Hi guys, if anyone with the patience for a 99.9% beginner can help out, as an educational experiment I'm interested in bypassing the relays in the Sony TA-FB940R amplifier. I've never done this before obviously.
I've attached a photo of the amp if anyone can tell me how to go about it in simple steps I would be very grateful!
Many thanks!
P1120817-1 — ImgBB
I've attached a photo of the amp if anyone can tell me how to go about it in simple steps I would be very grateful!
Many thanks!
P1120817-1 — ImgBB
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Here is a schematic of the area for those with the experience. Let me know if you need higher res schematic photos. Thanks again in advance!
Sony-ta-fb940r-Main-Board-Schematics — ImgBB
Sony-ta-fb940r-Main-Board-Schematics — ImgBB
What's wrong with it ?
Do You realize if there is a DC fault on the output it will cook Your speakers ?
In order to bypass the relays, just shunt the contacts on the left (four horizontal wires) but not the coil contacts on the right (vertical).
Don't mess with the lower one, since it is used probably for the headphone switching.
Do You realize if there is a DC fault on the output it will cook Your speakers ?
In order to bypass the relays, just shunt the contacts on the left (four horizontal wires) but not the coil contacts on the right (vertical).
Don't mess with the lower one, since it is used probably for the headphone switching.
Thank you for the reply!
Yes, I'm OK with the risk, I'm good with some aspects of the hobby (I know it might come as a surprise!) I've built power amps without any protection and I'm OK with taking the risk on the Sony. I just struggle to learn when I hit a brick wall with taking in new knowledge. And I get embarrassed when asking for help like this. Some people can be really rude and troll you just because you don't have the same level of knowledge as them.
Please bear with me here, I don't mean to be exasperating but which four wires do you mean? Sorry. Are you going by the schematic of the board or the photo? I've attached a photoshopped photo of the area. Thanks again for your patience and time!
Basic-Questions-on-Bypass — ImgBB
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Formal electronics training always involves an education in safety, which recipients are expected to take with a healthy dose of respect. The question you have asked happens to wave a red flag to members on that level. It is not against the rules to ask such a question, but it is in the rules that the nature of the issue should respectfully be made clear.
diyAudio Rules (in particular the areas highlighted in red)
diyAudio Rules (in particular the areas highlighted in red)
I see, I can see why the safety red flag. It does cause an issue though, although it's not at all a problem for anyone here, I'm obviously going to try and teach myself how to do it now with trial and error, and usually in this situation it's just a matter of online study and reading up on points where one is stuck until things fall into place and you solve the problem/project. But this is a relatively obscure operation as for general google research information gathering.
That is the mistake, you don't look for "bypassing Sony relays" or anything like that. This may be something almost no one would want to do to their amp, but electrically it is not obscure at all. You just want to replace relays with wires.
I will tell you this: a relay is nothing more than a switch. A switch connects two points together or it doesn't, depending on whether it is "ON" or not. The switch symbols are printed within the relay om your layout drawing.
I will tell you this: a relay is nothing more than a switch. A switch connects two points together or it doesn't, depending on whether it is "ON" or not. The switch symbols are printed within the relay om your layout drawing.
Remove the relays, and put a bulb or suitable indicator to see there is a supply from the circuit.
Check the relay coils for continuity.
Check the relay contact condition.
Relays coils rarely fail, unless they got a wrong voltage.
Contacts do wear out.
Please understand why those relays were put there, then work out your problem.
But still, you have any reason to do this?
What is your problem?
Check the relay coils for continuity.
Check the relay contact condition.
Relays coils rarely fail, unless they got a wrong voltage.
Contacts do wear out.
Please understand why those relays were put there, then work out your problem.
But still, you have any reason to do this?
What is your problem?
No problem with the amp.
Reason is for sound quality experiment, I've heard before and after on amps in which a friend used to do it and I could always hear an improvement.
A different subject but I've also heard this Sony improve with all hardwired inputs and output and then potted, obviously you take a massive risk wth potting, and some people can be funny with the idea, it does sound a bit woo and esoteric when used outside of its typical uses.
Shorting the relays is always foolhardy. There is the safety aspect of course, and anyone who does that to equipment ought to be in jail.
Relays also mute the output while the amplifier and circuits are stabilizing on turn-on and turn-off. Highly recommended as operation of an amplifier is not spec'd or guarantied under those changing conditions.
If shorting the relay improves the sound, you either need new relays, or there is something called expectation bias involved. Relay contacts can degrade over time if the volume is not zero on turn on or off. It is not unexpected to need new relays occasionally.
Speaker crossovers are never ideal. Your friend is wasting his time, and messing with a speaker's alignment. What you want is an active crossover system where each amplifier drives a speaker directly. So, if you want a real sound system, you need an electronic crossover, some amplifiers and knowledge to replicate the proper crossover points and slopes for the drivers in the speaker system.
What you guys are doing now is largely ineffective, possibly dangerous and incremental as far as improvements are concerned. You need new relays, that's all. Of course, a Sony isn't a great amplifier either.
So replace the relays and enjoy it. Otherwise you may find that your home owners insurance policy is null and void if it causes a speaker to burn. Never mind the risk you guys pose to people who live with you, and your neighbors. The risk of a speaker fire is very real. I know as I have serviced audio electronics for over 40 years. I have seen exactly your situation that did result in fire.
-Chris
Relays also mute the output while the amplifier and circuits are stabilizing on turn-on and turn-off. Highly recommended as operation of an amplifier is not spec'd or guarantied under those changing conditions.
If shorting the relay improves the sound, you either need new relays, or there is something called expectation bias involved. Relay contacts can degrade over time if the volume is not zero on turn on or off. It is not unexpected to need new relays occasionally.
Speaker crossovers are never ideal. Your friend is wasting his time, and messing with a speaker's alignment. What you want is an active crossover system where each amplifier drives a speaker directly. So, if you want a real sound system, you need an electronic crossover, some amplifiers and knowledge to replicate the proper crossover points and slopes for the drivers in the speaker system.
What you guys are doing now is largely ineffective, possibly dangerous and incremental as far as improvements are concerned. You need new relays, that's all. Of course, a Sony isn't a great amplifier either.
So replace the relays and enjoy it. Otherwise you may find that your home owners insurance policy is null and void if it causes a speaker to burn. Never mind the risk you guys pose to people who live with you, and your neighbors. The risk of a speaker fire is very real. I know as I have serviced audio electronics for over 40 years. I have seen exactly your situation that did result in fire.
-Chris
Definitely! I did a rebuild of an old Yamaha DSP A5 and judging each development all new relays did make a nice improvement, even after they had been taken apart and cleaned first, tested, then swapped for the new ones just made that bit more of a difference.
Thanks for the detailed reply! The only thing that confuses me now is one of my DIY power amp builds had a very, very clear increase in overall quality after experimenting with and without a relay board, with it in it sounded really good and I was pleased with the build, but then without it sounded so much better, enough to shock me, you know when you sit there and play a test song and you get mesmerised by the sound!
Those on the schematic drawn as switches. /
On the left You see the speaker contacts (horizontal). On the right You see a rectangle representing the coil contacts (vertical).
As what sound improvement concerns, unless the contacts are worn or dirty, there should be no difference, but it's Your ears.