.
I think the best thing you could do is get a multimeter that has continuity check on it. Read all your connections out to the case, to the heat sinks, and between each other. A quick YT search should provide countless results on how to use a multimeter.
Have you measured what is the resistance across 2 terminals that amplifier channel gets connected to? It should be around 4-8Ohms depending on the winding used on transformer.
Also try measuring resistance between in and outputs. There should be no connection there, if you do measure any resistance there then your transformers are not the isolating kind and should not be used.
I had a pair of transformers that where wound as auto transformers (meaning there is a shared part of the transformer winding) those are non isolating and definitely NOT what you want. In a tri-phase setup these could also damage your amplifier.
It doesn't really make a difference for their intended usage, and those are cheaper to construct. So if you did not use a known-good transformer that might be the case.
As a side-note: Although it should be fine the way you constructed things, I would not have opted for a metal case. Just to insure that extra bit of separation. It is also not required for heat dissipation, if those resistors get hot you are pushing way more current than anyone will be able to / want to handle.
mklndrs wrote: ↑Sat Mar 09, 2024 3:21 pm
Also try measuring resistance between in and outputs. There should be no connection there, if you do measure any resistance there then your transformers are not the isolating kind and should not be used.
I had a pair of transformers that where wound as auto transformers (meaning there is a shared part of the transformer winding) those are non isolating and definitely NOT what you want. In a tri-phase setup these could also damage your amplifier.
It doesn't really make a difference for their intended usage, and those are cheaper to construct. So if you did not use a known-good transformer that might be the case.
As a side-note: Although it should be fine the way you constructed things, I would not have opted for a metal case. Just to insure that extra bit of separation. It is also not required for heat dissipation, if those resistors get hot you are pushing way more current than anyone will be able to / want to handle.
I have no connection between in and outputs. I get between 4 and 6 ohms measuring between terminals on the input side. I am still not sure what I could be doing wrong here.
