Amp Camp Amp - ACA

No thermistor for inrush is necessary, the current draw for the ACA is relatively small at ~20w per channel. Inrush is more a functin of your cap bank than the size of the transformer. If you find yourself blowing fuses, then either a slow-blow fuse or thermistor will help. A thermistor was REQUIRED for my Aleph-X monoblocks that draw 400w and have half a farad of capacitance each.
 
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Looking for some help. Built my amp camp with premium parts with an external power supply.

Two torroidal transformers that are 22V 200VA so I see 28V rails with CapMX power supplies. Everything tested fine on the work bench with DBT but after trying to hook it all up today I’m blowing fuses.

I have a 3A slow blow on the back and one slo blow 2.5A on each transformer. The only inrush limit I have is a thermistor across each power button.

Do I need more inrush limiters or am I using too small of fuses?

Did the 3A fuse blow? Did you turn both switches on at the same time? If you turned on both switches at the same time, the inrush current may cause the 3A fuse to blow. It depends on the amount of capacitance you have and also the VA rating of your transformers. Large amounts of capacitance draw large amounts of current and high VA transformers allow large currents. When you tested with the DBT, current was limited by the DBT.

Thermistor for inrush limit should be in series (in line) with the switch, not across (parallel). Looking at your picture, I see something rectangular at the switches. A thermistor across the switch would defeat the switch and allow current flow. Is that possibly a capacitor?

If you have a large amount of capacitance and with 400VA total of transformer, the 3A fuse is on the low side. I would suggest a 3.5A or 4A slow blow. And please clarify the thermistor situation.
 
Yes. The 3A blew on the back of the external near the Inlet. but when I increase that, the 2.5A at each transformer blows.

I only flip one switch at at time.

I just checked on Mouser and the part I have installed is a safety capacitor. I wonder if that is my problem. Here is the link and a picture is below of how I have it installed.

R413F13300000M KEMET | Mouser

So, I need to find a way to incorporate a thermistor in a series with the mains... I have some CL-60 and wondering if I can incorporate those.
 

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I have each of the the transformer's red wires attached the fuse which are wired together then attached to the "L" on the inlet

The transformer's black wires are wired together then attached directly to "N" on the inlet.

So the fuses are only in line with each of the transformers primary RED wires...
 

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I have each of the the transformer's red wires attached the fuse which are wired together then attached to the "L" on the inlet

The transformer's black wires are wired together then attached directly to "N" on the inlet.

So the fuses are only in line with each of the transformers primary RED wires...

Where is the switch located? It should be inlet, then fuse, then switch, then CL60, then transformer primary.
 
It goes:

Inlet, fuse on back, then fuse for each primary, then switches for each primary, then each transformer primary is wired off the fuse.

The transformer black wires are all tied together hooked directly to neutral.

I can connect a CL60 right after the switches in between the switch and transformer primaries. So one CL60 for each switch between the switch output and transformer primary.
 
Ok. I made the change to one transformer but wanted to make sure this looked correct.

Removed safety cap and put it across the mains.

Added a CL-60 after the switch into the transformer (red) primary.

All I have left would be to remove the safety cap from the other button and stash it away because I won’t need. Then just add a CL-60 between the switch and transformer.
 

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Ok. I tried the changes but it still blows the 2.5A before each transformer.

When I was testing on the bench I did NOT have the added 2.5A Fuses in front of each transformer which probably explains why each amp worked fine then.

Any harm in increasing the rear single fuse to 4A and increasing each fuse in front of each transformer to 2.75A or even 3A?
 
Looking for some help. Built my amp camp with premium parts with an external power supply.

Two torroidal transformers that are 22V 200VA so I see 28V rails with CapMX power supplies. Everything tested fine on the work bench with DBT but after trying to hook it all up today I’m blowing fuses.

I have a 3A slow blow on the back and one slo blow 2.5A on each transformer. The only inrush limit I have is a thermistor across each power button.

Do I need more inrush limiters or am I using too small of fuses?

So, is this a dual mono setup? I hope you can get it working, and see how it sounds.