my 18 watt rocket-ish build
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- milkyBK370
- Posts: 79
- Joined: Wed Mar 16, 2011 10:36 pm
Re: my 18 watt rocket-ish build
Hi, I'd be interested to see the layout you used for this. How does it sound?
Re: my 18 watt rocket-ish build
Hi,
shouldn´t be the screens (329 VDC) lower than the plate (322 VDC)?
Probably 319 VDC or lower (the screens) or Pin 7 is 329 and Pin 9 is 322?
Otherwise ...
It should write: plates B+1 and screens B+2 (before and after the choke).
I´m shure it was a typo
Hans-Jörg
shouldn´t be the screens (329 VDC) lower than the plate (322 VDC)?
Probably 319 VDC or lower (the screens) or Pin 7 is 329 and Pin 9 is 322?
Otherwise ...
It should write: plates B+1 and screens B+2 (before and after the choke).
I´m shure it was a typo
Hans-Jörg
Re: my 18 watt rocket-ish build
i'll fire it up again and re-check the voltages. newborn taking all my time. i havent picked up the guitar in 2 months or so.
Re: my 18 watt rocket-ish build
sounds pretty good. havent gotten to play too much. but the layout is kinda trainwreck size board with z-wreck style layout.
Re: my 18 watt rocket-ish build
with a new baby i havent had a chance to check this out. havent fired any amps up in 6 months or so. hopefully fire it up this weekend to get a new voltage chart. wish me luck!!!
Re: my 18 watt rocket-ish build
hans-jörg wrote:Hi,
shouldn´t be the screens (329 VDC) lower than the plate (322 VDC)?
Probably 319 VDC or lower (the screens) or Pin 7 is 329 and Pin 9 is 322?
Otherwise ...
It should write: plates B+1 and screens B+2 (before and after the choke).
I´m shure it was a typo
Hans-Jörg
so i FINALLY got it back up to check the voltages. its been a while
all the voltages throughout the amp are lower than originally posted but im still getting 315vdc on pin 7 and 322vdc on pin 9 of the el84s. weird thing is now im popping fuses. and im out of fuses so i cant fire it up to see what the issue is until after i get some more. any reason why these voltages could be off?
Re: my 18 watt rocket-ish build
Guessing that the lower voltages are due to high PT loading. That is further supported by the popping fuses.
Pull the power tubes, look for shorts in the B+ string, stick a light bulb limiter in the AC mains and give it another go.
Good luck,
Dave O.
Pull the power tubes, look for shorts in the B+ string, stick a light bulb limiter in the AC mains and give it another go.
Good luck,
Dave O.
Re: my 18 watt rocket-ish build
will do. also going to buy some cheaper el84s. you dont want to know what i've been using to test up until this point.
Re: my 18 watt rocket-ish build
i hope im wrong, but i think i just saw a picture where i had B+1 and B+2 both actually wired to B+1
Re: my 18 watt rocket-ish build
nevermind. they are wired correctly. i'll keep poking around
Re: my 18 watt rocket-ish build
I think that I saw mention of a B+ line fuse in an earlier post.
Is that correct?
If so, which fuse has recently started popping?
And...yes..by ALL means! Do take care of those NOS Mullard EL84s!!!
Good luck mate,
Dave O.
Is that correct?
If so, which fuse has recently started popping?
And...yes..by ALL means! Do take care of those NOS Mullard EL84s!!!
Good luck mate,
Dave O.
Re: my 18 watt rocket-ish build
got the new tubes. a pair of jj el84s and a pair of EH - el84s. first fuse that popped was the main fuse. then i replaced it and the other fuse popped. the one coming off of the standby switch. so technically both fuses popped. I'll have to go back and look to see what fuses i should have in there. i believe the main fuse is 1a sloblow and the other fuse is 1/2 amp fast but i'll verify. when i fired up the amp a year or so ago i did use the light bulb limiter and had no issues. and the amp, at relatively low volumes, sounded pretty good.
Re: my 18 watt rocket-ish build
on a side note. anyone know where i can get a really cheap tolex headshell that would work for an trainwreck ceriatone chassis?
Re: my 18 watt rocket-ish build
so im having a little trouble with values for the fuses. since they both popped i seemed to have lost them and need to order new ones. what values should be in an amp like this for each fuse?
Re: my 18 watt rocket-ish build
I looked at a couple of 18W schematics and it looks like a 2A Slo-Blo for the mains fuse is a good choice.
Not sure about the HT fuse though. I would think that a 1/4 to 1/3 A Slo-Blo wouldn't do any harm there.
Do you know what your PT HT current rating is? ~1.25X that should work fine as well.
Cheers,
Dave O.
Not sure about the HT fuse though. I would think that a 1/4 to 1/3 A Slo-Blo wouldn't do any harm there.
Do you know what your PT HT current rating is? ~1.25X that should work fine as well.
Cheers,
Dave O.