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Pulled Q411, Q412, Q413 from the Better Map. They both tested within spec for hFE and showed no shorts. DBT was fine. Was able to set DC offset. Attempting to set bias on TP1 and TP2, the voltage reading on my DMM still rapidly descended to 0. Tested voltages on the pre-driver board and the...

Wow, I probably never would have thought to just remove the DBT and test! Haha. Well, I just did and checked some of the voltages on the pre-driver board of my Worse Amp. Most we're pretty close to spec. The jumper coming form the collector of Q411 (which tested with a low hfe the other day) was...

They're surprisingly easy to disassemble. I'm sorry I didn't post more photos of the process. But I'll keep updating this with whatever I discover—perhaps it'll be of some service to you or someone else!

Just pulled Q411 and Q412 from Worse Amp (still waiting to replace two caps in Better Amp). Tested each in diode mode on a DMM and they seemed reasonable—just over 0.5V drop where it should have been and naught elsewhere. Then put them into my DIY GM328 transistor tester. hFE of the A968(O)...

The hunt continues. Attached are the measured voltages (in red) around Q413—which, looking at the tech specs, seems to have something to do with bias stabilization. I pulled Q413 from Worse Amp and, with my mediocre test rig, it appears to be OK. So I think I'll order a new pair for Q412 and...

So, small victories. I've replaced all the electrolytics in Worse Amp, and it powers on (through a DBT) normally. I was short two 10uF caps, so Better Amp will have to be powered on in a few days. I also replaced the trimpots (VR401 and VR402). I managed to get the DC offset ±0.2mV though I...

I seem to have borked my initial post with a couple of attached images that duplicate the inline images. My apologies, will try to sort that out. In the meantime, I took some voltage readings from the output transistors. The amp that's better behaved than the other (from here on out the 'Better...

Hi everyone. I'm looking for some assistance in troubleshooting some HK775 monoblocks. I've used these on and off for about 15 years. They've been a bit fussy for the past few years. Typically they'll work fine for a couple of hours before a variety of oddities occur: static, decreased volume...

Hi everyone. Just joined AK whilst looking for some info about a pair of HK775's I've had kicking around for quite some time. Of course, selfishly, I have a ton of questions about those, but thought I'd say hey first. I don't sit in front of the hifi for hours on end like I did when I was...