schematic
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I presume neither of you searched for P128.
Here you are you lazy pair.
http://www.diyaudio.com/forums/showthread.php?s=&postid=844095#post844095
The two rail fuses are not F2A but are F4A.
The relay driver is not a transistor. It's a diac fired SCR, which repeatedly re-fires.
Here you are you lazy pair.
http://www.diyaudio.com/forums/showthread.php?s=&postid=844095#post844095
The two rail fuses are not F2A but are F4A.
The relay driver is not a transistor. It's a diac fired SCR, which repeatedly re-fires.
Andrew,
Thanks for the schematic, I just bought a pair of P128 and I will use it with a Musical fidelity P172 preamp. I hope it will work fine.
Regards.
Thanks for the schematic, I just bought a pair of P128 and I will use it with a Musical fidelity P172 preamp. I hope it will work fine.
Regards.
110 to 230 V
Hello
I lived in USA. Now I live in Europe. I have Sugden p128. It works on 110V but I must change it to 230V. Is it possible? How can I do it?
Hello
I lived in USA. Now I live in Europe. I have Sugden p128. It works on 110V but I must change it to 230V. Is it possible? How can I do it?
Yes, conversion back to 220/230/240Vac is possible.
All the mains voltage taps are brought out to 8pins on the PCB.
Soldered links adjust the voltage.
This is one of the most comprehensive pair of EI transformers I have ever seen implemented on a domestic Audio amplifier.
But,
remember you have two primary windings in each transformer that must be wired in series and each winding has 4wire taps (0,110,115,120).
The two transformers must then be wired in parallel.
And add a plastic cover to the internal mains' fuses if it's been lost.
All the mains voltage taps are brought out to 8pins on the PCB.
Soldered links adjust the voltage.
This is one of the most comprehensive pair of EI transformers I have ever seen implemented on a domestic Audio amplifier.
But,
remember you have two primary windings in each transformer that must be wired in series and each winding has 4wire taps (0,110,115,120).
The two transformers must then be wired in parallel.
And add a plastic cover to the internal mains' fuses if it's been lost.
Hello,
As you can see on the schematics (links bellow) you just have to connect the primary of the power tranformer in serial instead of paralallel.
The link : http://www.diyaudio.com/forums/showthread.php?s=&postid=844095#post844095
If you want more explanation, do not hesitate to ask ...
As you can see on the schematics (links bellow) you just have to connect the primary of the power tranformer in serial instead of paralallel.
The link : http://www.diyaudio.com/forums/showthread.php?s=&postid=844095#post844095
If you want more explanation, do not hesitate to ask ...
oops,
I'm past the forgetful stage.
There's no 115Vac tapping, only three connections to each primary winding.
I'm past the forgetful stage.
There's no 115Vac tapping, only three connections to each primary winding.
Sugden P 128 Diagram
Hi,
Has anyone got a circuit diagram for a Sugden P128?
I have 2 of them and need service.
Thanks
Hi,
Has anyone got a circuit diagram for a Sugden P128?
I have 2 of them and need service.
Thanks
hi there, does anyone out there know the quiescent current and bias settings for my sugden p128? as i am doing a full recap and would like to set them up right 🙂
please please please can someone out there help me!!!!!!!!!!
please please please can someone out there help me!!!!!!!!!!
Hi Andrew, i had an email the other day from Sugden regarding setting quiescent current on P128 monoblocks!
The guy was very helpfullish he told me the QC should be 250mA-270mA and the testing point for mulitmeter he said pull out the fuse and put my meter across where the fuse was and then set QC accordingly!! does that sound right to you?? and can you tell me the best and safest way for testing QC on my p128?? Please Please Help me as i have now fully recapped the amps and changed a couple or resistors all thats left to fit are my multi-turn pots and setup!!
Awaiting your reply 😕
Kindest Regards
Danny
PS what and where are the 5534 power pins, if that is the input gain chip, its been removed by Avondale audio in 1980!?
The guy was very helpfullish he told me the QC should be 250mA-270mA and the testing point for mulitmeter he said pull out the fuse and put my meter across where the fuse was and then set QC accordingly!! does that sound right to you?? and can you tell me the best and safest way for testing QC on my p128?? Please Please Help me as i have now fully recapped the amps and changed a couple or resistors all thats left to fit are my multi-turn pots and setup!!
Awaiting your reply 😕
Kindest Regards
Danny
PS what and where are the 5534 power pins, if that is the input gain chip, its been removed by Avondale audio in 1980!?
250mA is about right for the 2pair output stage.
I don't consider the amp to be 4ohms capable.
The Supply rails collapse into a 4r0 load and get even worse on a 2r6 test load.
Great as an 8ohms capable amplifier.
I did consider joining two together and replacing the four EI with a single 8secondary toroid ( 4@ 40Vac for the output rails and 4@ 45Vac for the front end rails). An 800VA or 1kVA would just fit.
But then it wouldn't be a Sugden any more.
I did change it to a 4pair output stage with the total bias increased to 300mA (75mA per pair), but it runs a bit hot.
The lower voltage of the toroid would allow much cooler operation and just as much power. And it would become a 4ohms capable amplifier.
I don't consider the amp to be 4ohms capable.
The Supply rails collapse into a 4r0 load and get even worse on a 2r6 test load.
Great as an 8ohms capable amplifier.
I did consider joining two together and replacing the four EI with a single 8secondary toroid ( 4@ 40Vac for the output rails and 4@ 45Vac for the front end rails). An 800VA or 1kVA would just fit.
But then it wouldn't be a Sugden any more.
I did change it to a 4pair output stage with the total bias increased to 300mA (75mA per pair), but it runs a bit hot.
The lower voltage of the toroid would allow much cooler operation and just as much power. And it would become a 4ohms capable amplifier.
Last edited:
OH!!!!!!
check the voltage on the 5534 power pins. Mine ran very high. I had ~+-24Vdc on some days.
7=+ve 4=-ve
So I added an 18V Zener to each rail to get the chip at a more sensible voltage. You could use 20V Zeners if you adjust the dropper resistors to ensure you don't exceed +-21Vdc.
5534 now runs on +-19.5Vdc
I increased, substantially, the MF decoupling on the front end supply rails. The 100V caps are expensive !
Now that I know a bit more I should go back and re-assess the layouts and components.
check the voltage on the 5534 power pins. Mine ran very high. I had ~+-24Vdc on some days.
7=+ve 4=-ve
So I added an 18V Zener to each rail to get the chip at a more sensible voltage. You could use 20V Zeners if you adjust the dropper resistors to ensure you don't exceed +-21Vdc.
5534 now runs on +-19.5Vdc
I increased, substantially, the MF decoupling on the front end supply rails. The 100V caps are expensive !
Now that I know a bit more I should go back and re-assess the layouts and components.
Last edited:
Re p128
Hi Andrew and thanks for getting back so soon!
But where do i need to put my multi meter to test quiescent current please as I don't think sugden told me right!!
Kindest regards
Danny
Hi Andrew and thanks for getting back so soon!
But where do i need to put my multi meter to test quiescent current please as I don't think sugden told me right!!
Kindest regards
Danny
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