Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Willabe on January 13, 2012, 02:08:18 pm

Title: Help Please, with 5E3 rebuild problem, Fixed.
Post by: Willabe on January 13, 2012, 02:08:18 pm

Well I finished my rebuild of my 5E3 last night. Plugged in to the lamp limiter, no smoke, no sparks, seemed fine.

Took it off the limiter, 6V6 next to 5Y3 is red plating slightly along a seam. Humm.....    :think1:

Changed 5Y3 and 6V6's with brand new matched tubes that work in my BF PR, same thing.

The PT and OT are Kendricks and were working fine. I did have a 330R 10w for the 6V6's cathode R. I don't remember why I used that value instead of Fenders 250R.

Here's the voltage readings I'm getting,

AC line,   121.7acv

Only 5Y3 pluged in, no other tubes, pin 8, 490dcv.    :w2:

5Y3 Rectifier tube with all tubes in, pin 4, 390acv, pin 6, 390acv, pin 2, 5.6acv, pin 8, 340dcv.

6V6, next to 5Y3, pin 3, 300dcv, pin 4, 276dcv. OT brown.

6V6, pin 3, 340dcv, pin 4, 279dcv. OT blue.

cathode pins 8, 29dcv, 250R/5w, 25uF/50v  

OT primary, Brown to CT, 325R, Blue to CT, 290R, Brown to Blue, 610R, secondary, 1.5R

Heaters, 6.7acv, 45dcv stand off.


Thanks in advance for any and all help!


          Brad      :help:



Edit;    Doh, I forgot to put in the 2, 220K grid return R's.       :BangHead:              :laugh:

        

Title: Re: Help Please, with 5E3 rebuild problem
Post by: archaos on January 13, 2012, 03:44:32 pm

Quote

Edit;    Doh, I forgot to put in the 2, 220K grid return R's.       BangHead              laugh

Well-spotted, & glad for you. I'll build a 5E3 in the next weeks as well.

Title: Re: Help Please, with 5E3 rebuild problem
Post by: Willabe on January 13, 2012, 05:26:40 pm

Thanks archaos. I had them in the schemo, but I forgot to include them on the layout drawing.  :laugh:

I should have pick up on it without the drawing thou.     :dontknow:    Well, no harm done thankfully.

I think your gonna like your 5E3 alot. (Don't know if you've never had one.) Nice little amps.

      
                Brad       :icon_biggrin:

Title: Re: Help Please, with 5E3 rebuild problem, Fixed.
Post by: Willabe on January 13, 2012, 05:44:43 pm

Well it works now that I put in the OP tube grid return R's.          :BangHead:         :laugh:

Sounds real nice, quit, I like it. I'll be able to tell better after I change the strings on my guitar. Want to run my lap steel through it too.

I've been using a Peavey Valve Verb with it for years, not bad. But I like my Fender stand alone unit I just built a whole lot better.   :icon_biggrin:

I have a Kendrick black frame 12" speaker in it, but I have a Tone Tubby alnico 12", hemp cone, I want to try in it.      

I'll post pics and voltages in a day or so.

Thanks to all, this is a great place to learn and grow. You guys and this forum are a real blessing.


        Brad       :icon_biggrin:    

Title: Re: Help Please, with 5E3 rebuild problem, Fixed.
Post by: stratele52 on January 13, 2012, 06:07:43 pm

Willabe,

Why do yo put a 330 K  1 watt, on the 20 MFD, before the standby switch ? 

Title: Re: Help Please, with 5E3 rebuild problem, Fixed.
Post by: Willabe on January 13, 2012, 06:45:23 pm

Quote from: stratele52 on January 13, 2012, 06:07:43 pm

Why do yo put a 330 K  1 watt, on the 20 MFD, before the standby switch ?

It's for safety.

It's a bleeder R to drain off the B+ dcv from the filter caps when you turn off the amp. That way when/if you go inside the chassis to work on something, the filter caps B+ dcv is already gone, so its safe to touch anything with out getting a shock.


I was unable to use the standby because the B+ dcv with no load was 490dcv and I'm using 450dcv caps.


          Brad      :icon_biggrin: