I have 2 pcs 405-2.
One is humming (50hz) through the speakers, probably the C5 that needs change.
The other one is humming through the cabinet?
Any thoughts?
Regards Michael
One is humming (50hz) through the speakers, probably the C5 that needs change.
The other one is humming through the cabinet?
Any thoughts?
Regards Michael
The mains transformers are prone to going noisy, many hum to a small degree but some are unusable. You can fit a 300VA toroidal transformer but you may have to make a bracket to mount it.
Stuart
Stuart
Quad may well still have stock of the original spec TX, they surprised me a couple of years ago with a new side cheek for the aforementioned amp, (personally I've seen a fair few (40+ of these amps and never had a buzzing TX , but if if it's buzzing it's buzzing)
Speak to Quad in the first instance, they may surprise you.
The small value at least electrolytic caps needs doing on both amps regardless before they kill the output stage.
Speak to Quad in the first instance, they may surprise you.
The small value at least electrolytic caps needs doing on both amps regardless before they kill the output stage.
possible. But two things: transformer will vibrate if there are any gaps, thus the laminated steel sheets in it are very tightly bound, should any looseness arise, it will have some sound output.
next is the shaking alone, and third is how it is mounted, some of the clones in 19" racks had a problem with the magnetic field vibrating the aluminium cover 😀
so, before pouring in anything into the transformer, see what makes it go zooommmm. and when it stops, of under which pressure.
This is a very common problem with the 405 transformer, they vary from almost inaudible to unstably loud, I have never found a cure, they can be replaced with a toroidal transformer but it is best to make a bracket to mount it to, you could also consider a switchmode power supply which will easily fit in the space.
Stuart
Stuart
This depends from the fact, if ‘E’ and ‘I’ type lamination assemblies are in use or if a toroidal was choiced.
Both versions are to find in this model - go to the attached images.
For toroidal transformers check out this threads:
https://www.diyaudio.com/community/...toroid-transformers-what-is-the-right.161428/https://www.diyaudio.com/community/...mary-of-the-most-interesting-comments.197849/For ‘E’ and ‘I’ type lamination assemblies in potted version a replacement will be the only possibility.
In both cases is this claim right, as long as the humming noise is also present when the electronics are disconnected from transformer (i. e. removed wires between secondary winding and rectifiers).
Attachments
The one on the left is a replacement, and BTW far too small. Quad never shipped a 405 with a toroid.
Practically available toroids with high power density were not available in those days. Even the ones soviets used in their color TVs were ultra, ultra heavy. Sure, the power rating was good, but it was only in recent decades that we got affordable toroids that have very high power rating in small package.
And don't get me started on the rating of ferrites over the last 21 years, the growth has been really insane, breaking record after record every year.
maybe need a dc blocker cirquit on power line to block the dc parts on the ac line .if posible try it to other house or other outlets.
A typical reason for the original transformers to make a noise (60Hz buzzing) is that sometimes the bands that hold together the cores gets loose or some of the winding gets loose. . As the transformer is fully potted it is not possible to repair. only replacing the transformer is solution. Either with an original one or a suitable new/toroid transformer.