stuck at the check the fuse stage

Lisa Lane-Collins

Lisa Lane-Collins

Sophomore
Dec 9, 2012
270
0
16
Adelaide, Australia
this desk wont turn on and i want to check the fuse but it wont budge. whats the secret? i thought twist anticlockwise so the lines line up but it wont rotate, i thought grab it with pliers and pull but they slip off, the plastic will give before this damn plug will. heeeelp

20140626_223031.jpg
 
Re: stuck at the check the fuse stage

Most probably you have to push it gentle and turn then...

Looks like this one is damaged too much, so maybe it has to be replaced. Pulling is no solution, maybe you get it out, but never back.
 
Re: stuck at the check the fuse stage

Normally you only have to desolder two leads and then unscrew the metal (or sometimes plastic) thingie (mutter) at the inside of the chassis.

Do it in reverse to replace it.
 
Re: stuck at the check the fuse stage

From what it looks like, I doubt if there is any need to replace the fuse holder, I've seen a lot worse than that. As long as you use a flat screwdriver that fits, there shouldn't be a problem.
 
Re: stuck at the check the fuse stage

Antoon said it first, but I'm not sure it was clear to you. That kind of fuse holder is spring-loaded, and the cap must be pushed INWARD against the spring force before it is free to rotate about a quarter of a turn counterclockwise. The cap is the small slotted center piece--the outer plastic shell is the stationary housing. If you are not able to push the cap deeper into the housing at all, it really IS stuck.
Best Wishes.
Jim Thorn
 
Re: stuck at the check the fuse stage

My friend was poking it with the side of his drum key last night and got it out (now I can see what you mean, gently push in and twist...it was twisting far enough just not 'springing' out, it's good now).

So, next problem. Bought a new fuse, put it in, plugged the desk in, powered it up and ZAPSPARKwhispofsmoke Tripped the household circuit breaker. What on earth?! Checked the new fuse after that, it still has continuity!!! O.O

The only things that were different were that the cover on the bottom is currently off (but it's grounded elsewhere so that shouldn't be a problem should it?) And this fuse is ceramic...(guy at the shop said this would be more stable for audio gear...)

Now what the heck do I do? Not keen to plug it in and repeat the zap spark thing...



Edit to add; visual inspection of the circuit reveals a cooked resistor. So, if nothing else, I'll need to replace that before going on. But still, if anyone has any idea why it sparked....
 
Re: stuck at the check the fuse stage

Lisa Lane-Collins said:
My friend was poking it with the side of his drum key last night and got it out (now I can see what you mean, gently push in and twist...it was twisting far enough just not 'springing' out, it's good now).

So, next problem. Bought a new fuse, put it in, plugged the desk in, powered it up and ZAPSPARKwhispofsmoke Tripped the household circuit breaker. What on earth?! Checked the new fuse after that, it still has continuity!!! O.O

The only things that were different were that the cover on the bottom is currently off (but it's grounded elsewhere so that shouldn't be a problem should it?) And this fuse is ceramic...(guy at the shop said this would be more stable for audio gear...)

Now what the heck do I do? Not keen to plug it in and repeat the zap spark thing...



Edit to add; visual inspection of the circuit reveals a cooked resistor. So, if nothing else, I'll need to replace that before going on. But still, if anyone has any idea why it sparked....
Click to expand...

So there's a reason that the unit says right on it "refer servicing to qualified service personnel"...

On the other hand, you have learned a couple valuable lessons from this exercise:
* Don't replace or reset protection devices (e.g. fuses) without knowing WHY they failed. Sure, fuses can fail from vibration, but they can also fail because of actual problems downstream. It's good practice to examine glass fuses for indications of why they failed prior to replacement.
* If you are replacing protection circuitry, make sure you replace it with an identical unit. I find it hard to believe that a 1A slow blow fuse let enough amp-seconds through to trip an upstream circuit breaker likely rated at >13A.
* Blindly bypassing or resetting protection circuitry can lead to further damage to the unit, and can also lead to injury. And can also be expensive.

If I were in your position, I'd be taking that unit to a local bench tech for diagnosis and repair. I'd also ask the tech to replace at least the insert on the fuse holder, because it's pretty beat up from failed attempts to open it.
 
Re: stuck at the check the fuse stage

Lisa Lane-Collins said:
My friend was poking it with the side of his drum key last night and got it out (now I can see what you mean, gently push in and twist...it was twisting far enough just not 'springing' out, it's good now).

So, next problem. Bought a new fuse, put it in, plugged the desk in, powered it up and ZAPSPARKwhispofsmoke Tripped the household circuit breaker. What on earth?! Checked the new fuse after that, it still has continuity!!! O.O

The only things that were different were that the cover on the bottom is currently off (but it's grounded elsewhere so that shouldn't be a problem should it?) And this fuse is ceramic...(guy at the shop said this would be more stable for audio gear...)

Now what the heck do I do? Not keen to plug it in and repeat the zap spark thing...



Edit to add; visual inspection of the circuit reveals a cooked resistor. So, if nothing else, I'll need to replace that before going on. But still, if anyone has any idea why it sparked....
Click to expand...

Take it to a qualified service technician. If *anything* blows a 2nd fuse it's broke and you, the user, probably shouldn't be poking around inside it with the expectation that you will do anything other than break it more. Seriously.
 
Re: stuck at the check the fuse stage

It sounds like you replaced the fuse with one that wasn’t exactly the same, in other words the wrong fuse. Now you have let out the magic smoke.

Time to take it to someone who knows what they are doing.
 
Re: stuck at the check the fuse stage

Bah! I want to know how to fix it (hence the jumping in and having a go).

Advice taken though, went hunting and found an electronics tafe course that might help my knowledge. Giving up till later.

(weirdest thing, replacement fuse is intact.)
 
Re: stuck at the check the fuse stage

Lisa Lane-Collins said:
Bah! I want to know how to fix it (hence the jumping in .)
Click to expand...

Great! In order of likelyhood of failure check for shorted bridge rectifiers, three terminal regulators, filter caps and transformer windings. Any of those unfamiliar terms? Well take that electronics course and you'll be ready to go. As wide a field as electronics can be luckily the skills required to repair a regulated DC power supply are at the early and easy end of the spectrum.
 
Re: stuck at the check the fuse stage

Hello Lisa

Is your NEW fuse 1A slow - or ist it like the one, that happened be there before - possibly 10A or...?

If house fuse blows when load is supposing to be 1A there is SERIOUS problem around - a short somewhere - likely chance of fire and/or physical injury.

Now primary side of x-former with fuses and main switch IS NOT something you want to "try out " just to see what happens - get the unit to electronic shop and ask them to precisely explain to you what the problem is.

Then study electronics basics with a teacher - not just read books alone - to get clear understanding of basics.

Electricity is a very nice servant, but it will kill you, if you do not control it.
 
Re: stuck at the check the fuse stage

Lisa Lane-Collins said:
Edit to add; visual inspection of the circuit reveals a cooked resistor. So, if nothing else, I'll need to replace that before going on. But still, if anyone has any idea why it sparked....
Click to expand...

The FIRST thing you do is find out what CAUSED the resistor to burn. They typically do not just burn up on their own. Something CAUSES them to burn.

Yes you have to replace the resistor-but simply doing that is going to cause it to burn again.

Electronics repair is not a guessing game carried out on the internet-sorry.
 
Re: stuck at the check the fuse stage

original glass fuse on the left reads T1AL 250v. then what looks like a s in a box. replacement fuse on the right reads T1AH 250v

20140629_160102.jpg

also,
As wide a field as electronics can be luckily the skills required to repair a regulated DC power supply are at the early and easy end of the spectrum.
Click to expand...
Yay!! :-D
 
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Re: stuck at the check the fuse stage

Lisa Lane-Collins said:
My friend was poking it with the side of his drum key last night and got it out (now I can see what you mean, gently push in and twist...it was twisting far enough just not 'springing' out, it's good now).

So, next problem. Bought a new fuse, put it in, plugged the desk in, powered it up and ZAPSPARKwhispofsmoke Tripped the household circuit breaker. What on earth?! Checked the new fuse after that, it still has continuity!!! O.O

The only things that were different were that the cover on the bottom is currently off (but it's grounded elsewhere so that shouldn't be a problem should it?) And this fuse is ceramic...(guy at the shop said this would be more stable for audio gear...)

Now what the heck do I do? Not keen to plug it in and repeat the zap spark thing...



Edit to add; visual inspection of the circuit reveals a cooked resistor. So, if nothing else, I'll need to replace that before going on. But still, if anyone has any idea why it sparked....
Click to expand...

Resistors do not spontaneously burn up, usually that is evidence of some other associated component(s) failure. Replacing the resistor is likely to just burn up the new resistor. The fuses are generally to prevent fires.

Get some repair help.

JR
 
Re: stuck at the check the fuse stage

Lisa Lane-Collins said:
original glass fuse on the left reads T1AL 250v. then what looks like a s in a box. replacement fuse on the right reads T1AH 250v
Click to expand...

The replacement fuse is the right one, they are both slow 1 amp fuses, the sand-filled one offers some extra protection against a spark or arc jumping across after the fuse is tripped. You probably did nothing wrong as such (you used the correct fuse and most of us would do the same, that's why we have spare fuses in our tool-kit :blush: ), but the initial failure that blew the first fuse is now likely worse than at the original tripping time.
Think of it as dropping the patient on his head a second time, if the first time caused damage, the second time around is going to make it worse :twisted:
 
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