Rocket Issue

[strato17]

Hey that's great news! Now you can find the problem and fix it.

Pulled it out of the cab, and now it's working. Pretty frustrating. Has to be a bad connection or something...

[martin manning]

Well that is a piece of info you can use. Connect a speaker and power it up with some kind of continuous signal going into the input, or if there is enough noise already maybe just use that (and there may be with the cover off). Poke around systematically with a chopstick, nudging every joint, component, and wire. You should be able to find where the intermittent connection is.

[strato17]

I'm pretty sure it's a tube issue at this point. Everything else checks out. Just need to wait a few days for new tubes to come in.

[Allynmey]

Split the 40uf caps with the standby. It does wonders for the rectifier!

[martin manning]

Allyn, I'm not sure that it does (see above).

[strato17]

Well that is a piece of info you can use. Connect a speaker and power it up with some kind of continuous signal going into the input, or if there is enough noise already maybe just use that (and there may be with the cover off). Poke around systematically with a chopstick, nudging every joint, component, and wire. You should be able to find where the intermittent connection is.

Went over every single point, can't get a noise out of anything, other than the expected "tap" sounds through the speaker when I touch the grid wire to V1, etc. I tightened and rechecked all grounds, all is good. Voltages are great. Amp seems to be working fine now. So bizarre. I have a whole new set f tubes coming in from KCA. Hopefully that will eliminate the problem.

[strato17]

Also, here is a pic of the GZ34.

[martin manning]

Hope it works! When it cuts out does it go silent, like no sound what-so-ever? Are the filaments still glowing when it happens? Rectifier failures are usually pretty spectacular, and not intermittent, so I'm betting against that.

[strato17]

Thanks everyone for the help. When it cut out, I was in the middle of a show and didn't get to check it. The heaters were on, but I didn't check to see if the blue glow was there.

The amp made it through tonight's show ok with v1 and v2 replaced. I also threw a small fan behind it blowin on the 84's. Tonight was show 4 of eleven shows in 12 days. I'll keep you guys posted. I really appreciate it!

[strato17]

Hope it works! When it cuts out does it go silent, like no sound what-so-ever? Are the filaments still glowing when it happens? Rectifier failures are usually pretty spectacular, and not intermittent, so I'm betting against that.

And yes it goes completely silent instantly. I also don't suspect the rectifier.

[2tone]

I've had a couple amps do that after working well for about a year..Both were cold solder/ no solder on a heater pin..maybe reheat these?

[strato17]

I've had a couple amps do that after working well for about a year..Both were cold solder/ no solder on a heater pin..maybe reheat these?

I'll try it! I don't recall losing heaters when it died but I can't hurt

[Mark]

Hi Martin

Have you seen this by Blenecowe?

He rates Ken Fischer's standby switch quite poorly. His point is well taken.

http://www.valvewizard.co.uk/standby.html

[martin manning]

Hi Martin
Have you seen this by Blenecowe? He rates Ken Fischer's standby switch quite poorly. His point is well taken
http://www.valvewizard.co.uk/standby.html

Yes, and I have a great deal of respect for him. But, a LOT of Fender amps were set up the same way (HT - Rec - Res - standby - choke) and many of them are still around, some as many as 50 years later. You can pamper them by turning the power switch off before the standby to drain the caps and choke, but not everyone does. To Merlin's point, one could then just as well leave the standby switch out.

[M Fowler]

Hi Martin
Have you seen this by Blenecowe? He rates Ken Fischer's standby switch quite poorly. His point is well taken
http://www.valvewizard.co.uk/standby.html

Yes, and I have a great deal of respect for him. But, a LOT of Fender amps were set up the same way (HT - Rec - Res - standby - choke) and many of them are still around, some as many as 50 years later. You can pamper them by turning the power switch off before the standby to drain the caps and choke, but not everyone does. To Merlin's point, one could then just as well leave the standby switch out.

If you run GZ34 I don't see any reason to have a standby switch with a slow start tube like that. I do as you stated turn the power off first.