Fun with Feedback
- Cressy Snr
- Amstrad Tower of Power
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#196 Re: Fun with Feedback
Well I’ve had the break and fixed the amp by replacing the offending part. Blown mains TX was the thing that had stopped it working; no further damage.
Glad you like the design Mike.
Glad you like the design Mike.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
- izzy wizzy
- Old Hand
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#197 Re: Fun with Feedback
As I found out to great cost, fuses in secondary can save iron from destruction. Primary fuses not so much. It's a small thing as you don't want it to happen again for whatever reason ...
- Cressy Snr
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#198 Re: Fun with Feedback
Cheers Stephen, I have a couple more things to do to tidy up loose ends and will incorporate fuses in the HT line.izzy wizzy wrote: ↑Wed Jan 11, 2023 5:12 am As I found out to great cost, fuses in secondary can save iron from destruction. Primary fuses not so much. It's a small thing as you don't want it to happen again for whatever reason ...
Wouldn’t have thought to do it….until now that is.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
#199 Re: Fun with Feedback
Yep, a fault in a single secondary in a multi secondary transformer may draw enough current to kill the transformer but not enough to blow a primary fuse. As I found to my cost.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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#200 Re: Fun with Feedback
Mmmm. So should we use fast blow fuses in secondaries? Or is a close tolerance to expected current draw more important?
#201 Re: Fun with Feedback
I think slow is fine, its the thermal inertia of the windings that give the overload margin. Won't cover marginal overload I guess, but that rarely happens. Also won't cover a shorted turn, but its better than nothing. A thermal fuse in the primary side embedded in the windings would be the safe (as in CE, protecting the user, not the transformer) option.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- izzy wizzy
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#202 Re: Fun with Feedback
Just saying.... waiting until I tidied up a few things is how I lost mine.Cressy Snr wrote: ↑Wed Jan 11, 2023 7:56 am Cheers Stephen, I have a couple more things to do to tidy up loose ends and will incorporate fuses in the HT line.
Wouldn’t have thought to do it….until now that is.
- Cressy Snr
- Amstrad Tower of Power
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- Joined: Wed May 30, 2007 12:25 am
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#203 Re: Fun with Feedback
Well yes, It appears there are one or two other issues that require further investigation of the power supply. Something has happened to the PSU, resulting in LF instability. OK on one pair of speakers but not on the other, which is no good either way. May have a rogue time constant in the output stage. Whatever it is, the test gear will have to come out again.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
#204 Re: Fun with Feedback
You have two about 1s time constants in the power supply decoupling.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
- Cressy Snr
- Amstrad Tower of Power
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#205 Re: Fun with Feedback
Yikes! Yes, thanks for saving me the calculation. That’ll need sorting.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
#206 Re: Fun with Feedback
Well, 0.75s and 0.82s, but them both being about the same is itself more likely to be a problem.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#207 Re: Fun with Feedback
I'm scratching my head here, what RC figures were you using?
There's nowhere you can be that isn't where you're meant to be
#208 Re: Fun with Feedback
4k2 and 50uf for example
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#209 Re: Fun with Feedback
Though just released I was quoting the frequency not the period. So 0.75Hz and 0.82Hz. My bad.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
#210 Re: Fun with Feedback
that's better cos I made it 0.2 seconds
There's nowhere you can be that isn't where you're meant to be