[amb]

Yup, measuring the transformer windings' DC resistance doesn't tell the full story. Who is the vendor of your transformer and are the wiring color codes provided? Why not post them and how you had wired them up?

 

[Iniamyen]

Quote:

Originally Posted by amb /img/forum/go_quote.gif Yup, measuring the transformer windings' DC resistance doesn't tell the full story. Who is the vendor of your transformer and are the wiring color codes provided? Why not post them and how you had wired them up?

Definitely. They are both from SumR. From memory right now - beginning of winding marked with a * on spec sheet:

Primaries: *Black/white & *brown/orange (both 110Vac). These are wired in parallel with white & orange connected to one side of the SSR, and black & orange connected to AC mains neutral.

Secondaries: *Blue/gray & *red/yellow (both 30Vac). These are wired in series with blue and yellow unconnected to anything at the moment, and gray & red both tied to star ground.

FWIW, I have it wired exactly the same as the 30VA unit with the same color coding, and that one seems to be working without issue.

 

[Iniamyen]

Quote:

Originally Posted by amphead /img/forum/go_quote.gif If your circuit is unloaded <scratches head>, as Amb stated you must have something wired wrong or maybe there is a winding shorted in the trafo(not likely on new ones however). There shouldn't be any reason not to just get the PS working first. Build quality looks impeccable. Good Luck and I'm hoping you find the solution soon.

Yes, that's what I thought, too

From my measurements both primaries have a small but non-zero DC resistance across them (less than 1ohm.) And they have infinite resistance between each other. Same story with the secondaries. So right now it looks like the trafo should behave ok, but if all other possibilities are eliminated....

 

[Iniamyen]

Some more information, the circuit I am testing on is a bedroom circuit and it is 15A, not 20A. And it is on a AFCI breaker, which after researching, could be the issue. I still do not understand, however, why it would blow my 10A slow-blo fuse. The current would have to be very high for a very long time to accomplish this, and it was almost instantaneous.

 

[Beefy]

I don't know if this is your problem, because you haven't specified what sort of fuses you are using. But I have found that ceramic slow blow fuses are MUCH more prone to blow than equivalently rated bog-standard glass fuses......

 

[Iniamyen]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif I don't know if this is your problem, because you haven't specified what sort of fuses you are using. But I have found that ceramic slow blow fuses are MUCH more prone to blow than equivalently rated bog-standard glass fuses......

If I can verify that my trafo is working properly (and I am fairly confident it is, I did have it running the very first power-up) I will buy glass fuses instead of the ceramic ones when I make my next order. Thanks for the info. Until then I'm leaving the fuse out to try to eliminate possible sources of error.

edit: Sorry Beefy, to actually answer your question, the fuse that I blew is a Littelfuse ceramic-type. Here is the Mouser part #: 576-0326010.HXP

 

[Beefy]

You could probably get appropriate fuses locally at Radioshack or a hardware store....?

 

[Iniamyen]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif You could probably get appropriate fuses locally at Radioshack or a hardware store....?

Yes I'm sure I can, I will check on my way home today.

However I will still trip my breaker with my current setup, assuming the fuse conducts for a little while

 

[Beefy]

Yes, I see your point there

 

[digger945]

Having one primary wired out of phase would cause fuse-blowing and breaker-tripping with nothing on the secondaries.

I've got a diagram that came with a 320va Sumr around here somewhere. Gimme a minute to dig it up.

 

[Beefy]

Quote:

Originally Posted by Iniamyen /img/forum/go_quote.gif Primaries: *Black/white & *brown/orange (both 110Vac). These are wired in parallel with white & orange connected to one side of the SSR, and black & orange connected to AC mains neutral.

Wait, what? I missed this first time round......

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif I've got a diagram that came with a 320va Sumr around here somewhere. Gimme a minute to dig it up.

On my four SumR units, for 115V I have to connect black and brown together, and orange and white together.

 

[digger945]

Quote:

Originally Posted by Iniamyen /img/forum/go_quote.gif Definitely. They are both from SumR. From memory right now - beginning of winding marked with a * on spec sheet: Primaries: *Black/white & *brown/orange (both 110Vac). These are wired in parallel with white & orange connected to one side of the SSR, and black & orange connected to AC mains neutral. Secondaries: *Blue/gray & *red/yellow (both 30Vac). These are wired in series with blue and yellow unconnected to anything at the moment, and gray & red both tied to star ground. FWIW, I have it wired exactly the same as the 30VA unit with the same color coding, and that one seems to be working without issue.

^^^ white and orange, then black and orange. Maybe you just posted that wrong and meant black and brown?

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Wait, what? I missed this first time round...... On my four SumR units, for 115V I have to connect black and brown together, and orange and white together.

The bolded parts do not match to me(between the two of you, I'm sure you have it right Beefy as you've done this many times already). It's been a long day so.....
One way to find out if it's a primary phase problem( without a diagram ) is to just switch the wires on one set of primaries.
It would seem to me that the two primary wires with the "*" would need to be connected together in order to have them in phase parallel.

I found the diagram in the car the other day but I don't know where it is now???

 

[MASantos]

AMB, I tried to find the information, but didn't succeed...

With standard biasing, how many whats are biased into class A at idle?

Is there any problem with making this a "full" class A amplifier by increasing the biasing, apart from the need of much larger heat sinking?

The new hifi2000 5U dissipante 500mm long would probably suffice, rated 0.11W/C

 

[Iniamyen]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif ^^^ white and orange, then black and orange. Maybe you just posted that wrong and meant black and brown? The bolded parts do not match to me(between the two of you, I'm sure you have it right Beefy as you've done this many times already). It's been a long day so..... One way to find out if it's a primary phase problem( without a diagram ) is to just switch the wires on one set of primaries. It would seem to me that the two primary wires with the "*" would need to be connected together in order to have them in phase parallel. I found the diagram in the car the other day but I don't know where it is now???

I probably didn't explain very well, I have the white and orange wires physically connected together, I didn't mean that they constituted one of the primaries. Similarly I have the black and brown wires physically connected together, as they constitute the other side of both primaries, which are in parallel.

Small victory, though - I got home and lugged the beast downstairs onto a circuit breaker without the damn AFCI functionality (same amperage rating), and... IT WORKS! I am keeping an eye on it until I get another fuse, but I think this was the primary source of the tripping.

As for the fuse, is it possible the tripping action itself could have blown it (twice in a row too??) Is this a really bad choice of fuse for this application?

 

[digger945]

Quote:

Originally Posted by Iniamyen /img/forum/go_quote.gif Definitely. They are both from SumR. From memory right now - beginning of winding marked with a * on spec sheet: Primaries: *Black/white & *brown/orange (both 110Vac). These are wired in parallel with white & orange connected to one side of the SSR, and black & orange connected to AC mains neutral. Secondaries: *Blue/gray & *red/yellow (both 30Vac). These are wired in series with blue and yellow unconnected to anything at the moment, and gray & red both tied to star ground. FWIW, I have it wired exactly the same as the 30VA unit with the same color coding, and that one seems to be working without issue.

On the PS schematic the center taps are connected to ground. Does your transformer have center tapped secondaries?

If not, then don't connect any part of your dual secondaries to ground, anywhere(See below)

EDIT: My bad if you're talking about 4 wires(in series) for only one secondary of one transformer, and using the two wires as center tap. Maybe I need to shower and hit the sack now.