Pars

Happy Birthday! Sent from my iPhone using Tapatalk

Wayne and Antonio, What awful news! My condolences to both of you. Sent from my iPhone using Tapatalk

What did you pay for it? That is where I would start...

RIP Stan... ?

Happy Birthday!

Happy Birthday Chris! I hope you have a great one!

Something I noticed in the mini BOM was that the power switch listed (8161SH9AV2BE2) isn't rated for AC power duty. Instead, use either the "G" or "Q", which are both rated for 120/250VAC. Use 8161SH9AV2GE2 or 8161SH9AV2QE2 instead. Mouser stocks the "Q".

The SLX might be slightly stiffer. The seamed Columbus tubing (Chromor, Aelle, etc.) is pretty good riding stuff though. So much so that back in the ‘90s a mag did a test with some riders on identical frames other than material and the Chromor frame won IIRC (think it was Chromor, but it was one of the seamed tubes). The back bike in the picture looks like it was a bit small for the rider judging from how high the seat is. That’s some serious drop! Sent from my iPhone using Tapatalk

Yeah, just seems like the AC voltage measurements on the Fluke 89 at least are RMS. I used my bench HP 3269 or whatever it is for this though. I was just trying to correlate the AC current draw with the DC biasing conditions but I can see that would get into a fairly complex calculation involving factors you mentioned and more probably. Just knowing the current dropped with the heatsinks in place was enough confirmation. And 10mA AC is probably more significant that it seems. Sent from my iPhone using Tapatalk

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Yeah, that really sucks, and glad your kids weren't around there Greg! Hits close to home.

Ran a test after taking one amp back to its original config (402R, LTST-C170CKT and 255R bias resistors). I placed an ammeter in place of the fuse, and ran it for 30 minutes when it was no longer increasing. It showed a max of 245mA AC (is that RMS?). I checked the bias on this one and it was right around 15mA (300-315mV). I then installed the heatsinks and did the same test. Current draw had dropped to 235mA at a stable condition. So my theory: having the heatsinks on seems to reduce the transistor temperature a bit, resulting in lower current draw (a bit). For these two tests I was not able to have the top in place but did set it there as best I could.

Sorry to hear as well Todd.

Yes, I had considered doing this (insert DMM in amps mode in place of fuse) in order to estimate bias (@15mA should be 4 * (4 * 15) or ~240mA + a bit for the other circuitry). I thought this way I might be able to estimate the bias with heatsinks attached. Sound reasonable? Sent from my iPhone using Tapatalk

Ted had better lose... another pos that needs to lose is Nunes. Fucking traitor (among traitors)...

Understood... thanks for the data. Those are the other LEDs I have. I was thinking about trying the 402R with current C170 LEDs ( which I am getting 17- 18mA bias) and dropping the 255R down to 240R and see what I get when warm. One thing I don’t quite understand about the operation of these CCSes is the increase I see in bias of around 5mA or more between cold and hot. Is this caused by the LEDs being heated? Doesn’t seem very “constant” to me... EDIT: Put 240R in one channel. After warming up 30 minutes, it was right where I wanted it (290-304mV or 14.5-15mA). The other channel was at 340-360mV, or 17-18mA. This is 402R and the LSTS-C170 LEDs. My one concern is at startup, bias is only in the 8-9mA range, which from experience sounds a bit flat. EDIT2: And to my last previous question, I guess the output transistors heating up probably have more to do with the bias increasing with heat than the LEDs do.

Nice! So you’re using 422R and the LTST-C170 LEDs? 255R bias resistors? What are you getting for V drop across the LEDs initially and after 30 mins or so? And what bias on the 20R output resistors (V drop / 20)? If everyone building these could post this info, it would be appreciated! Maybe I’ll toss a google sheet up to record this so everyone can access. Sent from my iPhone using Tapatalk

You have to carefully pry the heatsinks off. They will come off without damaging anything, just take your time and be careful about where you are prying. Those heatsinks you linked are rather large, not sure they would fit, particularly with FET inputs (TO-71). Any comments on the biasing questions I asked above?

Out of curiosity, what did you use for LEDs and the CCS resistors? 402R or 422R? Note that the temps I am seeing(IR gun, no sinks) are higher than what you show, even at lower bias. Sent from my iPhone using Tapatalk

How much lower temp is it? Also, what were your impressions regarding building ease of the 2oz boards vs. the 3oz? Sent from my iPhone using Tapatalk

Condolences Brent. RIP Alex. Sent from my iPhone using Tapatalk

Rechecking with reduced bias (13-14mA). Max device temp (no heatsinks) that I measured was 92C (R- bank, back around the AC/DC SMPS). Most are around 80-85C. Still sounds good, maybe not quite as good, but not really noticing much difference sound-wise. These temps are just an artifact of the form factor. Unlike your full-size, the output devices on these are concentrated in a 4"x2.5" area. My thru hole full size runs much cooler as well.

I just ran pretty much the same on the 2nd amp, with more or less the same results. I'm going to play around with the bias a bit and will report back, though these things normally sound the best biased as high as you can get away with (within reason; I think Kevin had commented regarding the full-size that around 20mA was the sane max).

Without the heatsinks, I am seeing the following (IR gun): ~45 minutes (no music playing) Top: 41C Transistors (hottest): 102C Bias is a bit hot at ~345-360mV = 17-18mA (this is with 402R resistors and the LiteOn LTST-C170CKT LEDs (1.56V drop). Maybe I'll toss in some 422R for the bias and recheck; that had always measured low initially (12-13mA), but I'd never run it this long in that configuration.

Yes, that is the same size I used. As I noted above, I'm not sure these run cooler with the heatsinks. I'm going to do some more testing tonight.