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Is my amp dead for good?

#21
@subdude67
Hi brother. Been awhile. This is a strange one,same set up as UK should mean
Main fuse on the meter board,Trip fuses for sockets/lights/cookers etc, fuse in the plug and finally internal fuses in the amp.

That's a lot of safe guards even for the surge. You've checked the trip switches and the sockets are OK ? They,like the lights will be on 2 or 3 rings.
 
#23
Fuses are really only there to protect against high-current events, short-circuits and their ilk. They typically work by melting a thin wire with resistive heat generation, but in particular they don't care a damn about voltage, only current.

As such, if you've got a bunch of delicate semiconductor based electronics, it's fairly easy to destroy them with significant overvoltage without creating a large enough dead short that you'll melt the wire inside a fuse.
 
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#24
Um, ok. So the amp was off, correct? That would mean that the on/off switch was open. Meaning no voltage should have reached the fuse, which is on the other side of the circuit. I would to make sure you have the correct voltage coming from the outlet. Then, check the resistance of the power cable while moving it around and bending it into different positions. And to clarify, always check the continuity of the meter leads first by setting your meter the ohms/Omega and touching the leads together. You should have near 0 resistance. When measuring the continuity of the cable you should also measure near 0 resistance. If while you are bending the cable the resistance changes, then you have a faulty cable that should be replaced. If when you measure the fuse, you have more than a couple of tenths resistance (0.2 is normal) replace the fuse. Being in your environment it would probably be wise to invest in a couple of spare fuses and power cables.
 
#25
Let’s step back and debug the problem by breaking it down.

1) Test your wall outlet by plugging in another appliance. Test you amp in another room that is on a different circuit breaker.

2) The power cord on the BH250 is detachable. Remove it from the amp, then reinsert it, making sure that it is properly seated. Test the amp.

3) Test the power cord by plugging it into another appliance. If you can’t do that, a local repair shop should be able to check just the cord out for you.

4) Some 240 vac power cords have a fuse in the plug. If this is the case, you’ll need to check that fuse. Fused plugs can either be disassembled or there is a way to pop the fuse out. You’ll have to inspect it to see.

5) If the wall outlet and the power cord are fine, the next step is to have the amp checked out. If the internal fuse is glass, it is easier to see if the fuse has blown but not always. A ceramic fuse may not show any visible sign that it has blown. Ideally you want to test the fuse with an ohm meter. If in doubt, change the fuse with one of the correct ratings. Some amps have more than one internal fuse.

In general, I unplug all my amps when they are not in use. The slight inconvenience is well worth while.
 
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#26
Thanks a lot for all the input, here is a summary:

The amp was plugged in but not running when the surge happened. I used the amp the evening before and it worked as usual.
The fuse that is inside the power socket of the cable is OK as is the fuse inside the amplifier, I have checked both with my multimeter and I have tried 2 other power cables to be sure. I have also tried sockets in various places that I know are working with other appliances plugged in, same result.

I am no electrician but from what I understand the ampere's are what would blow a fuse, not the volts?
A tech from the power company told me that during the 2 hour surge there was 400 volts on both the hot and neutral lines of the grid, is that why everything got toasted even if it was not actually switched on?

here some pictures from the inside:

IMG_20180106_173150.jpg




IMG_20180106_173213.jpg

IMG_20180106_173242.jpg


Thanks a lot for all your contributions!
 
#28
subdude67 said:
Thanks a lot for all the input, here is a summary:

The amp was plugged in but not running when the surge happened. I used the amp the evening before and it worked as usual.
The fuse that is inside the power socket of the cable is OK as is the fuse inside the amplifier, I have checked both with my multimeter and I have tried 2 other power cables to be sure. I have also tried sockets in various places that I know are working with other appliances plugged in, same result.

I am no electrician but from what I understand the ampere's are what would blow a fuse, not the volts?
A tech from the power company told me that during the 2 hour surge there was 400 volts on both the hot and neutral lines of the grid, is that why everything got toasted even if it was not actually switched on?

here some pictures from the inside:

View attachment 2866240



View attachment 2866241
View attachment 2866242

Thanks a lot for all your contributions!
Click to expand...
Your understanding of all of this is a little bit off.
Fuses blow based on the current, but if the voltage is higher than normal, this can create an over current situation.
You can't have current without voltage and when the voltage increases in a circuit, so can the current.

Did you have the meter set to Ohms when you checked the fuse?
Did you remove the fuse from the amp to test it?
YOU CANNOT TEST A FUSE WHILE IT IS INSTALLED. You may get a false reading telling you that it's OK.
 
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#30
David A. Davis said:
If when you measure the fuse, you have more than a couple of tenths resistance (0.2 is normal) replace the fuse. Being in your environment it would probably be wise to invest in a couple of spare fuses and power cables.
Click to expand...
You cannot make such a determination as you don't know the accuracy of the meter being used, how well it zeros out, or if the battery is in good shape. There are too many variables to apply absolute numbers.
 
#31
subdude67 said:
I have a TC Electronic BH 250.
A few days ago we had an electrical problem on the power grid and the voltage went up to almost 400 volts for about 2 hours. (I live in Africa in case you wonder.....) Every single light and appliance in the house got fried. My amp was plugged in but not running when this happened, however, since that day it doesn't work anymore, when i switch it on nothing happens.
Is it possible that the amp got damaged even though it was not running at the time?
Click to expand...
Maybe not. Most amps have internal fuses. Check with the manufacturer.
 
#34
I have used a multmeter on the setting that beeps when there is continuity.
Both fuses, the one inside the power socket of the cable and the fuse inside the amp were removed and tested and both had continuity.
I also tested all 3 cables that I used to check on 7 different sockets that were all working with other electrical equipment.
 
#35
I remember reading a story here from a member who had a GK combo or powered cab (can't remember which) that hummed even when switched off. Which we all thought was extremely strange. Turned out that it was designed such that the primary side of the power supply transformer is always hot/on when plugged in. Strange but true. The power switch just closes the secondary side of the transformer. So if your amp is designed this way (I have no idea) it could be that the power supply transformer is ruined. Put your meter across the power lead socket in the amp with the switch ON. You should see some resistance. If not, you're no closer to a solution but you will know something has definitely blown.
 
#36
subdude67 said:
I have used a multmeter on the setting that beeps when there is continuity.
Both fuses, the one inside the power socket of the cable and the fuse inside the amp were removed and tested and both had continuity.
I also tested all 3 cables that I used to check on 7 different sockets that were all working with other electrical equipment.
Click to expand...
OK. Sounds like you 'be done all that you can do.
I'm afraid it will need to go to a tech for repairs
 
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#37
David A. Davis said:
Ok, so let's send the meter (with the battery that will be used) and the leads to be calibrated. Give me a break.
Click to expand...
No sir. You need to give the OP a break. Telling him that he should measure X resistance or less without knowing what he is using to make that measurement will just ad to his confusion. And please bear in mind that he has said he doesn't know much about electronics. He's likely pretty well overwhelmed by all this to start with.
 
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#38
On some products there is a standby supply always connected across the line. If this is the case, the standby supply is almost surely damaged. The standby supply handles housekeeping tasks along with power-up and auto voltage configuration before the main supply stabilizes.

This is not user serviceable.
 
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#39
The guy told you that there was 400V on the grid but that doesn't tell you if there was a large voltage spike at the very start which would jump on/off switches and bridge traces if large enough. Switches and components have breakdown values and if exceeded, the magic smoke disappears.

If you checked the fuse and it's ok, unless you can see burned up components you'll likely have a very difficult time finding the reason your amp isn't working. Burned up traces can be buried within the boards and unless you have a test sheet from the manufacturer and a scope, you'll never find the problem.

Most electronics are now replaced when damaged instead of repaired so though I hope you find the problem and it's a quick repair, I fear your amp is a goner.
 
#40
David Jayne said:
I remember reading a story here from a member who had a GK combo or powered cab (can't remember which) that hummed even when switched off. Which we all thought was extremely strange. Turned out that it was designed such that the primary side of the power supply transformer is always hot/on when plugged in. Strange but true. The power switch just closes the secondary side of the transformer. So if your amp is designed this way (I have no idea) it could be that the power supply transformer is ruined. Put your meter across the power lead socket in the amp with the switch ON. You should see some resistance. If not, you're no closer to a solution but you will know something has definitely blown.
Click to expand...

I have done as you suggested, when the switch os in the off position the reading on the meter is 0, when I switch it on it reads 1.322 MΏ
 

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