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Philippe Backès (phil971)
Username: phil971

Registered: 05-2012
Posted on Wednesday, May 09, 2012 - 08:16 am:   

Hi from Guadeloupe !
I have a 115RP since 30 years, and some problems with this old guy...
Two months ago, the preamp stopped to work : no sound with instrument input, no effect by turning knobs...
So, as it is very difficult here in Guadeloupe to find a GOOD technician, I plugged a Behringer V-Amp 2 in the effect loop, 3 volts input (100 millivolts input is linked to the preamp, so doesn't work).
Sound was nice, but maybe there was a loss of output power : near non amplified drums, I was not earing my amp, with V-amp2 output level to max...
Two days ago, the red light began to blink, sound began to disappear...and a fuse, inside, blown out : 250V T1A...
I replaced the fuse with the same one, and now :
If amp is on, and standby switch on high or low position, and I don't play guitar, the light remains lighted.
If I play guitar, after about 15 seconds the light blink and the sound disappear.
After that :
- If power is on and standby switch is on the middle position : no light
- If power is on and standby switch on high or low position, the light brights, but sound is very low and distorded...
What is the function of this fuse ?
Thanks in advance
Phil
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Mike Kaus (mm210)
Username: mm210

Registered: 05-2006
Posted on Friday, May 11, 2012 - 03:52 pm:   

That fuse in on the primary transformer for the high voltage side. It appears that every lead on the PT is fused seperately. The standby then passes the high voltage to the rest of the circuit. With no sound and distorted sound, you need to check and see if the voltages are corrct as they leave the transformer and then progress through the circuit. It looks like there are 4 different fuses just on the PT alone. I'm not really familiar with the RP's but the tracing is still the same. You might want to build or get a light bulb limiter to keep from eating fuses and start tracking the voltages through first. If Lars pops in, he's more familiar with the export versions. I've never even seen one. THe fact that the amp blows fues though and that there are filter caps in the high voltage side after the standby, I'd look at them first.
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Philippe Backès (phil971)
Username: phil971

Registered: 05-2012
Posted on Sunday, May 13, 2012 - 09:44 am:   

Thanks Mike !
I found a Fender technician, he knows Musicman gear, so I shall bring my amp on next week...
Have a nice day !
Phil

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