bose 901 series iv equalizer service manual

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bose 901 series iv equalizer service manualConsumer Electronics, If you follow any of those links and end up acquiring a manual, it will not be from us. Here is why we may deserve your business. We love our Vintage Audio and other built-to-last electronics equipment in an age of disposable products for a throw-away society. We might sell the kids before our classic silver Pioneer or Vintage Marantz, Kenwood and Sansui gear. If you also value High Quality Manuals that enhance the ownership satisfaction of your vintage audio treasures, you found the right place. (continued below.) It IS Our Guiding Principle Add Site to your Favorites Other sites we host: Phase Linear History Vintage Technics Database We sponsor two free Yahoo Audio Groups We are meticulous and give genuine best efforts to produce clean, well-constructed manuals for you. A side-by-side comparison of our reproduction manuals with those from many other vendors will usually reveal an overall better appearance, construction, and print quality. Sometimes strikingly so. Our Customer Comments page is a fraction of what we receive from real customers and electronics technicians. The vast majority of our printed reproduction manuals are Very Good to Excellent on our Guaranteed Quality Ratings scale. But every single item is not and we refuse to give a false impression that they are. We want you to see a detailed description and individually-assigned quality rating before you purchase. This time-consuming extra service is almost never provided by our competitors. Customer complaints are nearly zero, perhaps one per 500-1000 sales. We believe that virtually none of our competitors could truthfully make a similar claim. We are a USA based family business operating old-school style. That means real people trying to serve you as if we were a walk-in store in your local neighborhood. We always combine shipping on multiple-item orders and do not rip you off on shipping charges.http://www.vds-construct.pl/userfiles/bosch-maxx-wfl-2062-manual.xml

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If interested, check out About Our Manuals and other site sections with the menu links at the top of all pages. If you would like for us to be here in the future, you can help by telling your friends and by sharing links to our site in your discussion groups, forums, blogs and web sites.We have been slowly updating these manuals lists over the years. As time allows we will replace the spare Factory ORIGINAL Manuals Catalog section with the same page format as these here in the reproduction manuals section. We also have more than 400 Gigabytes of various manuals, schematics, brochures, etc in (mostly) PDF format. They number perhaps 400,000 files. Truth is that we may never get them listed on our site. But they are available. Click here for further PDF manuals informatiion. If an item has a description and Price Code, then CLICK THAT PRICE PRECISELY identify the item you want with company brand. If you want multiple Whether your email is to order Tell us EXACTLY You may findIndividually-assigned Overall quality is Normally folded Normally folded and mailed in ordinary business Includes equalizer voltage conversion instructions Overall quality is Very Good to Excellent. Overall quality is Very Good. Models covered: 901 Series IV. Overall quality is Very Good to Excellent. Overall quality is Very Good to Excellent. Supplement If an item has a description and Price Code, then CLICK THAT PRICE PRECISELY identify the item you want with company brand. If you want multiple Whether your email is to order Tell us EXACTLY You may findIndividually-assigned It makes a difference. Seekers of truth mayImages may be used with. Scored a pair of series 3.I refoamed all 18 drivers bought a EQ on eBay sent it in for re-cap and upgrade then hooked them up to Pioneer SX 1250.Ha ha heaven. Reviewed Nov 21st, 2018 by Artfrobadoo My buddy has a pair of supposedly original 901s which I have suspicions of being fakes. The wood does not match. There is no labeling. The terminals are crude.http://tunisie.mawarids.org/mpfiles/bosch-maxx-wfl-2260-service-manual.xml He thinks they are the cats meow. So I searched craigslist and I found a pair of 901s for 200 dollars. Then the guy throws in a beautiful working Kenwood KA 7300 amp. I like my Bose 301's better then these 901 VI. Perhaps it's the amp I have the associated speakers to what. Reviewed Nov 02nd, 2018 by OzDaddyBear I have 901 series VI and there i a plug between left and right termina, there is nothing in the manual to advise what this is fot. Any ideas?l Reviewed Jun 12th, 2018 by Mrsteve I have owned two pair of these. The first pair a series IV, the Second pair a Series VI. I took advantage of the Bose Trade-in program some years ago when they still offered it. There are several companies that offer the drivers, and replacing them for both pair is around 560.00-Plus the time involved.I need to do a repair on the equalizer. I cannot find the Series III Service Manual. Thanks To be use for PA system or Karaoke. Any suggestion for an appropriate mixer. I'm looking for resources to help me troubleshoot and repair the equalizer. I don't have much experience, but I would like to learn, and this seems like a fun project. If anyone is willing to help break things down as simple as is convenient, or could help guide me in this process, I would be very grateful. We all have to start somewhere. I refurbished the speakers myself, and would like to say I did the same to the equalizer. Due to purchasing from a second hand store and not really knowing enough about them I consequently now own two right hand speakers. Not sure how this will affect the speakers. While it might well be quite possible to fix, I would be more interested in feeding the speakers from another signal source. The cable from the preamp connects to the speakers via a five-pin 180 degrees DIN plug, and so I think it should be quite possible to connect to some other signal source, the same way I have used a pair of Philips MFB speakers. Am I right or am I right.http://www.raumboerse-luzern.ch/mieten/bosch-tankless-manual Anyone have any experience of the 901p active speakers. Or of other Bose Lifestyle 20 substitutes for them? No need to attend a live concert anymore. With Two Pair in the proper positions you've got your own live performance! To purchase 901 spares or accessories, please contact the company via their website or visit an authorised retailer. The Series IV was sold from 1978-1983 and its construction reflects this. The standard service for the Bose 901 Series IV Active Equalizer includes replacing the electrolytic capacitors and op-amp chips by default for best performance.In this case they’re LF353N op-amps; Bose used the LF335N, TL072, or 4458 op-amps interchangeably and the schematic and service manual allow for any of those chips.Every single one of the originals had high ESR and was changing in value. It’s measuring only 157 pF, nearly open. The curve came out textbook. The left channel on mine no longer works and I am trying to trouble shoot.I'm also 901 owner. and listener The problem I met was at the first place, the EQ. It's s-IV. They are designed long time ago, before CD and DVD players. And as we know, their output signal is about 2V. EQ s-IV and earlier are designed for tape deck, tuner and turntable signals, which is about 0.5V. The higher signal levels overload the EQ and begin distortions. That's why, if you use players without regulated outputs, or if your receiver or preamp inputs are not attenuated, you'll have problems with the quality of the sound.But you know this very well Lately I use mine with The Bose Spatial Receiver. And even with this old vintage, with dry old capacitors and mash of switches and wires inside, I think, they sound well. And my advice is - don't try to use them without the right EQ. It's waste of time.http://www.fiskene.com/images/bose-901-series-iv-manual.pdfBtw I think the 901's mid-century modern styling still looks cool, especially the black version and especially when the Bose pedestals are used with them (they were used this way in a cellphone commercial about four years ago, located in a swanky, light-colored modern apartment).OTOH, currently an old vintage speaker as the early series of 901 is much harder to beat than in those days, because the tendency of the sonic quality from today's commercial speakers have become significantly worse, even in the upper price class. Keep this always in mind. I am looking for a diy project with cheap but good quality full range transducers with the same design goals than by the 901, but higher quality.As I recall, they did sound amazing for their size.But for sure, it's not about the price, and for sure results are good By the way, I listen and a pair of 601s s-1, but they are fare from 901s, by my own Resources saved on this page: MySQL 15.79 vBulletin Optimisation provided by. Favor de enviarme manual para conection a mis 901 SPEAKER BOSE.If not Can I use a shelf that is 18 inches distance from the floor. Thanks in advance for your answer You could, but the boundary effect of the speaker being. The sound that comes from the speakers is muffled and crackles loudly. Is this what they sound like when the speaker is toast or is the a fix for this issue. Yes, if you hear I hadn't used them in about a year.the gentlemen that purchased them told me that when he used them he got a crackling. Any Ideas on best possible way The Bose EQ connects to the tape out and tape in on the amplifier or reciever. If. Search Fixya for the dozens of times I have answered this type of question.Bose 901 are speakers. Here is a video to show how a Bose CD tray was repair ed. It might help. Something went wrong. View cart for details. All Rights Reserved. User Agreement, Privacy, Cookies and AdChoice Norton Secured - powered by Verisign. Something went wrong.www.hptindia.com/wp-content/plugins/formcraft/file-upload/server/content/files/1626bcca19f692---case-580c-manual-download.pdfLearn more - opens in a new window or tab This amount is subject to change until you make payment. For additional information, see the Global Shipping Program terms and conditions - opens in a new window or tab This amount is subject to change until you make payment. If you reside in an EU member state besides UK, import VAT on this purchase is not recoverable. For additional information, see the Global Shipping Program terms and conditions - opens in a new window or tab Delivery times may vary, especially during peak periods. Learn more - opens in a new window or tab Learn more - opens in a new window or tab Learn more - opens in a new window or tab Learn more - opens in a new window or tab Learn more - opens in a new window or tab Contact the seller - opens in a new window or tab and request a postage method to your location. Please enter a valid postcode. Please enter a number less than or equal to 34. If you don't follow our item condition policy for returns, you may not receive a full refund. Refunds by law: In Australia, consumers have a legal right to obtain a refund from a business if the goods purchased are faulty, not fit for purpose or don't match the seller's description. More information at returns. My listing includes insured, return shipping only Honest seller. Great communication. He has done great work replacing the capacitors on my Series IV EQ in the past, and is now performing upgrades on this unit's RCA jacks as well as amp and audio sections. If you haven't heard the difference between an aged EQ and one that has been upgraded, I can tell you that there is a substantial difference in the upgraded system's ability to produce rich and detailed sound. In addition to my Series IV 901's with upgraded EQ, I also have a set of new Series VI.2 901's, and, surprisingly, I honestly cannot tell that there is a great deal of difference between the two. I cannot recommend him any more highly. So make the investment; it's way, way worth it! The speakers are 3.75 inches in diameter without a crossover. If you don't use the eq, then you ain't got no highs and you ain't got no lows so it must be Bose. It is totally the fault of low information listeners (some who's confidence level is truly amazing). Bose 901's aren't audiophile speakers and they never intended to be. They are fun, loud, small, dynamic and retro-cool. Buy a set or two of Series I or Series II speakers and get the eq updated. Awesome! The EQ upgrade made a huge difference in sound quality. My son in college loves them and they will rock the house! I was amazed at how good my bose sounded after Dave finished his work. Great job and would highly recommend to anyone to use Dave. He also called and went over everything with me, and that made the process even more special and put me at ease from start to finish. Great job Dave and Thank you With his repairs and upgrades to my equalizer my 901s are alive again. I had bought the speakers and equalizer a few months before, re-foamed all 18 drivers and thought some of them had blown speaker coils, there was a distortion but could not narrow down which drivers. I sent my equalizer to David. The unit was originally setup for 220volts since it was purchase in Germany in 1980. Whom ever tried to change it over to 110volts mess up, the equalizer board was only getting part of the power needed. After David's repairs these old speakers sound band new!!! Through a series of clear, timely emails Dave helped me decide on several upgrades. He then completed the work in a timely manner and when it turned out my speakers needed more work (NOT related his work) he continued his excellent service by advising me how to proceed. All Rights Reserved. User Agreement, Privacy, Cookies and AdChoice Norton Secured - powered by Verisign. Discover everything Scribd has to offer, including books and audiobooks from major publishers. Start Free Trial Cancel anytime.Use only replacement parts that have critical characteristics recommended by the manufacturer. 2. Make leakage current or resistance measurements to determine that exposed parts are acceptably insulated from the supply circuit before returning the unit to the customer. Use the following checks to perform these measurements: A. W ith the unit AC switch first in the ON position, then in the OFF position, measure from a known earth ground (metal water pipe, conduit, etc.) to all exposed metal parts of the unit (antennas, handle bracket, metal cabinet, screw heads, metallic overlays, control shafts, etc.), especially any exposed metal parts that offer an electrical return path to the chassis. Any current measured must not exceed 0.5 milliamp. Reverse the unit power cord plug in the outlet and repeat test.When the exposed metallic part has a return path to the chassis, the reading should be between 1 and 5.2 Megohms. When there is no return path to the chassis, the reading must be “infinite”. If it is not within the limits specified, there is the possibility of a shock hazard, and the unit must be repaired and re- checked before it is returned to the customer. Browse Books Site Directory Site Language: English Change Language English Change Language. It may not display this or other websites correctly. You should upgrade or use an alternative browser. The very first thing I noticed was that the tag next to the power cord says it's rated 210- 250 v, yet has a standard power cord. I opened it up to get a list of caps to replace and not sure how to proceed from here. Any insight or suggestions?Which version EQ is it. If I remember right, there is a resistor for dropping the voltage from 220 to 110. I definitely remember that there is a method for conversion. Do you have the service manual. I have one for my series III. I also changed my neon lamp to a red LED, it won't fail again in my lifetime GlennThere is a wire wound power resistor that needs to be removed to run it on 115v. It's as easy as that. Glenn EDIT: One other tip, wrap the transformer in copper shielding tape as this will reduce the noise these units are known for.I have a series IV and no service manual. I've been scouring the net for one, but haven't found any other than series I or II. I don't see a wirewound anywhere and bought this from a fellow AKer who said that is functional so maybe I won't have any problems. Just being cautious. I'm looking forward to getting this thing up to par and would like some suggestions on caps also. There are only 10 electrolytics on the whole board and only 2 different values.They were super nice, and promptly emailed me the pdf. Worth a try. Glenn EDIT: Probably won't hurt to plug a 220v unit into 115v anyway. It may not function correctly, but I don't think you'll damage anything.Plug it in and see how it does. I'd definitely replace the 8x10 uF and 2x470 uF electrolytic caps at a minimum, though.Does anyone have any suggestions on a specific brand of caps I should use and should I also replace the op amps while I'm in there. One more question for now, does anyone know how the clip that holds the power light works. This one is just hanging in mid air with nowhere to attach it that I can see.I would recommend replacing the op-amps. The original RC4558s seem to go a bit noisy over time. The pin-out is the standard DIP-8 op-amp and nearly any will work fine. Bose specified either RC4558 or TL072 interchangeably in the Series IV. I've also used a TLE2072 and MC33078P, which offer respectively better noise and distortion specs. You can also pick up a TI OPA2604 in a DIP8 package, if you're looking for something a bit more exotic. I have a handful of those lying around I mean to try in the Series IV, I just haven't gotten around to it quite yet. And of course plenty of other audio op-amps out there. There's a red jewel that sticks through the hole from the front of the chassis, and the clip inside pushes over a lip on the jewel. If the jewel is missing, it won't hold in place.There's a guy online that rebuild these Bose EQs, and he says the carbon resistors used don't last well, and weren't that great to begin with. I rebuilt two EQ, a series 1 and a series 2 using all new metal film resistors (plus new caps and transistors), and the things sounded amazing. Details are in the thread below: Please do not hesitate to contact me if you need further assistance. I don't have a schematic though. Lee.There's a guy online that rebuild these Bose EQs, and he says the carbon resistors used don't last well, and weren't that great to begin with. I rebuilt two EQ, a series 1 and a series 2 using all new metal film resistors (plus new caps and transistors), and the things sounded amazing. Details are in the thread below: Please do not hesitate to contact me if you need further assistance. I don't have a schematic though. Lee. Click to expand. I'm hoping Bose will send me a service manual so I can compile a parts list. I hooked this thing up today and it distorts like crazy. I'm guessing a rebuild is in order.There's a guy online that rebuild these Bose EQs, and he says the carbon resistors used don't last well, and weren't that great to begin with. Click to expand. Click to expand. I think I'll see what happens when I change out the caps look into some opamps. I'm thinking I will put sockets in.People have been asking me where I got that board from. Lee.Is there any benefit either way?Bose released a service bulletin saying they're bad and to replace them with TL072 or RC4558s. You can replace all 4 with the same kind and it'll be fine.Early production runs of the 801 and 901 Series IV equalizers used National LF 353 op-amps. It has been shown that some of these components have lead contamination problems and are prone to failure. Typically, they exhibit high noise, although many will fail completely. National has since modified their processes so that this failure mode is no longer prevalent. Additionally, we have changed vendors to Motorola TLO 72 or Raytheon 4558 and 4559. It is suggested that for all equalizer failures that are using the LF 353 IC, that all four IC's be changed for the Motorola or Raytheon IC's mentioned. Click to expand. How do I convert the bulb to an LED. I was thinking that since the jewel is missing an LED conversion would be easier to mount and a better replacement anyway.Huge distortion at any volume. I'm guessing because of the voltage discrepancy. Finally got in contact with Bose. Not sure if I want to keep putting more money into this eq. When all is said and done I would have a couple hundred into a cosmetically challenged unit. Anyone have any suggestions?Click to expand. If it's a 240v transformer, it should be half what it's supposed to be. Either buy a new transformer, or post the voltages here. I have a bunch of transformers (somewhere) that I pull out of old equipment that's beyond economical repair. I'm sure other people on here do that too, maybe one of us has something. Lee.According to the schematic posted here it should be 30v so I am only getting half voltage. I did this from the top of the board so I'll pull the board and see what I get out of the transformer. Please do not offer the downloaded file for sell only use it for personal usage. Looking for other manual? For this no need registration. May be help you to repair. You could suffer a fatal electrical shock. Instead, contact your nearest service center. Note! To open downloaded files you need acrobat reader or similar pdf reader program. In addition, Also some files are djvu so you need djvu viewer to open them. These free programs can be found on this page: needed progs If you use opera you have to disable opera turbo function to download file. If you cannot download this file, try it with CHROME or FIREFOX browser. Basszus vegfoka 2-3mp mulva megfut vagy pozitivba vagy negativba ha nincs a hangszoro rarakva, hangszoroval azonnal letilt, (amikor a kimeneten eljut DC 4V-ig a vedelem lekapcsolja relevel az erositot). Mikor a MUTE hibat kerestem, volt olyan eset is, hogy nem futott meg a kimenet es szolt a basszus rendesen, de ujboli bekapcsolaskor ha nem halkitottam le a potit akkor kikapcsolt a rele, ha lehalkitottam akkor jo lett, de nagyon susogott, arra hasonlitott mint amikor FM radio nincs az allomason, van egy kozos mute tranzisztor az kapcsolja az osszes tobbit, ha azt kiszedtem akkor is megmaradt a susogas, szerintem visszafele jott valamelyik oldalrol ezert szedtem ki mindegyik oldalrol a tranzisztorokat, nem akartam bajlodni vele, hogy honnet jon a susosgas vissza. Mi lehet a gond? Bose Sounddock 1 tapegyseg csati Sziasztok. Egy baratom megkert, hogy talaljak vagy gyartsak egy tapegyseget a Bose dokkolojahoz. Sajnos az eredetiket aranyarban adjak, igy gyartanom kell egyet. Talatam is egy elegans kis 4 pines csatit, de fennakadtam az eredeti csatlakozo labkiosztasan. Talaltam egy rajzot de nem tudom eldonteni, hogy a kabelen levot abrazolja, vagy a dokkoloban levot. Ha valakinek dolga volt ilyennel, es tudna segiteni, kerem ne tartsa vissza magat. Koszonom.. BOSE bekotesi rajz Legyszi legyszi ha valaki tudnasegiteni egy BOSE AMP2440-as erosito bekoteseben,azt nagyon szepen megkoszonem. Ez AUDI A3-asbol van, a steker nincsmeg. Bose Lifestyle CD-20 FLC kijelzo halvany Sziasztok! A fenti keszuleknek halvany a kijelzese. Eleg erdekesen van megoldva a kijelzo tapfesze, sokban fugg a bejovo 12VAC feszultsegtol. Kerdesem az lenne, hogy a futest probaljam emelni, vagy a -24V-ot. A D8-on a 30V is kevesebb, de az AC 4.5V is. Melyik befolyasolja jobban a fenyerot. A futes, vagy a negativ tapfesz? Udv: Jacint Similar manuals: You can write in English language into the forum (not only in Hungarian). I'll break it down the performance of the speaker into a few standard categories and how they perform in comparison to other options out there. After initial placement I never once felt like I needed to move the speakers to get more out of them. Imaging is huge and involved, but it is hard at least in my setup to place or pick out specific elements of the music. There is no denying the 901's ability to make you hear all of the music, but because the image is such a blur I don't seem to notice it as much as directional speakers, it instead you get the feeling of it. In contrast, Linkwitz dipole speakers create a soup of sound spread around the room, where the 901's transform the walls into massive speakers.These are some of the loudest speakers I've used in the 200Hz-10kHz range. Setup outside I was able to blast 112dB of non distorted music out of the back of the speakers measured from 10 feet away. The front was limited to about 98dB, which is still pretty damn loud for outdoors. I can see why there is a version of these speakers for PA use. When you start to get above 95dB the bass response falls off as the little drivers can't play deep bass at high volumes. This can also lead to them falling apart before 95dB on complicated tracks that are also bass heavy. For instance most Chemical brothers tracks are limited to about 85dB just because the full range drivers just can't do everything at once.If you sit and listen critically you will be met with harsh treble and bloated bass. Adjusting the EQ to fix these problems will leave the speakers sounding dull as it turns down all of the treble when the worst problems in the cone breakup range above 5k. Bass response is harder to nail down, it's hard to get away from the muddy bass, and honestly the Bass EQ options seem limited to either bloated bass or no bass.Some simple instrumental tracks sound good, but anything with female vocals or cymbals should be avoided. These speakers can be used in a party scenario, and will impress most drunk people with the quantity of sound they produce.My neighbors had to deal with 95dB sine sweeps for 3 hours straight, and then pink noise for another hour. I think you will find the results are totally worth it though.This the most quiet axis of the speaker, so it's not as important as other measurements, but this is definitely not a good start. We are seeing bass response down into the 30's and a jagged sloping response to the treble and a massive 7kHz peak. The jagged response is probably due to baffle reflections, and comb filtering from the 9 drivers all doing the same thing.It's damn near impossible to make out what is happening here, but generally the response gets much louder as you move around the back of the speaker.On the bottom we have the front power response, this is an average of 0-60 degrees. On the top we are looking at the rear power response, an average from 120-180 degrees. Yes, the rear is about 10dB louder, than the front.It's an average of all of the off axis measurements, or the total power response of the speakers, and it's flat. Normally a power response would be tilted to show a roll off of the treble, but it's hard to say that it's wrong given the strange dispersion pattern. Maybe this was the intended goal of the speaker, or maybe it's just a coincidence.This measurement was taken slightly above the axis of the speaker to better represent the suggested listening height. The red measurement is with the speaker 12 inches from the back wall, and the blue one is 18 inches. These are very similar, with the 12 inch being a little nicer. Also, note that the 7k peak is not hidden by the boundary, rear speaker interaction, or even being off axis vertically.I continued on like this until, finally I ended up cutting everything a little. While it definitely sounds better, the correction is far from perfect due to the inherent irregularity of the speakers response.