Computer Monitor Transformers

[Lusso5]

Our IT dept., where I work, throws out bad monitors all the time. If the PSUs are good, are they useable for small amp projects? A Gainclone? Are there any other components in there I should consider salvaging for a future Audio project?

I cant find specs on PC monitor transformers, but I did find these paragraphs; one mentions a "flyback" transformer...

Low voltage power supply. Most of the lower
voltages used in the TV may be derived from the horizontal deflection
circuits, a separate switching power supply, or a combination of the two.
Rectifier/filter capacitor/regulator from AC line provides the B+ to the
switching power supply or horizontal deflection system. Auto-scan
monitors may have multiple outputs from the low voltage power supply
which are selectively switched or enabled depending on the scan rate.

Degauss operates off of the line whenever power is turned on (after
having been off for a few minutes) to demagnetize the CRT. Better
monitors will have a degauss button which activates this circuitry
as well since even rotating the monitor on its tilt-swivel base can
require degauss.


CRT high voltage. A modern color CRT requires
up to 30 KV for a crisp bright picture. Rather than having a totally
separate power supply, most monitors derive the high voltage (as well
as many other voltages) from the horizontal deflection using a special
transformer called a 'flyback' or 'Line OutPut Transformer (LOPT) for
those of you on the other side of the lake. Some high performance
monitors use a separate high voltage board

 

[Colt45]

Rather useless for an audio amp.


The main power supply will be switch-mode, so tiny ferrite transforrmers.


the flyback-trafo is for boosting high voltage to exremely high voltage from the horizontal output. hmm. hard to explain. I kind of forget how it works now that I think of it

anyhow, flyback is ferrite core, so it is useless to audio freq's

 

[Tensop]

they are useless for parts beyond highspeed diodes and 400 volt capacitors of low capacitance.

 

[jackinnj]

since these are SMPS they have chokes on the a.c. line connection (to prevent switching noise from migrating back into the mains) -- these can be used, also the electrolytic capacitors can be reused -- sometimes these will actually have pretty high voltage ratings.

flyback designs "pump" an inductor -- the physics is explained on a lot of SMPS chip mfr web sites -- this is a pretty noisy topology to use for audio.

the transformers in the supplies are pretty difficult to repurpose-- you can get some idea if you google on "TL494 power" -- but most of the mod articles deal with souping up an ATX supply.