Sony TA N77ES Power Amp: Making it Work with Missing Speaker Selector Switch

[@dualityrepair4770]

Thanks for the shout-out Ray. And good work on this one. What a pain to get to those relays but very satisfying to see it working again.

[@raygianelli3612]

The shout out is well deserved. Out of all the KZbin channels I've seen/watched, I've never seen the sheer amount of information presented in such short times. And yeah, the satisfaction of fixing something is what keeps me doing this kind of work. That feeling of seeing something that wasn't working spring to life after you finally diagnosed and fixed it is unparalleled!

[@AstrosElectronicsLab]

They're Omron 24V relays, they aren't that hard to get, however, I believe I saw these were SPDT's (2 contact terminals per side), and most Omron's are DPDT. I suppose you could cut the unused leads off to fit the foot print, as long as the centre and NO terminals are in the right place...

[@AstrosElectronicsLab]

New sub. By the way, with the 680R resistor, you mean "limit the current", not "drop the voltage". I did a rough, dirty calculation, for a relay coil of around 980R, that's a current draw of ~24.4mA. Take the supply voltage from the relay voltage (39-24=15) then divide the result by 0.0244, we get close to the 680R chosen (614R approx). As for the wattage of the resistor, P=E*I = 24*0.0244=586mW. So, there chosen resistor is correct. Sony knew what they were doing.

[@roroseppel2077]

Good Job Ray, and as always, improving Murphy's law...

[@craigm.9070]

Excellent troubleshooting video! Those ES series amp's were real brutes (not many in the wild either); I bet your customer will be very happy! Thank you for your time.

[@raygianelli3612]

Thanks Craig! It's only the second one I worked on. First one had a blown channel, this one was different. Hey, at least it wasn't another Sansui! I like to mix it up to keep me sharp. Even if it's not working. 🤣

[@AstrosElectronicsLab]

@@raygianelli3612 what possessed whoever it was to remove the switch in the first place; and somehow "lose" it. Clearly, the issue was not switch... unless it was physically broken, of course. That just seems dumb to me.

[@salvadorrodenas3071]

I own two ta-n80es, so I know a little about it. I have several original relays as a backup just in case the coil is broken. If not, just cleaning the contacts with an ear button moistened with metal cleaner is enough to put it back in order. I'm sure there must be an engineer smart enough to design one switch for this amp out there in some place. Thanks for sharing your skills with the community 👍

[@raygianelli3612]

Thanks Salvador! I'm hoping to learn about CNC and 3D printing, in the hope that I can fabricate parts that are no longer available. Two more things on the list of things to learn. I should be good to go by the time I'm 150. 😁

[@salvadorrodenas3071]

@raygianelli3612 don't worry, this should be considered as an eventual project of yours, the construction of obsolete parts. In the meantime, keep doing videos like this, please😀👊.

[@philsanalogbasement]

Thanks Ray! Hopefully getting some actual equipment repair videos out soon. Man, you and some of the other guys sure make it look easy!

[@raygianelli3612]

Well, it only looks easy because 3 weeks of frustrations are condensed into a 30 minute video!

[@AstrosElectronicsLab]

@@raygianelli3612 and possibly most of those weeks were spent swearing at the unit. Lol.

[@Douglas_Blake_579]

Nice video ... I don't know if you do this or not, but I always put "notes to the next tech" in any unit where I've done a mod or work around explaining what was done and why.

[@raygianelli3612]

I have in the past, but didn't in this case. Appreciate the reminder!

[@Douglas_Blake_579]

@@raygianelli3612 No worries ... Make the next guy's job easier.

[@R.AudioElectronics]

Thanks Ray good to know I’m not the only one making dumb mistakes. Oh well at least nobody’s head caught on fire:/

[@raygianelli3612]

Mike, the head on fire was years ago. True story: I was working on something and needed a tool I'd left in my car. I flipped up the magnifying visor I wear and went out to get it. As I'm walking out to my car (in the hot Florida sun) I'm thinking, "why do I smell hair burning?" Humans make mistakes. And I'm only human. 😁

[@R.AudioElectronics]

@@raygianelli3612 stop you’re just trying to make me feel better lol. It would be interesting to hear some stories from people who have had similar experiences

[@Douglas_Blake_579]

@@R.AudioElectronics Years ago I was working on a transmitter power supply and one of the big caps decided to blow it's top ... I didn't know it then but eyebrows can take months to grow back in.

[@AstrosElectronicsLab]

@@raygianelli3612 I once put one of those magnifying glass PCB holder tools on the floor of a room... near a window. Well, it burnt a nice impression in the carpet around the base of the tool.

[@Douglas_Blake_579]

Hi again Ray... I'm wondering ... when you found out you could trigger "Speakers B", why didn't you just move the resistor to that center lead and tell your customer to use the B posts on the back? It would have saved you from having to move the relay...

[@raygianelli3612]

He wanted the A posts working. Now that it's reassembled he wants the bad relay replaced. I don't know why, the switch is NLA and the chances of finding one are about nil.

[@Douglas_Blake_579]

@@raygianelli3612 The Unobtanium problem... I suppose it's his money ... but yeah that doesn't make a lot of sense, unless he has access to a differently flawed but identical amplifier to get a speaker switch from.

[@AstrosElectronicsLab]

@@Douglas_Blake_579 I was wondering the same thing. Why not just use B, makes no difference, except to move speaker wires to the bottom posts?

[@AstrosElectronicsLab]

@@raygianelli3612 surely you could cobble a normal rotary switch in there somehow? It doesn't need a PCB, you just solder the resistors in series with the ribbon lead, and solder the legs of the switch together to fashion it in to a working selector. How many positions does it have? 4? Off, A, B and A+B? Shouldn't be that hard, the knob is a different story... you may have to mould a new one using one of the others as a template to cast.

[@raygianelli3612]

@@AstrosElectronicsLab I imagine something could be fabricated to work, but this repair was a favor to a friend, and I just didn't want to devote the kind of time it would have taken to do so.