Hello everyone!
I want to change the Power Transformer from a Vintage 16 CH Mixing Console. Schematics just says it must be -/+25Vx2. No word about VA and A.
I have just basic electronic knowledge so I need some help from the experts
Original E power transformer says:
T1: 220V * power in
G: 0V
T2: 240V
T3: 23V
G:0V
T4: 23V
Nothing about VA nor A.
Measures with multimeter shows the following:
T3: 19.5V - A: 580mA
T4: 20.2V -A: 620mA
(lower values considering I have 230V from outlet and goes to T1.
I am not sure how much VA and A will be good enough.
Do you think that a new toroidal power transformer with 24V(x2), 60VA, 1.25A(x2) will be a good supply?
The original Bridge Rectifier is a W-02 (50-1000V / lo 1.5A)
Original Regulators are 7815UC (Output Current max. 1A / Output Voltage max. 15V.)
Some help will be much appreciated.
Thank you guys!
I want to change the Power Transformer from a Vintage 16 CH Mixing Console. Schematics just says it must be -/+25Vx2. No word about VA and A.
I have just basic electronic knowledge so I need some help from the experts
Original E power transformer says:
T1: 220V * power in
G: 0V
T2: 240V
T3: 23V
G:0V
T4: 23V
Nothing about VA nor A.
Measures with multimeter shows the following:
T3: 19.5V - A: 580mA
T4: 20.2V -A: 620mA
(lower values considering I have 230V from outlet and goes to T1.
I am not sure how much VA and A will be good enough.
Do you think that a new toroidal power transformer with 24V(x2), 60VA, 1.25A(x2) will be a good supply?
The original Bridge Rectifier is a W-02 (50-1000V / lo 1.5A)
Original Regulators are 7815UC (Output Current max. 1A / Output Voltage max. 15V.)
Some help will be much appreciated.
Thank you guys!
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It is a 35 years old transformer. As said, the values supplied for it are below specifications.
That's very unlikely (impossible actually) for the transformer's turns ratios to change.
Is your line voltage correct? If so, have you replaced the main filter capacitors?
If the regulators are 15V outputs, and have more than 18VDC at their inputs under load,
then all is operating ok.
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AC line voltage is 230V. Connected to T1 (220V)
Power Transformer should supply 23 0 23 AC (before rectification and filters. But actually is supplying a lower voltage as said in my post.
As I do not have full power transformer specifications the question was would a new toroidal power transformer with 24V(x2), 60VA, 1.25A(x2) be a good enough supply?
Are you sure that your meter is accurate on the AC Volts function?
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Right, as long as there's more than 18VDC at the regulator input,
and no current limiting due to a fault, the output will be 15VDC.
Which is it? +/-23V or +/-25V and you think +/-24V is ok? Yes it is and so is +/-23V
To avoid any complication I want to change the power transformer
This won't be helpful, and it could result in more noise and/or hum.
Also, messing around with 230VAC isn't for beginners.
Strongly NOT recommended.
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Thank you for reply but I am not a beginner. I have knowledge about how to do some things but not to calculate (if there's possible) how to get to know how much power (VA) and current (A) need a new transformer substitution.
Thank you to all for answering. By now this thread have around 10/12 answers but none asnwered to my original question. So I repeat once again to somebody who knows really how to do this:
With the information provided, there is a way to know if my calculations of a 24 (x2) Volts, 80VA, 1,25 (x2) new transformer is correct??
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One more reply for the sake of safety. No offence meant, but the evidence in your posts does not support the above claim. You seem to think that increasing the voltage from 23V to 24V is going to make a difference, it isn't. The voltage is regulated to 15V, this will not change. Please understand there is nothing to be gained by replacing the transformer and possibly something to be lost. Take care
One more reply for the sake of safety. No offence meant, but the evidence in your posts does not support the above claim. You seem to think that increasing the voltage from 23V to 24V is going to make a difference, it isn't. The voltage is regulated to 15V, this will not change. Please understand there is nothing to be gained by replacing the transformer and possibly something to be lost. Take care
Here you expose your negligence. I meant 24V because I can't find 23V. In the shop to buy parts, from 18V jumps to 24V. My question is related to VA and A no Volts. You are just assuming that I am a beginner because of a silly bias from your part. Since your very first answer you didn't read with attention my thread and the information provided.
Please guys, let who knows how to do the maths helps me. Thank you!
I have read the thread carefully end to end. You have measured current draw as roughly half an ampere, so yes, 1.2 amperes will be more than enough.
I think the reason we are directing your question elsewhere is that you SEEM to be looking at the AC spec of your old transformer without considering its context. If it is feeding 15v regulators it only needs 3v of headroom, which is to say 18v of DC. The actual raw voltage at the rectifier could be anywhere from 18 to 30 volts and be just fine.
So in other words, if your 23vAC is only 20vAC, then the resulting DC drops from 32vDC to 28vDC. Even if your unit has 18v regulators, you still have a whopping 10v of headroom into the regulators. This is what we THINK you might be missing.
VA is just volts times amps, so...
I think the reason we are directing your question elsewhere is that you SEEM to be looking at the AC spec of your old transformer without considering its context. If it is feeding 15v regulators it only needs 3v of headroom, which is to say 18v of DC. The actual raw voltage at the rectifier could be anywhere from 18 to 30 volts and be just fine.
So in other words, if your 23vAC is only 20vAC, then the resulting DC drops from 32vDC to 28vDC. Even if your unit has 18v regulators, you still have a whopping 10v of headroom into the regulators. This is what we THINK you might be missing.
VA is just volts times amps, so...
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