Reno 400 - shuts off

[Foster Haney]

Hello all, I recently got a Reno 400 with blown speakers (it was a bass guitar) for a good price. I put my Eminence ESG in to test it and it was performing and sounding great (you knew that already tho). but now that I got new horns in, the amp shut off after about a minute of playing. my 15" is 4 ohms, and with the horns in I am still at 4 ohms. I don't think the horn is whats triggering the problem. maybe I should bypass it and do more testing. Has anyone had this problem before, or can lend some helpful words?

Also, are all the 400 series amps the same circuit? just different EQs and speakers?

Thank you, forum members.

[Dave Simonis]

Foster, there is a Triac in the primary of the main power transformer that is used to control the AC to the transformer/amp. If your amp is shutting off, not blowing any fuses or tripping a breaker...I'd suspect something in this circuit and most likely the Triac or a capacitor leaking causing the Triac to shut down. If this is the issue, not an expensive fix. Find a local amp repair guy (or someone who works on amps) and he could replace easily.That would be my step one as that controls power to the amp. Next I would look at the filter caps in the 52V line, maybe leaking a bit and putting a load on the transformer...from there one thing at a time. Also, make sure speaker is 4 ohms - amp was designed for a 4 ohm only.

[Foster Haney]

Thank you Dave, I will start there.

[Ken Fox]

Note that the T.B. is normally closed and mounted to the top of an output transistor. You may have an output transistor overheating

As mentioned above power for the amp does not run thru the power switch, it runs through the Triac and fuse F3. The on/off switch handles a low current signal to operate the Triac

You could disconnect the horn to check that. Note sure if the original was 4 ohms, but it would have had a crossover, otherwise the amp would see a 2 ohm load if it was just in parallel with the speaker. That would overheat the transistors for sure

[Foster Haney]

Ken you hit the nail on the head, I hooked it back up and let it shut off again, that transistor is getting hot. Where can I get one? I am also having a hard time finding your website. Could you remind me of it?

I work on espresso machines for a living, and when I have free time I attempt to transfer those skills to amplifiers.
Thanks a ton.

[Ken Fox]

I would not recommend repairing it unless you are extremely familiar with power amp repair. Likely more wrong than just the outputs. I would send it to Peavey

[John Fields]

It would be a good idea to shotgun all of the TO-3 power transistors and replace the insulators with real mica and plenty of thermal grease. Many Renos used the plastic film insulators with no grease and will often fail.