This is going to be a real neewbie question, but would like to learn a little bit here. What is the art, or how do you view a schematic and know which resistors are in the signal path on a circuit board. I am looking on the phono board and preamp board of my Marantz receiver. It is a 2220B and I am pretty much done restoring it but would like to do a little more. Thanks for any help or pointers here.🙂
It's not as quite as easy as that.
As your knowledge and experience increases you will begin to understand the operation of the circuit... what each part does and what the effect of changing any value might have.
You need a thorough grounding and background in electronics to do that.
No short cuts to doing that I'm afraid. But don't let that stop you asking questions because it's the only way you learn.
As your knowledge and experience increases you will begin to understand the operation of the circuit... what each part does and what the effect of changing any value might have.
You need a thorough grounding and background in electronics to do that.
No short cuts to doing that I'm afraid. But don't let that stop you asking questions because it's the only way you learn.
Maybe someone could help me out a little bit on showing me what resistors are in the signal path that are critical if any. Thanks in advance. See the 2 pics below. You can click on the pic and then go and view at any size including full.
With the exception of R429, 415, 416 all resistors are part of the signal path, including feedbacks' R411 R423, R427 etc.
What you need to make sure of is that all resistors are metal-film, not carbon-film resistors. This design looks more than 20 years old and there is a good likelyhood that the resistors are carbon based. Metal-films will give you less noise and better temperature stability. E
What you need to make sure of is that all resistors are metal-film, not carbon-film resistors. This design looks more than 20 years old and there is a good likelyhood that the resistors are carbon based. Metal-films will give you less noise and better temperature stability. E
Yes it is probably 30+ years old. Thanks so much for taking the time to look at this for me. I would if possible like to do this in 2 phases, are there certain resistors in the path that would be considered critical that I could do first. There are 29 resistors on the board minus the 3 out of signal path leaves me 26 to do. If I could do critical ones first if that even applies I would like to go that route.
The concept of 'signal path' is one that is sometimes used, but almost always incorrectly. A good place to start is that all components are in the 'signal path'. If one does not affect the signal why is it there at all? Once you know enough to decide which ones are important you will know enough to ignore the concept of 'signal path'.
For what they cost you may as well just do them all tbh if that's what you want...
I think you will find all the resistors are still perfect, but I can understand the satisfaction of you wanting to do this.
The most critical tend to be the higher value ones and as mm points out, so look at the feedback networks. And C421 🙂
Probably easier to say what isn't critical assuming they aren't obviously faulty (they won't be) and thats R421, 419 and R415. Neither is R429 feeding power to the circuit.
I think you will find all the resistors are still perfect, but I can understand the satisfaction of you wanting to do this.
The most critical tend to be the higher value ones and as mm points out, so look at the feedback networks. And C421 🙂
Probably easier to say what isn't critical assuming they aren't obviously faulty (they won't be) and thats R421, 419 and R415. Neither is R429 feeding power to the circuit.
Hi and thank you I think I am catching on a little here. Can you tell me which resisters are in the feedback circuit? Thanks! All of the caps were replaced including the 2 tantalums.
replacing resistors (Unless faulty or drifted ) in a circuit like the above in an amplifier like the above will not make absolutelly any audible effect .
in the specific consumer amplifier (s) eventhough the specific circuits can be quite promessing and can also simulate relativelly good in real life the qualities of the circuit are compromized degarded and derated by the pcb , the power supply and mostly the wiring that introduce inside the signal noises and distortions that will overcome any upgrade with exotic parts.
In real life and even at the time simulators didnt exist the designer of the circuit done a good job but the manufacturer had to make it cost effective and easy to produce ... that reduces the quality of the original circuit by far less ...
kind regards sakis
Ps
upgrades in the power supply wiring and rooting of cables for this model can and will make audible diference .possible to make ?? well not really for an amature sorry to say
in the specific consumer amplifier (s) eventhough the specific circuits can be quite promessing and can also simulate relativelly good in real life the qualities of the circuit are compromized degarded and derated by the pcb , the power supply and mostly the wiring that introduce inside the signal noises and distortions that will overcome any upgrade with exotic parts.
In real life and even at the time simulators didnt exist the designer of the circuit done a good job but the manufacturer had to make it cost effective and easy to produce ... that reduces the quality of the original circuit by far less ...
kind regards sakis
Ps
upgrades in the power supply wiring and rooting of cables for this model can and will make audible diference .possible to make ?? well not really for an amature sorry to say
Hi and thank you for taking the time to answer. I have replaced all the capacitors in the unit. I have also replaced some of the small value caps with films. And I did rewire the Power Supply Board to main filter caps and the Amp Board to the Main Filter Caps (which are Mundorf M-Lytic) and have loved all the gains in sonics. (I used Kimber Tcss) Was just looking to see if I could do more. I do have Kendeil caps for the main filter caps coming, I do not know if they will be better then the Mundorfs. This is my 1st projecct trying to learn as I go.
procedure is fine ... it will be good though if possible to evaluate before and after status
if you want i can compose a text with mods that i would do for this amp aiming sound quality against safety and maximum power
( gosh mundorph is a complete waste of money in such an amplifier ... if you can afford it and the idea is to learn ...be my guest🙂 )
if you want i can compose a text with mods that i would do for this amp aiming sound quality against safety and maximum power
( gosh mundorph is a complete waste of money in such an amplifier ... if you can afford it and the idea is to learn ...be my guest🙂 )
amplifier section :
--- could replace input cap from elctrolytic to anything filmy ( C701-702 ) i could go up to 2.2 mfd ( increase of bass response /generally sounds better )
---could increase output caps to anything huge fits size wise ( C004-005 ) even up to 10.000 mfd add bypass film of 100nf add resistor 2K2 2W to terminate outtput to ground
--- could replace C723 724 miller caps to silver mica using better quality capacitors provides also a chance to lower them in value and that will improve sonics and high frequency response ( need to verify though with a scope )
--- same for C 713-714
--- make sure that either trimmers are replaced or working perfectly often just deoxit sprayis not enough, replace with multiturne provide more accurate adjustments
--- see if its possible to cancel speakers AB switch ( very messy and signal goes alla round the amp without a reason )
--- could relocate zobel to speaker terminal ..if so ( taking as a fact that speakers AB is removed ) and in this case return to ground has to be done with a seperated wire to the star ground
power supply
--- could increase main filter power supply cap to anything huge ...10.000 or even 15.000 will be just fine ... bypass with film 2.2 mfd
secondary power supply
----Local regulators are very poor there ... stabilty of voltage is not really an issue there but noise can be a story ... replacing zeners with regulators and transitors with some lm 317 will provide more clean power ....( up to you to decide how critical this might be )
---- could increase values of C 803-804-810 nothing extreme there you can go as much high as you like depenting only on size .... MKS for bypass there is really nice
---- tone control section
---- could increase input caps film type up to 1mfd C501-502..
---- same with output caps C513-514 there i could go even up to 10mfd and bypass with film of 0.22 mfd
--- study and understand the tone control operation playing with both the values of the capcitors and the quality of them could improove the tone control or change the frequency that the tone controll effects to something more up to date ....Tone controls are not that good for '' high end" amplifiers but some of them produce unbetable sonics and colourations that are very "dear" to the human ears ...
kind regards
sakis
--- could replace input cap from elctrolytic to anything filmy ( C701-702 ) i could go up to 2.2 mfd ( increase of bass response /generally sounds better )
---could increase output caps to anything huge fits size wise ( C004-005 ) even up to 10.000 mfd add bypass film of 100nf add resistor 2K2 2W to terminate outtput to ground
--- could replace C723 724 miller caps to silver mica using better quality capacitors provides also a chance to lower them in value and that will improve sonics and high frequency response ( need to verify though with a scope )
--- same for C 713-714
--- make sure that either trimmers are replaced or working perfectly often just deoxit sprayis not enough, replace with multiturne provide more accurate adjustments
--- see if its possible to cancel speakers AB switch ( very messy and signal goes alla round the amp without a reason )
--- could relocate zobel to speaker terminal ..if so ( taking as a fact that speakers AB is removed ) and in this case return to ground has to be done with a seperated wire to the star ground
power supply
--- could increase main filter power supply cap to anything huge ...10.000 or even 15.000 will be just fine ... bypass with film 2.2 mfd
secondary power supply
----Local regulators are very poor there ... stabilty of voltage is not really an issue there but noise can be a story ... replacing zeners with regulators and transitors with some lm 317 will provide more clean power ....( up to you to decide how critical this might be )
---- could increase values of C 803-804-810 nothing extreme there you can go as much high as you like depenting only on size .... MKS for bypass there is really nice
---- tone control section
---- could increase input caps film type up to 1mfd C501-502..
---- same with output caps C513-514 there i could go even up to 10mfd and bypass with film of 0.22 mfd
--- study and understand the tone control operation playing with both the values of the capcitors and the quality of them could improove the tone control or change the frequency that the tone controll effects to something more up to date ....Tone controls are not that good for '' high end" amplifiers but some of them produce unbetable sonics and colourations that are very "dear" to the human ears ...
kind regards
sakis
I really want to give you a sincere thank you for the time and effort you put in to give me a template for upgrading my Marantz 2220B.
On the Main Amp Board I will do the recommended C701 and C702 input cap replacements with films
For the Main Filter Caps I could not be happier with the Mundorf M-Lytics, and especially after I rewired with the Kimber TCSS.
I do not see any C723, C724 or C713, C714 the ones you suggest replaceing with silver mica? Where are they at?
The A/B speaker switch sounds like a great idea but I know I would need help with this, as I beleive you just can not clip the wires off.
For the Power supply board film bypass, where would you put it?
I may increase C803, C804, and C810 on the power supply board.
I also can not find C502, and C502 and C513 and C514 that you are saying change over to film.
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