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#1 2013-06-18 18:17:33

elvis_hogjaw
New member
Registered: 2013-06-18
Posts: 2

v-4 cutting out. intermittent on the 2nd preamp board

hi guys
i've been following the v-4 forum for a while.
my amp, it's a v-4, magnavox series, probably a 76.  i have a problem with power cutting out, the same problem i've seen so many forum posts about.
in  my case, i took the head out of the cabinet, set it on some books and fired it up plugged into the cabinet. as soon as the cutting started to become evident, i started poking around the boards with a rubber hammer. as soon as i hit the board where the 6k11 tube was, the signal started to come back.

i soldered the tube socket joints on the 6k11, and it got a little better but not perfect. i noticed there is a big resistor there, i think its r217, a big heat resistor. the board is burned deep brown around that resistor, but the resistor appears intact.

at practice, after the resolder, the amp still cut out. most of the pre amp and power tubes have been replaced, except the 6k11. I am hesitant to replace that tube, since the amp didn't do this two years ago when i got it and the tube isn't smoked, doesn't appear to have any broken connections.

has anyone isolated what component on that board would cause the whole power section to just drop ??


thanks!

e out

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#2 2013-06-25 19:50:24

elvis_hogjaw
New member
Registered: 2013-06-18
Posts: 2

Re: v-4 cutting out. intermittent on the 2nd preamp board

so get this. i'm playing the amp at volume at rehearsal before the show, and it's cut-out city.
i unplug my line and go direct into the board and it goes crackly.
i take the short cable that i use from the tuner to the head out
and plug a different cable into the input, and it worked fine.

i was amazed.

the way the volume was cutting in and out, when i tapped on the board around the 6k11 tube made me think it was the circuit board.

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