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Post subject: Sort of a Fender project amp
Posted: Wed Feb 26, 2014 5:19 pm
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It's been a busy few nights, here's what I have done so far. I am getting a lay-down style bell set for the PT and should be able to start wiring this weekend.

I'm using another brand solid state head cabinet because in actuality, I like it and I got it dirt-cheap.

Image

I cut out the area of the chassis that had all the funky stamping and holes that weren't going to work and replaced it with a piece of aluminum sheet, then drilled the tube mounting holes.

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Post subject: Re: Sort of a Fender project amp
Posted: Wed Feb 26, 2014 5:25 pm
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Hey jimolson1963....is there a start to this thread? What are you building?

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Post subject: Re: Sort of a Fender project amp
Posted: Wed Feb 26, 2014 6:13 pm
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Jim,

I have one little suggestion on the layout of your DIY project. Put the output tranny over on the side of the amp --- nearer to the PT & far from the pre-amp tubes. This will cut down on hum picked up by the high-gain section of the amp.

You oriented them correctly (90-degrees). With that arrangement you can actually place the PT and OPT next to each other.

Are you going to use DIY turret or eyelet tagboard for the circuit?

Good luck with the project!


https://sp.yimg.com/ib/th?id=HN.6080524 ... 2&pid=15.1


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Post subject: Re: Sort of a Fender project amp
Posted: Wed Feb 26, 2014 6:26 pm
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This is the start of the project, I had another thread asking about the transformers.

I wondered about the placement of the OT, on my Bassman 50 it's on opposite ends but on my Bassman 100 they're next to each other. It was just a thought and I appreciate the info on hum.

I'm going to make an eyelet board, I don't like the turret boards for some reason that I can't explain.

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Post subject: Re: Sort of a Fender project amp
Posted: Thu Feb 27, 2014 8:14 am
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BMW2002Ti wrote:
Jim,

I have one little suggestion on the layout of your DIY project. Put the output tranny over on the side of the amp --- nearer to the PT & far from the pre-amp tubes. This will cut down on hum picked up by the high-gain section of the amp.

You oriented them correctly (90-degrees). With that arrangement you can actually place the PT and OPT next to each other.




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Post subject: Re: Sort of a Fender project amp
Posted: Thu Feb 27, 2014 11:21 am
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Yep, I'm going to do that.

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Post subject: Re: Sort of a Fender project amp
Posted: Fri Mar 28, 2014 8:18 pm
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Here it is as of tonight. The fourth tube socket is for future reverb.

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Post subject: Re: Sort of a Fender project amp
Posted: Fri Mar 28, 2014 10:06 pm
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This looks like a very cool project. Your work looks great. 8)

What ever happened on your other thread?

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Post subject: Re: Sort of a Fender project amp
Posted: Fri Mar 28, 2014 11:23 pm
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Do you have plans for a cap cover for those electrolytics, Jim?

It may provide some hum reduction in addition to its obvious safety function.

Arjay

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Post subject: Re: Sort of a Fender project amp
Posted: Sat Mar 29, 2014 1:25 am
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Retroverbial wrote:
Do you have plans for a cap cover for those electrolytics, Jim?

It may provide some hum reduction in addition to its obvious safety function.

Arjay



IMO not for hum , it is DC voltage , but for safety it must be in a close box.


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Post subject: Re: Sort of a Fender project amp
Posted: Sat Mar 29, 2014 1:34 am
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It will be DCV coming out of the filter array. But the incoming voltage will contain an element of AC ripple.

Arjay

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Post subject: Re: Sort of a Fender project amp
Posted: Sat Mar 29, 2014 1:51 am
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Retroverbial wrote:
It will be DCV coming out of the filter array. But the incoming voltage will contain an element of AC ripple.

Arjay



To small IMO and not close enough to 12XX7 tube .In my opinion it is only for safety it must be in close boxe. A hand could easely touch lethal high voltage in open back cab.


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Post subject: Re: Sort of a Fender project amp
Posted: Sat Mar 29, 2014 7:07 am
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I realize you guys don't know me from Adam so yes, I am absolutely safety-conscious and aware and it will definitely have a cover. Otherwise they would be inside the chassis. They may still end up inside in a different configuration, I made that cap board for my Bassman 100 that has severely warped, unusable boards.

I started working with electronics back in 1973-74 when was ten or eleven years old. I got into music real heavy and all I had to work with was a crappy hand-me-down stereo. My first project was tearing apart transistor radios and building cardboard boxes with multiple speakers to get better sounds. I started playing drums at 12, guitar at 13 and bass at 14 and that's been my main focus since. I love making women's hips sway with a good groove. ;)

I'm a working musician in a classic rock/blues band in mid-Michigan and actually worked on Fender amps for a short time about 25 years ago. I never got into the theory part though which is why I have so many questions now. Replacing obviously bad parts is really easy, it's when you get into the other issues that's a challenge but I'm up to it and thanks to guys like you I'm learning a LOT.

My first real electronics project was building a color organ to run off my stereo around the time I got my first drum kit when I was 12. That's when I learned about how quickly things can go bad when you aren't being safe.

I had the circuit out of the light cabinet and it fell off my dresser into my stereo chassis that was also open and started a small but momentary fire inside the stereo chassis. I quickly put it out and since then I have been all about working safely. I use clips on my meter leads so I'm not poking around in the amp and I don't wear a watch or anything else on my hands except my wedding ring. I discharge caps before touching anything inside a chassis and in general take all the normal safety steps before doing anything. High voltage doesn't scare me but I do respect it.

I'm working on several projects, Lou, which one are you referring to? The Sunn Spectrum II just needs some finishing up and it'll be ready for sale, that was just a re-cap & tube along with some jacks and pots. Oh, and a three-wire power cord.

The mini-amp I built from an old DuKane intercom amp was just to see if I could do that with very little help and I was able to, that'll get tweaked and such when I get some other things done.

The most important thing is I know my limitations and even though I have a good track record on typical amp repairs, I'm not afraid to ask questions and I love solving problems, especially those caused by someone that knows how to melt solder but not much else. Almost all of the questions I've had in the forums have been focused on my own equipment that I'm either heavily modifying or custom building. It's sort of like my tube amp capabilities are at a 4-5 and I want to push that much higher, hence the custom builds.

I have much to learn and I'm willing and eager to do so. :)

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Post subject: Re: Sort of a Fender project amp
Posted: Sat Mar 29, 2014 1:36 pm
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jimolson1963 wrote:
...I'm working on several projects, Lou, which one are you referring to?...


The one about the transformer, with the DC supply giving you over 1,000 VDC.

http://forums.fender.com/viewtopic.php?f=12&t=92501

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Post subject: Re: Sort of a Fender project amp
Posted: Sat Mar 29, 2014 3:05 pm
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Ah, yeah. That is this amp, the Yamaha solid state head I converted to the 5F6 Bassman. I unhooked the PT and tested all the leads again, then put it back in using the 127v input instead of the 110v input lead. The voltages came back at a much more reasonable level. Still trying to figure out some of the bugs and I still have no sound at all.

These are the voltages I'm reading now:

C1=247v
C2=506v
C3=505v
C4=441v
C5=434v

V1
1 - 269
2 - 0
3&8 - 1
6 - 292
7 - 0

V2
1&7 - 243
2 - 0
3 - 1
6 - 434
8 - 256

V3 (PI)
1 - 224
2 - 15
3&8 - 54
6 - 205
7 - 17

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