Help In Identifying Power Transformer Replacement

Hi All!

Never done a forum post before but I thought I'd give it a shot to see if anyone out there had any insight into an issue I'm running into on a repair I'm doing!

QUESTION:
I need help in identifying what the specifications are on this power transformer (pictures below!).



It appears to be

--------------------------
BILLION
1-80229-0A
E2-66RTF-NS1-0026

66X36PRI 3 (?)
--------------------------

DISCLAIMER: I just enjoy repairing things as a side hobby, but have NO formal training or certifications. YouTube is my teacher haha. I say that because I might be missing something that's completely staring me in the face but can't see it because I didn't know what to look for. Still learning.


BACKSTORY:
So I'm trying to repair this Advent AV570 70-Watt speaker (links below!). All my fault tracing leads me to this power transformer. I feel like I've exhausted all my mental capabilities of finding out what this transformer could be.

Checked BILLION's website and couldn't find any information on their power transformers. Also searching around I couldn't find any schematics that would explain what the part could be.

As to my limited understanding of power transformers, it appears the PCB where the secondary leads connect to, has a fuse that is rated at 125V/4A. I guess my confusion on this is if the part is a step-down transformer, why would the fuse be rated at a level close to the primary voltage? So then... is it not a step-down transformer at all? This is where my lack of knowledge hits a wall.

*Don't mind the burn spot, everything works fine still*



If anyone has any insight I will be very grateful!!

-Conor

BILLION's Webiste: ADVENT Speaker Link: **broken link removed**

A note about fuses. They have a voltage rating and a trip curve.
An automotive fuse has a rating of say 32VDC.
I'll pick a datasheet off the top of my head: https://www.littelfuse.com/~/media/...cle/blade-fuses/littelfuse_atof_datasheet.pdf

You can find glass fuses rated at 32V, 125V and 250V. When a fuse blows, and the voltage is higher than the designed limit, the circuit can be replaced with an arc which gives you no protection..

So, that's why the voltage rating is there.

Switches/relays can have an AC rating, a DC rating, a minimum current rating, a maximum carry current rating and a maximum switching current rating.

I've dealt with a high voltage SPDT relay which had to be switched with no current flowing.
it was used to switch 15 kV. Carrying current was about 1.5A.

From the fact that the unit is also capable of being supplied from a 14 volt DC supply the transformer secondary voltage will probably be about 13 volts RMS. It;s rated output current will probably be 4 or 5 amps. I found a user manual but could not find a schematic. I did find this company that claims to sell the service manual. What evidence made you believe the transformer was faulty ?

Les.

I'd also suggest that the claimed 'power' is completely imaginary.

As it runs off 14V DC (car battery), and is presumably bridged (as it has 4 output transistors), it's real output will be around 16W to a 4 ohm speaker.

So double that, and add a bit, for AIP (American Imaginary Power ) to get to 35W imaginary watts, then you've got two of them - that gives your claimed 70W.

So the transformer is probably rated far lower than you might have imagined.

I also wonder why he thinks the transformer is faulty?, it's a dead simple thing to check, but I don't think he has?.

Check the big blue capacitor on the bottom of the picture, right next to the small black bridge rectifier. The voltage rating of that cap will give some indication of the maximum DC voltage it can handle. In real life, the actual voltage will be 20-30% less. Work backwards from there and divide by about 1.414 to get an estimate of the transformer secondary AC RMS voltage.
I agree somewhat that the transformer is not likely the culprit. Measure to resistance on both secondary and primary. If you get low resistances, the windings/transformer are likely good.
A 125V fuse is a common rating and easy to find replacemens. The voltage rating is just the maximum safe voltage limit, you can use a 125V fuse for a 5V circuit as long as the current rating is correct. In your circuit, you could even use a 250V 4A fuse, makes no difference.