Just Google nhb 108 schematic, should be some hits.
So that's the plan for cap replacement: first removing the back panel, then desoldering the input caps, should be possible without having to unscrew the amplifier board, because the caps are very close to the edge.
Then going directly from the input connector the PCB, as these Miflex MKP10 have long legs like Claudia Schiffer, so the input wires can be left out.
There is a small hole in the PCB where I'll fix the cap with a cable tie.
Hope the picture clarifies how I want to do it:
I am not very convinced if mundorf caps, I never liked them.
So that's the plan for cap replacement: first removing the back panel, then desoldering the input caps, should be possible without having to unscrew the amplifier board, because the caps are very close to the edge.
Then going directly from the input connector the PCB, as these Miflex MKP10 have long legs like Claudia Schiffer, so the input wires can be left out.
There is a small hole in the PCB where I'll fix the cap with a cable tie.
Hope the picture clarifies how I want to do it:
I am not very convinced if mundorf caps, I never liked them.
Awesome a lot more wiggle room going with that placement. Looking forward to hearing your thoughts!
Disaster for me 🫣 I blew one of the channels. Some of the transistors caught on fire! I replaced the output speakers cable and possibly I didn't make a good solder connection on the pcb so there was no load on the amp when I turned it on. I've sent it in to get the blown channel replaced and hopefully fix my dodgy solder job!
Oh no! 😳I was not aware that the amp needed a load before powering it on! Good to know, hopefully yours can be fixed easily?
😀I also like the Miflex, but I have only used the KPCU caps (quite expensive and big, but sound great in my tube preamp and dac). Great idea to do it directly using the legs, should be possible indeed! Looking forward to your results 👍
I think the reason 2 caps are used is that this way you have quicker response for power stabilization, transient response, and reduced ripple and oscillations?
Well I'm not exactly sure that's the problem but the wire was the only thing i changed and then after it blew I tugged on the positive internal speaker wire and it came off the PCB pretty easily. You learn from your mistakes! 😁 They got back to me quickly and told me they would replace the channel.
I found the schematic now, and had a look at it as well. And also was wondering if you were to remove the amp board for better access, what would be worth it to replace with better parts?
Would that be the parts marked with ABCD in the picture below?
Oh my...Been there done that several times...there is always a risk when tweaking, hopefully it's coming back to full glory.
Those Miflex sound rather different from the KPCU, but they are affordable and sound better than some much more expensive caps.
If you remove the amplifier board, you can go wild with swopping parts of course.
Then you could tackle the white 0,1R emitter cement resistors; very good replacement are Futaba MPC 71 non magnetic resistors, which are pretty cheap and sound smoother than the simple ones.
And yes, it's number 1 and 2, 3 and 4 should have some impact as well.
I am too lazy for big surgeries, also because the amps sounds really really good, which reduces the urge to change a lot.
While this is in for repair, I have some pretty nice (and much more expensive) 300b monoblocks that I've put back in made by a builder over here with nice output transformers and parts (Vcap CUTF and KPCUs). Great amps. The 300b's are a little more holographic in the midrange but that's about it. The D5 pretty much smokes them in every aspect whilst still sounding very tube like. I'm using big ultra efficient Altec horns too. Truly a fantastic amp, cant wait to get it back and do some more mods. Got the Z Foils here waiting to go in.
What I like most about it is that it sounds neutral, but not boring, the big soundstage and the ability to let the music flow, which is rare in a transistor amp.
I wouldn't say it sounds tube like though, but it has this relaxing quality for sure, so I can listen to it the whole evening. Very curious about the Z foils, should be a big step towards clarity.
Yesterday I had a first look into how to take out the power supply board and I am scratching my head over how to get to the screws at the bottom, they are hidden under the big caps. Don't want to remove the transformer or bottom plate🤔
I wouldn't say it sounds tube like though, but it has this relaxing quality for sure, so I can listen to it the whole evening. Very curious about the Z foils, should be a big step towards clarity.
Yesterday I had a first look into how to take out the power supply board and I am scratching my head over how to get to the screws at the bottom, they are hidden under the big caps. Don't want to remove the transformer or bottom plate🤔
my curiosity is aroused , is it possible to buy only the kit or to you've to purchase the complete amp ?
If yes where is the safest way to buy it ?
If yes where is the safest way to buy it ?