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Hi all,
I just bought a used vintage MA1 (12 output tubes) with 4 12SX7 modded.
The AMPMETER's fuse (250mA) inside keep blown. I have 2 ampmeters, one is cheapy and other is fancy electrician type. It didn't blow right away, but after adjust and readjust both DC offset and bias, all certain the fuse is out
Anyone has same issue when adjust bias using ampmeter ?
Something is wrong with the amp? Seem like there is some spike in current that cause it, is this normal ?
NOTE: the blown fuse mention here is the one INSIDE the ampmeter
Please advise
Thanks
Thuan
Edits: 11/07/11 11/07/11Follow Ups:
What tyu said. But also, 250mA seems like a low value for that fuse. It may be simply that someone before you has replaced that fuse with the wrong value. I would guess that you need at least a 1A or 2A fuse there, but I am not sure where the ammeter is inserted into the circuit. So, ask Ralph.
If the amps are running fine and sound good, and if all the voltage readings check out ok (before the fuse blows, if you have been able to listen or take the V measurements), then that increases the likelihood that the fuse needs to be rated for a higher amount of current. But, ask Ralph anyway.
Thanks all,
I did call Ralph, he suggest that use the meter that can handle at least 2A
Best
Take the amps back............ the amps have been moded....An that fine but who did the Mod????
Now if you gave $500 for the pr you may wont to send them to Ralph...
But you well be spending big money......An you may have big money thats coool....goodluck
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