Hafler Transnova P3000 PT Replacement

[andYz00m]

Hey there, have a P3000 I use to power my NS10s and it has a hum. I have it on the bench right now and with all the spade connectors disconnected, the hum is still there.

The diode bridges are also producing a fizzy buzz but its not audible when the unit is closed in the rack, however the PT hum is.

Anyone know where I can find one of these transformers? Its pretty unique and the whole chassis and layout is designed around this thing. I dont want to DIY as solution, just want to either replace the exact part or find a new amp.

Haha. I paid 280$ for this thing maybe 10 years ago.

 

[Tubetec]

I know you said you werent looking for a DIY fix but it might not be a major job to do it .
Having the transformer dipped in varnish might cure the problem quickly and easily
and keep an otherwise good component from going onto the heap .
Getting a bit of heat into the core helps the varnish penetrate ,
A motor re-winding place probably wont charge you much to do it , a boat building yard is also likely to use large quantities of varnish and maybe willing to help .

 

[andYz00m]

I know you said you werent looking for a DIY fix but it might not be a major job to do it .
Having the transformer dipped in varnish might cure the problem quickly and easily
and keep an otherwise good component from going onto the heap .
Getting a bit of heat into the core helps the varnish penetrate ,
A motor re-winding place probably wont charge you much to do it , a boat building yard is also likely to use large quantities of varnish and maybe willing to help .

Woah, all interesting ideas. I live near a harbor.

I'll check that out. Thank you!

 

[tony hunt]

Have you checked those lamination bolts for tightness?
Simple check. Loose lams can physically "hum".

 

[andYz00m]

Have you checked those lamination bolts for tightness?
Simple check. Loose lams can physically "hum".

Yeah I did try that. There are bushings and such which help with that but I have tried tightening and checking for physical vibration but that didnt help.

I think the idea of laminating or potting the whole thing might work!

 

[andYz00m]

Im thinking about potting this thing myself. It has aluminum mounting legs that would protrude the potting mold and allow for mounting easily. All the leads come out the bottom of the trafo as well so I think its totally doable. Would just build a mold out of poly lined mdf for easy release.

@CJ whats the best potting compound for something like this?

 

[Snatchman]

Hello..FWIW, I have that same setup. P-3000/NS-10s..I was having humming issues, so I replaced the on/off power switch and it stopped hummimg..Don't know if it's your problem or not..Good luck..

 

[Tubetec]

Ive sorted a few buzzing transformers by simply dropping varnish between the bobbin and the core , good as new afterwards .
Potting it in two part epoxy , that stuff is expensive and fairly viscous compared to varnish , if it doesnt get into the core and fix it theres nothing more you can do after that .

 

[andYz00m]

Hello..FWIW, I have that same setup. P-3000/NS-10s..I was having humming issues, so I replaced the on/off power switch and it stopped hummimg..Don't know if it's your problem or not..Good luck..

Strange! I can try that.

Ive sorted a few buzzing transformers by simply dropping varnish between the bobbin and the core , good as new afterwards .
Potting it in two part epoxy , that stuff is expensive and fairly viscous compared to varnish , if it doesnt get into the core and fix it theres nothing more you can do after that .

Any recommendation on varnish type?

 

[Tubetec]

Ultimeg 2000/372 antitrack enamel. Aerosol - AEV-Iberica

Anti flash varnish finish Alkyd air drying Available in aerosol </ strong> thermal class H (180 ° C). UL Listed (File E220579) Available in other colors (gray, black, blue, etc.) APPLICATION: Suitable for noise reduction and moisture protection in small transformers, anti-flash varnish and...

aeviberica.com

The gold coloured spraycan was what we normally used at the rewinds place , it runs nice and thin so seeps into the gaps well ,
Dipping the entire thing is preferable but in a one off situation like this thats going to be very wasteful .
The best way I've found to keep waste to a minimum is dispence a small amount at a time from the spray can into metal tin , now use a paint brush to drop the varnish in between the bobbin and core and into the windings , it will seep down into the gaps , you can put a strip of tape at the lower open end where the core exits the bobbin , but allow gaps so the liquid can displace any air , once it starts to drip out the lower end , take a short break , after the varnish has dried a bit flip the transformer up the other way and apply more varnish , again allow time for it to seep into the gaps and dry a bit before reapplying .
At the end a good overall coat of varnish directly from the can to seal the whole thing from moisture and it should be good ,

Setting the transfomer to bake for a few hours before starting might be as good idea too , that way any moisture is driven off , a warm core will also help the varnish get into any loose lams more easily
You dont want too stink out your house or cooker with fumes , but if you have a furnace/boiler in the basement sit the transformer on top near the flue , get the core upto around 100C . Probably best not vapourise the can in the vicinity of the hot transformer just in case ,
but dropping in liquid with a brush isnt a problem ,

As I mentioned a boatyard or motor winders might have a large drum of varnish , usually its white spirit based so it will take time for the fumes to go after , the Ultimeg cures fast and wont give off much bad smells .

The product specifically mentions noise reduction in the description .

 

[CJ]

You can try shimming the coils with thin pieces of hardwood, angle one edge and tap it in between the coil and core. Is that a layered paper coil or nylon bobbin?

The press board stretched over time and thus loosens up the coil.

If no room for the thinnest of wood shims you can try some thin sheet metal like 22 ga.
Try not to cut thru the PB.

You do not have to dip the whole XFMR, you can simply bleed some epoxy between the coil and core. Pry the coil back gently with a small screwdriver. Heat up the epoxy a bit.

You can use any varnish as long as it is not water based. I use minwax spar varnish, gloss type does not matter.

 

[andYz00m]

Amazing. Thanks for the advice. I’m gunna try these tricks!

 

[mikeiver]

I know you said you werent looking for a DIY fix but it might not be a major job to do it .
Having the transformer dipped in varnish might cure the problem quickly and easily
and keep an otherwise good component from going onto the heap .
Getting a bit of heat into the core helps the varnish penetrate ,
A motor re-winding place probably wont charge you much to do it , a boat building yard is also likely to use large quantities of varnish and maybe willing to help .

I was thinking the same. I would find a place that does motors as they will have a vacuum impregnator. Pulling a vacuum is the only way to get the varnish inside and stop the buzzing.

 

[andYz00m]

There is a bunch of boat building here as we have a fairly large harbor. Im going to start there.

There is a motor rebuilding business here but I talked to them and they just warm things out to another company.