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#1
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info needed for 6L6GC tube voltage or shematic for old TUSC guitar head
I bought an old "TUSC CF 50", 50 watt guitar head. It uses (2) 6L6GC
power tubes. The TUSC CF 100 version uses (4) 6L6GC power tubes. It appears that they share the same circuit board which is setup for (4) 6L6GC tubes. Does anyone have a schematic for either head? I would like to find out the voltage readings for the 6L6GC power tubes. One tube was dead. I replaced a burnt resistor at pin 4 (4.6K ohm). Then took the following DC voltage readings. socket 1 - pin 4 reads 441V and pin 5 reads 50.2V socket 2 - empty no tube on the 50 watt model socket 3 - pin 4 reads 441V and pin 5 reads 49.7V socket 4 - empty no tube on the 50 watt model Based on tube data, do these seem right for a 6L6GC? Thank you, Mark |
#2
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info needed for 6L6GC tube voltage or shematic for old TUSC guitar head
"misterc57" wrote in message oups.com... ** Groper Alert !! I bought an old "TUSC CF 50", 50 watt guitar head. It uses (2) 6L6GC power tubes. The TUSC CF 100 version uses (4) 6L6GC power tubes. It appears that they share the same circuit board which is setup for (4) 6L6GC tubes. Does anyone have a schematic for either head? I would like to find out the voltage readings for the 6L6GC power tubes. One tube was dead. I replaced a burnt resistor at pin 4 (4.6K ohm). ** NO WAY is that resistor 4.6 kohms !!!! Maybe YOU are colour-blind - 12 % of males are. Measure the other similar resistor with an ohm meter. Betya it is 470 ohms. Then took the following DC voltage readings. socket 1 - pin 4 reads 441V and pin 5 reads 50.2V ** Betya it is ** MINUS ** 50.2 volts !! Based on tube data, do these seem right for a 6L6GC? ** Yep. ........ Phil |
#3
Posted to alt.guitar.amps,rec.audio.tubes
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info needed for 6L6GC tube voltage or shematic for old TUSC guitar head
"misterc57" wrote in message oups.com... I bought an old "TUSC CF 50", 50 watt guitar head. It uses (2) 6L6GC power tubes. The TUSC CF 100 version uses (4) 6L6GC power tubes. It appears that they share the same circuit board which is setup for (4) 6L6GC tubes. Does anyone have a schematic for either head? I would like to find out the voltage readings for the 6L6GC power tubes. One tube was dead. I replaced a burnt resistor at pin 4 (4.6K ohm). Then took the following DC voltage readings. socket 1 - pin 4 reads 441V and pin 5 reads 50.2V socket 2 - empty no tube on the 50 watt model socket 3 - pin 4 reads 441V and pin 5 reads 49.7V socket 4 - empty no tube on the 50 watt model Based on tube data, do these seem right for a 6L6GC? Thank you, Mark Pin 4 = G2; rated for 500v max, but some tubes will tolerate more and some less. To be safe, stay below the max. What is voltage on pin 3 (plate)? I assume on Pin 5 (grid) you mean the voltage is negative 50? Seems like this should be more towards the mid 30's, but the real answer depends on the amp and how much currrent the power tubes are pulling. Have you/do you know how to check bias and calc static plate dissapation? Look for something about that he http://aga.rru.com . Just guessing here, but it could be that the amp had a burnt resistor because it's not running properly. If so, this should be tended to. |
#4
Posted to alt.guitar.amps,rec.audio.tubes
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info needed for 6L6GC tube voltage or shematic for old TUSC guitar head
I am hear to learn...
What is Groper Alert? You are right. I think I am color blind. My meter says the resistors are .460 K ohms So the math is .460 X 1000 = 460 ohms. I thought the color bands were yellow, blue, red. But I guess they are yellow, blue, brown. I pulled the matching resistor out of socket 4 on the board to use in socket 1. You also right about my readings at pin 5. They were MINUS, I had not noticed until you mentioned it. Thank you for all the clarifications and confirming the readings are in spec. - Mark Phil Allison wrote: "misterc57" wrote in message oups.com... ** Groper Alert !! I bought an old "TUSC CF 50", 50 watt guitar head. It uses (2) 6L6GC power tubes. The TUSC CF 100 version uses (4) 6L6GC power tubes. It appears that they share the same circuit board which is setup for (4) 6L6GC tubes. Does anyone have a schematic for either head? I would like to find out the voltage readings for the 6L6GC power tubes. One tube was dead. I replaced a burnt resistor at pin 4 (4.6K ohm). ** NO WAY is that resistor 4.6 kohms !!!! Maybe YOU are colour-blind - 12 % of males are. Measure the other similar resistor with an ohm meter. Betya it is 470 ohms. Then took the following DC voltage readings. socket 1 - pin 4 reads 441V and pin 5 reads 50.2V ** Betya it is ** MINUS ** 50.2 volts !! Based on tube data, do these seem right for a 6L6GC? ** Yep. ....... Phil |
#5
Posted to alt.guitar.amps,rec.audio.tubes
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info needed for 6L6GC tube voltage or shematic for old TUSC guitar head
438 Volts at pin 3 on both sockets.
441 Volts at pin 4 MINUS 50 Volts at pin 5 There appears to be a bias adjust knob on the board. I do have a probe to test bias. Will check out the site you referenced Thanks, Mark Phil S. wrote: "misterc57" wrote in message oups.com... I bought an old "TUSC CF 50", 50 watt guitar head. It uses (2) 6L6GC power tubes. The TUSC CF 100 version uses (4) 6L6GC power tubes. It appears that they share the same circuit board which is setup for (4) 6L6GC tubes. Does anyone have a schematic for either head? I would like to find out the voltage readings for the 6L6GC power tubes. One tube was dead. I replaced a burnt resistor at pin 4 (4.6K ohm). Then took the following DC voltage readings. socket 1 - pin 4 reads 441V and pin 5 reads 50.2V socket 2 - empty no tube on the 50 watt model socket 3 - pin 4 reads 441V and pin 5 reads 49.7V socket 4 - empty no tube on the 50 watt model Based on tube data, do these seem right for a 6L6GC? Thank you, Mark Pin 4 = G2; rated for 500v max, but some tubes will tolerate more and some less. To be safe, stay below the max. What is voltage on pin 3 (plate)? I assume on Pin 5 (grid) you mean the voltage is negative 50? Seems like this should be more towards the mid 30's, but the real answer depends on the amp and how much currrent the power tubes are pulling. Have you/do you know how to check bias and calc static plate dissapation? Look for something about that he http://aga.rru.com . Just guessing here, but it could be that the amp had a burnt resistor because it's not running properly. If so, this should be tended to. |
#6
Posted to alt.guitar.amps,rec.audio.tubes
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info needed for 6L6GC tube voltage or shematic for old TUSC guitar head
On 16 Oct 2006 19:07:25 -0700, "misterc57"
wrote: 438 Volts at pin 3 on both sockets. 441 Volts at pin 4 MINUS 50 Volts at pin 5 There appears to be a bias adjust knob on the board. I do have a probe to test bias. Will check out the site you referenced Thanks, Mark Pin 3 (plate) should measure higher than pin 4 (screen grid). -Dave |
#7
Posted to alt.guitar.amps,rec.audio.tubes
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info needed for 6L6GC tube voltage or shematic for old TUSC guitar head
On Tue, 17 Oct 2006 05:52:31 -0500, flipper wrote:
On Tue, 17 Oct 2006 06:40:16 -0400, Dave Curtis wrote: On 16 Oct 2006 19:07:25 -0700, "misterc57" wrote: 438 Volts at pin 3 on both sockets. 441 Volts at pin 4 MINUS 50 Volts at pin 5 There appears to be a bias adjust knob on the board. I do have a probe to test bias. Will check out the site you referenced Thanks, Mark Pin 3 (plate) should measure higher than pin 4 (screen grid). Depends on the components. Idle current through the OPT primary DC resistance will cause a slight drop from B+ to the plate and then there's idle screen current through the screen resistor, if it has one, to B+. So a few volts might be correct. -Dave As I wrote that, I was wondering if he had tubes in it, and it turns out he didn't. (Aha!) -Dave |
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