Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kfs90 on January 23, 2017, 01:59:49 pm

Title: What does this capacitor do?
Post by: kfs90 on January 23, 2017, 01:59:49 pm

I see a cap on this Ceriatone diagram from the 500mA fuse to ground, but it isn't there on this Triode diagram. Can someone tell me what the purpose of it is on the Ceriatone and why it isn't on the Triode?

Title: Re: What does this capacitor do?
Post by: PRR on January 23, 2017, 02:54:01 pm

> Can someone tell me

No. I can't see why.

But also note that one fuses the high side, the other fuses the ground leg. There are probably other differences. Each designer has different preferences. I suggest you not be looking at both when you actually wire.

Title: Re: What does this capacitor do?
Post by: shooter on January 23, 2017, 03:32:30 pm

Is it just for spike suppression when flipping outta stby?

Title: Re: What does this capacitor do?
Post by: sluckey on January 23, 2017, 04:56:11 pm

I hate those ceriatone drawings. They make you waste time looking for stuff that should be obvious.

Title: Re: What does this capacitor do?
Post by: kfs90 on January 23, 2017, 06:13:17 pm

Thanks. It makes sense about the popping when switching the standby.

What about the diodes on the rectifier tube. The Ceriatone has them and a cap; the Triode doesn't. What's the purpose? At this point, I'm likely going off of the Ceriatone, because my transformer markings are a match for that diagram.

Title: Re: What does this capacitor do?
Post by: shooter on January 23, 2017, 07:19:33 pm

Quote

What about the diodes on the rectifier tube

I'm a schematic guy, so...my guess they are in case the rec tube goes south, the amp won't go with it?

Title: Re: What does this capacitor do?
Post by: HotBluePlates on January 24, 2017, 01:49:22 pm

Quote from: kfs90 on January 23, 2017, 06:13:17 pm

What about the diodes on the rectifier tube. The Ceriatone has them and a cap; the Triode doesn't. ...

The JTM45 built by Marshall in the 60's didn't have them either.  Ceriatone is adding modifications to the original circuit.

Quote from: kfs90 on January 23, 2017, 06:13:17 pm

What about the diodes on the rectifier tube. ... What's the purpose? ...

If the rectifier tube shorts from plate to cathode, the solid-state diodes will have already pre-rectified the voltage.  Amp continues to play as if nothing happened, although d.c. output voltage will be a little higher.

Quote from: kfs90 on January 23, 2017, 06:13:17 pm

... At this point, I'm likely going off of the Ceriatone, because my transformer markings are a match for that diagram.

It will be to your benefit to learn to translate layout and schematic diagrams so you can visualize using any part-in-hand in the circuit, as appropriate.

Title: Re: What does this capacitor do?
Post by: kfs90 on January 24, 2017, 05:36:57 pm

Thanks a mil, everyone! I appreciate you all.