The problem is not on the QSK board, it's on the Filament/AC board. Q1
and/or Q2 are bad. You'll need to pull the board out so you can get to
Q1, which is on the back side of the board. To do that, you need to
heat the large filament lead till the solder flows and then pull up on
that corner of the board to separate it from the filament lead. Before
doing that, there are a couple of screws to remove that hold the board
in place. You don't need to remove any of the other leads attached to
the board - you'll be able to turn it over easily. This problem can
occur when a tube shorts, or if you fail to allow time for the filter
caps to drain their charge before removing the cabinet top. If the
cabinet interlock closes and draws an arc, you'll probably lose Q1
and/or Q2. When you disassemble the aluminum piece on he rear of the
board from the board, don't lose the two spacer washers or the two
ceramic washers. The metal washers are necessary to properly space he
board so it isn't bent when you reassemble and tighten the two screws
that engage the metal lugs. Use a 2N3055 for Q1 no matter what's there
now. Q2 is obsolete, but you can find them on eBay. They may not have
the same case type as the original - don't be concerned about that.
You can email me if you have any further questions about the fix.
73, Floyd - K8AC
On 3/27/2018 10:09 PM, Rodney wrote:
I have plate current of 190m in stand by should be 0 , trouble is on the QSK
board no.81542 I think it is Q1 and D2 anyone have any info on this problem. 73
Rod
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