Thank you.Other than the large output caps how many (large and small) parts get changed when undergoing a freshening up?
We love pictures.
Glad you got the results you like
I was in a bit of a hurry to try it out yesterday, so I didn't shot so many pictures.
Here's what I got.
The new caps that replaces the older 150 Ohm ESRs:
and the two, slightly bigger, caps next to one of the pre amps:
Will take some more pictures when I tear it down for the next upgrade.
How many caps you need to change depends of how thorough you want to be I would say.
I'm a rookie so there definitely people here with better insight, but my take is:
If I just wanted to fix it, it would have needed two caps for 0,5€ each.
What I see as a bare minimum is to refresh all caps in the close vicinity to any heat sinks or parts sitting where the PCB shows sign of excessive heat.
If you look closely at my first picture you can see that the top left corner to the right of the big blue cap the PCB is brown, and even clearer at the bottom right of the yellow box. The caps there will have a high risk of being dried out so they have to go, along with the ones I've now changed on the right of the heat sinks in the green box. This would take about 14 small caps around 0,5€ a piece.
What I would recommend is to change all the PSU-lytes. A bad PSU is not only giving your amplifier noisy DC, but risk damaging your amplifier too.
Add another 6 small, 4 medium size á 5€ and the four big 10€.
This is what I'm going to do, and to this add the rest of the small caps in the amplifiers, 18 in total, since they were not great to start with and I don't think they age like wine...
You could go on from this too and change caps in the protective circuits and for the volume motor and so on, but I will stay with whats give me better sound.
@A Jedi Thanx. Did everything work out for you?
@Audio Service Thank you for your help!
Did a checkup on the 64V rails as recommended by @Rallyfinnen and they are stable at 70V. A bit close to to 80V maybe...
Gonna see if I can find some caps at a reasonable price that are rated for 100V to get a bit more head room.
Please note there are electrolytic capacitors inside the vertical black modules shown in your photo, they are in the Audio signal conditioning circuit so you may want to also replace them.
The modules once desoldered are removed by releasing the small phillips screw.
Do not fully remove it as internally it clamps larger driver transistors to a heat sink.
The plastic top cover clips in place so if you remove it use a thin flat blade screw driver and prise up slowly from either end.
It not uncommon for the plastic location pegs to snap off due to the plastic becoming brittle.
I would not over look the electrolytics in the protection circuit.
If you look at the board you can see they are close to a high wattage power resistor.
The capacitors are an integral part of the protection circuit, and if they fail the protection circuit will fail to operate.
The modules once desoldered are removed by releasing the small phillips screw.
Do not fully remove it as internally it clamps larger driver transistors to a heat sink.
The plastic top cover clips in place so if you remove it use a thin flat blade screw driver and prise up slowly from either end.
It not uncommon for the plastic location pegs to snap off due to the plastic becoming brittle.
I would not over look the electrolytics in the protection circuit.
If you look at the board you can see they are close to a high wattage power resistor.
The capacitors are an integral part of the protection circuit, and if they fail the protection circuit will fail to operate.
The vertical black modules are the pre amps, no?
In there there are no electrolytics according to the service manual.
I have opened them and looked inside and can only see small surface mounted components.
Ok. I listen to you and @A Jedi , I'll change the other caps too.
It's not about the money or time, I'm just scared to **** something up that needed no fuckups...
Protection circuit sounds like something that prevents you from having a good time if something goes wrong, but I guess you can say that about most of the things I'm about to tamper with.
You have achieved a great deal and your jumping in at the deep end.
This is no low end entry level Amplifier.
As long as you make the time and take the time to complete the work all should be good.
Just check your work at each stage.
Most importantly your learning a lot, for all of us on the forum we all started at the beginning and knew nothing.
Our experience has been gained over many years and we are all still learning.
Believe in yourself and your doing the right thing asking for guidance and support.
That's why we are all here.
This is no low end entry level Amplifier.
As long as you make the time and take the time to complete the work all should be good.
Just check your work at each stage.
Most importantly your learning a lot, for all of us on the forum we all started at the beginning and knew nothing.
Our experience has been gained over many years and we are all still learning.
Believe in yourself and your doing the right thing asking for guidance and support.
That's why we are all here.
What @Audio Service said. When I opened my 370 for the first time I was utterly clueless. I still don't know much but I know way more than just a few months ago. Just take your time and the very smart and super helpful people around here will help.
Thank you!
Your help and support means a LOT to me.
This project was a lot more fun than I thought, and that too I have to thank you guys for!
Been overclocking computers since I got my 486 DX66 so I'm pretty used to risk breaking things.
This however seems so much more repairable if you screw something up.
Will take my time and try to understand what everything does.
Now it's just small parts of the wiring diagram that I actually feels I got a hang on.
These are my new lesson since the most caps I got left to change are located here, and I have no idea what they're doing.
The red caps are located to the left of the big ones, and the bottom parts are located over them and a bit to the right.
My next step forward now is to chose the rest of the caps and order them.
Will check the temperatures at the hot spots too, but my IR thermometer was out of juice...
A small update.
I checked the temps on the hot parts and they were ok.
Wouldn't hurt if they were 10C lower, but it's good enough for me to save time not custom cut bigger heat sinks for them.
The 5V and 34V rail was in the fifties, the 68V in the eighties and the main 64V in the forties.
As long as the amplifier gets to breed I don't think there will be any heat issues.
Do you?
All caps are ordered and Digi-Key has shipped them.
If DHL are right I'll have them by the end of the week.
So @wasabii , 66 caps in total.
I went with 80V main caps. Should be enough I hope.
To compensate some I got six of them instead of four, but 8,000uF instead of 10,000uF.
The Epcos can take nearly the double ripple current than the popular Mundorf M-lytic at 10,000uF (6.9 vs 3.9) so I think they will be fine,
and hopefully those extra 20% of capacitance will do some good for the sound.
I checked the temps on the hot parts and they were ok.
Wouldn't hurt if they were 10C lower, but it's good enough for me to save time not custom cut bigger heat sinks for them.
The 5V and 34V rail was in the fifties, the 68V in the eighties and the main 64V in the forties.
As long as the amplifier gets to breed I don't think there will be any heat issues.
Do you?
All caps are ordered and Digi-Key has shipped them.
If DHL are right I'll have them by the end of the week.
So @wasabii , 66 caps in total.
I went with 80V main caps. Should be enough I hope.
To compensate some I got six of them instead of four, but 8,000uF instead of 10,000uF.
The Epcos can take nearly the double ripple current than the popular Mundorf M-lytic at 10,000uF (6.9 vs 3.9) so I think they will be fine,
and hopefully those extra 20% of capacitance will do some good for the sound.
So, finaly got my caps and had some time to start changing them.
I took the boring stuff first since I know that the chances are slim to none that I tear it completely down to change that cap in the front for the IR-reciever if that's all that's left. (And the one in the left that surely does something important)
At the same time I fixed the 68V and 5V rails.
I tried my best to bend the legs the right way to get some extra distance to hot parts while still keeping them as short as possible. Hopefully adds a couple of years to their lifetime.
I took a break here and reassembled the amp and did a function check. Should have been easy to figure out where I went wrong with just these changes, but everything worked as supposed. Even the remote that I haven't used in years since it's too uggly to be laying on a table works.
Now it's time for the rest of the main board caps!
I took the boring stuff first since I know that the chances are slim to none that I tear it completely down to change that cap in the front for the IR-reciever if that's all that's left. (And the one in the left that surely does something important)
At the same time I fixed the 68V and 5V rails.
I tried my best to bend the legs the right way to get some extra distance to hot parts while still keeping them as short as possible. Hopefully adds a couple of years to their lifetime.
I took a break here and reassembled the amp and did a function check. Should have been easy to figure out where I went wrong with just these changes, but everything worked as supposed. Even the remote that I haven't used in years since it's too uggly to be laying on a table works.
Now it's time for the rest of the main board caps!
Thank you @Audio Service!
Now all caps except the ones on the amp stages, and a little bugger on the main board, are changed.
The small blue one on the left (C783) was stated to be 47uF in the component list. It was 4,7uF however, and futher down there was a text that the cap should indeed be changed to 4,7uF and reversed. It was OK so I resoldered it...
The main caps looks small compared to the old 100Vs.
Somewhat too big, but I think it worked out good enough.
Here I ran in to some more trouble.
First off, my mistake. I ordered a 50V 330uF instead of a 16V. There was room enough, but not by a big margin.
The next problem was that the small blue one (C784) is 47uF/50V, but the one that was there is 100uF/25V. I hope the manual is right.
Not my proudest work, but slightly thicker leads than the old ones and a bit tidier than the originals anyway.
Now I'm gonna let it play for a day or two before I start with the amplifiers to be sure it works as it should.
It does right now at least!
Now all caps except the ones on the amp stages, and a little bugger on the main board, are changed.
The small blue one on the left (C783) was stated to be 47uF in the component list. It was 4,7uF however, and futher down there was a text that the cap should indeed be changed to 4,7uF and reversed. It was OK so I resoldered it...
The main caps looks small compared to the old 100Vs.
Somewhat too big, but I think it worked out good enough.
Here I ran in to some more trouble.
First off, my mistake. I ordered a 50V 330uF instead of a 16V. There was room enough, but not by a big margin.
The next problem was that the small blue one (C784) is 47uF/50V, but the one that was there is 100uF/25V. I hope the manual is right.
Not my proudest work, but slightly thicker leads than the old ones and a bit tidier than the originals anyway.
Now I'm gonna let it play for a day or two before I start with the amplifiers to be sure it works as it should.
It does right now at least!
I don't know if it's my mind playing tricks, but I feel like the deep bass isn't really there as much as it has been (or the treble is more pronounced?)
It's not that it won't go deep if I make it, but it's like someone slightly lowered the eq in the very low register. It's like it's a bit kept back under 100Hz.
Can anything I did have an impact like this?
It's not that it won't go deep if I make it, but it's like someone slightly lowered the eq in the very low register. It's like it's a bit kept back under 100Hz.
Can anything I did have an impact like this?