Well my transformer is cactus. Works on one side but blows a fuse on the other even with just the test leads attached. Back to the ordering and waiting for parts scenario.
Are your rectifier bridges attached when the fuse blows? If so, disconnect them and see if the fuse still blows, If not, measure the output voltage, which should be about 18V.
And if you are measuring the voltage directly on the secondary with bridge detached, remember to switch the meter to AC measurement. And don't worry if it's higher than 18V AC since you don't have a load attached.
No without the rectifier bridges I get 19.6 from one pair and with the other pair connected to the multi meter both slow blow fuses go in the switch. I've gone through 8 fuses now just to be sure.
I've placed the order for another Antek. Ouch.
It's my own stupidity. I admit last night when I ran out of fuses I connected using some fine fuse wire. Bad move indeed. As I have now understood the schematic which I had not seen before I can clearly see the way the LED's are supposed to go. So I've hooked up new ones and 10K resistors for them and a pair of 4.7K big 5W resistors for bleeders.
Such a shame, I may possibly have had it running tonight were it not for last night's foolishness. It goes back to my youth. The only other amp I built was 40 years ago and I could never work out the power supply with that either so I was kind of expecting trouble.
Just hope I didn't damage anything in the amp boards or that'll be another long wait.
This isn't a hobby, it's an obsession.
I've placed the order for another Antek. Ouch.
It's my own stupidity. I admit last night when I ran out of fuses I connected using some fine fuse wire. Bad move indeed. As I have now understood the schematic which I had not seen before I can clearly see the way the LED's are supposed to go. So I've hooked up new ones and 10K resistors for them and a pair of 4.7K big 5W resistors for bleeders.
Such a shame, I may possibly have had it running tonight were it not for last night's foolishness. It goes back to my youth. The only other amp I built was 40 years ago and I could never work out the power supply with that either so I was kind of expecting trouble.
Just hope I didn't damage anything in the amp boards or that'll be another long wait.
This isn't a hobby, it's an obsession.
In operation, the juice will drain quite quickly when hooked up to an amplifier. Not so much when it isn't. I took a power supply, after testing it and set it aside. When I came back to it for installation, I blew the tip off a nice pair of Ecelite needle nose....yup, no bleeders installed!
Russellc
Hmmm ... 😕
What I don't understand: How can an upstream fuse (fuse before the primary) blow when one connects a multimeter set to AC voltage measurement mode across the secondary ? 🙁
Even old analog multimeters had internal resistance in the 10's of kiloohms, and the DMMs are more like Megohms ... ?
There shouldn't be any real current flowing !
Best regards,
Claas
Another check would be to disconnect the transformer from the circuit and measure the resistance of both secondaries. If one secondary is bad or shorted, its resistance would be much lower than the that of the good secondary.
There's no measurable resistance on any of the coils.
I took the primary black and red apart and measured each of those coils too.
I don't think my meter is terribly accurate so there may be a small resistance but many things that have no resistance show .2 or so , so anything down there I treat as none. In any case it's very small. It must have some, being such a big fat coil but it's a mystery. Maybe I should send it back to Antek for repair or evaluation[except the freight is more than the cost of the unit]. I certainly wouldn't ask for a free ride though.
No I don't understand why it blows a fuse on that side when connected to the meter but it does.
Who knows maybe the transformer was faulty from the factory . I'll never know because there have been too many various things done before this test now.
I'll be doing all these tests with the new one out of the box before power then with power unconnected , then with nice new bridge recs, and then hopefully onwards and upwards.
Thanks for your concern guys, and sorry I got a bit grumpy when it first happened.
My breakthrough was seeing the schematic after all my questions about the LED's. It is crystal clear with that. Thanks for all your help. I'm hopeful it will go next time.
Cheers.
That does not make logical sense. Please explain (and photograph) exactly what you are doing. 🙂
Test continuity from red to black (twice) and from green to blue (twice). If the coils are intact the transformer is fine... As it's essentially no more complicated than 4 pieces if wire wrapped around a steel donut.
Continuity from each winding's lead wire to it's trail wire, and no shorts across any winding to any other winding should be all you need to determine transformer health.
Yes, resistance checks can be difficult due to very low resistances.
Yes, resistance checks can be difficult due to very low resistances.
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I understand how it is made so I'm also bemused by the result. I first measured continuity between each pair of red and black, then with the centre red and black joined I measured between the outer red and black. There is a result of 3.5ohms.
Then I checked continuity for each of the secondary coils without power.
Then I applied power with the result described above. One pair yields 19.5 AC volts. The other pair blows the fuses. I'm not going to blow any more. I have checked and rechecked this as I couldn't believe my eyes but as we know the definition of an abject fool is someone who does the same thing again and again and expects a different result.
I have also checked across between the primary and secondary in every combination and resistance wise at least there is no spill over.
Riddle me that.
???
😕😕😕
Huh. That looks like your'e doing everything right, unless you've actually got the outside primary leads tied together and your connecting to the insides... but that doesn't necessarily explain why the fuse blows when you connect the suspect secondary...
Maybe with the 1-ohm bleeders you shorted a section of winding to another. Dunno.
😕😕😕
Huh. That looks like your'e doing everything right, unless you've actually got the outside primary leads tied together and your connecting to the insides... but that doesn't necessarily explain why the fuse blows when you connect the suspect secondary...
Maybe with the 1-ohm bleeders you shorted a section of winding to another. Dunno.
Put a 1K resistor in series with your meter and resistance check the secondaries... maybe with a bit more R it might register a notable difference. (if there is one)
Tried that. Fuses blew again.
I'm just wondering if I could use the good side to power up with by linking the inputs on the PCB?
I'm just wondering if I could use the good side to power up with by linking the inputs on the PCB?
Did you over-tighten the transformer bolt? Lift the transformer, i.e unbolt it and then try.
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Stop blowing fuses by removing the fuse and wire a 60 watt light bulb across the fuse holder. This will allow you to troubleshoot to your heart's content and not blow a pile of fuses. The bulb should not glow unless there is a fault. The bulb will glow as the capacitors charge and then dim once the caps reach full charge. At that point you should read full voltage at the output of the power board. Unplug the line cord and the bleeder resistors should discharge the capacitors. You will then need to remove the bulb and replace the fuse once you clear the fault and then connect the amplifier board. Hope this helps
