i recently received a 3 ch dual rectifier as a gift and was told it needed tubes so after getting my new set of tubes and installing them ,. i went through the warm up part took it off of standby heard the click that most amps have and had no output/sound i have been playing guitar for over 30 years and always been able to trouble shoot anything but i have never had to deal with a issue with a tube amp also i noticed that the power indicator light along with the front panel LEDs and footswitch lights are also out so after troubleshooting for a bit i found no power/heater in the preamp tubes can someone please help and shed some light ...and i hope im not breaking any rules with my post this is my first one
dual rectifier no preamp heater n no front panel lights
- Thread starter sledge760
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Welcome to the forum.sledge760 said:
Are your Power & Rectifier tube heaters working? Are the tubes in the correct locations?
Did you check to see if the pilot light bulb is good? Maybe it's burnt out?
Are you using the footswitch? If so, try switching through the channels using the channel selector knob on the back. Do the LED's now respond?
Dom
thank you Dom , yes sir all tubes are new all are correct all the 6l6's heaters light both 5u do to but the preamp tubes dont .yes pilot was bad but i replaced it with no results , although it was a radio shack bulb (correct bulb?) ,still out... and I have tried to use it with the FS unconnected no change in anything
so does the indicator lamp have anything to do with this?
thank you for your help
sledge
so does the indicator lamp have anything to do with this?
thank you for your help
sledge
The indicator lamp is only for the power. One you turn on the amp (in standby preferred), the indicator lamp next to the power switch should be lit.
Since I do not have the schematic for the Dual Rectifier, not sure which preamp tubes use the regulated supply and which have the AC heaters. Heaters for the power tubes are sourced from the filament transformer. The Rectifier tubes heater source is part of the diode circuit which is also sourced from the filament transformer. Note: the filament transformer is the same as the power transformer.
If some of the preamp tubes are not operating (no glow on the heaters) it is possible there is a short in one of the preamp tubes that is pulling the voltage regulator down to ground. If you remove the preamp tubes (all of them) and power up the amp, the channel indicators and footswitch would work, just no sound from the amp. I suspect it may be a cathode follower that is causing the issue. What preamp tubes did you use? I am uncertain to which tubes are Cathode Followers, it may be the last gain stage V3 and the effects loop V4. From what I have learned thus far, the Russian tubes do not tolerate the cathode follower circuits well and tend to short out or fail. Mesa branded (JJ) tubes work well as do the Chinese (Shuguang) tubes that have the small clips on the plates. I have both the current Shuguang and vintage Mesa Chinese tubes, the vintage Mesa tubes sound the best overall. In my Roadster, I am only using the Mesa stock tubes as I find this sounds great.
It is also possible that you have a short in one of the Rectifier tubes. If you have a multi meter, there should be no resistance when measured from pin 4 to pin 6, pin 4 to pin 2 or pin 8, pin 6 to pin 2 or pin 8. The heater on the rectifier tube is pin 2 to pin 8 and should be a low resistance. If you had a short in one of the Rectifier tubes, the fuse would be blown. Check your fuse for open circuit. This may be the cause for all lights including the power lamp to be out (note, the heaters would also be off). However, check the fuse anyway, if the glass is not clear and looks as if it was hazed over (foggy) even if it tests okay, replace it. I had a Rectifier tube short out on me in my Mark V which caused similar issues you described. Heaters were operating on the power tubes but the rest of the amp was dead. There was just enough voltage to drive the heaters on the power tubes which operates on a separate circuit than the rectifier tube. Not sure if the power lamp is sourced from the AC input or from the filament transformer (or dc supply of the low voltage section).
I hope this helps you find the issue.
Since I do not have the schematic for the Dual Rectifier, not sure which preamp tubes use the regulated supply and which have the AC heaters. Heaters for the power tubes are sourced from the filament transformer. The Rectifier tubes heater source is part of the diode circuit which is also sourced from the filament transformer. Note: the filament transformer is the same as the power transformer.
If some of the preamp tubes are not operating (no glow on the heaters) it is possible there is a short in one of the preamp tubes that is pulling the voltage regulator down to ground. If you remove the preamp tubes (all of them) and power up the amp, the channel indicators and footswitch would work, just no sound from the amp. I suspect it may be a cathode follower that is causing the issue. What preamp tubes did you use? I am uncertain to which tubes are Cathode Followers, it may be the last gain stage V3 and the effects loop V4. From what I have learned thus far, the Russian tubes do not tolerate the cathode follower circuits well and tend to short out or fail. Mesa branded (JJ) tubes work well as do the Chinese (Shuguang) tubes that have the small clips on the plates. I have both the current Shuguang and vintage Mesa Chinese tubes, the vintage Mesa tubes sound the best overall. In my Roadster, I am only using the Mesa stock tubes as I find this sounds great.
It is also possible that you have a short in one of the Rectifier tubes. If you have a multi meter, there should be no resistance when measured from pin 4 to pin 6, pin 4 to pin 2 or pin 8, pin 6 to pin 2 or pin 8. The heater on the rectifier tube is pin 2 to pin 8 and should be a low resistance. If you had a short in one of the Rectifier tubes, the fuse would be blown. Check your fuse for open circuit. This may be the cause for all lights including the power lamp to be out (note, the heaters would also be off). However, check the fuse anyway, if the glass is not clear and looks as if it was hazed over (foggy) even if it tests okay, replace it. I had a Rectifier tube short out on me in my Mark V which caused similar issues you described. Heaters were operating on the power tubes but the rest of the amp was dead. There was just enough voltage to drive the heaters on the power tubes which operates on a separate circuit than the rectifier tube. Not sure if the power lamp is sourced from the AC input or from the filament transformer (or dc supply of the low voltage section).
I hope this helps you find the issue.
I dont want to be rude or seem like a tech or no it all but could you please READ my post be for trying to help so we can get to the issue and not waste anyones time thank you.
bandit
like I thought was said in the starting post I have put all new tubes also changed the pilot lamp i also took all the power and rec tubes out to test them they have heaters ...... but preamps dont warm up NO GLOW with or with out the "large" tubes in the amp while its powered up (lets use the term "large" for the power and rec tubes) the preamp tubes still dont have heaters and of coures the fuse is good how would "big tubes " light or how would it make a clicking sound when its taken off standby? im only a newbee to this forum i have been playing on amps for 30+ years
so for all purpose lets assume i even know the basics of amp circuits my prob is i dont know the steps to take to check or what to check and where it is on this amp i hope im not confusing you or sounding ungrateful for your help or time that you are taking so if i am please accept my apologies
also ALL OF THE PRE AMP TUBES ARE NOT LIGHTING not just some and the only LED's that light is the one for the rectifier mode and yes i tried the diode mode test so the amp doesnt use the tubes and uses a silicone diode still same results
i have spent 2 weeks of doing research on this issure and cant fix it but then again i could have done other tests if i knew what i had to do in order to get a proper reading im very confused about what i have to do to test the pT and the OT and im using MESA BRAND TUBES ALL OF THEM ARE NEW
bandit
like I thought was said in the starting post I have put all new tubes also changed the pilot lamp i also took all the power and rec tubes out to test them they have heaters ...... but preamps dont warm up NO GLOW with or with out the "large" tubes in the amp while its powered up (lets use the term "large" for the power and rec tubes) the preamp tubes still dont have heaters and of coures the fuse is good how would "big tubes " light or how would it make a clicking sound when its taken off standby? im only a newbee to this forum i have been playing on amps for 30+ years
so for all purpose lets assume i even know the basics of amp circuits my prob is i dont know the steps to take to check or what to check and where it is on this amp i hope im not confusing you or sounding ungrateful for your help or time that you are taking so if i am please accept my apologies
also ALL OF THE PRE AMP TUBES ARE NOT LIGHTING not just some and the only LED's that light is the one for the rectifier mode and yes i tried the diode mode test so the amp doesnt use the tubes and uses a silicone diode still same results
i have spent 2 weeks of doing research on this issure and cant fix it but then again i could have done other tests if i knew what i had to do in order to get a proper reading im very confused about what i have to do to test the pT and the OT and im using MESA BRAND TUBES ALL OF THEM ARE NEW
I dont want to be rude or seem like a tech or no it all but could you please READ my post be for trying to help so we can get to the issue and not waste anyones time thank you.
bandit
like I thought was said in the starting post I have put all new tubes also changed the pilot lamp i also took all the power and rec tubes out to test them they have heaters ...... but preamps dont warm up NO GLOW with or with out the "large" tubes in the amp while its powered up (lets use the term "large" for the power and rec tubes) the preamp tubes still dont have heaters and of coures the fuse is good how would "big tubes " light or how would it make a clicking sound when its taken off standby? im only a newbee to this forum i have been playing on amps for 30+ years
so for all purpose lets assume i even know the basics of amp circuits my prob is i dont know the steps to take to check or what to check and where it is on this amp i hope im not confusing you or sounding ungrateful for your help or time that you are taking so if i am please accept my apologies
also ALL OF THE PRE AMP TUBES ARE NOT LIGHTING not just some and the only LED's that light is the one for the rectifier mode and yes i tried the diode mode test so the amp doesnt use the tubes and uses a silicone diode still same results
i have spent 2 weeks of doing research on this issure and cant fix it but then again i could have done other tests if i knew what i had to do in order to get a proper reading im very confused about what i have to do to test the pT and the OT
bandit
like I thought was said in the starting post I have put all new tubes also changed the pilot lamp i also took all the power and rec tubes out to test them they have heaters ...... but preamps dont warm up NO GLOW with or with out the "large" tubes in the amp while its powered up (lets use the term "large" for the power and rec tubes) the preamp tubes still dont have heaters and of coures the fuse is good how would "big tubes " light or how would it make a clicking sound when its taken off standby? im only a newbee to this forum i have been playing on amps for 30+ years
so for all purpose lets assume i even know the basics of amp circuits my prob is i dont know the steps to take to check or what to check and where it is on this amp i hope im not confusing you or sounding ungrateful for your help or time that you are taking so if i am please accept my apologies
also ALL OF THE PRE AMP TUBES ARE NOT LIGHTING not just some and the only LED's that light is the one for the rectifier mode and yes i tried the diode mode test so the amp doesnt use the tubes and uses a silicone diode still same results
i have spent 2 weeks of doing research on this issure and cant fix it but then again i could have done other tests if i knew what i had to do in order to get a proper reading im very confused about what i have to do to test the pT and the OT
Don't mind bandit2013, I'm sure he means well.sledge760 said:
He is right about all the filaments being from the same supply (Power Tranny tap), and I too would suspect something amiss in the preamp tubes (new tubes do fail) and/or sockets.
You could also call Mesa. They'll help troubleshoot, warranty or not.
Good luck,
Dom
I am only trying to help, and you do not need to be a tech to understand. I would probably do the following, which is a simple process of elimination. This may help you find the issue, however if the amp remains dead with no tubes in it, the issue is internal.
The focus of this test is to determine if there is an issue related to a tube or if it is something else that would require servicing.
For starters, the amp will power up without any of the tubes in the sockets. Obviously there will not be any sound from this test. It is meant to help find the tube that may be causing the issue. Remove all tubes (small and large including the Rectifier tubes) Make sure you keep the rectifiers separate from the power tubes so they do not get mixed up. The Manual of the amp has a tube socket guide in it, if you did not get the manual, you can download it from Mesa. Also there should be a plate with tube positions indicated on the inside of the amp. After removing all tubes, plug in the amp and turn on the power switch. leave the amp in standby. The LED's and power indicator lamp should be on. If it is not, there may be a loose wire internal to the amp or a failed part inside that is preventing the low voltage power supply from operating.
With tube amps, diagnosing issues can be accomplished by removing the tubes. With no tubes in the amp, preamp (small tubes) and power tubes (larger ones), there will be function of the low voltage circuits that control the LED's, channel switching, etc... Some of the preamp tubes have their heaters supplied by the low voltage circuit (DC heater) for refined sound and low noise. There are others that have the heaters powered by a low voltage AC circuit directly supplied by the filament transformer.
With no tubes in the amp at all, if you can get the power light to turn on and the channel lights on the footswitch to work that would be great. If no change, you need to have the amp serviced.
Suppose the lamps and LED's turn on, Great. The next step would be to turn the amp off and install one preamp tube and power the amp back on. If the LEDs and light are on, repeat until all the preamp tubes are installed. Just a simple process of elimination. A preamp tube can cause issues too. Keep the amp in stand by. If you can get all of the small preamp tubes installed and the lights are working, the next step would be installing the Rectifier tubes. Before installing the large tubes, verify that only the rectifier tube is being installed into the rectifier socket. Note, the octal receptacles are all the same on the amp, The manual and or plate should help you with what tube goes in what position. Generally the preamp tubes are all the same, some amps may use a lower gain tube on the effects loop such as a 12AT7. No fear if you install the wrong tube in that position, the amp will still operate but will not sound a good.
Install the first one. and turn the power on. If all LEDs come on with the power light, turn it off and install the next Rectifier tube and repeat. Continue the process with the power tubes, one at a time and turn on the power, Do not take the amp out of stand-by, if you do no harm will be done, just make sure you have a load on the speaker output.
During this process of elimination, if you encounter the same symptom (assuming the amp turns on) the last tube inserted would be the faulty part. You can almost consider it like a chain of Christmas tree lights, one bulb goes out and it kills the rest. That is a poor analogy but if a tube has an internal short, it may prevent the amp from turning on even thought the fuse is good.
The focus of this test is to determine if there is an issue related to a tube or if it is something else that would require servicing.
For starters, the amp will power up without any of the tubes in the sockets. Obviously there will not be any sound from this test. It is meant to help find the tube that may be causing the issue. Remove all tubes (small and large including the Rectifier tubes) Make sure you keep the rectifiers separate from the power tubes so they do not get mixed up. The Manual of the amp has a tube socket guide in it, if you did not get the manual, you can download it from Mesa. Also there should be a plate with tube positions indicated on the inside of the amp. After removing all tubes, plug in the amp and turn on the power switch. leave the amp in standby. The LED's and power indicator lamp should be on. If it is not, there may be a loose wire internal to the amp or a failed part inside that is preventing the low voltage power supply from operating.
With tube amps, diagnosing issues can be accomplished by removing the tubes. With no tubes in the amp, preamp (small tubes) and power tubes (larger ones), there will be function of the low voltage circuits that control the LED's, channel switching, etc... Some of the preamp tubes have their heaters supplied by the low voltage circuit (DC heater) for refined sound and low noise. There are others that have the heaters powered by a low voltage AC circuit directly supplied by the filament transformer.
With no tubes in the amp at all, if you can get the power light to turn on and the channel lights on the footswitch to work that would be great. If no change, you need to have the amp serviced.
Suppose the lamps and LED's turn on, Great. The next step would be to turn the amp off and install one preamp tube and power the amp back on. If the LEDs and light are on, repeat until all the preamp tubes are installed. Just a simple process of elimination. A preamp tube can cause issues too. Keep the amp in stand by. If you can get all of the small preamp tubes installed and the lights are working, the next step would be installing the Rectifier tubes. Before installing the large tubes, verify that only the rectifier tube is being installed into the rectifier socket. Note, the octal receptacles are all the same on the amp, The manual and or plate should help you with what tube goes in what position. Generally the preamp tubes are all the same, some amps may use a lower gain tube on the effects loop such as a 12AT7. No fear if you install the wrong tube in that position, the amp will still operate but will not sound a good.
Install the first one. and turn the power on. If all LEDs come on with the power light, turn it off and install the next Rectifier tube and repeat. Continue the process with the power tubes, one at a time and turn on the power, Do not take the amp out of stand-by, if you do no harm will be done, just make sure you have a load on the speaker output.
During this process of elimination, if you encounter the same symptom (assuming the amp turns on) the last tube inserted would be the faulty part. You can almost consider it like a chain of Christmas tree lights, one bulb goes out and it kills the rest. That is a poor analogy but if a tube has an internal short, it may prevent the amp from turning on even thought the fuse is good.
My last attempt, if the amp came with tubes when you got it, did it work before the tube overhaul?
If the basics do not work out to help solve the issue, it gets more complicated after that. Your best option is to take the amp for service to a reputable tech. Good luck in resolving your issue. Sorry I could not help you with your problem.
If the basics do not work out to help solve the issue, it gets more complicated after that. Your best option is to take the amp for service to a reputable tech. Good luck in resolving your issue. Sorry I could not help you with your problem.
That's a pretty crappy, as well as disrespectful attitude from a newbie.........sledge760 said:
I have no idea of your electronics background and I'm not going to just tell you to jump into a tube amp and start poking around..... there are lethal voltages stored in the amp, even when off and unplugged. Do you know how to properly discharge the filter caps in that amp?? This is my disclaimer that if you do not know what you are doing.... DON'T DO IT.
If this were me I would start with basics..... make sure that every tube in the amp is 100% good. I've learned the hard way by chasing my tail for hours because I had a bad "new" tube.
ALL pre and power amp tube heaters are connected to the same 6VAC tap on the power transformer. The pilot lamp is also supplied from this tap, so if the pilot lamp works (or if there is ~6VAC at the socket) the transformer is fine. After the pilot lamp comes the 6L6 heaters & preamp tubes V2-V5. If the 6L6 heaters work and V2-V5 do not it is tech time. Next comes a bridge rectifier to convert to DC voltage. This DC voltage supplies the heater for preamp tube V1 as well as the switching matrix. If the only tube heater not working is V1, and the switching is not working I would suspect the rectifier section of the circuit, and again time for a tech.
The 5U4G(B) rectifier tubes have their own 5VAC heater tap from the PT.
http://diy-fever.com/wordpress/wp-content/uploads/2009/12/dual_rectifier.pdf
I hope this helps,
Dom
sorry if you think im being disrespectful Dom i thank you all for your help .i guess i need to figure out how to get the amp to a tech only thing only the only one is 80 miles
and yes i know about the "death caps"and how to discharge the amps stored power
and yes i know about the "death caps"and how to discharge the amps stored power
The schematics can be found doing a simple search...I looked at several of them for the dual rectifiers (primarily the power supply section and they all seem to be the same in that area.)
Since you stated that the heaters are working on the 6L6 power tubes. If this is correct, the same source used for the heaters on the 6L6GC tubes are also used to supply the preamp tubes V2-V5. V1 is supplied by the same circuit but rectified into 6Vdc first, also the LED's and other low voltage parts are sourced from the 6VDC supply after being reduced to 5V.
I believe you do not need to diagnose the transformer. Your issue is probably related to a jumper wire that crosses over from the power tube circuit board to the preamp circuit board. The 6VAC source for the heaters is supplied by the two green wires on the Secondary of the transformer. The heater circuit connects to Pin 2 and Pin 7 on the 6L6 tubes, if you can follow the connections and perhaps find the jumper wires that connect to the preamp circuit board you may find the problem. It becomes more difficult if there is a broken trace on the circuit board as it may be harder to find. If the issue was preamp tube related (shorted cathode follower) the 6L6 tubes would also loose the heater as well which was the reason for pulling the tubes. Since there was no change, it is obvious that there is a missing connection between the preamp circuit board and the heater feed to the 6l6 tubes. None the less, you will have to pull the chassis out of the shell to find the issue. If you leave the amp off long enough the power caps will reduce their potential (there are bleed resistors). It is best to always assume the caps are fully charged regardless of your skill level in electronics. Safely first. One way to discharge the supply caps is to unplug the amp. leave the power switch to off since it will not do anything, and switch the stand by switch as if you are going to use the amp. This will connect the high voltage source to the bleed resistors and other passive devices that will discharge most of the high voltage capacitors. Best to treat the caps as being live regardless.
I hope you find the problem. Good luck.
Since you stated that the heaters are working on the 6L6 power tubes. If this is correct, the same source used for the heaters on the 6L6GC tubes are also used to supply the preamp tubes V2-V5. V1 is supplied by the same circuit but rectified into 6Vdc first, also the LED's and other low voltage parts are sourced from the 6VDC supply after being reduced to 5V.
I believe you do not need to diagnose the transformer. Your issue is probably related to a jumper wire that crosses over from the power tube circuit board to the preamp circuit board. The 6VAC source for the heaters is supplied by the two green wires on the Secondary of the transformer. The heater circuit connects to Pin 2 and Pin 7 on the 6L6 tubes, if you can follow the connections and perhaps find the jumper wires that connect to the preamp circuit board you may find the problem. It becomes more difficult if there is a broken trace on the circuit board as it may be harder to find. If the issue was preamp tube related (shorted cathode follower) the 6L6 tubes would also loose the heater as well which was the reason for pulling the tubes. Since there was no change, it is obvious that there is a missing connection between the preamp circuit board and the heater feed to the 6l6 tubes. None the less, you will have to pull the chassis out of the shell to find the issue. If you leave the amp off long enough the power caps will reduce their potential (there are bleed resistors). It is best to always assume the caps are fully charged regardless of your skill level in electronics. Safely first. One way to discharge the supply caps is to unplug the amp. leave the power switch to off since it will not do anything, and switch the stand by switch as if you are going to use the amp. This will connect the high voltage source to the bleed resistors and other passive devices that will discharge most of the high voltage capacitors. Best to treat the caps as being live regardless.
I hope you find the problem. Good luck.
Thanks bandit im going to see if i cant find the circuit and follow the path when doing a visual a few days ago i found a couple of things that if they are in that circuit may be the prob i'll let you know what happens thanks for all your help sorry about any misunderstandings about me already knowing and already had done the basic tube diags
thanks again
thanks again
During your visual inspection, if nothing jumps out at you, look closely at the wires. The jumper that cross over may not be green in color. In most of the Mesa Amps I have opened up, the jumper wires are red in color (generally a lighter gauge of wire) and may actually connect directly onto the preamp tube socket terminals or on the PCB next to the terminals. 12AX7A heater terminals are pins 4 and 5 with a center lead connected to pin 9. The socket does have molded numbers that is somewhat readable.
I hope you discover the issue and have an opportunity to repair your amp. I can understand your frustration. Well, out of my 36 years of guitar playing, 24 years of that up to current date was with Mesa Boogie. However, I have never had any issues as you are having with your first tube amp. I have had a similar issue as of late but with a different amp and was tube related.
I hope you discover the issue and have an opportunity to repair your amp. I can understand your frustration. Well, out of my 36 years of guitar playing, 24 years of that up to current date was with Mesa Boogie. However, I have never had any issues as you are having with your first tube amp. I have had a similar issue as of late but with a different amp and was tube related.
That is great. 
+1bandit2013 said:That is great.
Glad to see it all sorted out.
Dom
yes so am i dom and yes bandit the greatest besides the first time me and my son whos a awesome kid and soon to be rockstar played and nailed a song together is there any chance any one can tell me the best way to use the fx loop i hooked my line6 hd500 up pretty much with no prob but my old GSP 2101 thats fully updraded to the ver 3 that i use live because it smokes the hd500 live wont work using its fx loop i have to use the guitar input and output on the back panel
is there any chance any one can tell me the best way to use the fx loop i hooked my line6 hd500 up pretty much with no prob but my old GSP 2101 thats fully updraded to the ver 3 that i use live because it smokes the hd500 live wont work using its fx loop i have to use the guitar input and output on the back panelSimilar threads
