Greetings all
So I have this amp with crumbling printed boards I've been trying to fix. There is mostly working components but they are literary falling off of the PCB
Question is if it would be possible to build something simplified from the scraps as the cabinet, PSU and heatsinks, pot, etc. etc. is there and working fine. I was thinking stripping out all electronics besides pcu and build something from the power transistors and whatever can be used, on a proto board or even p to p.
I've been reading and looking around at circuits but this would mean designing circuitry, witch I could not do solo. I have received a good bit of help here in my attempts to fix it so I thought I should seek some advice before delving into something too advanced
Thanks in advance
So I have this amp with crumbling printed boards I've been trying to fix. There is mostly working components but they are literary falling off of the PCB
Question is if it would be possible to build something simplified from the scraps as the cabinet, PSU and heatsinks, pot, etc. etc. is there and working fine. I was thinking stripping out all electronics besides pcu and build something from the power transistors and whatever can be used, on a proto board or even p to p.
I've been reading and looking around at circuits but this would mean designing circuitry, witch I could not do solo. I have received a good bit of help here in my attempts to fix it so I thought I should seek some advice before delving into something too advanced
Thanks in advance
hi,
Of course, the most expensive and heavy things need to be reused (transformer and PSU, power transistors and heat-sinks) in any case, this amp will not be easy project for beginner and will be a little dangerous with + -60V rails...the original marantz has an output triple EF : you can build leach amp ( or slewmaster amp...but they are not that simple ...
Of course, the most expensive and heavy things need to be reused (transformer and PSU, power transistors and heat-sinks) in any case, this amp will not be easy project for beginner and will be a little dangerous with + -60V rails...the original marantz has an output triple EF : you can build leach amp ( or slewmaster amp...but they are not that simple ...
I agree, but there is also available 24,9V as it is switchable to class A. A few of the circuits I've seen uses 24V rails so should be safer. Maybe some kit would be a better way to go
The most simple way to do that is using the original pre amp and power amp PCB to built, so that no need to do a new PCB and the most difficult chassis metal works. Please take pics of your pre amp, power amp PCBs front and back sides to see if they can reuse it to rebuilt the amp.
As I have explained to you, and stated in the opening post, the original PCB's is the problem so using them is not an option. All the traces is cracking and falling off the boards. I have worked for months trying to fix this thing, only chasing my tail with the PCB's falling apart
I read your post these days and you did quite a lot testing jobs for your amp.
Ok, buying kits to built the amp is the easy way to built the amp.
Ok, buying kits to built the amp is the easy way to built the amp.
Have a look at the Pass Amplifier thread for ideas and conclusions about the Pass amplifiers.
A lot of people have built the F5 although I was disappointed with my version.
I've built the Aleph 4 but that is outside of the normal First Watt family of 25W amplifiers.
The Aleph J is supposed to be very good and uses +/- 24V rails.
The boards are available from the DIY store. The semi-conductors are obsolete but are still reasonably easy to get hold of.
A lot of people have built the F5 although I was disappointed with my version.
I've built the Aleph 4 but that is outside of the normal First Watt family of 25W amplifiers.
The Aleph J is supposed to be very good and uses +/- 24V rails.
The boards are available from the DIY store. The semi-conductors are obsolete but are still reasonably easy to get hold of.
I was actually considering the F5 and have been reading about it. Would you elaborate why it failed to impress? Seems to get mostly good reviews.
Although it seems doable implementing that in my chassis, it looks to me as my PS would be inferior to what instructions call for, my heat sinks seem to small so that leaves me with very few usable parts and the whole idea makes little sense
My speakers are B&W CM8.
In my opinion the F5 just couldn't provide enough bass current. If you read all the threads on the F5 you will find that other people have observed the same issue with low impedance / low sensitivity speakers.
In my opinion the F5 just couldn't provide enough bass current. If you read all the threads on the F5 you will find that other people have observed the same issue with low impedance / low sensitivity speakers.
At ±60 Vdc rails the Honey Badger would be an option. Do it's PCB's fit into the given case?
Best regards!
Best regards!
Honeybadger would be possible, maybe. It would be a tight squeeze tho. Im worried the heatsinks will be too small. They are 21x12x30.
In regards to the F5 I probably would suffer the same issues in lower region. My current speakers are low impedance and around 90dB
Thanks for suggestions!
In regards to the F5 I probably would suffer the same issues in lower region. My current speakers are low impedance and around 90dB
Thanks for suggestions!
Pick up a flat screen TV on garbage day. The Samsung 50" I picked up had about 15 12x30x100 heat sinks. Had a dozen or more NFET transistors that might fit into some split supply amp. (I build single supply amps). The mains caps in the power supply blew up, not the screen switching parts.
I just folded up the screen on a 32" flat screen I broke. Wear gloves & safety glasses, score the front of the screen with a carbide scribe, fold backwards towards the plastic side, insert in garbage bag. Saw up the plastic cover. No recycle fee.
Here's my take: Start from scratch. I've tried using parts from another project and it always ends up taking forever to get anywhere because it doesn't quite work. Use what you have as a parts supply but don't try to use any sub-circuit as it won't work. This isn't a recommendation from an expert, it is a recommendation from a complete amateur at this. It sounds like you are too. Take it from one, don't bother. An experienced electronics person could do it but face it, you're not! This isn't a criticism it is reality.
I have all the parts necessary to make my push-pull tube amp into a fully transformer coupled amp, but the parts have sat on the bench for 3 years now. In order to do this I'd need to disassemble what I have and use it as the basis for the new amp. I'll be without a decent amp in the interim, and there is absolutely no guarantee it will work, nor will I be able to restore it to the original condition. Nah, not gonna take the chance. I also have a non-working SS amp that I tried to fix, but after all of the work it still was kaput, blowing the fuse. I have that sitting on a shelf, not even as a parts donor. I thought about adapting it to one of the Pass amps but took one look and said nope.
With a scratch build of a Pass amp at least you have a working chance of getting it built and working, since you'll have help here and everything you need is available. Having pre-drilled metalwork is a good thing too as that takes more time than anything.
I have all the parts necessary to make my push-pull tube amp into a fully transformer coupled amp, but the parts have sat on the bench for 3 years now. In order to do this I'd need to disassemble what I have and use it as the basis for the new amp. I'll be without a decent amp in the interim, and there is absolutely no guarantee it will work, nor will I be able to restore it to the original condition. Nah, not gonna take the chance. I also have a non-working SS amp that I tried to fix, but after all of the work it still was kaput, blowing the fuse. I have that sitting on a shelf, not even as a parts donor. I thought about adapting it to one of the Pass amps but took one look and said nope.
With a scratch build of a Pass amp at least you have a working chance of getting it built and working, since you'll have help here and everything you need is available. Having pre-drilled metalwork is a good thing too as that takes more time than anything.
I would vote for some kit, and reuse the case and power supply (but it probably needs re-capping). If you need lots of power, go for some kit that takes the high rail voltages. If you need an amp for normal listening go for the lower rails.
Keep in mind that even with the lower rails a class A will run hot, maybe your heat sinks are not enough if you want to bias it for 4 ohm speakers. Not sure if the transformer will like class A bias for 4 ohms either?
Keep in mind that even with the lower rails a class A will run hot, maybe your heat sinks are not enough if you want to bias it for 4 ohm speakers. Not sure if the transformer will like class A bias for 4 ohms either?
No worries, I don't take it as criticism. You basically put to words what my gut feeling has been saying since I threw the question out there. After all the advice here, the stuff I've been reading I feel there will be too much compromising for my skill-level. That's why I have started to look at various and more complete kits.
I need to consider what speakers I want for the future also, as I'm beginning to feel the need for change
Thanks to you all for chiming in and sharing knowledge and ideas.
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