Noisy 9090 Transformer

Actually wouldn't be that tough to pull off. If you can find or rent a small vacuum pump like they use in HVAC refrigeration.
 
How do you put a vacuum on it? Vacuum bag it when it's submerged in a vat of liquid epoxy? After mixing the epoxy you only have a few minutes before it starts to set up.

- Pete
 
I appreciate the suggestions. However I am going to go with the basics first . Tightening the laminated plates . My transformer is screwed to the chassis on 4 legs so making the those tight will not tighten the lamination but just the legs of the transformer . (Plus they are already super tight as I tried )

Now coming to the transformer laminations, they are in vertical position and there are four empty holes in the each corner that is 4in left , four on right . These holes are in the horizontal position.

So I was thinking I will heat up the transformer by just keeping the system ON until the PT is hot and pour hot varnish on all sides and then I will use long screws with nuts and washers in the horizontal holes so I can tighten it while it's hot .(remember screws are in the horizontal position and laminations are in the vertical position so it's should be good for tightening) I only hope the sound is from the plates and not from the inner core which means if is inside the core the process I will try will not work
I will see how that goes then....
Then I will try the what both of you are recommending..

PS my transformer takes about 40-45 mins for the buzz freq to get high like in this video I took

Just for you to understand I am sharing the link and my right VU led peak meter comes on sometimes . There is a loose connection inside
 
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How do you put a vacuum on it? Vacuum bag it when it's submerged in a vat of liquid epoxy? After mixing the epoxy you only have a few minutes before it starts to set up.

- Pete
I don't think its fast cure epoxy resin. I think it needs to be baked to hardened. As far as a vacuum chamber goes. A new unused paint can or similar. Large enough to submerge the transformer in liquid resin. The proper vacuum fittings on the lid as well as a fitting for a vacuum gauge.:idea: I have a vacuum pump,fittings and gauges I could even come up with a stainless steel container even better than a paint can. Paint can may not have the integrity for much of a vacuum.:idea: I'm going to ponder this idea. Probably wouldn't want to bake it in the kitchen oven though.:D
 
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I am gonna try to get something close to temco . What do u think ? Is it worth a shot if I get the insulation varnish and do it my self st home ?( I did it before in 2013 but that was purely varnish for wood and the noise did go away but came back less than a year )
Il pour it on the transformer while it's hot on all sides and let it seep in ..
 
If you are missing the screws that run horizontally through the transformer that's your problem there should be four very long screws holding it together. If they are missing that why it is buzzing.

I can send pictures if you wish.
 
Here is a picture. This is a 9090DB transformer but the 9090 Transformers have the same screws. There are four two on the top and two on bottom. There are washers and nuts on the backside.
3a_1.JPG
 
If you are missing the screws that run horizontally through the transformer that's your problem there should be four very long screws holding it together. If they are missing that why it is buzzing.

I can send pictures if you wish.
I bought it brand new back on 1985 there were no screws in the 4 holes by default . And also my transformer is naked , not like yours which has a fully encased box . I noticed that some pioneer systems have this sort of naked transformer with no full outer case even though they could have put one and fixed 4 screws .it just has basic casing running around in one direction only . I noticed the same in my pioneer m-c11 power amplifier. It's the same as my pioneer A-7 . Not fully encased but just basic casing & 4 horizontal empty holes . But the m-c11 transformer does not make any noise like my A-7 does .what's the difference between your PT and mine ? Yours has a fully encased box wherr mine has basic encasing

Thank you for sending the pics, very useful. I have not had time to take a pic of mine but I can show u a pic if my m-c11. Very similar design like my A-7
IMG_20180215_111801586.jpg
My dad is Very confident about tightening it wit 4 screws . He feels that a good solution. I already got the 4 screws and washers ready to do the job .they are " machine " screws . That's what the guy at the shop told me I really hope it won't do any harm in terms of magnetic interference wit the PT
IMG_20180219_085517803.jpg
 
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Allanmatters, you're working on a Pioneer A-7/9, right? Probably be a good idea to start your own thread about it rather than in a nearly 11 year old thread about a Sansui receiver with an entirely different transformer.
 
It's certainly a good idea to start a separate thread but are you suggesting he start a thread on a Pioneer transformer in the Sansui Forum? That will be interesting.

- Pete
 
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