Hi guys,
First things first, i usually know enough about this kinda stuff to not worry but after i noticed a fairly burnt el34 in my new (second hand) amp, i want to just make sure everything is correct.
The thing i need a bit of help with is the markings on the inlet - it says to use 115v (even though its a UK made amp). Might i add there is no voltage switch and the dude i bought it from ran it on 240v. This leads me to belive its an autotransformer or some auto switching type or the conpany suck at marking their amps.
The other concern is that the fuse in the amp is a T2A but from the markings, it says to use a T2A for 115v (or a 115v T2A). This makes me worry as the output tube is slightly burnt around the mica and has a faded logo. I suppose this could be general wear but it might be a sign of a failing tube where i would expect the fuse to blow (it hasn't)
I just want to clear all of this up to prevent further damage to the amp.
Thanks.
First things first, i usually know enough about this kinda stuff to not worry but after i noticed a fairly burnt el34 in my new (second hand) amp, i want to just make sure everything is correct.
The thing i need a bit of help with is the markings on the inlet - it says to use 115v (even though its a UK made amp). Might i add there is no voltage switch and the dude i bought it from ran it on 240v. This leads me to belive its an autotransformer or some auto switching type or the conpany suck at marking their amps.
The other concern is that the fuse in the amp is a T2A but from the markings, it says to use a T2A for 115v (or a 115v T2A). This makes me worry as the output tube is slightly burnt around the mica and has a faded logo. I suppose this could be general wear but it might be a sign of a failing tube where i would expect the fuse to blow (it hasn't)
I just want to clear all of this up to prevent further damage to the amp.
Thanks.
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You are making a lot of very dangerous assumptions.
You can´t be uncertain about equipment mains voltge and in a Devil may care attitude "just plug it in to see if it works"
Is it a Guitar amplifier?
That label actually reads:
"Mains input 120VA (VoltAmperes, not plain Volts) 115V@1A" (which is roughly 120VA)
It shows 2 Voltage and Fuse pairs, so it presumably *does* have some way of switching voltage; it might a visible switch or you rewire transformer primary, either by soldering or plugging certain connectors on certain tabs.
Besides brand and model (we might find a manual or schematic), open that chassis and post a couple pictures showing power transformer and its wiring.
Do NOT plug that amp into mains untill you are certain of its proper voltage.
No, No and No.
You can´t be uncertain about equipment mains voltge and in a Devil may care attitude "just plug it in to see if it works"
Absolutely irrelevant and completely useless to determine whether the amplifier is set to 120V or 240V mains.
You don´t tell us what that amplifier is, we need brand and model.
Is it a Guitar amplifier?
Agree on that.
That label actually reads:
"Mains input 120VA (VoltAmperes, not plain Volts) 115V@1A" (which is roughly 120VA)
It shows 2 Voltage and Fuse pairs, so it presumably *does* have some way of switching voltage; it might a visible switch or you rewire transformer primary, either by soldering or plugging certain connectors on certain tabs.
Besides brand and model (we might find a manual or schematic), open that chassis and post a couple pictures showing power transformer and its wiring.
Do NOT plug that amp into mains untill you are certain of its proper voltage.
It is a bit confusing and not marked well for the actual voltage being used. But the marking that is there for the Mains input is 120V-A. Volt/Amps. Or Watts. It is just as good as 230v and 1/2 Amp, which is why the recommended fuse for 230v is smaller, 1A. But you may have to open it up to inspect the primary side to see if there is a diagram for the leads to swap it to 120v service. I don't know about UK 240v sockets for the cord. Are the prongs in that socket on the back the same as a 120v service cord would plug onto?
Thanks for the reply,
I'll be honest, i really didnt think my original post through since I'm really tired. Anyways, i can tell you that the amp is an Ashdown Peacemaker 60 guitar amp. I thought about contacting Ashdown however the peacemaker series has been discontinued. The one downside to the amp is that the design is quite poor because the chassis cannot physically be removed without ripping off two blocks on the back. I also noticed that there is a silver permanent marker that looks like someone wrote '120' then wrote over '240'. From what i can see on google, its from the factory as they didnt use stickers. As i said, I feel confident that its 240v however as stated in my last paragraph, i have no idea what fuse i would need to use and if this fuse is correct.
I do apologise if there is a policy against posting the schematic - i only have it downloaded and no link.
I'll be honest, i really didnt think my original post through since I'm really tired. Anyways, i can tell you that the amp is an Ashdown Peacemaker 60 guitar amp. I thought about contacting Ashdown however the peacemaker series has been discontinued. The one downside to the amp is that the design is quite poor because the chassis cannot physically be removed without ripping off two blocks on the back. I also noticed that there is a silver permanent marker that looks like someone wrote '120' then wrote over '240'. From what i can see on google, its from the factory as they didnt use stickers. As i said, I feel confident that its 240v however as stated in my last paragraph, i have no idea what fuse i would need to use and if this fuse is correct.
I do apologise if there is a policy against posting the schematic - i only have it downloaded and no link.
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The markings are typical for a transformer with 115/230V mains input. The usual setup is for two 115V primaries, internally wired in parallel for 115V and in series for 230V. Not sure about the 'kettle' input socket, but not uncommon to find that on an amplifier.
As said then, you will need to access the transformer primary itself, where you will probably find the necessary bridges, hopefully with annotations to clearly indicate what should be what.
Further also as asked, can you name the brand and type of amplifier? You mention the EL34 'burnt' around the mica - if you mean the base, that is not mica but other synthetic stuff (the only mica is inside the tube - hopefully not burnt there!). It also suggests that the tubes may be working upside down as in some guitar amplifiers; not good practice but there it is.
Also, where did you get it from? (Someone in what country?)
Easiest would be then to access the transformer internal connections which should not be difficult, otherwise a brand and type so that more information can be had.
P.S: I typed simultaneously to the previous post; will peruse the schematic.
As said then, you will need to access the transformer primary itself, where you will probably find the necessary bridges, hopefully with annotations to clearly indicate what should be what.
Further also as asked, can you name the brand and type of amplifier? You mention the EL34 'burnt' around the mica - if you mean the base, that is not mica but other synthetic stuff (the only mica is inside the tube - hopefully not burnt there!). It also suggests that the tubes may be working upside down as in some guitar amplifiers; not good practice but there it is.
Also, where did you get it from? (Someone in what country?)
Easiest would be then to access the transformer internal connections which should not be difficult, otherwise a brand and type so that more information can be had.
P.S: I typed simultaneously to the previous post; will peruse the schematic.
Follow:
.... and my previous reply also the victim of a late night!
If the previous owner ran it on 240V as you said then the transfomer is most probably internally set for 240V - otherwise there would have been a real grand catastrophy inside, tubes all burnt out and more. One can then presume that the setting is for two primary windings in series; 240V mains input.
Our luck; the schematic does not show the power supply! Anyway, for any kind of further troubleshooting you would need a dvm - and be very careful of high d.c. voltages around!
I am also calling it a night here - hope you sleep tight!
.... and my previous reply also the victim of a late night!
If the previous owner ran it on 240V as you said then the transfomer is most probably internally set for 240V - otherwise there would have been a real grand catastrophy inside, tubes all burnt out and more. One can then presume that the setting is for two primary windings in series; 240V mains input.
Our luck; the schematic does not show the power supply! Anyway, for any kind of further troubleshooting you would need a dvm - and be very careful of high d.c. voltages around!
I am also calling it a night here - hope you sleep tight!
CE logo tells me 230V/50Hz (240V/50Hz for UK)
A 120V trafo on a 240V mains should be carbonized.
Guitar amplifier tells me that this is the wrong forum. 😀
A 120V trafo on a 240V mains should be carbonized.
Guitar amplifier tells me that this is the wrong forum. 😀
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Thanks for the replies everyone, they have been really useful. I noticed a very recent pass test sticker on it so i think it should be good to go. Only one way to find out 😀
Boom test, put the power on, stay far away, if it does not explodes then it is for 240V/50Hz.
Replace the fuse as indicated, the MacGyver solution is very dangerous, I see it daily on TVs... people are reckless...
Today fuses are not reliable, so anything between 1A and 2A should be fine.
The fuse is already protected by Murphy's laws, it is there only to avoid the equipment caught on fire.
Replace the fuse as indicated, the MacGyver solution is very dangerous, I see it daily on TVs... people are reckless...
Today fuses are not reliable, so anything between 1A and 2A should be fine.
The fuse is already protected by Murphy's laws, it is there only to avoid the equipment caught on fire.
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The ECC83 supplies are labeled HT1, HT2, and HT3 on the schematic, and they’re probably set between 200 and 330 volts. The DC voltage between the cathode and the plate of an ECC83 should be kept at or below 300 volts.
You can use a variac to slowly ramp up the voltage supplied to the amplifier and keep an eye on the ECC83 supply voltages with a voltage meter. Any good amp tech will have a variac, and they’ll know how to check that the voltages and currents are at reasonable values.
You can use a variac to slowly ramp up the voltage supplied to the amplifier and keep an eye on the ECC83 supply voltages with a voltage meter. Any good amp tech will have a variac, and they’ll know how to check that the voltages and currents are at reasonable values.
ok guys - tested it today. i plugged it in and got no pieces of glass shredding into me so thats a good sign 😀😀😀
whilst the amp is on standby, there is a damn loud hum (louder than my other amps) but i assume its just the PT (much larger than the ones in my other, smaller amps). but then i noticed something - that tube that looks burnt has no glowing filament which leads me to believe it really did die. i won't ask too many questions here since this is about the PT however i suspect i should replace the power tubes and see what happens. hopefully the original owner didn't replace the power tubes and thus naturally went as you would expect from hours of playing. the only way to truly know is to either open the amp up or just test with some ol' el34s.
whilst the amp is on standby, there is a damn loud hum (louder than my other amps) but i assume its just the PT (much larger than the ones in my other, smaller amps). but then i noticed something - that tube that looks burnt has no glowing filament which leads me to believe it really did die. i won't ask too many questions here since this is about the PT however i suspect i should replace the power tubes and see what happens. hopefully the original owner didn't replace the power tubes and thus naturally went as you would expect from hours of playing. the only way to truly know is to either open the amp up or just test with some ol' el34s.
If in time, Aran,
Don't switch on the amp with only one EL34 working. Because of a common cathode bias resistor the remaining EL34 will have too low bias and be overloaded. First get another EL34 before proceeding.
Is the loud hum over the loudspeaker or mechanical from the power transformer itself? If over the loudspeaker it might come from not having a balancing EL34 in place of the dead one. [I presume the EL34 anode voltage comes from the 'raw' end of the power supply, before any filtering, in which case there will be quite some ripple present (this will be 120 Hz, reasonably different from 60 Hz)].
Don't switch on the amp with only one EL34 working. Because of a common cathode bias resistor the remaining EL34 will have too low bias and be overloaded. First get another EL34 before proceeding.
Is the loud hum over the loudspeaker or mechanical from the power transformer itself? If over the loudspeaker it might come from not having a balancing EL34 in place of the dead one. [I presume the EL34 anode voltage comes from the 'raw' end of the power supply, before any filtering, in which case there will be quite some ripple present (this will be 120 Hz, reasonably different from 60 Hz)].
Yeah, the second i saw the deaf filament i switched the amp off. Ive ordered a matched pair of 34s so hopefully that will fix the problem.
I would assume its mechanical noise from the PT but i bet a dead filament contributed to the noise. It wasn't coming through the speakers from what i could tell.
I would assume its mechanical noise from the PT but i bet a dead filament contributed to the noise. It wasn't coming through the speakers from what i could tell.
1. If you're not sure about the ac voltage your amp is set for, find that one out first!
That means to remove the amp from the cabinet and lok if its' visible. Maybe there are some hints on the power trafo.
If still no idea, apply the mains via a variac set to 110V and measure the heater voltage.
If 't's around 3.5V or so then the amp is set for 230V.
If around 6.5V then it's set for 110V.
NEVER CONNECT DIRECT TO THE MAINS IF THERE ANY DOUBTS ABOUT THE MAINS VOLTAGE!
And use a ligth bulb in series with the mains connection of the amp.
But you allready connected it to the mains in the hope it will not catch fire!
2. Measure all voltages around the power tubes (EL34) without tubes.
This will give you an idea if the voltages are correct and youcan insert the new tubes without fear. If the 1K resistors at pin 4 of the EL34's are gone, your new tube will die soon after getting red for a while.
3. If all voltages are present, come back first with the results before inserting the tubes, and the forum says ok, then insert the tubes.
Good luck and think before you proceed.
Also, be carefull when inside the amp.
Allways use one hand and the other on the back. In case you touch the High voltage!!!
That means to remove the amp from the cabinet and lok if its' visible. Maybe there are some hints on the power trafo.
If still no idea, apply the mains via a variac set to 110V and measure the heater voltage.
If 't's around 3.5V or so then the amp is set for 230V.
If around 6.5V then it's set for 110V.
NEVER CONNECT DIRECT TO THE MAINS IF THERE ANY DOUBTS ABOUT THE MAINS VOLTAGE!
And use a ligth bulb in series with the mains connection of the amp.
But you allready connected it to the mains in the hope it will not catch fire!
2. Measure all voltages around the power tubes (EL34) without tubes.
This will give you an idea if the voltages are correct and youcan insert the new tubes without fear. If the 1K resistors at pin 4 of the EL34's are gone, your new tube will die soon after getting red for a while.
3. If all voltages are present, come back first with the results before inserting the tubes, and the forum says ok, then insert the tubes.
Good luck and think before you proceed.
Also, be carefull when inside the amp.
Allways use one hand and the other on the back. In case you touch the High voltage!!!
Thanks for the detailed response, i feel pretty confident now and am fairly sure replacement tubes will fix the problem. If it doesn't than it looks like im going to have to literally break into the cabinet to check it.
Comparison of the EL34s (one on the right clearly has visible burn marks around the top mica and has a completely faded logo)
Comparison of the EL34s (one on the right clearly has visible burn marks around the top mica and has a completely faded logo)
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1) push pull tube amps balance most hum out because both plates are at the opposite ends of a transformer.
Now in yours, you have two (related) problems:
a) 1 tube is missing/dead so it does not balance anything.
b) the other one is underbiased, runs too hot, passes too much current, and increased ripple is free to appear outside.
2) good point, that amp *sucks* at labelling, doubly dangerous because we are talking potentially catastrophic mains voltage miswiring.
Checked other Ashdown products and that is a constant .
Stating: "power consumption 120VA" is fine; writing the 115V example is stupid dangerous since people may rightfully assume IS wired for 115V
To boot they show both mains voltage nd fuse pairs, but absolutely NO indication as which one is valid.
Standard practice in such cases is to silkscreen a small table with all possible and a red paint dot or at least (much easier to erase) black felt marking shows the proper one.
Or small stick on label.
None of that here.
3) to make things worse, User manual only states that "amplifier must be connected to proper mains voltage" .... if they only showed which is which !!!!!
4)even "worser" (he he 😉 ), amp schematic does not show any power transformer nor mains wiring.
Power supply only shows connector pins where transformer secondaries must be plugged. Weird.
5) if glued wood blocks forbid pulling chassis backwards, then it probably slides forward.
You might need to remove speaker panel first.
Post a couple closeup pictures showing bolts possibly holding the chassis, how the speaker panel is mounted, etc. , but be *certain* that chassis is removable, one way or the other.
The chassis might be sitting on side wooden "rails" or plain bolted to cabinet roof.
FWIW here´s links to user manual
http://ashdownmusic.com/files/uploads/Peacemaker.pdf
and full schematic
http://www.prowessamplifiers.com/schematics/images/Peacemaker_60.pdf
both equally obscure about mains voltage 🙁
In fact, Pacemaker 100 has a rotary mains voltage selector 100-120-220-240V freely accessible on the back, .... but shows just *one* fuse value: 5A , which may be fine for 100/120V but absolutely gross for 220/240.
Now in yours, you have two (related) problems:
a) 1 tube is missing/dead so it does not balance anything.
b) the other one is underbiased, runs too hot, passes too much current, and increased ripple is free to appear outside.
2) good point, that amp *sucks* at labelling, doubly dangerous because we are talking potentially catastrophic mains voltage miswiring.
Checked other Ashdown products and that is a constant .
Stating: "power consumption 120VA" is fine; writing the 115V example is stupid dangerous since people may rightfully assume IS wired for 115V
To boot they show both mains voltage nd fuse pairs, but absolutely NO indication as which one is valid.
Standard practice in such cases is to silkscreen a small table with all possible and a red paint dot or at least (much easier to erase) black felt marking shows the proper one.
Or small stick on label.
None of that here.
3) to make things worse, User manual only states that "amplifier must be connected to proper mains voltage" .... if they only showed which is which !!!!!
4)even "worser" (he he 😉 ), amp schematic does not show any power transformer nor mains wiring.
Power supply only shows connector pins where transformer secondaries must be plugged. Weird.
5) if glued wood blocks forbid pulling chassis backwards, then it probably slides forward.
You might need to remove speaker panel first.
Post a couple closeup pictures showing bolts possibly holding the chassis, how the speaker panel is mounted, etc. , but be *certain* that chassis is removable, one way or the other.
The chassis might be sitting on side wooden "rails" or plain bolted to cabinet roof.
FWIW here´s links to user manual
http://ashdownmusic.com/files/uploads/Peacemaker.pdf
and full schematic
http://www.prowessamplifiers.com/schematics/images/Peacemaker_60.pdf
both equally obscure about mains voltage 🙁
In fact, Pacemaker 100 has a rotary mains voltage selector 100-120-220-240V freely accessible on the back, .... but shows just *one* fuse value: 5A , which may be fine for 100/120V but absolutely gross for 220/240.
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