Higher wattage rating is ok but the size may become difficult to deal with. I have 5 w resistor in R6 and run 365V for B+. It dose get hot but that will also happen even if you have 7w resistor. If you can't fit horizontally, you can put one lead in the hole and stand the resistor at an angel so that the other lead (longer) can be bent down and reach the other hole.PaulyT said:
18 AWG should be fine for it. As for OPT, use the leads that come with it to connect to the board and speaker terminals.PaulyT said:
For input jack to the board, I use RG-59 which is cheap and common coax cable used in audio application and it will suffice. There have been posts mentioning some boutique cables for this but as you may already be aware, spending extra there may make you just "feel" better. Spend your $$ wisely.
rknize said:
ack, I finally found it on the Getting Started page. I mostly skipped that since it looked the same as the SSE page.
Still, it sounds like the 5W should be fine (at least for a while), it's just going to get toasty.
I *did* find the comments on R14/R25 and they are chosen correctly for the 400V B+ on my build. So I should be good until my next Digikey order...
This is mentioned in several places on his site (front page, the instructions, component value list, and the parts list) and they are all in different states of being up-to-date. Too bad his site's not a Wiki...I'd just fix it for him.
Or even a content management system. I use Joomla for my web site and it is really easy to use and manage - and you can add/change/delete content via a web interface.
I use RG174 for the input sigs, it works fine. I also use cat5 wires for signal wiring as it is free if you find old Cat5 laying around and the conductors are usually teflon insulated. The unterminated in-the-wall kind is usually solid core, and the terminated Cat5 that you connect to the PC, etc is stranded.
There was an entire post a few months ago about signal wiring IIRC.
There was an entire post a few months ago about signal wiring IIRC.
I'm a long way from any power-up work, but I'm starting to think about safety precautions so I can prepare. Few questions:
1) Anyone know where I can get some electrically insulating floor mats? I have concrete floors in the basement where I'll be working. (Fortunately I already have a dehumidifier down there.) Doing a google search finds mostly stuff in rolls of 75' or more... (Yes, I tend to go shoeless indoors; I will also find a wooden bench/stool for the work area.)
2) GFI protection: I don't currently have a GFI plug down there; is it sufficient to use a good quality GFI power strip (like this one) for the stuff on the bench? This would also provide a master switch.
3) Specific to the TSE - it looks like the circuit has bleeders (e.g. R7, R30) so that when the unit is powered off, all cap charges will dissipate. Correct? (Assuming of course that it's assembled properly...) I know, one can never assume that anything is electrically neutral, but wondering if this is part of the design.
4) Dust: I was thinking of having a cover over the enclosure that is a grating or otherwise vented with small holes of some sort. But then (partially conductive) dust could become a problem over time. Suggestions on how to deal with that?
I'll probably think of more...
1) Anyone know where I can get some electrically insulating floor mats? I have concrete floors in the basement where I'll be working. (Fortunately I already have a dehumidifier down there.) Doing a google search finds mostly stuff in rolls of 75' or more... (Yes, I tend to go shoeless indoors; I will also find a wooden bench/stool for the work area.)
2) GFI protection: I don't currently have a GFI plug down there; is it sufficient to use a good quality GFI power strip (like this one) for the stuff on the bench? This would also provide a master switch.
3) Specific to the TSE - it looks like the circuit has bleeders (e.g. R7, R30) so that when the unit is powered off, all cap charges will dissipate. Correct? (Assuming of course that it's assembled properly...) I know, one can never assume that anything is electrically neutral, but wondering if this is part of the design.
4) Dust: I was thinking of having a cover over the enclosure that is a grating or otherwise vented with small holes of some sort. But then (partially conductive) dust could become a problem over time. Suggestions on how to deal with that?
I'll probably think of more...
1) I think you are looking for a "switchboard mat".
2) That will work. Note that GFCI isn't going to help much if you are standing on a floor mat because they can only detect a current imbalance between the plug and the rest of the world. So if your bench is grounded and you zap yourself because you had your leg up against a metal part of your bench, then the GFCI may trip. If you zap yourself because you were touching the ground of your amp, it can't detect that.
3) Yes, he has bleeders on there. Note that if you are using an external cap, precautions should be taken if is has been disconnected from the PCB.
4) Are you going to be welding/grinding near your amp? If you are talking about adding a "cage", then I wouldn't worry about that too much. Just keep the dust off the top so that you have good convection. Wipe it down on occasion....
2) That will work. Note that GFCI isn't going to help much if you are standing on a floor mat because they can only detect a current imbalance between the plug and the rest of the world. So if your bench is grounded and you zap yourself because you had your leg up against a metal part of your bench, then the GFCI may trip. If you zap yourself because you were touching the ground of your amp, it can't detect that.
3) Yes, he has bleeders on there. Note that if you are using an external cap, precautions should be taken if is has been disconnected from the PCB.
4) Are you going to be welding/grinding near your amp?
If you are talking about adding a "cage", then I wouldn't worry about that too much. Just keep the dust off the top so that you have good convection. Wipe it down on occasion....
McMaster Carr has lots of rubber mats
http://www.mcmaster.com/#
search for mats
You can also install a GFI recepticle in the wall; it will also protect all the recepticles down stream when wired properly (just wire "line" and "load" properly. A GFI power strip will also work, or a mains isolation transformer for the workbench. There are some caveats when using an isolation transformer with a scope, although I'm no expert regarding this.
Yes, R7 and R30 are bleeders for the caps.
Lot's of folks vent their chassis with perf metal, drilled holes, etc. I blow off all of my stuff including the PC every six months or so with my compressor. Now you've got me curious if anyone has had a dust related failure (that wasn't from 50 years of layered gunk on an old amp)
http://www.mcmaster.com/#
search for mats
You can also install a GFI recepticle in the wall; it will also protect all the recepticles down stream when wired properly (just wire "line" and "load" properly. A GFI power strip will also work, or a mains isolation transformer for the workbench. There are some caveats when using an isolation transformer with a scope, although I'm no expert regarding this.
Yes, R7 and R30 are bleeders for the caps.
Lot's of folks vent their chassis with perf metal, drilled holes, etc. I blow off all of my stuff including the PC every six months or so with my compressor. Now you've got me curious if anyone has had a dust related failure (that wasn't from 50 years of layered gunk on an old amp)
PaulyT said:
IIRC, the board artwork shows 1/2W R's (for R10 and R21) and George is now spec'ing 1/4W for better sonics, so they are smaller than the silkscreen artwork. The artwork for the large power resistors are for the white ceramic type, if you have bought wirewounds they will be smaller than the artwork also.
PaulyT said:
Yeah, his boards have lots of space for boutique components up to 1/2W or more, but most of the resistors only need to be 1/4 W. Plus. those nice little green Panasonic resistors are actually miniature 1/4W...as they are about the size of a typical 1/8W. They have better noise characteristics than the "standard" blue Yageo metal films. But yeah, they look a little silly in those big spots with the huge solder pads.
Panasonic makes some nice power resistors too, not to mention their capacitors.
rknize said:
Someone step in I have got this screwed up, but my understanding is that a GFCI is an earth leak interrupt breaker. If you get a leak from active to ground, it will trip. If your chassis is connected to ground (as it should be for safety) and you short out something on the primary side of the power transformer to the chassis, the GFCI will trip. What happens if there is a short between the secondary side of the transformer and the chassis? For example, you stick your big fat finger on to a live B+ wire while holding the chassis with the other hand. Does the GFCI protect you (I suspect not, as it is isolated from the mains by the power transformer)?
Cheers,
Chris
Yes, you're right, I believe. Nothing can really protect from shorts across voltages within the amp itself. That's where the "one hand working and the other tied to your back" technique is key, along with standing on a insulating rubber mat and otherwise not grounding any other part of your body. You may get a shock across your hand or arm, which could do some damage, but it (most likely) won't kill you because it won't travel through your torso.
Yeah, sorry...I didn't quite have the facts straight in my head when I wrote that. My memory is getting worse all the time, it seems. It won't detect if you zap yourself via the secondary side at all. All GFCI does is look at the current moving between the hot and neutral wires. If they become out of balance, then that implies that current has found another path and it trips. The ground wire becomes important because that it most often the other path when there is some internal failure of the device, but I don't think the GFCI is in any way monitoring the earth ground directly.
The transformer will keep that balance perfect, so GFCI won't trip. It's a "nice to have" but don't expect it to save you life when working on tube amps. If you also work on appliances or other electrical devices on your bench, then it becomes a little more useful. I have a GFCI breaker on the circuit feeding my shop, since I have some small machinery and so forth.
The transformer will keep that balance perfect, so GFCI won't trip. It's a "nice to have" but don't expect it to save you life when working on tube amps. If you also work on appliances or other electrical devices on your bench, then it becomes a little more useful. I have a GFCI breaker on the circuit feeding my shop, since I have some small machinery and so forth.
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