Now for some good news, for a change
Yesterday I replaced R22, R6 and the TL341 [NCP431ACLPRAGOSCT-ND], graciously provided by William2001 .
I biased the left channel to .171 Vdc zeroed out offset.
After running a combined 15 hours - everything works and sounds great!
Both channels are running around 50C.
Being gun shy, I will start to believe things are sorted after more hours on the clock.
Thanks to all in this forum who had the patience to help me over the last 3 months. I could not have done it without all the patient assistance.
So thanks again,
Chip
Yesterday I replaced R22, R6 and the TL341 [NCP431ACLPRAGOSCT-ND], graciously provided by William2001 .
I biased the left channel to .171 Vdc zeroed out offset.
After running a combined 15 hours - everything works and sounds great!
Both channels are running around 50C.
Being gun shy, I will start to believe things are sorted after more hours on the clock.
Thanks to all in this forum who had the patience to help me over the last 3 months. I could not have done it without all the patient assistance.
So thanks again,
Chip
Pass DIY Addict
Joined 2000
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I had bolted an F4 channel to an unused heat sink and powered it with a lab supply...the idea being that as you guys called out measurements I would check them on my own F4...helping me to understand the circuit a bit better. Now that Chip's issue has been solved (hooray!) I'm left to my own experiments. The first being to pump up the supply voltage incrementally until I hit 30V, but that didn't seem to translate into much more usable wattage on the output.
Anyway, I'm sure you guys are getting your voltage readings off a sim of the F4 when calling them out to Chip. I'm a novice using LTSpice at best. Would it be to forward to ask someone to share their simulation? I know there's a lot of work that goes in those things.
Anyway, I'm sure you guys are getting your voltage readings off a sim of the F4 when calling them out to Chip. I'm a novice using LTSpice at best. Would it be to forward to ask someone to share their simulation? I know there's a lot of work that goes in those things.
Mosfets ok?
I ordered an F4 transistor kit from the DIY audio store.
Surprisingly, the contents were not packaged in bubble wrap or a static-safe envelope. As a result, they don't appear to have weathered transit very well.
Some pins are bent; and the silvered surface of several of the mosfets seem to have been scratched by the pins of the others.
Similarly, the two tiny TL-431s were loose - not taped like shown on the image on the store site. Their pins are also bent.
Can folks with experience tell whether these transistors are good for use? Or should I ask for replacements? I'm past the store's 30 day return/exchange policy so I can only hope they'll help.
Any suggestions?
I ordered an F4 transistor kit from the DIY audio store.
Surprisingly, the contents were not packaged in bubble wrap or a static-safe envelope. As a result, they don't appear to have weathered transit very well.
Some pins are bent; and the silvered surface of several of the mosfets seem to have been scratched by the pins of the others.
Similarly, the two tiny TL-431s were loose - not taped like shown on the image on the store site. Their pins are also bent.
Can folks with experience tell whether these transistors are good for use? Or should I ask for replacements? I'm past the store's 30 day return/exchange policy so I can only hope they'll help.
Any suggestions?
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I can only speak for myself, but mine were shipped the same way in several different orders. And work just fine 
Mark Johnson, I think it was he who wrote it, says it is a good idea to sand the surface with very fine paper anyways in general. I guess iot ensure even contact with the pads. Either way, they look OK to me.
That said, some of the ones I got weren’t as tightly matched as expected. Is the reason damaged surfaces during transport and therefore uneven pad contact? I must say I haven’t thought about it, but I guess everything is possible. But I don’t think so.
Wrt returns, I have tried that once. But you might have more luck than me
Cheers.
Andy
Mark Johnson, I think it was he who wrote it, says it is a good idea to sand the surface with very fine paper anyways in general. I guess iot ensure even contact with the pads. Either way, they look OK to me.
That said, some of the ones I got weren’t as tightly matched as expected. Is the reason damaged surfaces during transport and therefore uneven pad contact? I must say I haven’t thought about it, but I guess everything is possible. But I don’t think so.
Wrt returns, I have tried that once. But you might have more luck than me
Cheers.
Andy
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