I have finally gotten back to finishing these amps. I plan to use two Avel Lindberg's (Y236752; 330VA with 35V secondaries) on the AAK boards. I should get +/-49 volts from these. These are not centered tapped so I was wondering how can I use these (if I can at all) with the AAK/Ryssen boards? Or do I need to find transformers with a center tap?
Thanks,
SteveA
Thanks,
SteveA
Hi,
easy to convert a dual secondary to centre tapped.
Use a bulb tester to prevent damage if you wire the primaries or secondaries out of phase.
Measure the secondaries to find which ends are on the same winding. Label them.
Connect your primaries as you think the instructions tell you.
Leave the secondaries open circuit and insulated (in a terminal strip is ideal).
Power up through the bulb.
Is the bulb lit or dim or off?
If off you are OK to proceed.
Measure the voltages at the 4 secondary terminals.
Switch off. Unplug from mains.
You are now ready to series connect the secondaries.
Link two secondary from different windings terminals together. That leaves two secondary ends on different windings without any connection, (open ends).
Power up through the bulb.
Measure the voltage across the two open ends. It should be double the single winding voltage.
If you test near zero volts then the secondaries are out of phase.
Move one end of link from one secondary end to the other end of the same secondary winding.
Measure the test voltage is double the single voltage, you are ready to connect to the PCB.
switch off. Unplug.
Take the two ends that are linked together and connect them both to the CT pad.
Take the other two open ends and connect one to each AC pad.
Power up through the bulb. Is the bulb on or dim or off?
If it's off, then measure the DC voltage at the rectifier.
easy to convert a dual secondary to centre tapped.
Use a bulb tester to prevent damage if you wire the primaries or secondaries out of phase.
Measure the secondaries to find which ends are on the same winding. Label them.
Connect your primaries as you think the instructions tell you.
Leave the secondaries open circuit and insulated (in a terminal strip is ideal).
Power up through the bulb.
Is the bulb lit or dim or off?
If off you are OK to proceed.
Measure the voltages at the 4 secondary terminals.
Switch off. Unplug from mains.
You are now ready to series connect the secondaries.
Link two secondary from different windings terminals together. That leaves two secondary ends on different windings without any connection, (open ends).
Power up through the bulb.
Measure the voltage across the two open ends. It should be double the single winding voltage.
If you test near zero volts then the secondaries are out of phase.
Move one end of link from one secondary end to the other end of the same secondary winding.
Measure the test voltage is double the single voltage, you are ready to connect to the PCB.
switch off. Unplug.
Take the two ends that are linked together and connect them both to the CT pad.
Take the other two open ends and connect one to each AC pad.
Power up through the bulb. Is the bulb on or dim or off?
If it's off, then measure the DC voltage at the rectifier.
Use a light bulb tester as Andrew recommends any time you connect something new to the mains.
You can skip a few steps above by going to the Avel website and checking the connections for your transformer. Transformers and Power Converters From Avel Lindberg, Inc. Connect primaries parallel and secondaries in series. (top drawing for primaries, middle for secondaries) Test with a bulb tester.
I've used a bunch of Y23 transformers and not found any mislabeled leads. Nothing says that Avel is perfect, and if they goofed and mis-coded leads you would get the bulb to light. Andrew's procedure will identify the problem and let you wire it correctly.
You can skip a few steps above by going to the Avel website and checking the connections for your transformer. Transformers and Power Converters From Avel Lindberg, Inc. Connect primaries parallel and secondaries in series. (top drawing for primaries, middle for secondaries) Test with a bulb tester.
I've used a bunch of Y23 transformers and not found any mislabeled leads. Nothing says that Avel is perfect, and if they goofed and mis-coded leads you would get the bulb to light. Andrew's procedure will identify the problem and let you wire it correctly.
Bob and Andrew,
Thanks for the responses. I have used Avel Lindbergs in other amp power supplies but they have always been connected as per top diagram (http://www.avellindberg.com/pdf/avel_y23_range.pdf). It seemed intuitive that I should tie the orange and red secondaries to make the CT but I wasn't sure (chemist by training but didn't get along well with physics, particularly regarding electronics).
By light bulb tester are we talking about something like this? http://www.amazon.com/Michigan-Indu...Z4TO/ref=sr_1_2?ie=UTF8&qid=1292880252&sr=8-2
Thanks again,
Steve
Thanks for the responses. I have used Avel Lindbergs in other amp power supplies but they have always been connected as per top diagram (http://www.avellindberg.com/pdf/avel_y23_range.pdf). It seemed intuitive that I should tie the orange and red secondaries to make the CT but I wasn't sure (chemist by training but didn't get along well with physics, particularly regarding electronics).
By light bulb tester are we talking about something like this? http://www.amazon.com/Michigan-Indu...Z4TO/ref=sr_1_2?ie=UTF8&qid=1292880252&sr=8-2
Thanks again,
Steve
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After a little hiatus from the hobby I have returned to this project. I've built a dim bulb setup. I get 40V accross each of the secondaries (why not 35V I don't know). Linking the end of the different secondaries I do measure twice the voltage 80V (again, why it wasn't 70V is unclear to me).
When I powered up thru the bulb as you suggested the light comes on briefly and then goes out (DMM voltage measurement started increasing so I shut down).
I assume the CT is 0V so the rails should show + amd -49. Why this was not observed is also unclear.
Any thoughts on what I've done wrong?
If the bulb briefly glows and then goes out, that tells you the start up surge drew enough current for long enough to warm up the filament to dull red. It then tells you the current after that surge was too low to maintain that dull red glow and confirms the running current is now quite low.
The circuit/equipment attached to the other end of the transformer is not going to blow up. There is simply too little power available to cause serious damage.
The DMM readings were changing ! Do you know how to set the DMM to get a reading from it?
The circuit/equipment attached to the other end of the transformer is not going to blow up. There is simply too little power available to cause serious damage.
The DMM readings were changing ! Do you know how to set the DMM to get a reading from it?
I am not sure what happened yesterday. Today I read 40V between the CT and reach rail so, with the exception that I should be reading 35V everything seems okay. Any reason why I should see 40V instead of the 35V (I do have a second identical transformer I can measure for a comparison)?
Thanks Andrew, your help is much appreciated.
Steve
Hi,
From your earlier post, Y236752 was the transformer part code I believe you mentioned. From the data sheet, these have a quoted regulation of 6% (typical) which is determined by the formula:
Reg% = (VN - VL) / VL * 100
where VN is the no-load voltage and VL is the full-load voltage (=35V)
Rearranging, VN = 35+(35 x 0.06) = 37.1V. This assumes that your mains voltage matches the manufacturer's quoted primary voltage. In essence, 40V measured off-load isn't anything to be concerned about.
Thanks currentflow,
So then the +/-52.3 V I read at FC3 and FC1, respectively, is also nothing to be concerned about (vs +/-49V) correct?
It's AAK's design with the PSU on the board as well. See post #53 of this thread for amp schematic and post #114 for PSU schematic.
Your off-load measured voltage of 52.3V DC is fine and will reduce when the amplifier is delivering higher power levels into a load. This is a perfectly normal characteristic of unregulated power supplies.
I bought 6 (and rec'd 12) of the version 1.3 amp quite some time ago. I have now returned to the project having completed all the boards(except for output transistors on 4) I have tested the 8 boards which are complete (complete with dim bulb tester).
The bad news is 3 failed the smoke test. The somewhat better news is that the other 5 all passed the smoke test (all 8 board display the correct rail voltages of +/- 52.3 V which is inline with noload conditions for a 35-0-35 transformer I'm using). Testing the 5 boards with the 100R safety resister inplace I measured voltage drops accross this resistor ranging from 1.4V tp 1.7V. The assembly manual for version 1.4 indicates this drop should be 2.5-3.5V. Should the voltage drop for version 1.3 be the same or, if not, what should it be (and do I have an issue with the 5 smoke free boards)?
Thanks,
SteveA
The bad news is 3 failed the smoke test. The somewhat better news is that the other 5 all passed the smoke test (all 8 board display the correct rail voltages of +/- 52.3 V which is inline with noload conditions for a 35-0-35 transformer I'm using). Testing the 5 boards with the 100R safety resister inplace I measured voltage drops accross this resistor ranging from 1.4V tp 1.7V. The assembly manual for version 1.4 indicates this drop should be 2.5-3.5V. Should the voltage drop for version 1.3 be the same or, if not, what should it be (and do I have an issue with the 5 smoke free boards)?
Thanks,
SteveA
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