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AUDIO FORUMS >> General Discussion and Support >> Torii MKIV voltage regulator tubes not working
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Message started by bikehappy1 on 07/01/25 at 19:26:19

Title: Torii MKIV voltage regulator tubes not working
Post by bikehappy1 on 07/01/25 at 19:26:19

Hello everyone, I recently had a new RCA jack put in my MKIV. When I put the tubes back in and turned on the amp, the rectifiers both flashed more than usual and now the OC2 and OA3 tubes aren't lighting up. One of my OA3 tubes was bad but I've swapped out tubes and they still don't light up. Could it be a fuse? Any input would be appreciated. - Bike

Title: Re: Torii MKIV voltage regulator tubes not working
Post by CAJames on 07/01/25 at 19:43:00

Quote:

Posted by: bikehappy1 Posted on: Today at 11:26:19

...the rectifiers both flashed more than usual and now the OC2 and OA3 tubes aren't lighting up...

What rectifiers are you using? I'd say no rectifier flashing is normal, if your rectifiers flash they are a problem. Have you replaced them?

If any of the tubes light up the main fuse is OK. I don't know if the Torii MKIV has fuses with the rectifier, but if it does those might need to be replaced.

Title: Re: Torii MKIV voltage regulator tubes not working
Post by Lon on 07/01/25 at 19:52:06

I am with James as far as suspecting one of the fuses under the chassis--if the Torii Mk IV HAS those. I don't know enough about this amplifier to know if there is a fuse panel below.

Title: Re: Torii MKIV voltage regulator tubes not working
Post by bikehappy1 on 07/01/25 at 20:38:52

I had some other 5UG4 rectifiers and I swapped them in but still had the same result. I'm not sure I'll be able to find any spare fuses that came with the amp. Steve told me to replace the fuses as it was blown when the rectifiers flashed.

Title: Re: Torii MKIV voltage regulator tubes not working
Post by will on 07/01/25 at 23:33:56

My MkIV did not come with interior fuses, only the one 5 amp fuse in the IEC inlet. Not sure if at some point Steve integrated interior fuses or not, but when a failed rectifier has caused my fuse (singular) to blow, there is no power to any part of the amp until the fuse is replaced... ie nothing lights up. I can't tell if this is the case with yours from your descriptions, or from what you wrote about Steve's response: "Steve told me to replace the fuses as it was blown when the rectifiers flashed," "fuses" being plural, and "as it was blown" singular. But if the latter, and nothing is lighting up now, the chances seem good that your amp has just the one fuse, and all you need is a 5x20mm 5 amp fuse and rectifiers that are not compromised. Typically, the amps will have come with a spare fuse in a little box section of the IEC fuse holder part, so worth a look. If the main fuse is blown, and it is a stock glass fuse, usually you can see that the wire is broken.