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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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fuse/ power supply question or problem on amplifier
Our amplifier was on yesterday and suddenly stopped working, the T1A fuse on
the 240V side of the transformer had blown, for no apparent reason. I did an 250V insulation test on the 240V side of the t/f and it was clear, there didn't appear to be a short circuit on the 240V side of the t/f or an interwinding fault or a fault to earth on the LV side, the connector from the LV side is connected to a rectifier board with, I presume, some current limiting feature. As far as I could see there was no obvious fault component in the amplifier. I didn't have any T (antisurge) fuses so I used a F1A quick blow fuse. The amplifier worked fine last night but today the fuse blew within a few seconds (or less) or the amplifier being switched on (using the button on the front which switches the 240V circuit). The amplifier is a Marantz about 12 years old. Is it possible that using a quickblow rather than an anti surge fuse has caused the fuse to blow the second time. Is there likely to be some current limiting device on the rectifier board? Any other pointers things or things I should look for. Thanks Ian |
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fuse/ power supply question or problem on amplifier
"ian nicoll" bravely wrote to "All" (09 Sep 03 15:33:44)
--- on the heady topic of "fuse/ power supply question or problem on amplifier" in From: "ian nicoll" in The amplifier is a Marantz about 12 years old. in Is it possible that using a quickblow rather than an anti surge fuse in has caused the fuse to blow the second time. Is there likely to be some in current limiting device on the rectifier board? Any other pointers in things or things I should look for. in Thanks in Ian Yes, a fast fuse will go... well... faster! What can happen with a fast blow fuse in an application requiring a surge rating is that one might switch the power at the instant the line voltage is at maximum and the fast fuse goes pfffft... If the slo blow one goes again then worry... Asimov ****** .... Power is obtained by current meeting resistance |
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fuse/ power supply question or problem on amplifier
"ian nicoll" bravely wrote to "All" (10 Sep 03 08:23:57)
--- on the heady topic of " fuse/ power supply question or problem on = amplifier" in From: "ian nicoll" in Thanks for answers. in The original fuse is stamped T1A 250V, it also has four coloured bands in on the glass body (like a resistor) they are brown, black, red and a in thicker blue line. What do the colours signify? The colours represent the current in milli-amperes so brown, black, red would be 1,000 milli-amperes or 1 ampere. The last blue band would similarly likely represent the voltage rating, in this case your 250V. The significant symbol is the letter "T" which represents a slo-blo fuse for use with inductive or capacitive surges. They are designed to blow with up to 400% of the rating outside a time period of about 2 seconds. A similar ampere rating fast blow fuse will open within 0.3 seconds, so rest assured the fast blow fuse you tried to use never stood a chance. No need to "special" order a fuse. "T" fuses are very ordinary. Asimov ****** .... Power is obtained by current meeting resistance |
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