Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

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neopl
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Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

Post by neopl » Sat Sep 12, 2020 1:07 pm

So I had a slightly strange thing happen today...

Two days ago I got the CV Trigger mods from Vermona to put in my DRM1. I put the trigger modules in, no problems, the machine has been working for two days without a hitch... but today, I heard a tiny pop and the machine turned off and would not power on. As you might imagine, I was pretty worried as to what it could of been, but upon opening it I quickly discovered that one of the fuses on the power board has blown. Why this happened, I have no idea... would anyone hazard a guess?

I am now looking to buy a replacement for this fuse and I keep coming up on Quick blow and slow blow fuses, does anyone know which one I need?

The fuse that blown has got this written on it: l250v t 315ma there is also what appears to be a logo ELU

I keep looking for a fuse of this spec but keep coming up against quick blow and slow blow and have no idea which one I need for this application. I'm sure this is a piece of cake of a question to some of you DIYers here!

Many thanks!

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gelabs
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Re: Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

Post by gelabs » Sat Sep 12, 2020 1:12 pm

l250v t 315ma should be slow-blow, Low Breaking Capacity I reckon. See https://www.swe-check.com.au/pages/lear ... rkings.php
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neopl
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Re: Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

Post by neopl » Sat Sep 12, 2020 1:30 pm

gelabs wrote:
Sat Sep 12, 2020 1:12 pm
l250v t 315ma should be slow-blow, Low Breaking Capacity I reckon. See https://www.swe-check.com.au/pages/lear ... rkings.php
Thank you for the swift answer, slow-blow it is. And BTW, upon closer inspection, I notice that both of the fuses have blown. Very strange

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Re: Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

Post by EATyourGUITAR » Sun Sep 13, 2020 1:31 pm

What does the connector look like on the trigger expansion? Is it possible that you bumped something or moved something? Blowing two fuses makes me think it is drawing too much current. Or maybe you had a spike in your mains that caused both fuses to fail. This is very hard to diagnose from over here. After you put fuses in, you can see if it blows fuses again. Then maybe you can find the short circuit or power it from a current limited bench supply while you probe it with one hand. How good are you at diagnose and repair? I don't know if I need to talk about safety sticking your hands into exposed live mains. I'm not telling you to do it if you don't have the ability. Probing live mains is definitely not something you do for your first project.
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neopl
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Re: Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

Post by neopl » Tue Sep 15, 2020 5:43 am

EATyourGUITAR wrote:
Sun Sep 13, 2020 1:31 pm
What does the connector look like on the trigger expansion? Is it possible that you bumped something or moved something? Blowing two fuses makes me think it is drawing too much current. Or maybe you had a spike in your mains that caused both fuses to fail. This is very hard to diagnose from over here. After you put fuses in, you can see if it blows fuses again. Then maybe you can find the short circuit or power it from a current limited bench supply while you probe it with one hand. How good are you at diagnose and repair? I don't know if I need to talk about safety sticking your hands into exposed live mains. I'm not telling you to do it if you don't have the ability. Probing live mains is definitely not something you do for your first project.
I don't think it is to do with the trigger mode, the trigger mod looks like this https://djjondent.blogspot.com/2014/07/ ... ggers.html

The ribbon cable with rigid wires slots into a series of slots without the need to solder. I don't think I bumped anything, and considering that it worked for two days after, I think it might be a coincidence. The day before the fuses blew I mounted the Vermona in a vertical 19inch rack, perhaps there was something loose inside that caused a short after it got moved around... :despair:

Anyway, I'm pretty handy with a soldering iron, my recent kit was the Ornaments and Crime Plus through hole kit, which was pretty involved, but truth is that I know nothing about troubleshooting electronics. I've been lucky and SUPER CAREFUL with my builds, as I knew that if I were to screw something up, I would not even know where to start troubleshooting. (Though, I do have a pro grade multimeter, Brymen BM867, which I bought mainly to calibrate the OCP kit, but hoping to learn a bit more about troubleshooting eventually, so it is good that I already have the kit)

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Re: Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

Post by EATyourGUITAR » Tue Sep 15, 2020 6:47 am

20140703_094054.jpg
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neopl
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Re: Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

Post by neopl » Tue Sep 15, 2020 10:43 am

EATyourGUITAR wrote:
Tue Sep 15, 2020 6:47 am
20140703_094054.jpg
You mean that dropping screws on those points would cause the fuses to blow? I am positive that I didn't drop any screws, so that is unlikely, but perhaps some metal shavings from the production process have been kicking around in there, super unlikely but who knows. I have the fuses arriving in the post tomorrow so we'll see if it blows again.

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Re: Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

Post by EATyourGUITAR » Tue Sep 15, 2020 10:54 am

if it blows fuses again then it is some other failed component or short circuit. I marked the AC input side to show that if you drop a screw there it will trip the circuit breaker in your house without blowing the fuse. if you blow a fuse then it must be on the load side. some equipment has fuses at the mains power entry before the transformer. this vermona looks like it has the fuses before the rectifier probably between the secondary of the mains transformer and the beginning of the DC power supply that starts with a half wave or full wave rectifier. a failed transformer primary would in theory trip the breaker if there is no fuse there.

if you blow fuses immediately this is a good thing because that means you can test for shorts with power disconnected. when the problem happens at random times, you are forced to do vibration and temperature stress testing to recreate the problem. this also has mains AC involved so this is not a project I would recommend unless you already have some years in the repair business. a bad repair could burn your house when you are not home if you make a mistake and you leave it plugged in turned on not fused properly etc.
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neopl
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Re: Blown fuse in my Vermona DRM1 MK3. Not sure which one I need as replacement..?

Post by neopl » Thu Sep 17, 2020 8:05 am

EATyourGUITAR wrote:
Tue Sep 15, 2020 10:54 am
if it blows fuses again then it is some other failed component or short circuit. I marked the AC input side to show that if you drop a screw there it will trip the circuit breaker in your house without blowing the fuse. if you blow a fuse then it must be on the load side. some equipment has fuses at the mains power entry before the transformer. this vermona looks like it has the fuses before the rectifier probably between the secondary of the mains transformer and the beginning of the DC power supply that starts with a half wave or full wave rectifier. a failed transformer primary would in theory trip the breaker if there is no fuse there.

if you blow fuses immediately this is a good thing because that means you can test for shorts with power disconnected. when the problem happens at random times, you are forced to do vibration and temperature stress testing to recreate the problem. this also has mains AC involved so this is not a project I would recommend unless you already have some years in the repair business. a bad repair could burn your house when you are not home if you make a mistake and you leave it plugged in turned on not fused properly etc.
Many thanks for all the tips. I replaced the fuses yesterday and had the machine on for most of the time since, with no problems. Fingers crossed it was just some freak accident and it ain't coming back.

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