Trying to identify a transformer

[eman]

Hi All:

I got an amp from a friend for repair and the power transformer primary is open. I found a thread with the schematic here:

http://music-electronics-forum.com/t32639/

but it doesn't identify the the secondary voltage or current rating. Anyone know or have an idea? I imagine anything close should do. This is a 120V model. Thanks in advance.



ET

[52 Bill]

Hi All:

I got an amp from a friend for repair and the power transformer primary is open. I found a thread with the schematic here:

http://music-electronics-forum.com/t32639/

but it doesn't identify the the secondary voltage or current rating. Anyone know or have an idea? I imagine anything close should do. This is a 120V model. Thanks in advance.



ET

If you read the thread that you referred to, there is a post from J M Fahey that lists the approximate specs for the secondary voltage.

"The LM3886 loaded with 4 ohms is happy with +/_ 28V DC rails, so you will need a 20+20VAC transformer, power/VA rating around 80 to 120 VA.
Some catalogs show transformer physical size, so it should be another guide to get a similar one.
Weight is also a guide."

[eman]

If you read the thread that you referred to, there is a post from J M Fahey that lists the approximate specs for the secondary voltage.

"The LM3886 loaded with 4 ohms is happy with +/_ 28V DC rails, so you will need a 20+20VAC transformer, power/VA rating around 80 to 120 VA.
Some catalogs show transformer physical size, so it should be another guide to get a similar one.
Weight is also a guide."

Thanks, I was lazy and didn't read all the posts. What do you think of this Hammond at the link below?


Eman



165P25 Hammond Manufacturing | Mouser

[52 Bill]

Thanks, I was lazy and didn't read all the posts. What do you think of this Hammond at the link below?


Eman



165P25 Hammond Manufacturing | Mouser

No, you need a secondary of 40-45 vct (20-0-20) to get the voltages you need.

[eman]

No, you need a secondary of 40-45 vct (20-0-20) to get the voltages you need.

right thanks.


ET

[eman]

No, you need a secondary of 40-45 vct (20-0-20) to get the voltages you need.

If you have a source let me know. Not having much luck.

ET

[52 Bill]

If you have a source let me know. Not having much luck.

ET

Well, a quick check of Hammond's website shows model 166L42 maybe.

I suppose you could go as high as a 48vct secondary, which would be about +&-33.6 volts dc. Those will be easier to find.

[olddawg]

Have you checked that the primary doesn't just have an open thermal fuse? If it does and you can get to it you can solder a pigtail fuse in its place for test. It's not something you want to do as a final shop fix, but I have equipment that has been running for years after doing the same thing.

[eman]

Have you checked that the primary doesn't just have an open thermal fuse? If it does and you can get to it you can solder a pigtail fuse in its place for test. It's not something you want to do as a final shop fix, but I have equipment that has been running for years after doing the same thing.

Yes I did, still trying to find something not too expensive that will fit. I think I'll email the factory in China and see if they'll sell me the original one. Thanks for the reply.


Eman