| jarthel |
The primaries of the transformer was connected when it shorted. I have a Hammond 300 series (with plate: 225-0-225V and heater secondaries: 6.3V). When I turn it on, the bridged rectifier connected to the heater secondaries output around 30+V. I think this is completely wrong. Well after awhile, the 100ma 250VAC slo-blo fuse would just give up.
Did I have kill the transformer? How do I test if it still works.
Thanks
jayel |
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| moamps |
Hi,
check your primary connection at site http://www.hammondmfg.com/300series.htm
Primary fuse for 50VA/220V transformer can be rated at 0.5A slow.
You can check windings resistance (primary ca 50ohm, HV secondary ca 100ohm, tube heating secondary ca few ohm).
Regards |
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| jarthel |
| quote: | Originally posted by moamps
Hi,
check your primary connection at site http://www.hammondmfg.com/300series.htm
Primary fuse for 50VA/220V transformer can be rated at 0.5A slow.
You can check windings resistance (primary ca 50ohm, HV secondary ca 100ohm, tube heating secondary ca few ohm).
Regards |
Primary connection is alright to me. I followed that hammonds page when I connected it.
when you say test for resistance:
1. my primary is 240VAC. so for me to test the primary resistance, I connect the transformer to its appropriate mains rating and then measure resistance at the 2 primary wires?
2. what about the secondary? the plate and heater secondaries have 3 wires with the middle one usually center-tap. must I measure the resistance at the outside wires (not the center-tap)?
Thank you
jayel |
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| jarthel |
I just tested for resistance according to what I believe is right (above post).
primary has 42ohms
plate secondary = can't determine. I also checked for continuity and doesn't get a beep.
heater secondary = resistance neglible. When I checked for continuity, I get a beep.
Hope this helps.
Thanks
Jayel |
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| moamps |
| quote: | Originally posted by jarthel
1. my primary is 240VAC. so for me to test the primary resistance, I connect the transformer to its appropriate mains rating and then measure resistance at the 2 primary wires?
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Between blue and white |
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| moamps |
| quote: | Originally posted by jarthel
[2. what about the secondary? the plate and heater secondaries have 3 wires with the middle one usually center-tap. must I measure the resistance at the outside wires (not the center-tap)?
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HV - between red and red/yel and red/yel and another red
heating - between green and green |
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| jarthel |
The reading of 41ohms for the primary seems to be okay. The heater secondary is giving me a value between 0 to 1ohm. When tested for continuity, the volt-ohm meter beeps.
I'll try the plate secondary tomorrow. |
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| contaxchen |
hello,| quote: | | The primaries of the transformer was connected when it shorted. I have a Hammond 300 series (with plate: 225-0-225V and heater secondaries: 6.3V). When I turn it on, the bridged rectifier connected to the heater secondaries output around 30+V. I think this is completely wrong. Well after awhile, the 100ma 250VAC slo-blo fuse would just give up. |
I am in the same situation as you were!
I have a hammond 270cx with 275-0-275 secondary. When i used it in my latest project , it simply went shorted! I didn't put any fuse in the power line, so it smoke a little bit before I unplugged the power.
I think I have already killed it, although it tested ok. My point is that when you power it up and it doesn't give the correct voltage. It's dead!
I am still looking for a reason when it dropped dead. I have use this transformer for many projects already. The wiring is so simple and I checked my wiring many times already. My concluion is either the rectifying diodes doesn't work or the transformer has some internal isolation problem.
I opened the transformer chassis. The construction was poor. The second scenario could be possible...
As for the first scenario, ill-functioniong diodes turing transformer 's secondary leads connected in some sense, it is possible. I am looking for any similar experience here. Anybody wants to say something.
BTW, I am happy to give away this 270cx away considering that somebody can use its steel core to wire a new transfomer or choke.
:cool: |
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