I recently fixed up a Hafler DH-220 which had a dead channel. Before I began I noticed the voltage across the +voltage fuse for one channel was 65v and the other was 85v. After the repair, and upgrading the capacitors to 22,000uF 80vdc, I'm seeing 84v on both channels. Is this something I should be concerned about? It runs fine, bias and offset calibrate fine. Just confused at the voltage I'm seeing.
Perhaps old cap was outside its useful live. I would be intetesting to measure ripple levels in place of DC only. In any case if voltages are ok and the behavior of the dut is ok too, there isn't any to worry about, no ;-)
Strange, is your AC line voltage too high? The capacitor life will be reduced due to the over voltage.
Possibly it is wired for 100VAC line instead of 120VAC, maybe you should check.
The manual has the wiring configurations for various AC line voltages.
Normal supply voltage is 65VDC, so the 85VDC is alarmingly 30% too high.
The manual has the wiring configurations for various AC line voltages.
Normal supply voltage is 65VDC, so the 85VDC is alarmingly 30% too high.
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Perhaps a resonance between trafo's secondary and cap. Again, 5% in excess for the cap is negligible, although not so for the semiconductors