Bottlehead Forum
Bottlehead Kits => S.E.X. Kit => Topic started by: FraGGleR on May 09, 2013, 10:41:13 AM
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As I continue to prepare for a complete rebuild, I have come to realize that I would happily buy new components to save myself the hassle of desoldering or otherwise destructively removing components. I have a new top plate so I can start fresh and plan to only reuse the iron. However, while I can find parts based on the assembly guide, there are variables (brand, size, etc.) that aren't covered.
Is their an official BOM that I can access? Does it matter beyond what is in the assembly guide? In general, I stuck to Vishay and IRC resistors, and Nichicon for all caps that aren't going to be boutique. The problem is that Nichicon has something like 20 variations for a single value of electrolytic capacitor.
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Everything matters to one degree or another. A lot of the caps in the SEX 2.1 have what they are written on them. If you're going to use leaded caps instead of snap-in caps, I would stick with the Panasonic ED's if at all possible. Nichicon's datasheets will tell you more about the design goal(s) of each capacitor, which may help narrow down your choices.
For the resistors, just be very careful about wattages.
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I will take a look under the hood for the capacitors and see what has long enough leads that I can salvage easily and reuse.
For resistors, I have matched up resistance and wattages, but I am not sure about voltage rating and tolerance. I have stuck with mostly 1% but some are 5%.
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5% tolerance is almost always good enough, though we use 1% because they are readily available in metal film which is inexpensive, quiet, and reliable. Wattage rating should be at least three times the actual dissipation. You can usually figure out the voltage from the voltage test data, and the data sheet will give a "working voltage" capability. Do not be deceived by the "insulation voltage"! In a few cases we use a larger wattage rating because we need the voltage rating - plate load resistors, C4S bias resistors, power supply bleeders, for example.
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Hi guys,
So in putting the S.E.X. back together with newly ordered components, I have found that the #6 shoulder washers are thicker than the ones originally included in the kit. Unfortunately, over time the included ones had become warped and were either impossible to remove or were so mangled so as to be unusable.
Two questions:
1. Are shoulder washers used to make sure the screw passing through them do not come in contact with the plate? As in it will cause a short of the screw does?
2. If so, does anyone have a model number or precise measurements for the included washers?
I feel kind of silly about asking, but I don't want everything to short out or something like that after putting it all back together again. I can use the washers as normal washers by removing the shoulder since it won't fit into the pre-drilled holes, but without the shoulder, the screw touches the base plate.
Thanks!
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1) Yes, try Ace Hardware. They have a great selection. Or email the parts replacement email for Bottlehead.
2) No, but I think they are sized for the screw that goes through them.
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Thanks, Grainger. That was what I was afraid of. I will cross my fingers that I can find something at the hardware stores this weekend when I can borrow a car. I am trying to finish the build before the 21st so I can take it to a headphone meet. Ordering something might take too long to get to me and I will run out of time to finish the build (I go very slow and I don't have a lot of spare time).
The ones I ordered have the proper hole through the middle, but the shoulder is thicker than the included one and won't fit into the hole.
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Sand them down a little?
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I don't suppose you could file down the ones you have a bit? You could probably even use an emory board for nails...
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Fingernails, that is.
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Maybe I am not describing things correctly. The raised ring (shoulder?) that is supposed to sit in the plate hole and prevent the screw from touching the plate is too wide (not too tall). Because of the size, it is difficult to use something to reduce the width of the ring with any sort of precision or efficiency.
Now that I am thinking about it, why are the shoulder washers used? For the chokes, one of the screws is tied to ground through the buss wire, same with the transformer. Would other parts of the transformer or chokes being connected to ground create some sort of loop?
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I have a ream that I bought years ago at Radio Shack. It is very useful for increasing a hole a little at a time. You can also use a stepped drill bit. It, too is efficient.
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Now that I am thinking about it, why are the shoulder washers used? For the chokes, one of the screws is tied to ground through the buss wire, same with the transformer. Would other parts of the transformer or chokes being connected to ground create some sort of loop?
Yes, it is to avoid the development of eddy currents in the chassis induced by the magnetic fields of the inductors. You can get shoulder washers similar to what we use from Mouser.
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Thanks for the explanation, Doc.
The ones I got were from Mouser. I didn't know there were any differences between them outside of the outside diameter. I might have to bite the bullet and try some of all of them. Just hurts to spend $8 on shipping for $0.80 worth of parts, so trying to avoid that at the moment.
I will explore my options. Thanks for the input, everyone.
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Digi-Key has a USPS option for shipping. That is why I use them for small shipments.
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Maybe I am not describing things correctly. The raised ring (shoulder?) that is supposed to sit in the plate hole and prevent the screw from touching the plate is too wide (not too tall).
Yeah, that was what I thought, but I guess it isn't clear which part of it is too wide. Is the inside or the outside edge of the ring/shoulder too wide?
If the inside is the problem (meaning the diameter of the raised ring is too narrow for the RCA jacks), then wrap some fine grit sandpaper around a pencil or marker and widen the hole from the inside.
If the outside is the problem (meaning the shoulder won't fit into the hole), then you have two options: (a) widen the hole in the metal chassis to fit your new, wider washer, or (b) file the outside of the shoulder ring (not the bottom, and not the outside of the washer itself) to make it thinner. I would do this by sliding the washer onto a tapered marker until it is firmly supported, then use a fingernail emery board to file down the width of the shoulder ring.
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The data sheet for the shoulder washers at Mouser is here:
http://www.mouser.com/ds/2/215/M60p132-14882.pdf
The dimensions are listed for each washer - three diameters and two depths. There are many combinations available!
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The inner diameter (where the screw fits through) is fine. It is the thickness of that ring that is the problem, as it won't fit into the hole in the plate.
Eileen is coming to my rescue and will send me direct replacements. Just waiting on the invoice now.