which EI Transformer to use?

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decommo

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Joined 2019
#1
Hello,

My old CD player has small EI transformer which is starting to hum badly so try to replace with a quality one.

When I measure the voltage of primary and secondary windings of existing transformer, I got below readings.

Primary: 52.8 Ohm, 245V
Secondary: 5 ohm, 30.3v

Dimension is 55mm L x 20mm D x 45mm H.

I am aware of that I need to get 230v primary voltage rating transformer but not sure,

(a) if I need to get 28V or 30V secondary voltage rating since actual AC feeding to it from main is 240~250v.
(b) what power rating transformer should be given the dimension of the transformer mentioned above.
(c) And, which company's EI transformers are reliable? I am thinking to get either Triad or Hammond from Mouser. Are they good enough?

Thank you so much for guidance and help on this.
 
#3
rayma said:
By hum, do you mean that it vibrates and makes audible noise?
What is the power rating printed on the back of the CD player?
Which CD player is it?
Click to expand...

Yes, transformer itself vibrate which transfer the vibration to chassis and makes noise when lid is on. When I take the lid off then it is not noticeable. I thought that coils are getting loose so put glue on but still does.

The power rating is 230v, 50Hz, 32VA. However, there are two EI transformers inside. One larger and the other smaller. Larger one is quiet and no vibration but the smaller one is causing trouble.

It is YBA Passion CD200 which is older model. The transformer does not show any marking on it so hard to know who the manufacturer it is. Tried to contact YBA but no response at all hence trying to repair it from my end.
 
#5
From a quick look, this appears to be a mod Philips CD80, but the original seems to only have
one power transformer, not two. Perhaps the second was added as part of the mod.

Suggest you try to trace out the connections on the small transformer, and see how many
secondary leads it has, two or three. The power is likely very low, 10W or less.
If your line is 60Hz, don't worry abut 50Hz types, they are larger and heavier.

How about some photos?
 
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#6
audiofan said:
Power rating of a transformer is proportional to the weight .. so if the new transformer have the same weight as the old one it should be OK. of course you must have a transformer with the specified voltage and ... the same frequency.
Click to expand...

Thank you. It is something new I learned today. I thought that size is the parameter to find out the power rating. I guess that it need to take it out completely to weigh it...
 
#7
rayma said:
From a quick look, this appears to be a mod Philips CD80, but the original seems to only have
one power transformer, not two. Perhaps the second was added as part of the mod.

Suggest you try to trace out the connections on the small transformer, and see how many
secondary leads it has, two or three. The power is likely very low, 10W or less.
Click to expand...

Thank you. Secondary has 3 pins.

Here is the internal photo with smaller transformer highlighted.
 

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#8
Did you measure between the to pins farthest apart (not connected together)?
If so, you need a 240V/30VCT transformer, probably 10W of about the same weight.
Could be a rated as 230V/28VCT instead. But it has to have two mounting ears, not pcb mount.
 
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#9
rayma said:
Did you measure between the to pins farthest apart (not connected together)?
If so, you need a 240V/30VCT transformer, probably 10W of about the same weight.
Could be a rated as 230V/28VCT instead. But it has to have two mounting ears, not pcb mount.
Click to expand...
Hi Rayma

Yes, I did measure two farthest apart. when I measure between middle pin I get 15.25v each side.

I will search one with 230v 28VCT. 10W

If you know any good reliable brand, please do share. I only know Hammond or Triad seen on Mouser so not sure which ones are to go for.

Thank you again.
 
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