Someone help about transformator

Thread Starter

Dzoro

Joined Feb 1, 2019
154
Hi guys i am currently repairing an 80 w amplifier and everything is okay but the transformer has no resistance on primary and secundary site.I even hook it up to mains to check if it's working and its not.I tried to open it to calculete the output voltage but it's realy hard beacose it's covered with some epoxy or resin.Never mind,on the transformer it has some numbers and letters and can that show how much voltage is outputing on the secondary or any help about that how can i find that
 

Thread Starter

Dzoro

Joined Feb 1, 2019
154
15512152555566462114815393403808.jpg 15512153201158023579333503668352.jpg here are the primary and secondary of the transformer and the serial number of it i reserched the internet but i can't find it.Please reply someone
 

Yaakov

Joined Jan 27, 2019
1,612
What is the brand and model of the amplifier? It is very unlikely anyone can identify that particular transformer from those photos.
 

MaxHeadRoom

Joined Jul 18, 2013
19,787
You need to know details of the amplifier requirements.
Unusual that both Pri and Sec are open!!??
It is common for a thermal fuse to be buried in the primary winding that may have blown, but that would not affect the secondary.
Max.
 

Thread Starter

Dzoro

Joined Feb 1, 2019
154
You need to know details of the amplifier requirements.
Unusual that both Pri and Sec are open!!??
It is common for a thermal fuse to be buried in the primary winding that may have blown, but that would not affect the secondary.
Max.
Yes i know that seemed strange to me but i don't know it has a fuse on the amplifier case and goes series with the transformer i checked it and its good and for the requerments of the amplifier it uses stk459 chip
 

MaxHeadRoom

Joined Jul 18, 2013
19,787
There appears to be two secondaries, highly unlikely that one is open circuit, let alone TWO?
And one is centre tapped by the look of it!
Are you sure you are measuring correctly?
Max.
 

Thread Starter

Dzoro

Joined Feb 1, 2019
154
What is the brand and model of the amplifier? It is very unlikely anyone can identify that particular transformer from those photos.
20190224_230309.jpg it's an old one and this is on the front side it has two cassete players it has an equalizer it has that big cd on the top but i don't know how it's called in english
 

Thread Starter

Dzoro

Joined Feb 1, 2019
154
There appears to be two secondaries, highly unlikely that one is open circuit, let alone TWO?
Are you sure you are measuring correctly?
Max.
You know like somethimes its mesuring something but somethimes not but that isnt going to help beacose the primary is burnt but now i am mesuring it and it's not giveing anything i think when i tryed to open it maybe i broke it or something
 

Yaakov

Joined Jan 27, 2019
1,612
View attachment 171082 it's an old one and this is on the front side it has two cassete players it has an equalizer it has that big cd on the top but i don't know how it's called in english
Ah, well. That sort of thing isn't like to be using a common transformer. As old as it is, you'll be lucky to find a replacement part. I would work on the basis that your measurements of the transformer are wrong because that's your best hope.
 

Thread Starter

Dzoro

Joined Feb 1, 2019
154
Ah, well. That sort of thing isn't like to be using a common transformer. As old as it is, you'll be lucky to find a replacement part. I would work on the basis that your measurements of the transformer are wrong because that's your best hope.
Yes but when i know the output voltage i am going to wound a new transformer but i don't know the output
 

sghioto

Joined Dec 31, 2017
1,038
If the power transformer is open on both the primary and secondary from some kind of power surge then the chip is probably toast.
The schematic for the STK459 shows a bi-polar supply.
SG
 

MisterBill2

Joined Jan 23, 2018
4,958
The first post said "no resistance" on the primary. Do you mean zero resistance? Or do you mean no conductivity? And if you are not able to do any more checking how do you expect to be able to wind another transformer and have it work?
My guess is that you have an ohm meter with a single resistance range with perhaps 1500 ohms mid scale, and a low resistance shows tha same as a short circuit.
So at this point you are going to need to do some circuit tracing and see what the two secondary windings feed. If the one set is just for the lights, then you are in luck.

If you can tell us the type number of the output transistors then we can figure out the voltage that is needed for 80 watts output.
One more thing, which is that the numbers in the picture are very hard to see.
SO please read them and post what they are , and THAT may provide us with some useful information.

What were you repairing on the amplifier before you found this problem?
AND, REALLY, if you can provide us with the type numbers of the output stage transistors than quite probabkly we can give some worthwhile assistance.
 
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