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intermitent static pops from speakers st70

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#2
That sounds typical of intermittent contacts with tube pins. A hissy pop. Wiggle the tubes a little and see if you get more or less. Be gentle on the board tubes so you don't crack any weak solder joints under those sockets. It could also be bad solder joints already on those, mimicking a dirty socket. Inspect those joints closly with a magnifying glass and reflow them if you have any doubts. I'd do that first just to eliminate any obvious bad joints. You will probably find some some wrinkley, dark, solder and that is usually the source of trouble and should be reflowed. Be quick and add a dab of new solder to help the old flow better. You could also be hearing noise from leaky caps reforming if this is an unused amp.

BTW, diytube.com has a dedicated st-70 section.
 
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#3
20to20 said:
That sounds typical of intermittent contacts with tube pins. A hissy pop. Wiggle the tubes a little and see if you get more or less. Be gentle on the board tubes so you don't crack any weak solder joints under those sockets. It could also be bad solder joints already on those, mimicking a dirty socket. Inspect those joints closly with a magnifying glass and reflow them if you have any doubts. I'd do that first just to eliminate any obvious bad joints. You will probably find some some wrinkley, dark, solder and that is usually the source of trouble and should be reflowed. Be quick and add a dab of new solder to help the old flow better. You could also be hearing noise from leaky caps reforming if this is an unused amp.
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thanks for the reply. ill reflow those joints. but now i have blown ANOTHER gz34. if i turn the amp off and on and dont wait for at least 30 seconds i blow a fuse and even then the rectifier gets damaged so that the next time it happens it is ruined and shorts out, sparks and dies. this is 3 rectifiers now! arrgh

any advice? sigh
 
#6
I have read that silicone diodes (eg UF4007) in series with the plates on the valve rectifier can help reduce the arcing/blowing. I did this on my latest project. There are generally plenty of spare pins on the socket to place the silicone diodes, so it is an easy mod.
 
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