dell G2410t monitor power board - Page 1
Forum section: electronics / repair

author: GOD
author_rank: Contributor
timestamp: June 24, 2021, 11:19:21 pm
content: I have dell G2410t monitor with high pitch noise from transformer in power board.

author: vintagepc
author_rank: Contributor
timestamp: June 25, 2021, 01:37:21 am
content: Are you sure it's the transformer? Usually they don't go bad; if they're whining it's a sign that something downstream is not right; most SMPS supplies will "chirp" and go into shutdown over and over if excessive current is being drawn, and they can also buzz a bit if operated at the lower end of their switching frequency. Some will also whine and go into shutdown if there is insufficient load on the outputs.The noise is just magnetostriction of the core and isn't a sign that it is bad.Unless you can physically see that the core is cracked or damaged, or if you've verified a winding has gone open circuit, I'd look elsewhere.SPMS deaths are very often either capacitors (they get driven hard with a lot of ripple in a hot environment) or things like resistors cooking themselves over time and going open.It'd also help if you describe the failure mode (how did it die, and how is it behaving if power is applied).

author: GOD
author_rank: Contributor
timestamp: June 25, 2021, 02:24:36 am
content: Thanks for reply vintagepc.I removed all the component boards from the monitor and reconnected to just lcd panel and by using 20mm diameter short pvc pipe to check the noise comes from the transformer.Power board is works fine but noise from power board is stressful. So I want fix.

author: perieanuo
author_rank: Frequent Contributor
timestamp: June 25, 2021, 12:20:30 pm
content: i bet transformer is oki replaced one smps transformer in some years of repairing, usually is pwm control circuit failing, that's generating the noisecan be simply the smps entering in protected state caused by short on output rail, bad cap, bad control ic etcaeteratalking transformer, re-winding him take some time and some insulated wire from another smps transformer with same gauge, but i seriously doubt this scenario

author: perieanuo
author_rank: Frequent Contributor
timestamp: June 25, 2021, 12:22:18 pm
content: the 2 caps from picture right side are maybe with the cap deformed? check first the output rails for short/deceased caps

author: vintagepc
author_rank: Contributor
timestamp: June 25, 2021, 09:42:53 pm
content: If it's just transformer noise that is the problem and there's nothing wrong with the board, make sure the core is not loose on the bobbin.If it is, any suitable means to secure it (silastic, whatever) should stop the noise.As others have also said,the transformer is not the problem here,only the symptom (and that is assuming the noise is new and has not always been this way). If it's always been this way there is nothing you can do except redesign the entire supply. No amount of transformer swapping will change the frequency at which the transformer operates (and the harmonics which leak into the audible frequency range)Think of it like a stereo amplifier with a speaker. If you hear static from the speaker (transformer) when the amplifier (monitor) is turned on ... it's foolish to replace the speaker, instead you inspect and service the amplifier that is driving the speaker (i.e. fix the cause and not thesymptom).