I just bought this little 12 watt Ace Tone Elite. It needs a bit of work, so I thought I'd hop on here and see if I could get some questions answered.
First of all, the pictures are here and here.
- The first thing I need to do, of course, is replace the 2-prong cord with a 3-prong cord. So my question is, how do I safely get to the underside of the power board so that I can drain the filter cap? Or can I do it without getting underneath it? Should I just screw the ground from the 3-prong directly into the power board?
- I replaced the 12AX7 (far right) but I also need to replace the other two tubes as well (the one on the left is a 6GW8 [triode + pentode] and the middle one is a 6AV6 [duplex diode + triode]).
- I'm assuming I need to replace the filter cap (just based on apparent age). Do I? Do I need to replace any of the other caps?
The amp sounds pretty good, but the tremolo and reverb aren't currently working. I had hoped that they were running off of the 12AX7 and that replacing that would have fixed it, but that didn't work. I suppose the triodes on the other two tubes could be for the tremolo and reverb, but I would think if the triode in the 6GW8 was out, then the pentode would be dead too), so I'm guessing something else is to blame for the tremolo and reverb being out. If anyone has ideas on that, I'd be interested in hearing them.
Once I get the power board off I'll pull the other board and draw the schematic for it and I'll post it here, as I have been unable to find a schematic for the Elite and I'm dying to know how it's put together.
Finally, it has no standby switch. Should I add one?
Any other recommendations? So excited about my first tube amp and glad to have it be one with a little character.
BTW, at $90, how'd I do?
First of all, the pictures are here and here.
- The first thing I need to do, of course, is replace the 2-prong cord with a 3-prong cord. So my question is, how do I safely get to the underside of the power board so that I can drain the filter cap? Or can I do it without getting underneath it? Should I just screw the ground from the 3-prong directly into the power board?
- I replaced the 12AX7 (far right) but I also need to replace the other two tubes as well (the one on the left is a 6GW8 [triode + pentode] and the middle one is a 6AV6 [duplex diode + triode]).
- I'm assuming I need to replace the filter cap (just based on apparent age). Do I? Do I need to replace any of the other caps?
The amp sounds pretty good, but the tremolo and reverb aren't currently working. I had hoped that they were running off of the 12AX7 and that replacing that would have fixed it, but that didn't work. I suppose the triodes on the other two tubes could be for the tremolo and reverb, but I would think if the triode in the 6GW8 was out, then the pentode would be dead too), so I'm guessing something else is to blame for the tremolo and reverb being out. If anyone has ideas on that, I'd be interested in hearing them.
Once I get the power board off I'll pull the other board and draw the schematic for it and I'll post it here, as I have been unable to find a schematic for the Elite and I'm dying to know how it's put together.
Finally, it has no standby switch. Should I add one?
Any other recommendations? So excited about my first tube amp and glad to have it be one with a little character.
BTW, at $90, how'd I do?
Okay, found the answer to my first question with the help of the photos here, I was able to determine how he removed the chassis without removing the boards, and from there, I can get to the filter cap, so that's awesome.
Found some tubes to replace the 6GW8 and 6AV6, so those are on the way.
I'll try to draw a schematic for it tomorrow.
Found some tubes to replace the 6GW8 and 6AV6, so those are on the way.
I'll try to draw a schematic for it tomorrow.
Here's the underside of the filter cap. I have no experience with can caps. I'm assuming the two red terminals are + and the black is ground? So can I just run a 10K resistor from each red to black for a few mins to drain it? I'm assuming that resistor (that connects the two red terminals) isn't a bleeder resistor. Or is it?
Moving to instruments and amps where the guitar guys hang out, and the right place for threads on guitar amps.
The resistor connecting the two red terminals on the cap is a 'dropper' resistor. It looks like it is 1k. To drain the cap, I would recommend making up a short flexible lead with a 10k resistor in the middle (in series) and small alligator clips at each end. Using one hand only, clip to the black terminal first and then to the red. Keep in mind that if the two clips accidently touched you would get a massive spark.
No need for a standby switch, IMHO.
How old do you think the caps are? They look in fairly good condition in the photos. If they are too old you may want to replace the other 4(?) electrolytic caps on the circuit board.
No need for a standby switch, IMHO.
How old do you think the caps are? They look in fairly good condition in the photos. If they are too old you may want to replace the other 4(?) electrolytic caps on the circuit board.
Thank you.
@Malcolm Irving, the big caps are Rubycon. I can't find them in Rubycon's catalog and mine are all gray, but if you do a Google image search on Rubycon capacitors, they're almost all black. I can hardly find a gray one among them. Also, the big filter cap has some discoloration on the back side that makes it look a bit older.
That said, surely they're not the originals. They wouldn't last that long, would they?
A bunch of the smaller axial caps are oil caps. Is that normal/good/bad?
I'm fairly certain on this, but just to make sure (mains voltage makes me paranoid), when I replace the power cord, it doesn't matter which side's hot and which side's neutral, right? And for the ground, can I just drill a hole and do a screw & nut into the power chassis with a star washer?
In this pic, the round black thing with the coiled wires coming out of either side is apparently a diode (I only know this because it has diode symbol on the case and the code "68A" on it). Does anyone know what kind of diode this is? I've never seen anything like it.
@Malcolm Irving, the big caps are Rubycon. I can't find them in Rubycon's catalog and mine are all gray, but if you do a Google image search on Rubycon capacitors, they're almost all black. I can hardly find a gray one among them. Also, the big filter cap has some discoloration on the back side that makes it look a bit older.
That said, surely they're not the originals. They wouldn't last that long, would they?
A bunch of the smaller axial caps are oil caps. Is that normal/good/bad?
I'm fairly certain on this, but just to make sure (mains voltage makes me paranoid), when I replace the power cord, it doesn't matter which side's hot and which side's neutral, right? And for the ground, can I just drill a hole and do a screw & nut into the power chassis with a star washer?
In this pic, the round black thing with the coiled wires coming out of either side is apparently a diode (I only know this because it has diode symbol on the case and the code "68A" on it). Does anyone know what kind of diode this is? I've never seen anything like it.
I am not familiar with the caps or diode you have in there - hope others will chip in. I also don't know the USA electrical safety requirements well enough to comment on changing to a 3-prong cord. I hope some experts on here will be able to advise.
Hi, I have some thoughts:
I am glad safety is important to you. But it should also be based upon knowledge of your situation. Get out a volt meter and see if any voltages remain in there. That does two things. it tells you your discharge has worked, plus bu doing that first you also know if there was a charge to start with. Every time you turn off the amp, it discharges itself soon enough.
Yes, the ground wire of a three wire mains cord is screwed to the chassis.
You replaced the 12AX7, but why do you need to replace the other two tubes? You said the amp sounds good.
Remember, this is just a small guitar amp, not a precision device.
Some electrolytic caps do dry out and need replacement, but others many times soldier on for decades. I would say surely those ARE original caps. But before just replacing them all, finish repairing the amp to see how they are. These caps are 40-50 years old, you won't find them in the catalogs. Besides, this amp was made in Japan, and the specific parts they used might never have been available in the USA.
There is no reason to believe this. Tubes fail in just one section all the time.
No, you don't need a standby switch.
The diode type? An OLD diode. It is just a rectifier, a plain old 1N4007 would be fine in its place. But it seems to be working, so why change?
The mains cord? You have hot and neutral. You should wire the hot to the fuse holder, from there a wire to the power switch, and from that to one of the transformer primary wires. The Neutral goes directly to the other primary wire.
Reverb. Have you checked the reverb unit? If one end of that is open, you get no reverb. I see two shielded cables running off, presumably to the reverb unit.
Please do draw up a schematic.
I am glad safety is important to you. But it should also be based upon knowledge of your situation. Get out a volt meter and see if any voltages remain in there. That does two things. it tells you your discharge has worked, plus bu doing that first you also know if there was a charge to start with. Every time you turn off the amp, it discharges itself soon enough.
Yes, the ground wire of a three wire mains cord is screwed to the chassis.
You replaced the 12AX7, but why do you need to replace the other two tubes? You said the amp sounds good.
Remember, this is just a small guitar amp, not a precision device.
Some electrolytic caps do dry out and need replacement, but others many times soldier on for decades. I would say surely those ARE original caps. But before just replacing them all, finish repairing the amp to see how they are. These caps are 40-50 years old, you won't find them in the catalogs. Besides, this amp was made in Japan, and the specific parts they used might never have been available in the USA.
There is no reason to believe this. Tubes fail in just one section all the time.
No, you don't need a standby switch.
The diode type? An OLD diode. It is just a rectifier, a plain old 1N4007 would be fine in its place. But it seems to be working, so why change?
The mains cord? You have hot and neutral. You should wire the hot to the fuse holder, from there a wire to the power switch, and from that to one of the transformer primary wires. The Neutral goes directly to the other primary wire.
Reverb. Have you checked the reverb unit? If one end of that is open, you get no reverb. I see two shielded cables running off, presumably to the reverb unit.
Please do draw up a schematic.
@Enzo Wow! Thanks for all that. I did multimeter the caps. The 2 10MFD axials were at about 27V (I drained them with a resistor), but the big 40MFD was already depleted by the time I got around to checking it.
The reason for replacing the other 2 tubes is in the hopes that the tremolo and/or reverb will come back to life. The tremolo actually did come on at one point, so I know it has the possibility of working. The guy I bought it from said the reverb has come on for him as well, so I'm hoping replacement of the 6GW8 and 6AV6 (both of which have triodes) will fix one or both. If not, I'll have some spare tubes, which is fine too. I'd want a spare set on standby anyway. But if, as you say, tubes fail in just one section all the time, then all the more reason to check to see if this is the cause of the tremolo and reverb being out.
Thanks for the info on the 3-prong cable. Currently one wire goes to the fuse and the other goes to the on/off switch (which is also the reverb knob). So I'll do hot to fuse holder, neutral to switch and ground to the power chassis.
The caps actually seem to be in pretty good shape, especially if they're originals. Wow! Really, the inside of this amp seems to be in very good condition for its age.
The reverb tank is really small. It's maybe 3/4" by 3/4" by 6" (You can see it in the third photo down on this page, to the right of the speaker.) Yes, those two gray wires (each with a pair of wires inside) go to the reverb tank. What do you mean if "one end of that is open"?
I lost a day because my wife had hidden away my soldering iron, so I didn't get to really crack the thing open until last night (had to desolder the speaker and output transformer connections to get access to everything). So I've only completed about 1/4 or maybe 1/3 of the schematic. I've never actually drawn a schematic from an existing circuit like this and I'm finding it to be more challenging than I expected. It was really slow going until I realized I could back-light the board with a flashlight to be able to see the traces (before that I was turning the board over every few seconds to try to see where stuff was and that was super slow!).
I'll post the schematic once I get it done. Probably this weekend.
The reason for replacing the other 2 tubes is in the hopes that the tremolo and/or reverb will come back to life. The tremolo actually did come on at one point, so I know it has the possibility of working. The guy I bought it from said the reverb has come on for him as well, so I'm hoping replacement of the 6GW8 and 6AV6 (both of which have triodes) will fix one or both. If not, I'll have some spare tubes, which is fine too. I'd want a spare set on standby anyway. But if, as you say, tubes fail in just one section all the time, then all the more reason to check to see if this is the cause of the tremolo and reverb being out.
Thanks for the info on the 3-prong cable. Currently one wire goes to the fuse and the other goes to the on/off switch (which is also the reverb knob). So I'll do hot to fuse holder, neutral to switch and ground to the power chassis.
The caps actually seem to be in pretty good shape, especially if they're originals. Wow! Really, the inside of this amp seems to be in very good condition for its age.
The reverb tank is really small. It's maybe 3/4" by 3/4" by 6" (You can see it in the third photo down on this page, to the right of the speaker.) Yes, those two gray wires (each with a pair of wires inside) go to the reverb tank. What do you mean if "one end of that is open"?
I lost a day because my wife had hidden away my soldering iron, so I didn't get to really crack the thing open until last night (had to desolder the speaker and output transformer connections to get access to everything). So I've only completed about 1/4 or maybe 1/3 of the schematic. I've never actually drawn a schematic from an existing circuit like this and I'm finding it to be more challenging than I expected. It was really slow going until I realized I could back-light the board with a flashlight to be able to see the traces (before that I was turning the board over every few seconds to try to see where stuff was and that was super slow!).
I'll post the schematic once I get it done. Probably this weekend.
A multimeter set to continuity (mine beeps) is great for reverse engineering. Instead of just visually tracing things you use the meter, if it beeps and shows 0 ohms then it is a part of that node.
Replacing tubes like that is just guessing. Just because tubes are in sockets doesn;t mean that are the likely problem here.
If the reverb used to come and go, then I'd look for corroded connectors on it, or if it is hard wired at the reverb unit, check the solder.
REverb units are mostly dynamic types. There is a coil of wire at each end. If that goes open, then no circuit is made. Just as if a speaker voice coil goes open, it makes no sound. A smaller percentage are awful piezo types. They use a piezo crystal at each end. Those will not have continuity even when good.
This is the value of a schematic, rather than guessing "maybe it's this tube" or "maybe it is this cap", we look at the circuit. When I draw a schematic, especially on a small relatively simple amp like this, I start with the tubes. I assume the pentode drives the speaker. verify that the output transformer is wired to its plate pin. The output stage will look a lot like this:
http://bmamps.com/Schematics/fender/champ_5f1_schem.pdf
Imagine if I was making that drawing, I'd draw the pentode and two triodes on a sheet, and then fill in the other stuff. Your drawing should look a lot like that one.
If the reverb used to come and go, then I'd look for corroded connectors on it, or if it is hard wired at the reverb unit, check the solder.
REverb units are mostly dynamic types. There is a coil of wire at each end. If that goes open, then no circuit is made. Just as if a speaker voice coil goes open, it makes no sound. A smaller percentage are awful piezo types. They use a piezo crystal at each end. Those will not have continuity even when good.
This is the value of a schematic, rather than guessing "maybe it's this tube" or "maybe it is this cap", we look at the circuit. When I draw a schematic, especially on a small relatively simple amp like this, I start with the tubes. I assume the pentode drives the speaker. verify that the output transformer is wired to its plate pin. The output stage will look a lot like this:
http://bmamps.com/Schematics/fender/champ_5f1_schem.pdf
Imagine if I was making that drawing, I'd draw the pentode and two triodes on a sheet, and then fill in the other stuff. Your drawing should look a lot like that one.
Ah, I see. Open as in open circuit. I'll check into that. I was under the impression, from the guy I bought it from, that when the tremolo worked, the reverb worked (that was not my experience, but that was how I understood what he was telling me when I bought it) so that was why I was expecting that maybe the 12AX7 (which I already had handy) might fix them both.
And while you're right, replacing the tubes is taking a guess, buying new tubes serves another purpose, which is to give me some idea of what the amp's sound range is. That is, I think it sounds good now, but who knows, with new tubes in it, it might sound better (or it might sound like crap). Lacking a tube tester, until I replace the tubes, I won't have a clue. The $30 expense won't break the bank
Tremolo circuits I've seen are generally triode based oscillators. The only thing that can usually fail in those is a resistor, capacitor, or tube (or, I suppose, a solder joint, but the soldering appears pretty competent on this). Once I figure out where it is in the circuit, I'll be in a better position to test it.
As for the schematic, I started at the power cord and I made it all the way to the pentode (well, screen grid and the plate) and 1 side of the output transformer.
The turret board on a champ is a bit easier to diagram out. It helps having all the components evenly spaced in a line. On this board, the components are all over the place in no particular order and the traces are equally all over the place, on the opposite side of the board, with one or two caps soldered on the trace side as well.
This is also a bit more complex of a circuit than the champ because it's got 4 triodes instead of 2. I'm assuming the setup is 2 triodes for gain stage, 1 for tremolo oscillator and 1 to drive the reverb.
And while you're right, replacing the tubes is taking a guess, buying new tubes serves another purpose, which is to give me some idea of what the amp's sound range is. That is, I think it sounds good now, but who knows, with new tubes in it, it might sound better (or it might sound like crap). Lacking a tube tester, until I replace the tubes, I won't have a clue. The $30 expense won't break the bank
Tremolo circuits I've seen are generally triode based oscillators. The only thing that can usually fail in those is a resistor, capacitor, or tube (or, I suppose, a solder joint, but the soldering appears pretty competent on this). Once I figure out where it is in the circuit, I'll be in a better position to test it.
As for the schematic, I started at the power cord and I made it all the way to the pentode (well, screen grid and the plate) and 1 side of the output transformer.
The turret board on a champ is a bit easier to diagram out. It helps having all the components evenly spaced in a line. On this board, the components are all over the place in no particular order and the traces are equally all over the place, on the opposite side of the board, with one or two caps soldered on the trace side as well.
This is also a bit more complex of a circuit than the champ because it's got 4 triodes instead of 2. I'm assuming the setup is 2 triodes for gain stage, 1 for tremolo oscillator and 1 to drive the reverb.
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Yep. 174 ohm (use an ohmmeter? I should have thought of that. lol). Okay, sweet. On a completely different subject I'm using DipTrace to draw out the schematic, but the triodes that it produces are the kinds where the filaments are also the cathode (so 2 cathode/heater connections, 1 grid and 1 plate connector). Since I'm not showing the heater connections anyway, I'm just treating one of the heater connections as the cathode.... Anyone know if there's a way to get a standard triode with separate heater & cathode connections in the DipTrace software?
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Okay, I have another question. The 6AV6 tube has 2 diodes. Only one of them is used. So in terms of how it operates as a diode, the cathode is shared among the 2 diodes and the triode (Pin 2) and the Pin 6 is the #1 diode anode, correct? So in the schematic I'd draw a diode going from ground, which is what Pin 6 is connected to, to the cathode, correct?
Okay, I'm still not done, but I'm getting pretty close. This is what I have so far.
I still need to trace the grid of V4. I'm not really sure how to label the two sides of the reverb tank. I don't know which is which.
First of all: It's my first schematic of anything involving more than 1 or 2 transistors, so take it easy on me. I spent a good chunk of my day yesterday working on this. Looking at it now, I would lay it all out very differently if I were going to start over, but that project is for another day.
As I mentioned before, the triodes in DipTrace use the heaters as a cathode, so since I'm not wiring the heaters in my schematic, I use the heaters of the triode as the cathode even though that's not the style of the tubes I'm using.
Even though I've got 2 ground lines in the schematic, it all grounds in the same place. I was just doing that to reduce the number of times my traces cross.
Also, I'm not entirely sure of the accuracy of what I have there. I spent a lot of time last night fixing problems in my schematic. Because there are several ground traces and they're unlabeled, there were a few times I'd trace a line to ground, not realize it was ground and start tracing it back up some other line, only to realize later that I had hit ground and gone back up. So I've had to clean up that a few times.
I'd appreciate any comments o stuff that looks like it might not be right. BTW, the pot for the tremolo is floating on the one side.
I still need to trace the grid of V4. I'm not really sure how to label the two sides of the reverb tank. I don't know which is which.
First of all: It's my first schematic of anything involving more than 1 or 2 transistors, so take it easy on me. I spent a good chunk of my day yesterday working on this. Looking at it now, I would lay it all out very differently if I were going to start over, but that project is for another day.
As I mentioned before, the triodes in DipTrace use the heaters as a cathode, so since I'm not wiring the heaters in my schematic, I use the heaters of the triode as the cathode even though that's not the style of the tubes I'm using.
Even though I've got 2 ground lines in the schematic, it all grounds in the same place. I was just doing that to reduce the number of times my traces cross.
Also, I'm not entirely sure of the accuracy of what I have there. I spent a lot of time last night fixing problems in my schematic. Because there are several ground traces and they're unlabeled, there were a few times I'd trace a line to ground, not realize it was ground and start tracing it back up some other line, only to realize later that I had hit ground and gone back up. So I've had to clean up that a few times.
I'd appreciate any comments o stuff that looks like it might not be right. BTW, the pot for the tremolo is floating on the one side.
Okay, I'm done with the initial schematic. Here it is in all its glory. If anyone wants to mess with the schematic, the DipTrace file is here.
This may not be entirely correct (in fact, I'd bet money on it), but it's a good start.
I'm not entirely sure of the stuff between the plates of V4 and V5. I'm going to run through all that again later (probably not today).
In the meantime, I'm going to go ahead and solder on the new power cable, throw in the replacement 6GW8 and 6AV6 tubes, and see how it does.
This may not be entirely correct (in fact, I'd bet money on it), but it's a good start.
I'm not entirely sure of the stuff between the plates of V4 and V5. I'm going to run through all that again later (probably not today).
In the meantime, I'm going to go ahead and solder on the new power cable, throw in the replacement 6GW8 and 6AV6 tubes, and see how it does.
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Got the amp put back together. Got the new tubes in. I discovered that there was a bad connection to the reverb unit, so I resoldered it.
But the reverb and tremolo still aren't working. So I guess the next step is to re-check the reverb connections and I guess I'll check all the caps that are part of the tremolo circuit and see if any of them are bad.
But the reverb and tremolo still aren't working. So I guess the next step is to re-check the reverb connections and I guess I'll check all the caps that are part of the tremolo circuit and see if any of them are bad.
Using the Ace Tone Model 101 found on the net as a guide, here is a possible schematic for the Elite using 6GW8 and 6AV6. PLEASE USE IT AT YOUR OWN RISK.
BTW, the schematic that you posted is not legible, I can only see a thumbnail.
BTW, the schematic that you posted is not legible, I can only see a thumbnail.
An externally hosted image should be here but it was not working when we last tested it.
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