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Post subject: Re: Home made 6G15 issue with voltage
Posted: Mon Jun 23, 2014 12:52 pm
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vince_fr wrote:
_____________________________________
vince_fr
Is the Triode layout IS the one you use ?

vince_fr = France ?


Statele, yes I used the triode layout as my main model.
Yes, I live in France, near Paris.[/quote]


I 'll be in Paris from August 26 to August 31


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Mon Jun 23, 2014 12:56 pm
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vince_fr wrote:
Sure !
I mainly folloed the triode schema :
http://site.triodestore.com/6G15ReverbLayoutV2.pdf

Having also a look to the weber one :
http://www.diyrecordingequipment.com/wp ... layout.jpg

The only difference I have is my filter caps : I have 47uf instead of 40.It is better
And I created my own diode based rectifier like in the schema here : http://i.imgur.com/8Ofqn.jpg Full wave rectifier = more voltage
This diode rectifier works fine (having DC at expected voltage).

Last minute : I will test the impedance on my reverb tank. Mayby it is burned.


A big thanks for your help.

Vincent


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Tue Jun 24, 2014 7:55 am
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http://site.triodestore.com/6G15ReverbLayoutV2.pdf


Check the voltage at B+3, on this layout. It should be around 250VDC. If it is, there is any issue between B+3 and the point you are reading. Like the soldering around the two 2.2 meg-ohm resistor network.

If it isn't 250VDC (but something much less) --- you have an issue with PSU power rail. Maybe, a bad cap or 10K-ohm rail resistor.


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Tue Jun 24, 2014 8:13 am
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BMW2002Ti wrote:
http://site.triodestore.com/6G15ReverbLayoutV2.pdf


Check the voltage at B+3, on this layout. It should be around 250VDC. If it is, there is any issue between B+3 and the point you are reading. Like the soldering around the two 2.2 meg-ohm resistor network.

If it isn't 250VDC (but something much less) --- you have an issue with PSU power rail. Maybe, a bad cap or 10K-ohm rail resistor.



:lol: He write he have 250 Volts on his first post


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Tue Jun 24, 2014 8:14 am
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I wait an answer about what I wrote before ;


have a original Fender Reverb 6G15

Some reading ;

No power on Reverb unit ,all caps discharge

Ohms from V1 pin 7 to ground; 1. 170 M


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Tue Jun 24, 2014 8:17 am
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One other question. I noticed that the V2 mod had 100-ohm resistors tied to the 6K6GT cathode (which is lifted off the ground by the 1k-ohm cathode resistor) --- from the heater line. I understand the artificial center tap idea. I wondered about injecting AC from the heater line directly into the cathode of the 6K6GT.

Maybe, better to connect those two 100-ohm resistors to the lamp --- as it is in most Fender amps. Like in the Triode layout. If the heater lines have a center tap off of them (like original 6G15 Fender Unit), you don't need the 100-ohm resistors.


http://i.imgur.com/8Ofqn.jpg


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Tue Jun 24, 2014 8:24 am
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BMW2002Ti wrote:

Maybe, better to connect those two 100-ohm resistors to the lamp --- as it is in most Fender amps. Like in the Triode layout. If the heater lines have a center tap off of them (like original 6G15 Fender Unit), you don't need the 100-ohm resistors.





I agree with you .


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Tue Jun 24, 2014 8:48 am
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He write he have 250 Volts on his first post.

Yeah, I knew that. :lol:

Puzzling problem. :?:


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Tue Jun 24, 2014 9:04 am
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BMW2002Ti wrote:
:

Puzzling problem. :?:


:?: :?: I don't understand , neither Google translation :lol:


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Tue Jun 24, 2014 9:14 am
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Le problème est une énigme. Oui?

:D


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Tue Jun 24, 2014 10:19 am
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BMW2002Ti wrote:
Le problème est une énigme. Oui?

:D



Merci :D

Oui, très mystérieux


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Sun Jun 29, 2014 6:57 am
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Hi guys,

Thanks for your help.

I made a test : I unsoldered one leg of the 2,2 resistor from the potentially faulty turret. The resistor is still soldered to the "B+3" turret and will receive 250V as input.
Result : on the "B+3" turret, I have 250V as expected. BUT on the resistor leg (pointing upwards and not soldered anymore) I now have 78-80V : far from 120V as expected but quite similar to 60V I noticed previously.
Note : I changed the 2,2M resistor twice in order to be sure the resistor is ok.

Link to the schematic : http://site.triodestore.com/6G15ReverbLayoutV2.pdf

My question : finally, should I worry about having 60v instead of 120 as shown on the fender schematics ? Because applying a 2,2M resistor to a 250V current seems, in all cases, to deliver something close to 60V instead of 120V ...

Last minute : I checked the reverb tank with my ohm meter. I have a different impedance (compared to accutronic specs) on input and no impedance on output.
Seems I have a $@!&*% up reverb tank ...

Many thanks

Vince


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Sun Jun 29, 2014 7:14 am
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" My question : finally, should I worry about having 60v instead of 120 as shown on the fender schematics ? Because applying a 2,2M resistor to a 250V current seems, in all cases, to deliver something close to 60V instead of 120V ... "



You need to know the current passing through this part of the circuit, in order to calculate the voltage drop. But, you can figure that the current passing is prolly around 1/2 of what it should be, since the voltage measured is about 1/2 what is posted on the schematic.

Since the tank maybe at issue... remove it from the circuit and see if anything changes on the other read points.

Good luck! Keep us posted.


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Sun Jun 29, 2014 9:51 am
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vince_fr wrote:
Last minute : I checked the reverb tank with my ohm meter. I have a different impedance (compared to accutronic specs) on input and no impedance on output.
Seems I have a $@!&*% up reverb tank ...


Quite possibly your tank is hosed.

Also be sure to confirm that your tank's grounding scheme matches what is specified in the schematic.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Home made 6G15 issue with voltage
Posted: Sun Jun 29, 2014 11:21 am
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Yes the tank is grounded according the shematics (input and output female jack plugs).

I'll put a hand on a magnifier and will try to see if I can repair the tank.

If not, I'll buy a new one (stupid as Iam, I throw the receipt away qnd now can't use the garantee ...).

Regarding the voltage difference, I'm completely lost.
I checked and rechecked my soldering. I really think I'm fine. No leak, nothing is touching the chassis, no short ...
250V is delivered to the 2,2M resistor and I'm having 60V instead of 120V after the resistor.
Maybe I'm daltonian and made a mistake on the resistor color codes ...


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