So I built this Rocket into a blues Junior sized chassis. Amp sounded great but had some oscillations. I couldn't figure out what the issue was. In any case I didn't like the stock cathode resistor value at 50ohms. So I couldn't find the oscillation but in the mean time I decided to add in some resistance to make it a it easier on the tubes as they were running hot. So as I was removing the 50ohm resistor I am pulling on the network and hear this hissing sound. This is what I found. Notice the opened hole and the liquid that has leaked from the cap body.
[img:500:375]https://farm4.staticflickr.com/3901/15124270029_747faa2341.jpg[/img]P1240939 by gbucha, on Flickr
I put in some more resistance (too much at this point, it made the amp less lively so I am going to reduce it BUT I also put in a new Cathode cap and Voila.....no more oscillation!
Drove me nuts!
Moderators: pompeiisneaks, Colossal
Re: Drove me nuts!
That baby be losing its juice!
Re: Drove me nuts!
Excellent work how does the amp sound?
Humbuckers just don't sound as nice as singles through my Rocket.
I'm still experimenting through.
Humbuckers just don't sound as nice as singles through my Rocket.
I'm still experimenting through.
Yours Sincerely
Mark Abbott
Mark Abbott
Re: Drove me nuts!
HeeBGB,
For the record, what brand and age was the cap that failed?
Thanks.
For the record, what brand and age was the cap that failed?
Thanks.
Re: Drove me nuts!
No smoke? You're lucky to find that before it really made a mess of things!HeeBGB wrote:So I built this Rocket into a blues Junior sized chassis. Amp sounded great but had some oscillations. I couldn't figure out what the issue was. In any case I didn't like the stock cathode resistor value at 50ohms. So I couldn't find the oscillation but in the mean time I decided to add in some resistance to make it a it easier on the tubes as they were running hot. So as I was removing the 50ohm resistor I am pulling on the network and hear this hissing sound. This is what I found. Notice the opened hole and the liquid that has leaked from the cap body.
Add that to the list of oscillation causes and sources.
Thanks for sharing.
Re: Drove me nuts!
Sorry Been busy and I forgot about this post.
The cap is a Mallory 220uf 100V Age unknown but I have had it for many years in my parts bin.
At this point I am not totally sure that the cap caused the oscillation. It came back after I re-assembled everything and lead dress was the answer. Specifically the input from the input resistor on the board to V1. That wire needed to be pushed down tight against the chassis. For some reason I had it pulled away from the chassis in mid air and it was causing a problem. BUT now the oscillation is gone...at least the audible portion of it.LOL
Mark....at this point the amp sounds great. The cleans are really what hooked me in. With the Tele they are just mind blowing for me. Got that really woody swirlie thing goin on. I just love finding a piece of gear that just makes me want to keep playing.
In any case I have decided on color for the cab. Sliberty and I were talking and he suggested I paint it instead of tolex or tweed. He suggested Metallic Ice Blue like the new thinline Tele I am doing atm. I found some nice metallic blue spray paint at Lowes for cheap so i am going to try that. It's more LPB than Ice Blue but it should look good. The paint was cheap enough that if I don't like it I can cover over it later.
I installed the chassis in the cab tonight. Faceplate will change when the cab is painted and I have decided if I like it or not. Gonna try to make a video this weekend I hope.
[img
2448]https://farm3.staticflickr.com/2945/15177877998_bcbf59fa1a_o.jpg[/img]
IMG_3309 by gbucha, on Flickr
[img2448]https://farm3.staticflickr.com/2949/15177944527_e417b51370_o.jpg[/img]
IMG_3308 by gbucha, on Flickr
The cap is a Mallory 220uf 100V Age unknown but I have had it for many years in my parts bin.
At this point I am not totally sure that the cap caused the oscillation. It came back after I re-assembled everything and lead dress was the answer. Specifically the input from the input resistor on the board to V1. That wire needed to be pushed down tight against the chassis. For some reason I had it pulled away from the chassis in mid air and it was causing a problem. BUT now the oscillation is gone...at least the audible portion of it.LOL
Mark....at this point the amp sounds great. The cleans are really what hooked me in. With the Tele they are just mind blowing for me. Got that really woody swirlie thing goin on. I just love finding a piece of gear that just makes me want to keep playing.
In any case I have decided on color for the cab. Sliberty and I were talking and he suggested I paint it instead of tolex or tweed. He suggested Metallic Ice Blue like the new thinline Tele I am doing atm. I found some nice metallic blue spray paint at Lowes for cheap so i am going to try that. It's more LPB than Ice Blue but it should look good. The paint was cheap enough that if I don't like it I can cover over it later.
I installed the chassis in the cab tonight. Faceplate will change when the cab is painted and I have decided if I like it or not. Gonna try to make a video this weekend I hope.
[img
2448]https://farm3.staticflickr.com/2945/15177877998_bcbf59fa1a_o.jpg[/img]IMG_3309 by gbucha, on Flickr
[img
2448]https://farm3.staticflickr.com/2949/15177944527_e417b51370_o.jpg[/img]IMG_3308 by gbucha, on Flickr
Re: Drove me nuts!
That is a fat build man, looks great.
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Reeltarded
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Re: Drove me nuts!
Hey it lives! It looks great too!
Signatures have a 255 character limit that I could abuse, but I am not Cecil B. DeMille.
Re: Drove me nuts!
Looks great Greg, and I can't wait to see it in blue. But more importantly, I can't wait to hear it. I love my Rockets, and I also love the BJ 1x12 form factor, so it should be awesome.
Greg and I bought the same cabinets and chassis', and I used mine to build a Brown Princeton (6G2) with a JBL K-120 installed. Love the amp. As you can see, I used a simple stain, but the blue paint is going to look great. Grab and go!
Greg and I bought the same cabinets and chassis', and I used mine to build a Brown Princeton (6G2) with a JBL K-120 installed. Love the amp. As you can see, I used a simple stain, but the blue paint is going to look great. Grab and go!
Re: Drove me nuts!
Take a look at some of the "Transtint" dyes. You might find something different and something you like..Also---in your cab, how is the baffle board attached to the cab..
Re: Drove me nuts!
Baffle is bolted from the front. You can see in the pics the four bolts from the front and the rear pic you can see the nuts on the bottom. I found some dark blue metallic rust oleum at Lowes. I am gonna go with that for now. Just need to get a good primer to cover the grain