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Post subject: Re: DRRI Redplating Problems
Posted: Fri Feb 10, 2017 11:50 pm
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For the cost and hassle of re-doing this all over again... just replace the cap with a nice 100mfd/100VDC one. F&T or Sprague Atom.


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Post subject: Re: DRRI Redplating Problems
Posted: Sat Feb 11, 2017 1:19 am
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BMW2002Ti wrote:
For the cost and hassle of re-doing this all over again... just replace the cap with a nice 100mfd/100VDC one. F&T or Sprague Atom.


+1!

The OEM Illinois cap is a notoriously mediocre POS -- if it were my amp I'd replace the diode as well......

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: DRRI Redplating Problems
Posted: Sat Feb 11, 2017 3:08 am
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Funny the 22 ohms resistor look open ! This circuit do not work hard.
Do you have a short in bias circuit to the tubes ? Or tubes's grid are short ?

Read AC voltage at the input of diode, you must have at least 50 AC volts.

Don't put 6V6's in circuit until you are shure they are not short, you may harm the amp.
A tube tester may tell you about the short.


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Post subject: Re: DRRI Redplating Problems
Posted: Mon Feb 13, 2017 7:47 pm
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I'm going to replace the capacitor, diode, and resistor tomorrow.
stratele52 wrote:
Funny the 22 ohms resistor look open ! This circuit do not work hard.
Do you have a short in bias circuit to the tubes ? Or tubes's grid are short ?

Read AC voltage at the input of diode, you must have at least 50 AC volts.

Don't put 6V6's in circuit until you are shure they are not short, you may harm the amp.
A tube tester may tell you about the short.

Any way to test the tubes for shorts without a tube tester?


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Post subject: Re: DRRI Redplating Problems
Posted: Tue Feb 14, 2017 2:32 am
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JZL wrote:
I'm going to replace the capacitor, diode, and resistor tomorrow.
stratele52 wrote:
Funny the 22 ohms resistor look open ! This circuit do not work hard.
Do you have a short in bias circuit to the tubes ? Or tubes's grid are short ?

Read AC voltage at the input of diode, you must have at least 50 AC volts.

Don't put 6V6's in circuit until you are shure they are not short, you may harm the amp.
A tube tester may tell you about the short.

Any way to test the tubes for shorts without a tube tester?


We talk about 6V6 ;
Fix you bias circuit first ; what about my answer few days ago ?

Crank bias negative voltage to maximum, you should read close to minus 50 volts DC (-50vdc ) at 6V6's pins 5 with no 6V6s, both tubes.
Plug tubes and read bias with your bias probe, if bias is too hot,( or red plating ) tube (s ) is /are short (if there is no other issue with the amp output section ) .

The purpose of bias is keep tubes work at 70% of their power dissipation. ( this is a short answer )
Power = watts
To calculate watts we need to know voltage and current
If curent is 28 ma
The voltage is ?
How many watts do we have ?

Plate voltage is a must


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Post subject: Re: DRRI Redplating Problems
Posted: Wed Feb 15, 2017 11:27 am
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Yesterday I replaced R69 and got the bias voltage back! I put the tubes back in and adjusted the bias pot. Everything is working just fine now, back to how it used to be. I also bought a diode, capacitor, and extra resistors just in case but it seems like everything is fine now. Thank you guys for all the help!


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Post subject: Re: DRRI Redplating Problems
Posted: Wed Feb 15, 2017 11:41 am
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JZL wrote:
Yesterday I replaced R69 and got the bias voltage back! I put the tubes back in and adjusted the bias pot. Everything is working just fine now, back to how it used to be. I also bought a diode, capacitor, and extra resistors just in case but it seems like everything is fine now. Thank you guys for all the help!



:D enjoy.


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