Tube DIY Asylum

Can you post a picture if the underside?

67.99.100.2

gusser

In Reply to: RE: OK.... posted by frankford on March 05, 2012 at 15:23:54

Full screen with as much detail as possible so we can analyze the wiring.

Follow Ups:

RE: Can you post a picture if the underside? - frankford 17:20:52 03/05/12 (14)
empty sockets 7.42 vac

first 6550 6.09 vac

first 6550 5.4 vac second 6550 4.33 vac

off variac straight in wall first 6550 5.58 vac second 6550 4.65 vac.

just lost a 5u4gb in the process, thru in the backup.
- another pic - frankford 17:22:57 03/05/12 (13)
  other 6550
  - Update on amp - frankford 15:05:07 04/07/12 (1)
    Got the new power tranny in this week, finished installing it last night. I first setup the 6550 heaters per picture in manual. Only 3.2 vac at the heaters of the 6550's. Went back and setup the heaters per schematic and I am now getting 6.25vac across both heaters with the tubes installed.
    
    Here is the kicker, I hooked up the amp to a pair of speakers, only one side was working. However I let it play for over an hour to see if the original motor boating would happen. Nothing. Went to bed at 5 am this moring.
    
    This afternoon I put a new 12ax7 on the side that wasn't working. I turned on the amp and the channel that was working last night started motor boating on me. I opened the amp back up and turned it on with 8 ohm resisters on the speaker term, I measured 6.25 vac on the 6550's.
    - I'm done with it. - frankford 17:11:54 04/07/12 (0)
      I am done with it, I was going thru measuring voltages and smoke started escaping.
  - RE: another pic - gusser 18:25:01 03/05/12 (1)
    It looks to me like the tube in the back has it's 0.68ohm resistor being fed from the 0.68ohm resistor on the first tube. Both 0.68ohm resistors should be fed from the blue wire which I assume comes from the transformer. So move that red wire from the front tube socket to the terminal strip where the front 0.68ohm is tieed to.
    
    That said it should still work they way you have it, one tube however will have less heater power.
    
    Did you test the 0.68ohm resistors?
    
    The soldering of the two blue wires and the terminal strip could use some cleanup. It looks like a short waiting to happen.
    - Flux Removal - gusser 13:35:59 03/06/12 (0)
      Standard pharmacy Isopropol alcohol will remove rosin flux. It takes a while though.
      I use Acetone. It's very fast and evaporates quickly. Just keep it away from plastic as it will eat it. However, not all states will allow sale of this product over the counter. Interestingly enough in California, the tree hugger state, you can buy Acetone by the gallons at any Home Depot or Lowes.
      
      Edits: 03/06/12
  - RE: another pic - Tre' 17:39:07 03/05/12 (8)
    It's hard to tell from the pictures.
    You said "I went back and wired the heaters per schematic, high side to .68 ohms to pin 7 of one tube. I wired from pin 7 to other .68 ohm and left the resister to pin 2 of other 6550."
    This is a little confusing. forget about pin 2 and pin 7 being swapped. You can swap them or not.
    The bottom line is, one filament of one 6550 should be connected to the filament winding through a .68 ohm resistor. The other filament of the other 6550 should also be connected to the filament winding through a .68 ohm resistor with nothing in series.
    pay no attention to the type of tube in the drawing. That's the only tube symbol of a tube that showed the heater connections I could find.
    If it doesn't work with one side grounded then you have a shorted (to ground) heater winding.
    Tre'
    
    Have Fun and Enjoy the Music
    "Still Working the Problem"
    
    Edits: 03/05/12
    - RE: another pic - frankford 17:47:07 03/05/12 (7)
      I had it wired up this morning the way you are showing. I was getting 3.35 across the heaters. This was the reason I wanted to lift ground. The amp oscillated with this method.
      - RE: another pic - Tre' 17:48:54 03/05/12 (6)
        
        In Reply to: RE: another pic posted by frankford on March 05, 2012 at 17:47:07
        
        You have a shorted heater (filament) winding.
        
        Tre'
        Have Fun and Enjoy the Music
        "Still Working the Problem"
        
        quick question Tre' - frankford 18:06:27 03/05/12 (4)
        
        In Reply to: RE: another pic posted by Tre' on March 05, 2012 at 17:48:54
        
        I just shut down the amp and the channel that wasn't' working came on for a second. Would this also fall in line with a shorted winding?
        
        RE: quick question Tre' - Tre' 18:25:20 03/05/12 (3)
        
        In Reply to: RE: quick question Tre' posted by frankford on March 05, 2012 at 18:06:27
        
        I have no idea about that. That could be a separate problem.
        
        The heater winding just powers the heaters in the tubes.
        
        You said you got only 3.3vac hooked up the right way?
        
        Try it without the resistors and measure what you get.
        
        I really do think there is a problem with the heater winding of the power transformer.
        
        BTW In a in-directly heated tube, like the 6550, they are called heaters, not filaments. We all say filaments even when we know better.
        
        Tre'
        Have Fun and Enjoy the Music
        "Still Working the Problem"
        
        RE: quick question Tre' - frankford 21:57:12 03/05/12 (2)
        
        In Reply to: RE: quick question Tre' posted by Tre' on March 05, 2012 at 18:25:20
        
        took the resister off of one of the heaters, front 6550 7.35 vac second 6.33 vac.
        
        RE: quick question Tre' - frankford 23:05:40 03/05/12 (1)
        
        In Reply to: RE: quick question Tre' posted by frankford on March 05, 2012 at 21:57:12
        
        well the oscellation returned with voltages of 5.34 on one tube and the other 5.6vac
        
        I'm pretty much done with this thing. Thanks for all your help today. I will get hold of the manufacturer tomorrow and see what I can do about.
        
        This isn't my first kit, probably my 9 or 10th kit and the first one to not work on me. Frustrating as heck. O well back to the dynaco 70 tonight.
        
        RE: quick question Tre' - frankford 08:56:14 03/06/12 (0)
        
        In Reply to: RE: quick question Tre' posted by frankford on March 05, 2012 at 23:05:40
        
        Well Brian is sending me another power tranny in the next week. I will keep you all posted. Thanks again for your help.
        
        RE: another pic - frankford 18:02:34 03/05/12 (0)
        
        In Reply to: RE: another pic posted by Tre' on March 05, 2012 at 17:48:54
        
        Thanks for the heads up.

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