Seriously, if anyone here wants them, tell me and I won't get into a bidding war with you, I just thought they'd be useful to keep handy for future projects. All you have to do is promise to post pics of your amp when it's done. 😉
Naaah, not again !!
How about setting up Wacko Mouse Ltd ? You handle the UK Ebay hustle, i flogg them across the continent. 40-60, minus my expenses ?
i only want two, the auction is for 5, anyone wanna go share this? probably best if they live in England as shipping accross the ocean could be expensive @ 2.5kg.
If you are interested email me konst(squigleyline)konst.co.uk
If you are interested email me konst(squigleyline)konst.co.uk
Konst, whereabouts are you in London? I'm up there quite frequently, so we could do a deal. 😉
Konst, are you building a KSA100 then, 'cos one of those will be adequate for a 50.
In fact, if you want a fancy one, I have a single blue anodised one you could have instead, it's the one I used for testing with shown here.
In fact, if you want a fancy one, I have a single blue anodised one you could have instead, it's the one I used for testing with shown here.
Pinkmouse, at the moment I am looking at the aleph30, and have boards mostly populated, just in need of output devices etc.
in the planning stages are ksa 50 and poss 100 (probably some time away).
so i am probably looking for 1 straight away and another 2 in some months time. how much do you want for that blue one?
in the planning stages are ksa 50 and poss 100 (probably some time away).
so i am probably looking for 1 straight away and another 2 in some months time. how much do you want for that blue one?
Hi,
I'm having a big problem with one of my monoblocks, and was hoping that someone might have an idea on how to correct it. Basically, I have built two monoblocks, and one works perfectly fine, but the other gets extremely hot.
The reason for that is that when I measure the voltage across all 6 emitter resistors, I get 3.6V. I tried turning the bias down through R126, but nothing changes, even if R126 is at its max resistance. I rechecked all the transistors and compared the faulty monoblock to the working one, and I couldn't find any difference in terms of components. If music is fed to the faulty one, it seems to amplify it well, but due to the weird biasing, everything gets very hot very fast, and both rails drop about 10V from what they should normally be, which I guess is normal with 3.6V instead of 0.4V.
Does anyone have any idea what can cause this?
Thanks.
Paul
I'm having a big problem with one of my monoblocks, and was hoping that someone might have an idea on how to correct it. Basically, I have built two monoblocks, and one works perfectly fine, but the other gets extremely hot.
The reason for that is that when I measure the voltage across all 6 emitter resistors, I get 3.6V. I tried turning the bias down through R126, but nothing changes, even if R126 is at its max resistance. I rechecked all the transistors and compared the faulty monoblock to the working one, and I couldn't find any difference in terms of components. If music is fed to the faulty one, it seems to amplify it well, but due to the weird biasing, everything gets very hot very fast, and both rails drop about 10V from what they should normally be, which I guess is normal with 3.6V instead of 0.4V.
Does anyone have any idea what can cause this?
Thanks.
Paul
Hi,
oscillation?
are the feedback caps properly soldered in?
Can you post a list of voltages around the Vbe multiplier with Driver and Output Stage Collector, Base and Emitter included?
oscillation?
are the feedback caps properly soldered in?
Can you post a list of voltages around the Vbe multiplier with Driver and Output Stage Collector, Base and Emitter included?
which boards are you using , joeyDD ?
just DON'T plug it in untill you've diagnosed your problem
Klaas
edit:glad youre here Andrew
just DON'T plug it in untill you've diagnosed your problem
Klaas
edit:glad youre here Andrew
I am using the Pinkmouse boards.
As for the voltages, I will begin measuring them, but it is hard since the amp gets way too hot very fast.
And which caps would the feedback caps be? Would they be the C102 and C103?
Paul
As for the voltages, I will begin measuring them, but it is hard since the amp gets way too hot very fast.
And which caps would the feedback caps be? Would they be the C102 and C103?
Paul
Hi,
stick a high wattage (150W or even 300W halogen) bulb in series with the amp mains input.
It will pull the transformer voltage down very significantly and may give you just enough voltage to measure things.
The front end LTP stage voltages will go a bit haywire but hopefully at the output end you can ignore them. I have not analysed what happens to the DC set points at very low supply voltages!
I keep referring to this bulb thing because it is virtually foolproof for first start up.
stick a high wattage (150W or even 300W halogen) bulb in series with the amp mains input.
It will pull the transformer voltage down very significantly and may give you just enough voltage to measure things.
The front end LTP stage voltages will go a bit haywire but hopefully at the output end you can ignore them. I have not analysed what happens to the DC set points at very low supply voltages!
I keep referring to this bulb thing because it is virtually foolproof for first start up.
These are the voltages I got for Q109, Q110 and Q111:
Q109:
E: 4.8V
C: 26.5V
B: 5.4V
Q110:
E: 5.0V
C: 26.6V
B: 5.7V
Q111:
E: 5.7V
C: 5.4V
B: 0.4V
edit: the rail voltages are about 26.4-26.6V
Paul
Q109:
E: 4.8V
C: 26.5V
B: 5.4V
Q110:
E: 5.0V
C: 26.6V
B: 5.7V
Q111:
E: 5.7V
C: 5.4V
B: 0.4V
edit: the rail voltages are about 26.4-26.6V
Paul
The PS is composed of a transformer with 28V dual secondary, each secondary goes to a bridge, then there are 4 10000uF capacitors on each rail, and each 10000uF cap is bypassed with a 0.033uF polypropylene cap.
On the faulty monoblock, the rails are very low, but on the working monoblock, the rails are at about 36V.
Paul
On the faulty monoblock, the rails are very low, but on the working monoblock, the rails are at about 36V.
Paul
Hi,
Thanks for your help guys, it now works normally. All along, I was looking in all the wrong places for the bug, and never thought about Q111; Pinkmouse was right on. Now that I look back on the voltages I posted earlier, it makes sense that Q111 should be at fault.
At least I've learned something from this 🙂
Thanks for pointing me in the right direction guys.
Paul
Thanks for your help guys, it now works normally. All along, I was looking in all the wrong places for the bug, and never thought about Q111; Pinkmouse was right on. Now that I look back on the voltages I posted earlier, it makes sense that Q111 should be at fault.
At least I've learned something from this 🙂
Thanks for pointing me in the right direction guys.
Paul
Guys, I am going to bid on those heatsinks on Ebay, as I only need 2 of those, anyone else in need is welcome to take the others.
Pinkmouse, if you still have that sexy blue one, I would be only too interested.
Pinkmouse, if you still have that sexy blue one, I would be only too interested.