Hi,
I have an old TAPS Avondale power supply which gets noisy [hummy/buzzy] after a period of warming up. It's quiet when turned on cold. It also makes the Linn LP12 motor noisy that it drives when the noise starts..
I have either measured or swapped out the obvious large capacitors that are in the unit that is now over 35 years old!
But the problem remains, can diodes or resistors deteriorate when warm, the unit is made of capacitors, transformers, diodes and resistors only
Any ideas? Thanks 🙂
I have an old TAPS Avondale power supply which gets noisy [hummy/buzzy] after a period of warming up. It's quiet when turned on cold. It also makes the Linn LP12 motor noisy that it drives when the noise starts..
I have either measured or swapped out the obvious large capacitors that are in the unit that is now over 35 years old!
But the problem remains, can diodes or resistors deteriorate when warm, the unit is made of capacitors, transformers, diodes and resistors only
Any ideas? Thanks 🙂
PSU transformer buzzing when warm and/or transformer being overloaded by motor drawing too much current?
Dunk transformer in varnish, check the volts under load, overhaul, or at least oil the bearings, as sticky bearings can cause high torque requirements.
Use the proper lube, clean off old lube with a solvent dipped cloth.
And if possible, check the motor with a spare supply.
I would blindly change all the electrolytics in a 35 year old unit, meters do not show on load behaviour.
Also I would check for leaky rectifiers and zeners / other elements in the voltage regulator section, if they are present.
And like Jeff says below, retirement is an option, you should be able to find a good one for sale in your area.
And use the bottom of a screw driver as a stethscope, keep your ear on the back of your hand, if it transmits hum, it is the culprit, there is a gap in the laminations or windings caused by years of thermal cycling.
Basically the tip of the screw driver touches the job, use insulated tip if possible, the handle is in the palm, and back of hand is what you listen to.
Do this for the bearings as well.
And as above, do service the electronics as well.
Use the proper lube, clean off old lube with a solvent dipped cloth.
And if possible, check the motor with a spare supply.
I would blindly change all the electrolytics in a 35 year old unit, meters do not show on load behaviour.
Also I would check for leaky rectifiers and zeners / other elements in the voltage regulator section, if they are present.
And like Jeff says below, retirement is an option, you should be able to find a good one for sale in your area.
And use the bottom of a screw driver as a stethscope, keep your ear on the back of your hand, if it transmits hum, it is the culprit, there is a gap in the laminations or windings caused by years of thermal cycling.
Basically the tip of the screw driver touches the job, use insulated tip if possible, the handle is in the palm, and back of hand is what you listen to.
Do this for the bearings as well.
And as above, do service the electronics as well.
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Maybe it's time to retire it, and move on to something that generates a synthetic sign wave. My old LP12 came with a Valhalla. The motor was never noisy.
jeff
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If you have a scope, you can look at the power supply output cold and compare it to hot. I would probably change all the resisitors and diodes, let's face it less than $10.
A trick is to hold a screwdriver against the transformer
and the handle against your ear.
It works a bit like a stethoscope.
If it turns out to be the transformer, NareshBrd has a good possible solution with the varnish.
A spray can is handy.
Hugo
I use a brush, Class F motor varnish is like $1 for a 250 ml. bottle here, the price has doubled after the pandemic!
Spray can is mostly propellant.
And I prefer to do it on load, the vibration actually acts like a vibratory feed, and allows the gap to stay open as the fluid flows in.
Also, the reduction in noise as it seeps into the gaps will tell you the treatment is working.
Spray can is mostly propellant.
And I prefer to do it on load, the vibration actually acts like a vibratory feed, and allows the gap to stay open as the fluid flows in.
Also, the reduction in noise as it seeps into the gaps will tell you the treatment is working.
Of course one uses a well insulated screwdriver and common sense.
If you don't feel comfortably, don't do it.
Hugo
Years back I got a used Heybrook TT2 that made quite a loud buzzing noise after it had been running for a short while. The original owner had thought it was the motor and tried everything to screen the noise. I took a closer look and decided it was almost certainly one of the capacitors on the simple supply board beneath the motor. It was cheap to replace them and it fixed the problem. The only frustrating thing was that whoever assembled the board had left component legs long and folded at 90 deg before soldering with generous quantities of solder. 😱
I have started another thread in components to try and identify some of the caps I want to swap out as some are not obvious. 🙂
Also found out one of the transformers get pretty hot = 100 Deg C with lid on and right near one of the winding contacts/leads
Also found out one of the transformers get pretty hot = 100 Deg C with lid on and right near one of the winding contacts/leads
I will re-solder the wire joint, but it 'looks' ok, good nudge as I have been wondering that. It's the one on the left that gets hot. This is where the winding joins the board, it just superficially looks ok.
I used a fluke infrared thermometer for temp readings
I used a fluke infrared thermometer for temp readings
Attachments
Repair both joints, separate, mild abrasion to clean and make surfaces rough, solder again.
Do the wires as well with abrasive.
220 to 600 grit paper used gently, or a brass wire brush is enough.
Use flux, clean up later.
Do the wires as well with abrasive.
220 to 600 grit paper used gently, or a brass wire brush is enough.
Use flux, clean up later.
What amperage is the circuit pulling? I'm not seeing an issue with the solder joints, but can't hurt to clean and resolder to make sure.
Left side one has brown marks...heat, flux residue, whatever...
And a turntable has to be at least 20 years old, the new ones hardly sell in volume, and those use SMPS for the most part.
A little TLC will not hurt.
Oh, I forgot, do the joints on the back of the board as well, where the pin and track are joined.
And a turntable has to be at least 20 years old, the new ones hardly sell in volume, and those use SMPS for the most part.
A little TLC will not hurt.
Oh, I forgot, do the joints on the back of the board as well, where the pin and track are joined.
Hello everyone, thanks for the help.
I have now got it quiet, by changing the capacitors, and realising it was getting too warm that was making the transformers noisy.
So some holes in the case and a small 5V quiet fan driven by a USB plug and it's all solved I think. We are at 45 Deg C now 🙂
THANKS!
I have now got it quiet, by changing the capacitors, and realising it was getting too warm that was making the transformers noisy.
So some holes in the case and a small 5V quiet fan driven by a USB plug and it's all solved I think. We are at 45 Deg C now 🙂
THANKS!