voltages are NOT right help

[Paul Birkeland]

Hello Jan,

OK, knowing that the Kreg was on one of the A/B side boards and not the power supply boards is very helpful (I mentioned this in a prior post?).

5.3V out of the regulator is not enough to get the tubes conducting all the way, when you have 6.3V, then judgements can be made about the functionality of the tubes.

-PB

 

[najo49]

Thanks paul, I appreciate what you say,and I have ordered a regulator. But if I might be so bold you are dead wrong about the tube. The preamp will work and play music with 5.3 filiment voltage. So if I sit and try the bad tube in both l and r sockets and neither Produces sound. And them try both left and right sockets and they both play music and supberb music at that. I think that is pretty clear as to what is going on. Jann

 

[Paul Birkeland]

Jan - the specified voltage for the heaters in this preamp is 6.3V +/- 5%.  (5.99V-6.62V)

5.3V will cause operational problems, and very likely ruin all of the tubes in your Eros (Google "cathode poisoning") with relatively quick speed.

Please do not use the preamp until you can get the 6.3V supply to operate properly.

 

[Grainger49]

Jann,

Trust in Paul.  The problem is that without enough heater voltage, and therefore heat, the tube will not pass current as it should. 

An extreme example, I have put a 12.6V tube in a socket that needed a 6.3V tube.  I got sound but it was way, way off from the designed sound.  It was all I had on hand.  When I put in the right tube it was amazing what differences it made.

 

[najo49]

Thanks Grainger for your input,but I understand fully what paul is saying and in theory I completely agree with him. But when I checked this am the filiment voltage was up to 5.7 volt,the regulator obviously can not decide on a filiment voltage, I am not worried about stripping or damage to any tube.Paul is with the paul Joppa, the final word in experience and total understanding of just about anything thats in this forum,they are giants. I am learning but Paul is light years ahead any of my thinking. I am saying only that the tube is BAD. And on that one thing,Paul is wrong. Thanks Paul and Grainger.  PS if I am wrong I will accept it,but until that time I would not bet on it

 

[Grainger49]

Jann,

Unless your input voltage is wandering all over the place (outside the regulation voltages) the three pin regulator (LM1085IT) should hold the output voltage at 6.3V DC.  That is, if the 124 Ohm and 499 Ohm resistors and the 16V Tantalum capacitor are good.  Maybe you should measure the resistances of the two resistors in the circuit.  As for the Tantalum cap, it either works or doesn't.  But the voltage is set by the two resistors in conjunction with the regulator.

With low voltage I wouldn't worry about damage to the tubes, just poor operation. 

 

[najo49]

I got the parts from Eileen, and I plugged my Eros in and it had perfect voltage. My filliment voltage is 6.0 still not 6.3 but within the 5 % plus or minus. I am going to listen tonight, I am excited. Thanks to all ,Eileen, Paul, and Grainger. Thanks jann Olsen. PS  For break in is it wise to let it run for a few days?

 

[Grainger49]

Jann,

Congratulations! ! !  Sit back and have an "adult beverage."  Feed it some old favorites and expect to be surprised. 

I have been at this for several, too many, decades.  The Eros is an eye opener.