Comparing to the 36 watt voltage chart posted by Richie aka Plexi I am gettng nervous as heck. My voltages seem way off.
Can someone please take a look and let me know if this seem normal and if not what is goign on? Many thanks!!!
This is a 36watt TMB done with Richie AKA Plexi's layout.
Donations
Are these 36watt voltages correct? I am nervous!!!
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Shad
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Shad
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Wanted to point out that I used the V designation in relation to chassis layout, which may or may not reflect the schematic. 
Agh! Also, the heater supply on the rectifier is incorrect. I am indeed using the 5V tap. I will get the rectifier voltage asap.
Seems to me so far, that everyone voltages on the EL-84's are higher on the Anode Pin7 then on the Grid2 Pin9. Mine is the opposite.
Agh! Also, the heater supply on the rectifier is incorrect. I am indeed using the 5V tap. I will get the rectifier voltage asap.
Seems to me so far, that everyone voltages on the EL-84's are higher on the Anode Pin7 then on the Grid2 Pin9. Mine is the opposite.
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Plexi
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Shad
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Just checked it. I have 354 on the CT and 352 on the screens. In checking all my values and wiring and such I found that my .01 on the first channels tone was going to ground instead of V1Pin1. Got that right but no change in voltage on 7 and 9 of the EL's.
That is crazy though because what I get and what the visual wires show is backwards. I need to check this again. I am using a 1K5 across the cap can as well as a choke! Is that bad!?
I also have the creen wire and the CT wire wrapped maybe once or twice. Could it be that?
I posted pics of my guts a few days ago too if it helps.
http://www.18watt.com/modules.php?name= ... pic&t=5720
That is crazy though because what I get and what the visual wires show is backwards. I need to check this again. I am using a 1K5 across the cap can as well as a choke! Is that bad!?
I also have the creen wire and the CT wire wrapped maybe once or twice. Could it be that?
I posted pics of my guts a few days ago too if it helps.
http://www.18watt.com/modules.php?name= ... pic&t=5720
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Shad
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Just saw this and removed the resistor I had in there along with the choke! 
http://www.18watt.com/modules.php?name= ... c&start=15
Not much difference though, 356 on the CT, 353 on the other side.
I have 352 on pins7 and 353 on pins9.
I checked the to make sure the OT is indeed going to the more positive side about 9 times. What do I do now? Increase screen resistors?
Something else must be haywire with what I am doing.
My trafos are HTS-7602 PT, and a 36-OT GDS/heyboers if it matters.
Also always wanted to ask if when using the primary of the PT if it matters which lead gets the hot, and which get the neutral?
On your layout it just has 0 and 120. With the trafo I used I had to jumper wires and when i asked heyboer they did not specify.
Is there some phase relationship I am screwing up?
I wanted to ask that about the GZ34 too.. On the layout is 0 and 5 volts but both wires are twisted and both yellow. I have the green yellow (5V according to heyboer) on pin8 of the GZ. Is that incorrect and screwing me up?
Is there a schematic made just for this sucker?
Well it is very late. I will try again tomorrow...
Thank you very much for the help!!!!
http://www.18watt.com/modules.php?name= ... c&start=15
Not much difference though, 356 on the CT, 353 on the other side.
I have 352 on pins7 and 353 on pins9.
I checked the to make sure the OT is indeed going to the more positive side about 9 times. What do I do now? Increase screen resistors?
Something else must be haywire with what I am doing.
My trafos are HTS-7602 PT, and a 36-OT GDS/heyboers if it matters.
Also always wanted to ask if when using the primary of the PT if it matters which lead gets the hot, and which get the neutral?
On your layout it just has 0 and 120. With the trafo I used I had to jumper wires and when i asked heyboer they did not specify.
Is there some phase relationship I am screwing up?
I wanted to ask that about the GZ34 too.. On the layout is 0 and 5 volts but both wires are twisted and both yellow. I have the green yellow (5V according to heyboer) on pin8 of the GZ. Is that incorrect and screwing me up?
Is there a schematic made just for this sucker?
Well it is very late. I will try again tomorrow...
Thank you very much for the help!!!!
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EBE
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Those voltages are not that far off. With a GZ34 and Russian 7189 equivalent power tubes I get 353 on the plates and 347 on the screens. For your amp I would try to get the screen voltages down some by upping the screen resistors. Phil has commented on how to do it another thread.Shad wrote:Not much difference though, 356 on the CT, 353 on the other side.
I have 352 on pins7 and 353 on pins9.
If I use a 5V4 rectifier my voltages go down to 345 on the plates and 337 on the screens. I am going to take it out this Sunday and try it out with the 5V4 in it.
Norm
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Shad
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I will search for Phil's post about it. Is there a range of voltage difference I am shooting for?
I have another concern lately. When bringing my amps voltages up I notice the recto I had was making yucky sounds. It wasn't until the amp was fully charged and I played it that it was obvious it was working poorly. I could hear it buzzing! I replaced it with a new JJ GZ34.
Is there a chance that when forming caps the shoddy recto messed things up and I have a bad cap somewhere?
When I turn my amp off I only have about 20V left on the cap can before doing any draining. Shouldn't the stored charge be higher?
Many thanks with all the help here guys. I promise my second build will not be quite as adventurous....of course I say that now, knowing I have schemata and gut shots of ODS's....LMAO!
I have another concern lately. When bringing my amps voltages up I notice the recto I had was making yucky sounds. It wasn't until the amp was fully charged and I played it that it was obvious it was working poorly. I could hear it buzzing! I replaced it with a new JJ GZ34.
Is there a chance that when forming caps the shoddy recto messed things up and I have a bad cap somewhere?
When I turn my amp off I only have about 20V left on the cap can before doing any draining. Shouldn't the stored charge be higher?
Many thanks with all the help here guys. I promise my second build will not be quite as adventurous....of course I say that now, knowing I have schemata and gut shots of ODS's....LMAO!
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Shad
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I have found this one with Aiken and Phil and am trying the math method out first to be sure I have this proceedure correct. I am assuming this is what I should be doing, yes?
http://18watt.com/modules.php?name=Foru ... c&start=15
Can someone double check my math for me?
Starting with determining my screen current I have voltages of 351 before my 130 Ohm resistor, and 350 after. So subrating that I have 1 divided by 130, which equals 0.0076. So my screen current is 7mA?
Ok then subracting cathode voltage (10.88 ) from the screen voltage (349) we get 338.12, multiplied by .007 is 2.36. So my wattage is 2.36?
So I am exceeding the dissipation at idle by 0.36W, correct?
Ok plate dissipation:
On one set I have 74mA, on the second set I have 75mA. So let's say 74mA, minus the 7mA for the screen, is 67, givening me roughly 33.5mA per tube.
Ok subracting the CV from the SV again we have 338.12 but here is where I get very confused. (my math is very poor if you have not guessed by now) when I try to multiply that by 33 I get 11157.96?
If I multiply 338.12 by .0033 I get 1.115796?
Neither of those makes much sense to me.
Now if I start with 338.12 and divide by 33 I get 10.24?
Could someone please show me where to put this decimal and how to do this math correctly?
http://18watt.com/modules.php?name=Foru ... c&start=15
Can someone double check my math for me?
Starting with determining my screen current I have voltages of 351 before my 130 Ohm resistor, and 350 after. So subrating that I have 1 divided by 130, which equals 0.0076. So my screen current is 7mA?
Ok then subracting cathode voltage (10.88 ) from the screen voltage (349) we get 338.12, multiplied by .007 is 2.36. So my wattage is 2.36?
So I am exceeding the dissipation at idle by 0.36W, correct?
Ok plate dissipation:
On one set I have 74mA, on the second set I have 75mA. So let's say 74mA, minus the 7mA for the screen, is 67, givening me roughly 33.5mA per tube.
Ok subracting the CV from the SV again we have 338.12 but here is where I get very confused. (my math is very poor if you have not guessed by now) when I try to multiply that by 33 I get 11157.96?
If I multiply 338.12 by .0033 I get 1.115796?
Neither of those makes much sense to me.
Now if I start with 338.12 and divide by 33 I get 10.24?
Could someone please show me where to put this decimal and how to do this math correctly?
Last edited by Shad on Sat 08/13/05 7:37 pm, edited 1 time in total.
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Shad
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Alright, a little away time and then some number crunching on Aikens example I think I got it.
338.12 multiplied by 33.5 is 11327.02 but if I am not mistaken I move the deciaml over and get 11.32W PD! ....I mean right?
That is an ok number right?
So I guess it is now time to fool with the cathode resistors and try for less screen dissipation.
Now my really big question is exactly how do I bring it to full power so I can measure "the average DC drop at full power and calculate to get the full-power dissipation, and use this as your worst-case dissipation to determine the final value of screen dropping resistor."?
I am reading Aikens article still but not grokking what I need to do to get this full-power dissipation measurements...
338.12 multiplied by 33.5 is 11327.02 but if I am not mistaken I move the deciaml over and get 11.32W PD! ....I mean right?
That is an ok number right?
So I guess it is now time to fool with the cathode resistors and try for less screen dissipation.
Now my really big question is exactly how do I bring it to full power so I can measure "the average DC drop at full power and calculate to get the full-power dissipation, and use this as your worst-case dissipation to determine the final value of screen dropping resistor."?
I am reading Aikens article still but not grokking what I need to do to get this full-power dissipation measurements...
Last edited by Shad on Sun 08/14/05 2:27 am, edited 1 time in total.
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Shad
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Well I hope I am approaching some of this correctly. My idle voltages are taken with a guitar plugged in, amp volumes at zero. I sure hope that is idle...
Unless my math is whack...ha ha.... I calculate that upping my screen R's to 200Ohms would give me a 5mA draw and 1.69W.
Now to give my brain another short break, then try and figure out how this change will affect my plate voltages and current, etc.
Groan... I get the feeling I am going know to Ohm's law a lot better before too long...
Yeah I know just swap things and see but I wanted to understand this math as best as I can so I can start to pre-determine things.
My brain is mad at me and is hurting. Back at it soon....
Unless my math is whack...ha ha.... I calculate that upping my screen R's to 200Ohms would give me a 5mA draw and 1.69W.
Now to give my brain another short break, then try and figure out how this change will affect my plate voltages and current, etc.
Groan... I get the feeling I am going know to Ohm's law a lot better before too long...
Yeah I know just swap things and see but I wanted to understand this math as best as I can so I can start to pre-determine things.
My brain is mad at me and is hurting. Back at it soon....
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Shad
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I must be really screwing this up badly. 
I upped my screens R's from 130 Ohms, to 205 Ohms.
Now here are my new voltages.
11V on the cathodes.
352V on the anode plates.
353V on the screens.
Plate current measures 75.3mA per pair minus the 9mA screen current leaving 66.3mA divided in 2 for a total of 33.15mA per tube?
Plate voltage 353V, minus the cathode voltage of 11V, leaves 342V, multiplied by the plate current of 33.15mA gives 11337.3, moving the decimal over and getting 11.33W plate dissipation?
I get 355V before the screen R, 353V after it. Difference of 2, divided by 205V is .0097. So again I am assuming my screen current is 9mA - 10mA?
My screen voltage of 353V minus the 11V cathode voltage leaves me with 342V multiplied by .009 equaling 3.07W ! WTF!?
So I did nothing but bugger my screen dissipation even further by increasing the screen resistors?
I upped my screens R's from 130 Ohms, to 205 Ohms.
Now here are my new voltages.
11V on the cathodes.
352V on the anode plates.
353V on the screens.
Plate current measures 75.3mA per pair minus the 9mA screen current leaving 66.3mA divided in 2 for a total of 33.15mA per tube?
Plate voltage 353V, minus the cathode voltage of 11V, leaves 342V, multiplied by the plate current of 33.15mA gives 11337.3, moving the decimal over and getting 11.33W plate dissipation?
I get 355V before the screen R, 353V after it. Difference of 2, divided by 205V is .0097. So again I am assuming my screen current is 9mA - 10mA?
My screen voltage of 353V minus the 11V cathode voltage leaves me with 342V multiplied by .009 equaling 3.07W ! WTF!?
So I did nothing but bugger my screen dissipation even further by increasing the screen resistors?
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NewGuitar
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Shad -
I also have a 36 watt build problem. Right now it is basically a very loud, expensive buzzer - built using the layout on 18watt with some obvious corrections.
If you send me your email address I'll see what I can do. I can't promis much at this point other than some good reference material and some general advice that will help prevent you from getting more and more frustrated.
utah_biker@hotmail.com
Hutson
I also have a 36 watt build problem. Right now it is basically a very loud, expensive buzzer - built using the layout on 18watt with some obvious corrections.
If you send me your email address I'll see what I can do. I can't promis much at this point other than some good reference material and some general advice that will help prevent you from getting more and more frustrated.
utah_biker@hotmail.com
Hutson
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