• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Keep Blowing Fuses

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W

Whiting

Member
Joined 2008
Hi AndrewT

Thanks for your reply mate, however I'm a newbie at this and don't have a Varaic.

This is only my second attempt at trying to diagnose & fix a tube amp, my first was only cap replacements based on visual inspection only.

This one appears to be a little more difficult.

Any other suggestion would be appreciated.

Cheers
 
A

AndrewT

R.I.P.
Joined 2004
but wait till a valve/tube guy confirms if the bulb tester works to protect/slow down the start up without damaging anything.
It certainly works with SS ClassAB and ClassA amplifiers and ClassA pre-amps. But, not with soft start circuits, these have to be shorted out.
 
kevinkr

kevinkr

Administrator
Joined 2004
kta-hifi.net
Paid Member
AndrewT said:
but wait till a valve/tube guy confirms if the bulb tester works to protect/slow down the start up without damaging anything.
It certainly works with SS ClassAB and ClassA amplifiers and ClassA pre-amps. But, not with soft start circuits, these have to be shorted out.
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Works fine with tube amplifiers too, and prevents catastrophic damage to the power transformer and other components in the event of a shorted cap or rectifier. Most likely to be either in this case. Something like a 100W bulb should be adequate for troubleshooting purposes to identify a failed component. Amplifier will not operate near normally with the bulb in series, a higher wattage bulb would permit that once the issue has been identified.
 
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