I replaced the 2 diodes on the TRR board when I replaced all its electrolytic's. On this board you can read DC voltages from the appropriate resistor to chassis to validate your power supply voltages. Mine are a couple of volts high compared to the schematic values. Also, the +40 and -40 volt supplies to the output transistors read 39 volts to chassis on F001 thru F004.
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3000A arrived damaged; worth keeping?
- Thread starter birchoak
- Start date
birchoak
Hi-Fi Nut
Nothing to be sorry about! I can get over-excited, overconfident, and make a hash of things! This thing was ridden hard and put away wet, so it's not really a big deal. I think it has become a "parts unit." When I find another 3000A I can use this one to help it out. But not for a while! That was exhausting.
So you have a shelf of shame, too? You just have to laugh. And it's easy, after the fact, to see what you should or shouldn't have done. I don't seem to learn until I get my hands dirty (today, burnt by the iron!) and make some mistakes. I wish you lived closer, man. We could probably help each other out in real life ("No Birchoak, that cap's backwards!" or "You do realize that amp's not plugged in, right?").
On a + note, I put the 3000A away in a darkened corner and revisited another problem child, a 1971 Panasonic SA-5800. This little baby was missing the left channel, had a terrible 60 Hz hum, and tons of static. I did some more recapping, freshened up what felt like several hundred feet of solder traces, and discovered a broken leg on a 2SC696A metal transistor. Soldered a new leg on, slipped the (ceramic! can you believe it?!) insulators back on and, voila, both channels strong and hum gone. Now, there's an ocean-static thing going on---I think it's old 2SA666 transistors so I'll be getting some replacements.
Sometimes hi-fi repair feels like Vegas: when you win, it's a big deal and you feel 10 feet tall. When you lose (don't fix it/make it worse/86 it) you feel one inch tall. At least I do, sometimes. I'm trying to pick cleaner, better cared-for units that haven't been abused/neglected. Pick your battles and all that.
birchoak
Hi-Fi Nut
The Sansui is in time out at the moment. I will keep your advice handy when it's ready to be nice again.
dly66
Addicted Member
Was there a problem with the driver transistors on the 3000A? The little Sony metal cans on the heat sink. Mine ended up to be working just fine. There is a dvm check you can do if you are not familiar you can use to check for blown diodes and can be used to id totally blown transistors. Treats a transistor as two diodes tied together at the base. NPN flows one way, PNP the other. After some practice don't often look at the schematic or datasheets, just swap probe tips quickly among the three legs and see it normal pattern stands out. If it doesn't, look at the details likely have a bad one. Trying to fix by swapping in new parts invites tail chasing - one may create new problems on top of the old. Easy trap to fall into, have done it some in the past. Sometimes it works, many times not. A certain level of diagnostic effort is needed. Like a car you can throw parts at a problem, and just drain your wallet and still have the problem. Especially if the real cause of the problem is an unidentified small vacuum leak in a small hose in one of the dark buried corners of the engine compartment.
In the wiring I look to de-solder at the connector or solder tabs. A number of times will have to cut since the way it was done can't get it to loop out so cut as close as physically possible to the tab then I can often heat with iron and push or loop out the little bit of wire out of it. Takes patience. Redoing the wires to and from the tape monitor in the S-8900A was not quick. It is close quarters and I had to loosen and shift a few pieces to get it back where I could solder it. The soldering on the tape monitor switch has it being a little balky now. May need to use the aux instead. Or open it up and see if I can adjust the inside - I think the service manual actually diagrams it as if that would be expected at some point in time.
Fixing these things is not for everyone. Takes a lot of patience, frustration tolerance, and looking at the schematics, unit, and coming up with possibilities in the mind and trying to figure out checks to narrow down where the problem is. I also expect most of these 40-50 year old electronics need some restoration to be back at full fidelity. Every one I have done so far the before and after has been appreciable. Its like car repair and other things, some will have a talent for it and some need to stay away from fixing things - they can be rather destructive when they try. Especially if by nature they are impatient and have a very low frustration tolerance.
In the wiring I look to de-solder at the connector or solder tabs. A number of times will have to cut since the way it was done can't get it to loop out so cut as close as physically possible to the tab then I can often heat with iron and push or loop out the little bit of wire out of it. Takes patience. Redoing the wires to and from the tape monitor in the S-8900A was not quick. It is close quarters and I had to loosen and shift a few pieces to get it back where I could solder it. The soldering on the tape monitor switch has it being a little balky now. May need to use the aux instead. Or open it up and see if I can adjust the inside - I think the service manual actually diagrams it as if that would be expected at some point in time.
Fixing these things is not for everyone. Takes a lot of patience, frustration tolerance, and looking at the schematics, unit, and coming up with possibilities in the mind and trying to figure out checks to narrow down where the problem is. I also expect most of these 40-50 year old electronics need some restoration to be back at full fidelity. Every one I have done so far the before and after has been appreciable. Its like car repair and other things, some will have a talent for it and some need to stay away from fixing things - they can be rather destructive when they try. Especially if by nature they are impatient and have a very low frustration tolerance.
birchoak
Hi-Fi Nut
A cool head is the most important tool to have. Maybe I should ice my noggin before I look at the 3000A again
birchoak
Hi-Fi Nut
Yah, drive trannies were bad--I used the diode test function on my BK.
Frustrating as this Sui has been, I can cut loose with low stakes pieces like this one (arrived smashed up, wasn't safe to use to begin with as DC offset was insane, someone else had butchered it, ended up paying $30 for it) and fail spectacularly. I did get the DC offset to pretty much 0.0mV and it does produce sound without blowing up or smoking, so there's that. And the rear panel is straight now
When I work on high value units (to me) -- (Yamaha CR-800, Marantz 2230, Hitachi SR-1100) it's a different story: the things are working well to begin with and are in outstanding shape--usually untouched by others. I am especially proud of a JVC VR-5551 I thoroughly rehabbed, down to reproduction Sanken TO-3s from Hong Kong. It sounds better than when I first got it and has quite a bit of power. It's also a receiver most people have never heard sing, let alone seen in the flesh.
Frustrating as this Sui has been, I can cut loose with low stakes pieces like this one (arrived smashed up, wasn't safe to use to begin with as DC offset was insane, someone else had butchered it, ended up paying $30 for it) and fail spectacularly. I did get the DC offset to pretty much 0.0mV and it does produce sound without blowing up or smoking, so there's that. And the rear panel is straight now
When I work on high value units (to me) -- (Yamaha CR-800, Marantz 2230, Hitachi SR-1100) it's a different story: the things are working well to begin with and are in outstanding shape--usually untouched by others. I am especially proud of a JVC VR-5551 I thoroughly rehabbed, down to reproduction Sanken TO-3s from Hong Kong. It sounds better than when I first got it and has quite a bit of power. It's also a receiver most people have never heard sing, let alone seen in the flesh.
dly66
Addicted Member
Those were used in the differential pairs of my S-7200. When I got it the ones in the right channel had this weird noise sort of like waves crashing in the background when you are a couple blocks from the beach and after playing it for some hours it changed to bursts of rat-a-tat-tat type noise after being on about 10 minutes. Identified using freeze spray which would quiet them back down for a minute or two. Putting in new modern Fairchilds for the differential pairs and that noise went bye bye. I used the KSA992 there. Based on Sansui posts the CDC flying saucers apparently not well regarded they too were replaced. At that point and recapping I could notice the white noise from the 2SC693Fs in the tone controls. That was an adventure that taught me a lot. Some units when thinking back about them, the Beatles' "The Long and Winding Road" should be the soundtrack.
Will have to find out with mine how stable/durable a 3000A is. When I checked the bias after running it a few months both were up to around 300 mV. But I also don't have a lot of confidence in the single turn trimmers I used - too touchy setting the DC. I have some multi-turns in my Mouser order figuring that would make bias adjustment more precise and hopefully more stable. Even overhauled, it may be one that needs periodic checking to be sure it is not going sideways. Only time will tell.
Reproduction Sanken TO-3s from Hong Kong? Ebay? The old JVC units have an interesting look but not very common. They used green for the dials like Sansui did. Was not familiar with that vintage JVC until this thread last fall. I think of the black digital types Circuit City was pushing in the early to mid 80s.
https://audiokarma.org/forums/index.php?threads/help-me-figure-out-which-receiver-i-had.840857/
For replacement TO-3s these are often recommended in this site and the units I have used them with sound very good (CR-800, 2000A, 3000A), the On Semiconductor MJ21193 (PNP) and MJ21194 (NPN) complementary pair. Available at Mouser or Digikey unless they run out of stock. I thought the only new TO-3 types were being made by On at the plant in Mexico. Listed as TO-204 but fits in the old sockets.
birchoak
Hi-Fi Nut
dly, I did a Google search for those Sankens and ended up at a site called UT Source, if memory serves. It seemed sketchy but I rolled the dice and they're working well so far. The JVC 5010, especially, is a wonderful little receiver--there's almost nothing inside it! I honestly don't know how it puts out the sound it does. Extremely simple, clean design and that S.E.A. equalizer is fantastic--not a gimmick, not a toy. It's like having five tone controls instead of two. I don't know if you're familiar with the site select45rpm.com but the guy has written more stuff about more receivers than anyone else on the planet. He turned me on to the old JVCs, the CR-800, the Panasonic SA-5800, and the Hitachi SR-1100. I trust his judgment; he hasn't steered me wrong on anything.
kevzep
Its all about the Music
I have a JVC 4VR5446, great little quadraphonic receiver, JVC (Japanese Victor Corporation) made some really nice gear...
dly66
Addicted Member
I get the impression the old JVC stuff was good. Flies under the radar, not very common, they seem to historically love having equalizers in their models. In my past watching on CL etc I am not sure I ever saw an old green dial analog JVC pop up down here. A number of less common brands and models popped up but my first exposure to the look of the old JVC models was with that thread last fall. I had a JVC CD player I bought back in 1990 had it for a long time. Not a top tier brand, but solid durable products so could be good buys for the money. I checked out and adjusted the bias a few years ago on a 1986 vintage RX-9VBK for someone I know that sold on Ebay. He was bothered by a hot spot, I checked it and the bias on that channel was a bit high. Adjusting it to spec cooled it down. This for a digital Super-A series that had a reputation for running hot so cool was relative. At nearly 30 years old everything was still working properly.
I have looked at select45rpm for several years as a reference. I think I mentioned their site several times in the past, they really liked the 3000A. I check their view on a particular model I am interested in if its there. Apparently they finally worked on their S-7200 putting new caps in it last year, in late fall the not so kind review that had been there for years got replaced by a positive one. Also good for info on which designs are similar inside, and if one manufacturer had apparently lifted part of someone else's design.
I have looked at select45rpm for several years as a reference. I think I mentioned their site several times in the past, they really liked the 3000A. I check their view on a particular model I am interested in if its there. Apparently they finally worked on their S-7200 putting new caps in it last year, in late fall the not so kind review that had been there for years got replaced by a positive one. Also good for info on which designs are similar inside, and if one manufacturer had apparently lifted part of someone else's design.
So far on my 3000A I have rebuilt the entire power supply section, Driver Amp TRD and Pre-power TRZ boards. I installed Bourns 22 turn trimmers for the bias adjusters, hung them on the heatsinks. I also built and installed the Guardian speaker protection board that I mentioned earlier in this thread. So with the unit put back to OEM, ie no service bulletin items, I was able to bias it fairly easily. Currently 75ish mA of bias current and under 20mV of offset at speaker terminals (using a load).
birchoak
Hi-Fi Nut
Wow! Nice work my man! I have no desire to keep checking the DC offset on a receiver, no matter how good it sounds (ok, if it sounded unbelievably good, maybe), and that protection board seems like a no-brainer.
birchoak
Hi-Fi Nut
I am listening to Damn the Torpedoes with the JVC VR-5551, through Wharfedale Dentons, and this is the absolute best these speakers have ever sounded. This is where the old JVCs with their S.E.A. sections really shine: tailoring the signal to "fit" a particular pair of speakers. I can't stress enough how well the SEA (Sound Effect Amplifier) works on these things. Forget all your experiences with cheesy graphic equalizers; cheap this ain't and it's as effective as a nun with a ruler. No kidding. The power this thing is pushing through those poor Dentons is a thing to behold; I feel like Petty and his band is playing on my desk (to be fair, the speakers are on my desk. And I'm sitting at the desk. So stereo imaging, staging, whatever the hell you wanna call it--is extraordinary.)
This is the receiver I replaced virtually everything on: caps, trimmers, output Sankens. FM isn't so great and probably never was, from the factory. I don't care--that's what the Sony 550ES tuner is for. But man, what an amp, and they sell for peanuts because....wait for it....it's not a Marantz, Pioneer, or Sansui. This is where the collective ignorance of the masses works in my favor. I have no problem rolling the dice on "lesser" pieces and quite frankly, the more a thing is hyped, the less I tend to want it (marital relations excepted).
The little JVC 5010, the tiny Sherwood S-7100A, the "low-powered" Concept 2.0, the Sansui 800---these are receivers I will never sell because they are so damned fun and hit so far above their weight class. Ditto for speakers: the Paradigm Titans were phenomenal speakers, period. Forget how cheap they were to buy and their cave-man build. They sounded incredible for their size. Totem Acoustic Dreamcatchers: oh man, if you get a chance to hear a pair of these....well, you'll never forget them. Unreal sound. Not for melting your face, with 4" woofers, but perhaps the sweetest sounding speakers I've ever heard in my life. Mirage M90i speakers: look like absolute crap, cheap as hell cabinets, play like nobody's business. Unreal bass from such tiny woofers/cabinets, and I mean I can set them up on top of a set of "full-size" 3-way speakers with 10" woofers and you'd swear it was the big speakers playing. The cabinet baffles were loose and making the speakers sound like they were blown. Enter hot glue and sheet rock screws (I plan to build new cabinets for them--this was just a test to confirm my hypothesis): speakers sounded perfect after that.
Wow, I went on quite the hi-fi tirade/digression there! But you get it.
birchoak
Hi-Fi Nut
I think select45rpm is just one guy. He says "We like the Sansui .... blah blah" but reading in between the lines I doubt there's anyone else. I'd love to meet him, but I don't know how that would go. I can't find any actual info on him, like his name, so I imagine he values his privacy and I totally get that. But man, my hat is off to him for sharing so much incredible information; he is, without a doubt, a genius in not only vintage hi-fi but also the actual product all this hi-fi was designed to deliver: music. I cannot think of any other site on the www that contains so much specific information about so many amps/receivers (except for AK, of course).
My thinking is (right or wrong, I don't know yet) these 3000A's worked good for the first 2-3 years then the problems started due to the bias diode manufacturing defects. So......with those diodes replaced and new bias pots installed along with a standard restoration, the 3000A's should run perfectly fine for years. Granted, being an early SS design, it does have some design issues relating to the bias circuit.
Watthour has run (see post 133) his restored 3000A for 6 years so far! He installed the output cap's per the service bulletin, but that doesn't prevent the unit from faulting, it just protects the speakers if the unit does fault. I've removed the service bulletin items and put the unit back to original design AND installed a speaker protection circuit. Based upon my reading of the 3000A, I wanted to restore it to OEM design but still protect my speakers, just in case.
I recently bought another 3000A off the bay for $85 shipped. Perfect chassis, like new. Very nice faceplate. This will be the one I keep. The plan is to finish up on the current unit, then restore this newest one, which will get the existing speaker protection board. The other will be reverted back to the service bulletin caps/items, to be sold eventually. But I am curious as to any sonic differences between the two. I may be throwing away money/time, not sure yet.
Also: I want to state again that I am following the lead of "fandersen" who I talk about in post #103 above. He gets the credit for my 3000A direction.
Jef
birchoak
Hi-Fi Nut
Never a waste of time/money, in the big picture. Look at all the bad things we don't do when we're restoring vintage hi-fi: we're not smoking, we're not getting drunk, we're not staring at the t.v., we're not high or surfing for kitty videos. We're not pouring money into a boat that gets used a few times a year or a second home. We're using our brains and our hands in an attempt to breathe life into electronic gems from yesteryear.
So, what does the 3000A sound like, anyway? It must be damned good if you all are sweating over them! Is the bass super rich and deep? I know the damping factor is 15, which lets the woofers swing like a pair of preschoolers the day after Halloween, and of course the thing is overbuilt and has transformers in the signal path (?). After floundering with this one, I'd be willing to pay a few bucks for one that's working well
Just not right now. I'm taking a break and enjoying the restorations that were successful.Jeez, the 3000As are cheap enough that you could have a whole nest of them, tweaking this one a certain way and that one a different way and compare the results.
My 3000A hasn't ever been in my house yet! It sits in the garage being experimented on, playing into some KLH-5's.
It sounded special the first time I heard it and the acoustics in the garage suck. fandersen, who I mention in post 137, says the midrange frequencies and in particular female vocals will just blow you away. Someone else said is is so smooth with fantastic separation and dynamics. Others have warned that the bass will go very low.
So I can't really give you a good answer yet except that I really like the unit. Build quality, layout, ease of working on and it's sound..............
Jef
birchoak
Hi-Fi Nut
So, tube-like.