Announcement

Collapse
No announcement yet.

Allied/Knight problem

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • dmartn149
    replied
    Thanks, I ordered the mallorys. My ears are pretty old. I don't think they can hear mojo anymore

    Leave a comment:


  • loudthud
    replied
    Any of those caps should help you get the amp going. Physical size is the only thing to watch out for. Mallory 150's are small and kind of mellow sounding. "Orange Drop" types are somewhat brighter sounding but bigger. Just get the amp working and add the mojo later

    Leave a comment:


  • dmartn149
    replied
    How about these?
    0.05uF @ 630V Tubular Axial Film Capacitors:QTY=30 (.05uF for Tube Electronics) | eBay
    or these from Hoffman amps
    047 mallory 473
    Mallory 150 series capacitor - 630 volt
    Price each = $1.08
    Last edited by dmartn149; 07-15-2012, 04:50 AM.

    Leave a comment:


  • dmartn149
    replied
    Thanks again Loudthud for your help.
    I tried other power tubes before I started measuring. They all sounded the same, one hot the other just warm.
    I was measuring DC on pin 5. It went to about 100v when I first turned on the power then dropped to 10 and 35 on the two tubes.
    I'll change those caps. I guess I should change all of them. I think there are 7.

    Leave a comment:


  • loudthud
    replied
    Originally posted by dmartn149 View Post
    I compared voltages on the two tubes and found that pin 5 had only 10v on the first tube and 35v on the second. I checked pins 2 & 5 at the PI and got 60 and 30v respectivley. I thought maybe I had a bad PI tube, so I switched it with one of the other tubes, and it sounded the same, first power tube still running cold.
    I don't know what I should check next.
    Swap the power tubes to see if you have a bad tube or the problem is with something inside the amp connected to that socket.

    AC or DC voltages? The DC voltage on pin 5 of a (good) 6L6 in this amp should be 0V. It should be zero volts iven with the tube removed. If it's not, replace the 0.05uF cap(s). That's probably what is pulling down the voltages on the PI pins 2 and 5 and making the 6L6s hot.

    Leave a comment:


  • dmartn149
    started a topic Allied/Knight problem

    Allied/Knight problem

    I've converted this Allied/Knight PA to a guitar amp. All I've done is change the obsolete in/out jacks to 1/4", change the power chord to a 3 prong, and replace the e caps.
    It sounds pretty good turned all the way up, but at partial volume it has a really ugly distortion and the volume fluctuates. I noticed that the first power tube (the one connected to pin 5 of the PI) doesn't get as hot as the other.
    I compared voltages on the two tubes and found that pin 5 had only 10v on the first tube and 35v on the second. I checked pins 2 & 5 at the PI and got 60 and 30v respectivley. I thought maybe I had a bad PI tube, so I switched it with one of the other tubes, and it sounded the same, first power tube still running cold.
    I don't know what I should check next.
    Advice anyone?Click image for larger version

Name:	schem 002.jpg
Views:	2
Size:	354.3 KB
ID:	865543Thanks
Working...
X