Pars

Had a recommendation from a UK user on diyaudio for this probe system for probing small pins etc. Seems like it could be just the thing for SMD shit. https://www.amazon.com/PCBite-SP10-probes-test-wires/dp/B08FGG1QWD/ref=sr_1_10?keywords=pcbite&qid=1685552010&sr=8-10

So sorry for your loss Todd. Sounds like she was a neat lady to have as an aunt.

It almost sounds like something is oscillating. Do you have a bench supply you could power the protector with to see how it behaves in that situation? I've only built one protector board and haven't used it yet in an application. I was saving it for a CFA3. On my DynaFET (30V GRLV), I use one of Amb's boards since it is SE only.

What are the voltage in pins on the LM339s (3 and 12) at? 30V inputs seem a bit excessive for the 12V regs, but not sure about that. And you have all unused inputs grounded it seems? You don't need to do anything with the unused outs I don't believe.

A Chinese parts vendor that actually seems to be legit, LCSC. Recommended to me by a guy on Diyaudio. They are associated with jlcpcb and provide all of their parts. Needed some TPS7A3001DGNR, which are currently out to Aug. 2023 (they were out further than that when I ordered these) at Mouser. Ordered some from LCSC and they appear to be genuine (and function so). Shipping is expensive, and the more economical options take awhile to get, so I will only use as a last resort, but good to have.

Happy Birthday Brent. And yes, have a biscuit.

Happy Birthday Rob!

I haven't had any issues with the 25K, but I'm using JFET input on the DynaFET (only option). If you use the THAT BJT quads on an SS input stage, that would probably be a problem as those require low input impedance. CFA3 with JFETs is probably not a problem, though Kevin could clarify.

I don't know what the normal temperature is, but it shouldn't be running really hot. I have an SE DynaFET running with a single GRLV at +/-30V using a 120VA SumR transformer. I've never even checked the transformer for heat (never even thought about doing so), and it has run fine since about 2017 or whenever I got this thing working. The DynaFET is biased at 140mA, with 2 pairs of output devices per side. It is on 300mm 2U Modushop heatsinks, with both DynaFET boards on one heatsink and the GRLV on the other. The GRLV side is cooler than the DynaFET side, but I can hold my hand on either heatsink for as long as I want after running for an hour or two. They both definitely get warm, but not say Nelson Pass normal operating temp (i.e., hot, with you only being able to hold your hand on them for a few seconds).

Thanks all! I had a nice day off from work, but didn't get much of what I had planned to do done, which was OK.

Just an FYI, the diyaudio store has Toshiba matched quads and octets of J74/K170. Octet is US $90 or $100 depending upon IDSS. These are BL devices. Good luck on the tube input, and if that is what you really want, I'd agree; go for it. I'm sure Dukei will be much help here.

Hmmm, ebay seller punkydawgs doesn't seem to have anything available right now, but says he's out until May 23. There is another seller there, ash_win, who is selling curve matched pairs of K170/J74s that looks to be the real deal. Austin, TX.

If it were me, I'd source 2 quads of Toshiba 2SK170/2SJ74 from punkydawgs on ebay, and just do the SS bal/ubal board with JFET input. But that's me. It seems like someone on HF has a tube input CFA3, but I didn't see any pics or direct posts by the person who supposedly has it. I know dukei has been talking about it. Kevin would probably know. A lot of the HF crowd seems to run a tube preamp into the CFA3 and use that to get their "tube" sound. I guess you could do that if you wanted. I used to have a tube pre, a Counterpoint SA5.1, which used 6922s and sounded good. It had a slight hum to it which took me about 6-7 years to find (PSU board layout error), and I sold it right after that and never listened to it after I fixed it, other than to verify it was now dead quiet. I feel like I need a shower now after being on HF for a few minutes

I don't know about going that high. Assuming this is a full wave bridge, you would have around 161 Vdc on the first filter caps. That is quite a bit of voltage to burn off. You could actually drop down to 80Vac and still get about 113Vdc, which would be plenty.

Not sure if the Hammond has enough current capacity. Hammond 229B88. It's only 88V, 130mA. The only issue with using 100V or so is a bit more heat on the pass device(s).