bach1010 Posted May 24, 2021 Report Share Posted May 24, 2021 Hi I just received an SB-1010 from one of my friends today and it seems to be built just like an SB-1000 but with shorter scale, but it seems to be missing out some parts. I just started the guitar restoration so I almost knew nothing about what’s wrong with the system that doesn’t make it work I’d be happy if I you could help me out by looking at what’s missing in my board and could bring the bass back in its original conditions. Please send me your email or social account if you agree to help! Thank you! Quote Link to comment Share on other sites More sharing options...
Prostheta Posted May 25, 2021 Author Report Share Posted May 25, 2021 Sure thing. PM me here for my email. The 80s circuit in the SB-1000 (passive/active) is problematic in that it requires dual value pots which are not really available commercially. I've always preferred the 70s active-only circuit. To my ears it sounds better, even though the only real difference is in the varitone filter. Quote Link to comment Share on other sites More sharing options...
Johnas Posted September 3, 2021 Report Share Posted September 3, 2021 On 9/4/2020 at 3:56 PM, Prostheta said: Hey Tony. Sorry, I didn't see this post. Not sure why I didn't get a notification, but there you go. I think you might have emailed me about this problem? I recall having a conversation about creaking coming from the amp when moving the instrument, but I can't remember if we solved it or not. Sorry have just realised that you replied, apparently the pick up has gone microphonic I am in the process on obtaining a replacement from Veijo Rautia , I have a SB elite 1 (1983) passive only and that is going the same way (ie microphonic) my batwing 1980 with Kent Armstrong pick up put in around 2005 is fine thanks Tony Quote Link to comment Share on other sites More sharing options...
Scar Posted March 21, 2022 Report Share Posted March 21, 2022 Prostheta, A guy brought me an SB1000.Cliff Burton model. he asked if I could put a new pickup in it. he brought it to me today, the original pickup has been removed, the hole filled and sanded smooth and the entire bony has been properly re finished. The replacement pickup is the same as original. you can see a shadow line in the reflection for where the pickup was. I need to re-route the pickup hole and I need the depth for it. also, I found the wiring intact with an empty red and grey wire not connected to anything.there is a hole for the LED but I find no connector for it. is this something that you can help me with ? Quote Link to comment Share on other sites More sharing options...
Prostheta Posted March 22, 2022 Author Report Share Posted March 22, 2022 I can. Just heading out to work, but I'll respond fully later today. Quote Link to comment Share on other sites More sharing options...
Prostheta Posted March 22, 2022 Author Report Share Posted March 22, 2022 Okay, let's have a look here. It sounds like the bass is an SB-1000 rather than the "SB Black n' Gold I" which Cliff favoured. The 80s SB-1000 model had the LED, and the pickup was a big dual ceramic mag humbucker. Cliff had a black SB-1000 for a very short period of time, but never got on with it. The weight, weird neck taper and maybe the active circuit in combination with that big humbucker....the SB Black n' Gold I (essentially the same as the Aria Pro II Elite-I and SB-R60) had a pickup more like an AlNiCo P-bass type. I recorded a value of 25mm as the pickup rout depth in my plan, however if you have pickup from Veijo then it might be wise to rout 26-28mm. the pickup is tensioned against foam blocks in the base with machine screws in threaded inserts to adjust height. 25mm might bottom out the pickup as Veijo's can be a mm taller sometimes. Bear in mind when re-routing that the original inserts may still be present. I think these were zinc, so not as problematic as steel but still not something you want to rout into at full bore! The LED circuit was separate from the rest of the preamp circuitry. I'd considered placing that onto the preamps that I make for SB-1000s, however the blinking induces too much noise into the audio via the supply lines. Generally I found that replacing the LED with a low current red LED to indicate battery presence was sufficient, and it's even possible to switch this using the unused fourth pole on the active/passive switch to either indicate "on in active mode", or using a bi-colour LED, when the bass is in active or passive mode. Where is this red/grey wire coming from? Drop a photo and I'll tell you what I see. Quote Link to comment Share on other sites More sharing options...
Scar Posted March 22, 2022 Report Share Posted March 22, 2022 Quote Link to comment Share on other sites More sharing options...
Scar Posted March 22, 2022 Report Share Posted March 22, 2022 Quote Link to comment Share on other sites More sharing options...
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Scar Posted March 22, 2022 Report Share Posted March 22, 2022 Quote Link to comment Share on other sites More sharing options...
Prostheta Posted March 23, 2022 Author Report Share Posted March 23, 2022 Okay! So this one is slightly different. It looks like a SB-1000RI (reissue) which is a modern model, not one of the 70s/80s Matsumoku models. The preamp circuit isn't quite the same as the originals, but in principle it does the same job. This is the schematic you need. It looks like the LED has been cut off for some reason, which corresponds to the red and grey wires. This acts differently to the original "dumb" LED blinker in that I think it blinks when the power is low. This long Mitsubishi SIL chip is a low-power alarm IC for that purpose. When routing for the pickup, bear in mind that if this bass was an SB-CB then the footprint of the original pickup may not match the repro from Veijo. Some of the reissues had weird soapbars instead of original MB-type pickups. If that's the case, I'd go by the new pickup's size adding a mm in size. No more since there is a draft angle on the case moulding that exaggerates perimeter relief after a point. How does that help? Quote Link to comment Share on other sites More sharing options...
Scar Posted March 23, 2022 Report Share Posted March 23, 2022 It does help ! Thank you! I’ll keep you posted. I have a box of LED’s, how do I connect them? is it just a simple matter of connecting them to the red and grey wires or is there a harness of some kind ? Quote Link to comment Share on other sites More sharing options...
Prostheta Posted March 24, 2022 Author Report Share Posted March 24, 2022 I'm unsure of the orientation with that circuit. I presume the current limiting resistor will be on the PCB. Generally I'd locate the resistor, identify the supply voltage behind that and replace it with one suited to whichever LED I selected. Bear with me till this afternoon.... Quote Link to comment Share on other sites More sharing options...
Prostheta Posted March 24, 2022 Author Report Share Posted March 24, 2022 Shot of the preamp circuit.... ....and the obverse.... ....so it looks like the LED is being current limited by R1, however I can't find a photo of that component's value and I haven't traced this circuit out to a schematic (yet). I would suspect that the Mitsubishi SIL IC (N1, Mitsubishi N5232L) is being powered at the full 18v supply, so the LED will be running at I=(Vcc-Vfv)/R; I'd suspect that the resistor colour coding is red-purple-orange (27kOhm) which would make the current something like 6mA or so assuming a 2v forward voltage drop over the LED. Let me know if you can eyeball those values on the component and I'll redo the math. That's about right for a typical "standard" LED but a lot of waste current....a low current red LED consumes something like 1mA-2mA for reasonable brightness and is kinder on the batteries. That would require changing out the resistor though, but that's your call. In principle you should be able to put any standard 5mm through-hole LED there and it'll work. I've never been much of a fan of these "modern" preamps and wiring harnesses as they were made down to a cost rather than up to a standard like the original SB-1000s out of the Matsumoku factory. It isn't to say that it's bad by any means....when up and running this bass will be a beast. It's like comparing engine blocks that came out of a factory during a period that were known to be ultra-reliable and/or tunable....that Japanese SB-1000s were unreal like that. I digress. Hopefully this should get you across the finish line? Quote Link to comment Share on other sites More sharing options...
Scar Posted March 24, 2022 Report Share Posted March 24, 2022 I hope so ! lol thank you so much ! Quote Link to comment Share on other sites More sharing options...
Prostheta Posted March 25, 2022 Author Report Share Posted March 25, 2022 No problem - get back to us with good news! Quote Link to comment Share on other sites More sharing options...
Scar Posted April 2, 2022 Report Share Posted April 2, 2022 Ok i re-routed and installed the pickup. All is well on that side. I connected the wires and they work fine until I flip the mini switch. im only getting a signal in one position. please advise !? Quote Link to comment Share on other sites More sharing options...
Prostheta Posted April 2, 2022 Author Report Share Posted April 2, 2022 Most likely you are only getting a signal in passive mode, which is one of the two positions of that switch. This can be proven by checking for continuity between the pickup signal hot and the central wiper tag of the 500k half (upper, at least in the diagram) of the volume pot. If this is the case, then fault-finding quickly becomes very complex with the active side of the circuit. I'd first trace the signal from the pickup as it comes to the switch pole, out to the relevant line on the preamp board which looks like the far left white wire. That lets you know the preamp is getting signal. Also check that the preamp is getting power, which should be +9v, 0v and -9v over two series PP3 batteries with a central tap being that virtual ground of 0v. Measuring from the union between the two batteries (0v), measure the voltage at the preamp with the long connector. The first one (blue) should be -9v. The third (red) should be +9v. You should also have continuity between the junction and the fifth wire (black) which is the 0v, or "earth" in that diagram. Quote Link to comment Share on other sites More sharing options...
Scar Posted April 15, 2022 Report Share Posted April 15, 2022 An update. I removed the battery box and found that the leads were not connected to anything because someone melted the contacts away from the plastic housing. ordered another, have it on hand now. Seems to me that the battery box should have 3 wires coming off of it. Do I connect the +&- to a ground and attach it to the back of the pot? also, just to confirm, the ground symbols on the diagram should all be connected to the pots per normal wiring correct?( see arrows on attached pic) lastly, the diagram shows a feed coming out of wire 3 slot feeding the tone switch, mine is not. Is this something that needs to be addressed or is it the same as the one in the image you posted? Quote Link to comment Share on other sites More sharing options...
Prostheta Posted April 17, 2022 Author Report Share Posted April 17, 2022 It looks like the black triangle is shorthand for a connection to the fifth point along the connector, at least in the diagram. There are 9+2 wires in total on both the PCB and the diagram, so the virtual earth 0v created by tying the two batteries together looks like it should be going to the black wire, or the sixth location across. Do not tie the virtual earth 0v to ground! This is part of how this differential preamp works....it might still function (I've not thought about this enough yet) however it loses some of the functionality in how it rejects noise. All the ground connections go to the pots, yes, so how you illustrated it in red is spot on. If you get hum that goes away when you touch the hardware, add a ground wire to the bridge. Just keep that 0v isolated from the grounding, since they're not the same thing. Quote Link to comment Share on other sites More sharing options...
Scar Posted June 12, 2022 Report Share Posted June 12, 2022 Quote Link to comment Share on other sites More sharing options...
Scar Posted June 12, 2022 Report Share Posted June 12, 2022 Here are more photos showing how everything went. I found that the original cavity had been filled with Styrofoam (?!) and the threaded inserts were removed so I replaced them with small nuts. the wiring went right together based on your diagram once the faulty battery box was replaced. The led light is held in place with a small amount of hot melt glue and works properly. the finish that the previous owner put on seems to be a bit fragile and chipped at the edges of the route so unfortunately I had to put a ring around the pickup,but that’s a small concession. thank you very much for your input and assistance with this ! Quote Link to comment Share on other sites More sharing options...
Scar Posted June 12, 2022 Report Share Posted June 12, 2022 1 Quote Link to comment Share on other sites More sharing options...
Prostheta Posted June 12, 2022 Author Report Share Posted June 12, 2022 No worries man, great to see the work went as planned. Bummer about the pickup ring, but those polyester finishes chip like hell unless you tape it up, take fractions of a mm at a time till you're through, and even then it still chips when you don't want it to. Quote Link to comment Share on other sites More sharing options...
Apophenia Savant Posted August 24, 2023 Report Share Posted August 24, 2023 On 6/12/2022 at 6:46 AM, Scar said: Here are more photos showing how everything went. I found that the original cavity had been filled with Styrofoam (?!) and the threaded inserts were removed so I replaced them with small nuts. the wiring went right together based on your diagram once the faulty battery box was replaced. The led light is held in place with a small amount of hot melt glue and works properly. the finish that the previous owner put on seems to be a bit fragile and chipped at the edges of the route so unfortunately I had to put a ring around the pickup,but that’s a small concession. thank you very much for your input and assistance with this ! Ah, Styrofoam. My favorite tonewood. Quote Link to comment Share on other sites More sharing options...
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