Hi gents ,
My monoblocks have the above heard through the speakers, the right mono is what I would consider a normal pop but the left mono sounds pretty bad , like a proper cracking sound . Also I the left mono needs more volume than the right mono ( the volume controls are separate on the Freya preamp )
They’re vintage British amps and look to be all original internally.
There are no schematics for them ( Alchemist Genesis)
So what should I look at replacing or testing?
Stock photo ( I can take some photos if needed)
My monoblocks have the above heard through the speakers, the right mono is what I would consider a normal pop but the left mono sounds pretty bad , like a proper cracking sound . Also I the left mono needs more volume than the right mono ( the volume controls are separate on the Freya preamp )
They’re vintage British amps and look to be all original internally.
There are no schematics for them ( Alchemist Genesis)
So what should I look at replacing or testing?
Stock photo ( I can take some photos if needed)
No doubt I would check solder joints first.
Edit: Make sure those big caps are discharged before attempting any other work.
The two green resistors in the PSU could be bleeders, but measure for residue voltage to be sure.
Hugo
Edit: Make sure those big caps are discharged before attempting any other work.
The two green resistors in the PSU could be bleeders, but measure for residue voltage to be sure.
Hugo
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Do some basic performance testing on a dummy load.
The apparent gain difference could be a more serious circuit problem.
The apparent gain difference could be a more serious circuit problem.
I’m not that experienced enough for that I’m afraid ( unless instructed like with my Stasis 2 😁 )
It should be easy to uncouple the heatsink-PCB assembly from the chassis to be able to work on it more easily and if possible take a nice photo of the top and 3/4 to see the references of the transistors and get an idea of what we have affair .
🙂
🙂
I currently have the preamp in front of me for a good clean really and then I’ll start on the monos , I’ll add photos as I go .
Disconnect the pre-amp wires first to the amp to establish if the pop is from the amp or pre-amp. Replace the electrolytic cap at the bottom of your last picture. What else you may want to try is swop the left and right channel op-amps.
Changing all the pcb caps now ( as I have them in my stash ) and new thermal paste as the old stuff is dry and cracked.
The 4 TIP36C output transistors are originals. The 4 BD249C are replacements put instead of TIP35C on a previous rep.
If this is the "bad" channel, whoever did this rep., probably missed some bad component/solder joint too.
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Are you referring to preamp or monoblock?
My eyes fail to see the speaker relays - are these present?
All outputs look like they are cut off but I think this is original. These BD's have pretty short legs making it impossible to bend them and reach the solderside.
Complement of output transistors BD249 is BD250, or for TIP36 that would be TIP35. Both could be original, but normally a manufacturer would stick to one of the pairs. That's all I can see. 🙂
I wouldn't worry about these output transistors for now but focus on the crackling channel.
Hugo