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Main => Monitor/Video Forum => Topic started by: carniello on September 15, 2025, 09:03:15 pm

Title: Neotec NT-S501 chirping constantly - no display
Post by: carniello on September 15, 2025, 09:03:15 pm
Hi all,

This monitor will stop chirping if yoke cable is unplugged. The yoke meters: green and yellow 6.7 ohms , red and blue 1.5 ohms.
Board has been recapped. b+ is 125v with yoke unplugged.

I'm lost!

Help!

John

Title: Re: Neotec NT-S501 chirping constantly - no display
Post by: lilshawn on September 28, 2025, 11:05:46 pm
double check your caps and make sure nothing is backwards and the uF ratings on the caps match the originals. there is errors on these chassis with cap markings so you REALLY have to pay attention...

Quote
The following caps should be installed using the polarity markings on the bottom (solder) side of the board, not the top markings:

C117
C121
C411
C414

The following cap should be installed using the polarity markings on the top (parts) side of the board, not the bottom markings:

C426

the chirping sound is the SMPS power supply booting up, it starts shoving power out of it into the circuits, sees there is a large load and the current is going too high, and shutting down (repeat until over current situation is resolved) every chirp is the power supply powering up and down and up and down, failing each time.

by removing the yoke, you remove a significant load off the power supply and allowed the supply to boot. I assume it went in chirping...you changed the caps...and it's still chirping, yeah?

in that case, i'd suspect the HOT. BU2525AF