Yes, I used AC setting on the DMM. With 5AR4 and 12AT7 out but 6L6s still in.
Russ, I just tried what you said. I placed black lead on pin 9 and red lead on pin 4 and then on 5. The meter kept flashing between 3.0 to 3.5V at both pins 4 or 5 and 9.
It should read over 6 volts. Verify that the brown wires from the Edcor are connected to the T1-GRN terminals on the rear edge of the board and the brown / white wire is not connected to anything.
You can check the voltage at the 6L6 tubes by pulling them out and measuring the AC volts with one probe on pin 2 and the other probe on pin 7. Remove the 5AR4 so that the possibility of finding 500 volts on the 6L6 pins is reduced.
It is possible that the board is receiving 3.15 volts. The 6L6 types have a big enough heater to dimly glow on low voltage while the 12AT7 may not.
Brown wires are connected to T1-GRN and white/brown is sealed with ele. tape.
Octal sockets: 6.2V on both sockets between pins 2 and 7. All tubes taken out.
Noval socket: Reads 4.5V between pin 9 and 4 or 5 with all tubes out. Then I took another reading with 6L6s back in and it was 3.4V between pin 9 and 4 or 5.
Note: Readings taken with OPTs still connected. 5AR4 was out at all times.
OK, the problem must be with the broken pad for R3. That pad not only connects up R3, but it connects the circuitry on the bottom of the board with the circuitry on the top of the board. You must have a good connection on BOTH sides of the board. The PC board has "plated through holes." There is copper plating INSIDE the component lead holes. This is used in some places to make the connection from the top of the board to the bottom of the board. R3 is one of those places. In fact it is the place where the power for the 12AT7 goes from the top side to the bottom side. Chances are the plating was still on the component lead when you removed it. The connection got broken in one or more places, so we need to figure out exactly where the connection is broken, and fix it.
To do this we are going to use the ohms function on the meter. The board must be powered off, and have been powered off for several minutes so that all the capacitors have discharged. Remove all tubes and disconnect the brown transformer wires. Flip the board over so that you can get to the back side. If you have to remove it from the chassis, this testing and repair can be done on a board that is not connected to anything. It might be helpful to mark pin 7 of V21 and pin 9 of V10 on the back side of the board with a sharpie, or at least be able to identify them, and the trace that connects them toigether as it travels from pin 7 of V21 to R3, therough the R3 hole to the back of the board, and to pin 9 of V10. We are looking for a break in this connection. Most likely it is right at the R3 hole on either side of R3.
Set your meter for the lowest OHMS scale. This is called "200" or "200 ohms" on most cheap meters. Verify that you get a low reading when you touch the two probes together (1 ohm or less). Some meters have a continuity function that beeps when you touch the leads together. If yours does, use it.
Step 1) Touch one probe to Pin 7 of V21 and the other to your R3 wire. Beep or low reading? Yes...good, move on to step 2. No? solder a short piece of wire (a resistor lead, wire wrap wire, or similar...insulation not needed) from V21 pin 7 to R3 on the back side of the board.
Step 2) Touch one probe to your R3 wire and the other probe to pin 9 of V10. Again you should get a low reading or a beep. If not a repair is needed. The simplest way is to solder a piece of wire from your R3 wire (or V21 pin 7) to pin 9 of V10. This wire is a few inches long and could come into contact with other circuitry, so it should be insulated. It should be heavy enough to carry heater current, but not heavy enough to cause damage to the board. Wire wrap wire, small gauge hook up wire, even a scrap of wire from trimming the transformer leads will work.
Verification) Flip the board over (top side up). Touch one probe to pin #9 on the 12AT7 socket and the other probe to pin 7 on the 6L6 socket. You should have a beep or low reading. Leave one probe where it is and touch the other to pin 7 on the other 6L6. Beep? Again move one probe to R3, Beep? And R4, Beep?
Now put one probe on pin 2 of a 6L6 and verify continuity to pin 4 and 5 of the 12AT7. Beep?
If beep happens, hook the board back up....it will work!
To do this we are going to use the ohms function on the meter. The board must be powered off, and have been powered off for several minutes so that all the capacitors have discharged. Remove all tubes and disconnect the brown transformer wires. Flip the board over so that you can get to the back side. If you have to remove it from the chassis, this testing and repair can be done on a board that is not connected to anything. It might be helpful to mark pin 7 of V21 and pin 9 of V10 on the back side of the board with a sharpie, or at least be able to identify them, and the trace that connects them toigether as it travels from pin 7 of V21 to R3, therough the R3 hole to the back of the board, and to pin 9 of V10. We are looking for a break in this connection. Most likely it is right at the R3 hole on either side of R3.
Set your meter for the lowest OHMS scale. This is called "200" or "200 ohms" on most cheap meters. Verify that you get a low reading when you touch the two probes together (1 ohm or less). Some meters have a continuity function that beeps when you touch the leads together. If yours does, use it.
Step 1) Touch one probe to Pin 7 of V21 and the other to your R3 wire. Beep or low reading? Yes...good, move on to step 2. No? solder a short piece of wire (a resistor lead, wire wrap wire, or similar...insulation not needed) from V21 pin 7 to R3 on the back side of the board.
Step 2) Touch one probe to your R3 wire and the other probe to pin 9 of V10. Again you should get a low reading or a beep. If not a repair is needed. The simplest way is to solder a piece of wire from your R3 wire (or V21 pin 7) to pin 9 of V10. This wire is a few inches long and could come into contact with other circuitry, so it should be insulated. It should be heavy enough to carry heater current, but not heavy enough to cause damage to the board. Wire wrap wire, small gauge hook up wire, even a scrap of wire from trimming the transformer leads will work.
Verification) Flip the board over (top side up). Touch one probe to pin #9 on the 12AT7 socket and the other probe to pin 7 on the 6L6 socket. You should have a beep or low reading. Leave one probe where it is and touch the other to pin 7 on the other 6L6. Beep? Again move one probe to R3, Beep? And R4, Beep?
Now put one probe on pin 2 of a 6L6 and verify continuity to pin 4 and 5 of the 12AT7. Beep?
If beep happens, hook the board back up....it will work!
It worked. Thank you George for your help and detailed instructions. I connected pin 7 with R3. Now the readings are 6.2V between pin 2 and 7 on octal sockets and 6.1V betweeen pins 4 or 5 and 9 on noval socket with all tubes out.
Since my roommates are asleep, I have not hooked up CD player to it tonight.
The XPWR035 transformer has lot of hum when powered on. Even on its own and without even connected to PCB, it's hum is so loud, I can hear it from 20 feet away right now at 1 am. The hum level of the transformer increases slightly while connected to the rest of the amplifier. I don't have it on chassis, the whole amp is on wooden table. I don't know if everyone's transformers have this sort of hum. I know some people report hum problems with their amp but I'm not talking about hum from the speakers (I have that too), I'm talking about hum from the transformer only...mine is kind of loud. The noise level is a bit higher than one of those AAA battery powered little pocket size fans. Is it possible I have a defective power transformer? See the last pic, The brown wires are located on primary side but on Edcor's webpage they are on secondary side.
Here is a picture of my amp. Notice the blue glow on 6L6s. There is a slight blue glow on one of the filaments of 12AT7 aswell. I checked and confirmed it's not the reflection of blue glow from 6L6s. I'm using 820 ohm resistors at R17/27 which is higher value than recommended for 6L6 tube yet still the blue glow. Perhaps defect in transformer?
http://img577.imageshack.us/img577/3205/img1566i.jpg
http://img219.imageshack.us/img219/76/img1561q.jpg
http://img836.imageshack.us/img836/1945/img1556g.jpg
Since my roommates are asleep, I have not hooked up CD player to it tonight.
The XPWR035 transformer has lot of hum when powered on. Even on its own and without even connected to PCB, it's hum is so loud, I can hear it from 20 feet away right now at 1 am. The hum level of the transformer increases slightly while connected to the rest of the amplifier. I don't have it on chassis, the whole amp is on wooden table. I don't know if everyone's transformers have this sort of hum. I know some people report hum problems with their amp but I'm not talking about hum from the speakers (I have that too), I'm talking about hum from the transformer only...mine is kind of loud. The noise level is a bit higher than one of those AAA battery powered little pocket size fans. Is it possible I have a defective power transformer? See the last pic, The brown wires are located on primary side but on Edcor's webpage they are on secondary side.
Here is a picture of my amp. Notice the blue glow on 6L6s. There is a slight blue glow on one of the filaments of 12AT7 aswell. I checked and confirmed it's not the reflection of blue glow from 6L6s. I'm using 820 ohm resistors at R17/27 which is higher value than recommended for 6L6 tube yet still the blue glow. Perhaps defect in transformer?
http://img577.imageshack.us/img577/3205/img1566i.jpg
http://img219.imageshack.us/img219/76/img1561q.jpg
http://img836.imageshack.us/img836/1945/img1556g.jpg
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I'm using the same transformer and mine is wired the same. It doesn't have a noticeable hum even from less than a foot away.
An externally hosted image should be here but it was not working when we last tested it.
I'm getting 943V across R4..yes..943V, please tell me this is not normal.
Thanks allentod for your reply, my XPWR035 hums like crazy. The 6L6s are running in triode mode with 8000 ohm load transformers(GXSE10-8-8k), and the speakers got louder than they can get with my 12Wpc EL84 amp.
Either I made a grand mistake somewhere or some Edcor employee needs to get re-trained.
Thanks allentod for your reply, my XPWR035 hums like crazy. The 6L6s are running in triode mode with 8000 ohm load transformers(GXSE10-8-8k), and the speakers got louder than they can get with my 12Wpc EL84 amp.
Either I made a grand mistake somewhere or some Edcor employee needs to get re-trained.
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Can't be. C1 and C2 would have long since exploded like grenades. Something is up with your meter, or the way you are taking measurements.
Maybe, but my bet is that the 5AR4 would have expired long before the caps built up steam if there really was 900 volts. Then a miswired HV secondary could cause a serious amount of high voltage. Check to see if C1 and C2 are getting real hot.
Blue glow inside a 6L6 type tube is somewhat normal, especially if its on the glass itself. The Russian versions seem to glow better than the Chinese tubes.
Some transformers hum more than others. Hammonds have a worse reputation than Edcors for hum. I have noticed that physical transformer hum is dependent on the quality (or lack of) of the electric power. All transformers will hum when fed a square wave. Make sure the screws that hold it together are tight. Buzz with nothing connected to any secondary is not normal.
I got 943V across R4 both times I turned on the amp. One alligator clip on each side of the R4 leads. My DMM is measuring 123V from power outlets so DMM is hopefully correct. I just turned on the amp again after Ty_bower's post but I got louder hum from speakers and it kept increasing, so I quickly turned off the amp. I turned it on again and the same thing happened. While this happened the voltmeter went upto 1000V and then went blank and upon turning power off the reading decayed slowly from 1000V to 0V. Upon inspecting the PCB, I see one of the 1500uF 50V electrolytic cap's top..sort of perforated, while the other looking normal.
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Just turned it on again and here is the pic of voltage across R4. I kept it on for about a minute. I'm not feeling brave enough to keep it on for longer because of really loud hum and all. The C1 and C2 were not super hot.
An externally hosted image should be here but it was not working when we last tested it.
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Your meter is on AC volts. What you should have across R4 is pure rectified DC. Try it again with the meter on the high voltage (1000V) DC range.
Oops...my mistake...now I see I'm getting 437V DC across R4. I'm using 33uF C1 and Triode C-14X choke(150 ohm), C17/27= 820 ohm. Then the blue glow must be normal characteristic with my 6L6GC as George has said. I'm using Ruby 6L6GCM-STR pair. Can OPT primary resistance of 8k cause this blue glow?
Played some Pink Floyd for 40 minutes without issues. Somehow this amp even in triode mode is louder than my 12WPC EL84 p-p amp.
BTW, my XPWR035 hums louder than the hum from speakers. It's like having a little battery powered fan on at all times...so annoying. Even without PCB connected to it's secondary, it hums quite loud, so It's going back to Edcor.
Played some Pink Floyd for 40 minutes without issues. Somehow this amp even in triode mode is louder than my 12WPC EL84 p-p amp.
BTW, my XPWR035 hums louder than the hum from speakers. It's like having a little battery powered fan on at all times...so annoying. Even without PCB connected to it's secondary, it hums quite loud, so It's going back to Edcor.
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Your voltage looks normal. The blue glow is fine, even in the 12AT7. I've had some tubes that get quite excited and glow a lot. There's nothing wrong with most types of blue glow. The blue glow is completely unrelated to the OPT primary load. It depends entirely on the materials used in the manufacture of the tube. I find the higher the plate voltage, the brighter it glows. As the tubes age, it wouldn't surprise me if the glow begins to fade. Here are some Chinese tubes in my SSE:
http://i69.photobucket.com/albums/i43/Ty_Bower/Tubes/Blue6L6.jpg
I always felt the SSE had a lot of gain, even in triode mode. Don't confuse gain for output power. High gain simply means you will likely need to keep the volume knob a little lower.
Sorry to hear your Edcor is a hummer. Some transformers hum because they don't know the words (sorry - bad joke). Just about every power transformer I own hums to some degree. Some are rather loud and annoying. The one Edcor (XPWR005) I have isn't too bad. Just make sure the four bolts in the corners are snug (but not overtight), and if that doesn't fix it there isn't much you can do. I wouldn't think it should hum at all if there is no load on any secondary. I think you are right to request an RMA.
My experience has been that the blue glow is a byproduct of a hot bias sounds good but short tube life 6l6/6v6 sound glorious EL34 can take the heat better with less distortion, share your circuitry and pin voltages with us that we may further evaluate. watch for hot spots on the plates as a tube failure can be painfull to your wallet .
Regards, Elwood
Regards, Elwood
Not even a tiny bit hum/buzz from 7-8 inches away? Although, I don't have to go that close to my XPWR035 since it's buzz can be heard clearly from across the room.
lol..
BTW, my tubes have similar blue glow, and some little blunt blue spots on bottom plates. Most likely due to materials as you have pointed out.
There are no orange spots on the plates, its a blue glow as visible in my and Ty's pics. There are few blunt blue spots on the bottom plate. All the PCB parts are identical to parts list with an only exception of using a 33uF C1 and 820 ohm R17/27. The rest is 150 ohm C-14x choke and I'm not using any supplemental cap. Foe 12AT7 voltage across pin 9 and 4 or 5 is 6.1VAC while for 6L6s voltage across pins 2 and 7 is 6.2VAC. Not sure how to test the rest of the pins.
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Not even a tiny bit hum/buzz from 7-8 inches away? Although, I don't have to go that close to my XPWR035 since it's buzz can be heard clearly from across the room.
Sorry...I missed-typed that. The one in the SSE is dead quiet for the most part. I have to put my ear few inches away to hear any buzz. It gets a bit louder if I push the amp hard with big power tubes and higher plate current. The one in the TSE was a bit more buzzy than the SSE.
Some tubes do glow in operating. Sometimes there is discoloration of the internal materials from welds, etc. If the plates aren't glowing orange, I wouldn't worry about it.
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