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ck42 HeadWizer Joined: Oct. 28, 2001 |  Message [#260] posted on: 12-03-2006 06:03 PM CST (US).   |  | 
Volume pot is attached. Entire amp is built and wired up. |
gewa HeadWizer Joined: Sep. 22, 2006 | Message [#261] posted on: 12-03-2006 06:07 PM CST (US). | | Just thinking out loud here, but are you sure that you used the correct voltage regulators and that they are oriented in the correct way? Regards |
runeight Headphone Council Joined: Mar. 8, 2002 | Message [#262] posted on: 12-03-2006 06:09 PM CST (US). | | The heater supply should be -12.6V whether the tube is in or out. If not, there is a problem with the regulator and associated components or a really bad short somewhere. |
| ck42 HeadWizer Joined: Oct. 28, 2001 | Message [#263] posted on: 12-03-2006 06:24 PM CST (US). | |
I originally measured -13.2V. At some point, this measured voltage at the test point went away. I'll go back through and double check all of the -12.6V related components and connections. |
tomb Headphone Council Joined: Mar. 1, 2006 | Message [#264] posted on: 12-03-2006 07:31 PM CST (US). | | I don't know - sure sounds like pulling the tube and plugging it back in had an effect. I've seen a tube conduct when it was almost pulled out, then go out when it was seated in all the way. That may just be me and my chintzy sockets, though. |
vixr HeadWize Fanatic Joined: Sep. 17, 2005 | Message [#265] posted on: 12-03-2006 08:31 PM CST (US). | | Greg, I find the voltage regulators are getting very hot. I used small heat sinks, but I think I will have to use a single larger one instead of two small ones. I have a temp sensor at work I will use to find the exact temp. I notice also that with the buffers stacked and 110 ohm BW resistors, the BUF634s are getting hot enough to make me worry... They probably won't last long at these temps. I ended up using two small solid tant caps @ 240nF. I see 1.5 volts DC offset without the caps. I have some of those 24uF tants for the e12 board but they seem like overkill. I believe I will end up using single buffer ICs instead of stacking, unless you guys think the buffers can tolerate high temps. (I mean really hot) The sound is just awesome, the SOHA is like a different amp with Gregs board. It is sure to be a rival to the Millett with the buffers/627s in... The amp always had pretty good bass, but now it has more of a third dimension. My corda cross my have something to do with it, I don't have the audiophile vocab to properly describe how much better the SOHA sounds buffered. Thanks Greg, you turned a SOSO into a SOAHHH... |
| ck42 HeadWizer Joined: Oct. 28, 2001 | Message [#266] posted on: 12-03-2006 08:41 PM CST (US). | |
Just verified components and connections. All is good. So...w/o the tube, I'm getting -3V from VR3. With the tube in, it drops to -13.2mV. I'm stumped for now.
[EDIT-2] Gonna be another day. Broken leg on the LM337 [Edited by ck42 on 12-03-2006 at 09:22 PM.] |
GregVDS HeadWizer Joined: Oct. 25, 2005 | Message [#267] posted on: 12-04-2006 03:09 AM CST (US). | | Yep, I fear the same, vixr, without proper heatsink, thnigs will not last long. I will put some clip-on heatsink where I can on OPA627s and Intersils, and the LM78/79 will also be heatsinked. At the mo, I don't listen to the SOHA, fearing to cook something  Thanks for the sound review! All the best, hoping to hear from the others. All the best, |
| gewa HeadWizer Joined: Sep. 22, 2006 | Message [#268] posted on: 12-04-2006 05:21 AM CST (US). | |
Don't be ashamed, I think we all had our fair share of those. Regards |
| vixr HeadWize Fanatic Joined: Sep. 17, 2005 | Message [#269] posted on: 12-04-2006 08:26 AM CST (US). | | here is some photos of the 634 board. here are the temps I'm seeing... LM337T =115 degrees, L7812 and L7912 =126 degrees, buffer board (temp probe touching BUF634s) = 138 degrees...
[Edited by vixr on 12-04-2006 at 08:51 AM.] |
| gewa HeadWizer Joined: Sep. 22, 2006 | Message [#270] posted on: 12-04-2006 08:45 AM CST (US). | | I hope those readings are not Celsius  Regards |
| vixr HeadWize Fanatic Joined: Sep. 17, 2005 | Message [#271] posted on: 12-04-2006 08:56 AM CST (US). | | I'm sorry, I forgot some of you guys are metric... LM337T = 62.2 C, BUF634s = 76.7 C, L7812/L7912 = 66.7 C |
| tomb Headphone Council Joined: Mar. 1, 2006 | Message [#272] posted on: 12-04-2006 09:38 AM CST (US). | |
Operating Temperature Ranges: LM337T: -55 to 150 deg. C. I think the Regs are fine. I'm assuming you have that surplus sink on the 337, but the other two are naked TO-220's - right? These temps seem right in the midrange for temps above freezing. EDIT: Check that - the BUF's may be OK, too. The 85 deg. C. is a max specification for normal operation. Max operating is 125 deg. C. and Thermal Shutdown is 175 deg. C. So, you may be OK there, too. Great work and great photos! [Edited by tomb on 12-04-2006 at 09:44 AM.] |
| vixr HeadWize Fanatic Joined: Sep. 17, 2005 | Message [#273] posted on: 12-04-2006 09:48 AM CST (US). | | thanks Tom... I have all these datasheets at home, I promise to be more forthcoming with all the facts, I'm not real fast, just half fast...
[Edited by vixr on 12-04-2006 at 11:06 AM.] |
| tomb Headphone Council Joined: Mar. 1, 2006 | Message [#274] posted on: 12-04-2006 11:39 AM CST (US). | | Vixr, Sorry for being so quick on the draw, but I've been trying to size heat sinks for the board to put on my next Mouser order. It sounds like we really don't need them, unless - Would you confirm what heat sinks and type you have on your LM337 and Vregs? You already had one on the 337, but I think you said you changed it awhile back. I'm not sure you had any on the Vreg's, though. That will help us form a baseline as to whether major mods are needed in the heat sink category. There are not too many that will fit for those Vreg's. Even if you put the caps on the bottom, the soldered leads would be shorted with a big heat sink. I'm guessing that some cheap stamped-tab sinks might be prudent, but nothing more. |
| vixr HeadWize Fanatic Joined: Sep. 17, 2005 | Message [#275] posted on: 12-04-2006 01:46 PM CST (US). | | the heatsink for the L7812,L7912 REGs is Mouser P/N 532-577202B00 (.75"x.50"x.50") you have to bend it a little. the right one gets much hotter for some reason, and the left only needed a flat aluminium plate. the one for the 337T is 1"x1.25"x.75" and I salvaged it from a RADAR power supply. I dont have a clue about make and model...
[Edited by vixr on 12-04-2006 at 01:55 PM.] |
| gewa HeadWizer Joined: Sep. 22, 2006 | Message [#276] posted on: 12-04-2006 02:11 PM CST (US). | | This is what I slapped on them. I don't know whether it will be sufficient because I still haven't finished my amp.   Regards |
| xelion Member Joined: Sep. 27, 2006 | Message [#277] posted on: 12-04-2006 05:11 PM CST (US). | | Okay, quick question. Mains = live, right? Also, about to wire up my transformer, live plug -> fuse -> switch -> board? or plug -> switch -> fuse -> board. or should I have the switch on the neutral line? edit: And the picture of my transformer, http://headwize.com/uploads/C2340.jpg is that from the top or the bottom? [Edited by xelion on 12-04-2006 at 05:33 PM.] |
| tomb Headphone Council Joined: Mar. 1, 2006 | Message [#278] posted on: 12-04-2006 05:48 PM CST (US). | |
YES plug -> switch -> fuse ->board ... but this can vary depending on preferences and what you really want to protect. For instance, if you were plugging a walwart in the wall, you'd want a fuse in the walwart, but a switch on the amp. If by stating "board," you are also including the transformer mounted in the same case as the amp, then the sequence is a good one, IMHO. There are some that will say fuse the xfmr and then switch the low power leads. This will leave one side of your xfmr exposed to wall power all the time, but your switch is not as critical used on the reduced voltage amplifier side. The other way requires a 120-250V rated switch, but those ratings are inherent with many switches, anyway. Regardless, you should fuse the hot leg of the xfmr so that it is always protected whenever connected to the wall source.
It was mentioned before - switching both legs is best, but if not - the LIVE line should be switched - and the fuse goes on the LIVE line, as you once drew it.
Note that the picture says "PIN VIEW." That means this is what it looks like when you look at the side with the pins. [Edited by tomb on 12-04-2006 at 06:07 PM.] |
| xelion Member Joined: Sep. 27, 2006 | Message [#279] posted on: 12-04-2006 06:40 PM CST (US). | | Okay, just to clear it up, as I didn't realize I was being ambigious eariler. plug->switch->fuse->transformer->ac1 right? |
| Garlicknots Member Joined: N/A | Message [#280] posted on: 12-04-2006 07:16 PM CST (US). | | Quick question, I'm buying some stuff from partsconnexion so I figured I may as well pick up the tube sockets from there. Here is a link to their tube socket page. www.partsconnex...ubesockets.html Which is the correct socket? I believe it is either: Chassis Mount (with solder lugs) PCB Mount I think the chassis mount is correct. Should I go gold or silver contacts? Thanks super. |
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