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RESOLVED - Sega Model 3 Audio amp (838-12796) Fuse rating

Lemony Vengeance

Lemony Vengeance

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RESOLVED: the fuse is F3A250V


Hey all, Got the ol' yaton especiale with an NVS-4000 so you know what that means.... no wiring harnesses, immediate cap kits needed, no LED light on the PSU, no sound at all.... a real rebuild sitch. This one is no exception.

Both the Amp PCB and the PSU PCB (the same one that's in a blast city) have been recapped by me. I have built the needed wiring harnesses to drop it into the trusty NAC and confirmed that I'm getting solid 5v and 3.3v... and a spongey 11.63v (any ideas beyond caps? lol). I've also replaced the 10 ohm fusible resistor on the audio PCB. I've even replaced the audio pot AND harness that connects it to the amp PCB, snd still no sound :( It turns out that both fuses on the Audio Amp PCB have blown. The board accepts 18v via a transformer and the power goes immediately through the Fuses which are rated at 5 amps.

if anyone can shoot me the correct voltage value of the fuses I would really appreciate it.
 
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voltage just needs to be higher than your using,
what matters is current (amps) and if they are F (fast) or T (time delay / anti-surge)
 
stj said:
voltage just needs to be higher than your using,
what matters is current (amps) and if they are F (fast) or T (time delay / anti-surge)
Click to expand...
I have the amps, however I don’t know if they’re F or T.
 
You probably need 250v 5A ceramic slow blo/time-delay fuses since they are on the AC line powering the amp. These will help deal with current inrush as the amp powers up.
 
Derick2k said:
You probably need 250v 5A ceramic slow blo/time-delay fuses since they are on the AC line powering the amp. These will help deal with current inrush as the amp powers up.
Click to expand...
This is after the transformer takes the power and pushes it to 18v.. it should be 18v DC though, right?
 
Lemony Vengeance said:
This is after the transformer takes the power and pushes it to 18v.. it should be 18v DC though, right?
Click to expand...
Doesnt matter, the fuses will work for AC/DC, you want a higher voltage rating, and what really matters is the amps or F or T like stj pointed out.

All the transformer is doing is stepping down the voltage, the 18v could be rectified DC voltage or AC being feed to the amp, and the amp has its own rectifier.

But again, you will need 250v 5A fuse, and most likely it will be a Time Delay/Slow blow, probably a 5mm x 20mm

Edit:

Found a pic, is this what you have?
Fuses.jpg


Check your fuses, see if they say T5.

And you will want ceramic, less prone to breakage.
 
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yes, always pay extra for ceramic - much better than trying to vac bits of glass out of stuff!
they are probably T because amplifiers have large capacitors that will have a big inrush current.

if your fuses are soldered like in the foto, dont waste money buying wire ended ones - fit a pair of 20mm fuse holders.
 
stj said:
yes, always pay extra for ceramic - much better than trying to vac bits of glass out of stuff!
they are probably T because amplifiers have large capacitors that will have a big inrush current.

if your fuses are soldered like in the foto, dont waste money buying wire ended ones - fit a pair of 20mm fuse holders.
Click to expand...
agree fit in some sockets in case they blow again :thumbsup:
 
they probably will blow,
i cant see a pair of T5A fuses blowing from old caps!
i bet there is some serious shorted parts involved.
 
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