Hammond B250
These are a few photos of my Hammond B250. Took them in here for sentimental reasons, although the quality is poor due to the Philips Vesta PCV680 webcam that I had to use for shooting.
Update (January 24, 2007)
Today Arnt asked for the volume pedal wiring and connector pinout. See the photos below for help and illustration.
Update (October 14, 2007)
See also Hammond B250 repair and cap replacement.
Update (June 6, 2009)
This is in answer to John’s question.
Update (Jul 20, 2022):
Because of request here is the service manual of the Hammond B250. I have taken pains. :-) Drop me a line if something should be illegible.
Hammond B250 service manual (~30 MB)
Hey,
I am about to buy this organ. What do you think about this organ. What do you thing is „good“ price for it.
Thanks.
Tom
Hi Tom,
as for me, I pretty much like the B250 and probably wouldn’t even sell it if I owned „the real thing“. Ok, this is a japanese Nihon-Hammond model and it is driven by custom LSI ICs instead of wheels or tubes, but nevertheless it is clearly one of the better sounding clones available – just play it over a Leslie speaker and it comes to life. If you want „hammondish“ organ sound with 2×61 keys and pedal and yet portable then go for it. A good price would be 300 Euro (good condition), I once paid 750 Euro (mint condition).
Kind regards,
Hajo
Hi folk
I’m very happy to find that, at least, two persons know this organ !
I’d like to buy a B 250 for my daughter.
Can I hope ?
kind regards
Good to se other people with the same organ:) My B-250 was the first instrument I bought, and thats where I spent the money-presents for my confirmation. My volume-pedal is broken, some of the cables are loose, and I don’t know where to place which cables. Does anyone of you have any schematics on that, or a photo of the cabels in the pedal-plug?
Arnt in Norway
I had a B250 that I used to gig around London in blues bands. They’re decidely unfashionable but I loved mine, I only sold it to raise cash for my A100. Lovely to see some pics again!
I’m running an old (and slightly battered) 250, which works quite well, and I love it. It’ll soon be going through a Leslie 825.
:p
Two questions…
1) What its the jack output „STA OUT“ for.
2) I have a problem with the ‚Key Click‘ which makes a grizzly ‚interference‘ noise – a high frequency crackle‘ – which pulsates at about 100-102 Hz. The percussive harmonics are a bit distorted too. Anybody had this and know of a fix ?
Hopefully,
Grady
Hi Grady,
„STA OUT“ is the output of the stationary signal, analogous to „ROT OUT“ for the rotary signal and „MIX OUT“ for all (mixed) signals. As for the key click noise, I didn’t have this problem yet. Drop me a line if I you need an excerpt scan of the schematic for this section (I won’t scan it completely).
Regards,
Hajo
Hi,
I will buy a Hammond B250, but he want 400,- euro for it.
Is that a good price?
Regards
Sven
Hi Sven,
it is a good price, imo. When I wrote about 300 Euro (good condition) sometimes in 2006 -see my post above- it was not a reasonable estimation. A few months ago, another B250 owner called me and told that he had payed 1.500 euros for his B250 in mint condition; well, we both agreed, that this is indeed a bit over-priced, but from today’s perspective, anything up to 1.000 euros -depending on the condition- wouldn’t cause me headaches.
Regards,
Hajo
hey, love your page.
I have a big problem and need your help.
I have a B-250 as well but lost my expressionpedal.
Can you support me to build a new one?
PLEASE reply
Hi John,
unless you want to control and use the internal Warmth circuit, you may as well use any other external swell pedal (i.e. Boss FV-50L, Yamaha FC 9) plugged behind the audio output. If you prefer a rebuild, I may help you with an excerpt of the B250’s circuit diagram or possible circuits, depending on your electronics know-how. Did you already chose a pedal type you’d preferably want to use?
Regards,
Hajo
ok my actual compromise is a standard volumepadel with phone jacks. I plugged it to the „SEND – RETURN“ jacks on the organ. the compromise is that this only works for the upper manual, so the lower stays untouched. the option to plugg it behind the audio output doesnt work because the organ is connected with an 11pol cable to a leslie 815.
maybe u have an idea how to connect it for both manuals.
It would be interesting to rebuilt the original Pedal. Im a student in electronic engineering so the curcuits should be no problem for me.
Thank u so much for your help.
Hi John,
option #1: insert a passive pedal in your 11pin cable to the leslie 815, either by soldering on the existing 11pin connector or -much more expensive- by ordering two addional 11pin connectors from Hammond and then fabricate some kind of breakout box.
option #2: I’ve added the necessary information to the post for you to rebuild the pedal, see „Update (June 6, 2009)“.
The schematic excerpt on the left shows the assignment of the 8-pin DIN volume pedal connector „Jack 1“ inside the B250 and how the voltage returned from the pedal on pin 3 runs on an op-amp stage (IC1) to then supply a volume control voltage for the output stages.
The appropriate schematic of the volume pedal is not available, but only an image of the board layout (component values added in blue letters). The additional LDR, which is lit by a small bulb, is connected to pin 5 & 6 of the PCB.
If rebuilding the optoelectronic part of the pedal is too complicated, have a look at the voltage divider R1/R2 on the schematic excerpt: you may passively control the volume with just an additional potentiometer connected to pin3 and pin 7 of „Jack 1“ (in parallel to R2). Possible value is 47k or the like.
Hope this helps.
Hiya-
I have a B-250 that I’m running through a Leslie 315. To be honest I don’t know a lot about the technical side but hell I love this instrument as far as looking and sounding great on stage gigging. This and a fender rhodes along side is my definition of heaven… Anyway- the only thing I find with it is that while switching on the percussion does have an effect it isn’t strong and certainly doesn’t have that real chunky ‚toc‘ sound that you get with the B-3’s. How do you find yours? Is it likely normal or do I need to get mine looked at?
Thoughts appreciated
Glenn
Hi Glenn,
sorry for the delay. The percussion on my B250 is exactly as you describe it, no strong effect and not that real ‚toc‘ sound. I may provide one or two sound files if this answer does not satisfy you. Still I would recommend to have your B250 serviced ASAP, it may be damaged by bad capacitors in the near future, see this article for reference.
Regards,
Hajo
Cheers Hajo- much appreciated
Hai i just bought a b250 do you have an manual ??
Regards Paul
Hi Paul,
sorry: I do not have the manual. Congratulations on your purchase, and have fun!
Regards,
Hajo
Great site on the B-250. I was recently given a B-250 in mint condition from a friend who wanted to use the space in his rec room for something else! It came with a Leslie 310, both in great shape. As I have several other keyboards, including a new Nord C2, I’m thinking about putting it up for sale. There seems to be a number of people interested in this model, so if anyone is interested send me a reply. Willing to let it go at a bargain – the problem may be I’m located on the east coast of Canada.
BTW – great information on the organ – helped a lot when I first set it up.
Hello Hajo :)
i greatly appreciate what your doing here, because its out of pure love and i just wanna send that right back to you and say thank you :)
I got this model not too long ago and i absolutely love it, probably one of the best clones. The problem is that it didnt come with a volume pedal, and recently ive realized volume control is necissary for true expression and magnum opus type epicness. I was wondering if these pedals, are still being sold or what what other pedals could also work with (and through which inputs they would be put through)?
Hi Jeff,
please see my updates on this article and especially this thread for a reference. Feel free to ask again.
All the best,
Hajo
Hi there Hajo
I’ve just got a B250. It’s a bit of a basket case (the seller was going to give it to me but I bunged him £20). The top manual is fine apart from the top G not sounding. The lower manual has quite a few keys not sounding, some sounding the wrong note, a missing key and even notes making a noise sometimes when no-one is near it!
Despite all that, I’m really enjoying playing it. I fully intend to gig it, even if I can only really use the upper manual.
Do you think there’s anything that can sensibly be done to get the lower manual more or less sorted? I took the back off and couldn’t see what I could possibly do.
Any help much appreciated.
Derek
…and while I’m picking your brain, do you know what size the bolts are that fit the organ to the stand? Unfortunately they’re not the same size as the ones that fit the cross brace (which I have).
Many thanks.
Derek
Hi Derek,
the bolts are 9.85 x 43 millimeters in size (M12 winding), apart from the twist knob.
Regards,
Hajo
Hi Derek,
great to hear from another happy B250 owner. I would highly recommend to check and (when indicated) replace the approx. 100 electrolytic capacitors which are spread all over the circuit boards of your organ (see this article for reference). Sorry for this kind of inconvenient answer that you will most likely not want to hear, but I would honestly not start to look after the missing keys or strange noises until this has been done. Feel free to ask for help or excerpts of the schematics when needed.
Good luck and all the best,
Hajo
Hajo
Many thanks. I posted a reply earlier but it doesn’t seem to have gone.
I played the B250 at a rock jam last night and had suitably admiring remarks from all. That’s just confirmed to me that I need to get this baby up and running!
I didn’t follow the bolt size. If it’s M12 it’s 12mm across, no? I assume the bolt is 4.3mm long but what does 9.85 relate to?
As far as the capacitors are concerned, yes, I can’t say I’m looking forward to that job. But if it needs to be done…How will I identify the caps? (Like miniature water towers, perhaps?) And can I use an ordinary multimeter to test them?
Once again, thanks for all the help.
Derek
Hi Derek,
the bolt size is 9.85mm in diameter and 43mm in length. 9.85mm is the diameter of the so-called outside thread of an M12 screw.
Indeed the capacitors look like „water towers“ :-), and on my B250 almost each of them had begun to leak (see this photo). This does not necessarily have to apply to your B250, but I would assume that it almost certainly will — better make sure before doing any work (visible inspection should suffice)! Please be aware that the replacement job requires advanced soldering skills and will take you many hours of time and concentration. However, the B250 is a great sounding organ and worth the effort. I would recommend to visit the „bad caps“ website and read the „Recapping Tutorials“.
Let me know how things go.
All the best,
Hajo
Many thanks for that. I’m not sure that advanced soldering skills are on my CV. If it involves anything more than hacking off the ones that the multimeter indicates are useless and putting new ones on, that’ll be beyond me. Incidentally, the jam night I referred to has been put on youtube. and you can see yours truly (briefly) on the B250 here [edit: link removed by Hajo].
Hi Derek,
great to see you on video! And OK, this „major operation“ is a bit more than just „hacking caps off“, and if you do not feel confident of it then you should better not start or maybe ask somebody else (a technician) for assistance. Anyway, feel free to ask for my advice in the future.
All the best,
Hajo
Progress! I got inside the beast tonight (didn’t realise there was a three tier hinge thing going on there). As you will know, there are 3 PCBs hanging off the back of each of the manuals, each covering a different section of keys. By taking off the connectors for each and cleaning them I managed to get some of the keys back to life, and in particular the top G on the upper manual, which was the only one on that manual that didn’t work. The lower manual is a bit more of a challenge. There are a few notes that won’t work at all and I doubt they ever will. I’m not too bothered about that but one thing that perhaps you can help with is this. ALL of the C notes on the lower manual make the same strange noise. Is there a particular PCB or part of one that just produces the C for that manual (the upper one is fine)? If so it might be possible for me to concentrate on that area and maybe get it working. (Alternatively I may just wire the lower manual to the upper for the Cs. Not quite sure how I’d do that…)
Once again, many thanks for any assistance.
Derek
..and there’s more. I got a few notes working with kitchen foil and toothpicks. I also patched some of the notes from the bottom manual to the top (so they call off the notes from that manual instead). As a result, it’s more or less working. I’d still like to know if there’s a way of getting the Cs to work (I’ve patched 2 across but couldn’t be bothered to do them all) but otherwise (and particularly since the upper manual is now fully working) it’s giggable. Now all I need to do is find a Deep Purple/ELP/Genesis tribute band….
Hi Derek,
good work so far! Did you observe the electrolytic capacitors by the way? As for the ‚C‘ notes on the lower manual: They all come from IC4 on board DV-13 (see it on this photo and btw the bloated cap next to it on the left). For a test, you may swap IC4 with either IC1, IC2 or IC3 and see wether the Cs will be OK then and other notes do produce this strange noise. If yes, then you will know the type of replacement part required. On my B250 all of these special „custom 440 LSI“ ICs are sitting in a socket; either use an extraction tool or just a small screwdriver to carefully pull them out (not bending the pins); note the orienation of the ICs on re-insertion!
Hope this helps,
Hajo
Hajo
You’re a star! Many thanks for that.
Just one thing. The terminals on the IC have separate connections for each C. It occurs to me that it would be quite a coincidence if all of them (but none of the others) were affected. Looking at the photo, it seems there’s a resistor just to the left of the IC that is marked C. Do you know if that governs all the C notes in the lower manual? If so, I’d have thought it a reasonable bet that that was the culprit.
Again, many thanks for your assistance.
Derek
Hi Derek,
in fact, the apparent resistor is just a wire strap; it is hidden by the capacitor. I was also unsure but just verified it from the service manual. The coincidence is not that implausible, as the frequency divider circuitry within the 440 LSI could be damaged, which may then affect all of the C notes. Give it a try, swap two of those and keep me updated.
All the best,
Hajo
Ok. I’ll give it a go at the weekend. Are these ICs available to buy?
Well I took the ic out but that only seemed to affect the upper manual. Also I had a real struggle to get it back in. I think my efforts to rectify the organ are at an end. Sine the upper manual is ok that’s the main thing. I’ll put up with the odd missing note on the lower and maybe keep an eye out for another B250 on eBay.
Once again, many thanks for your help and the best of luck with your site.
Derek
Hajo – I have a B250 running into a Motion Sound which I adore… My swell pedal just broke…when I plug it in there is a terrible noise! I am a musician not a techie, and I am afraid I just don’t understand „any other external swell pedal (i.e. Boss FV-50L, Yamaha FC 9)(I understand that, of course) – plugged behind the audio output“ – what does that mean? I take my lead out of the „Aux“ into my amp…so I can put a lead from there into this type of pedal and another out of it into the amp? Also, would any competent electronics person be able to identify the part that has broken with a multimeter, and are parts easy to find? On your June 2009 advice you talk about a „schematic“ being to the left of the post, but I can’t see it.. Any help gratefully received… Great site btw – I was thinking I was all alone in the world!
Sorry for being slow – I’ve just found the schematics… apart from that question other answers still appreciated! Thanks for everything. Bill.
Hi again, Hajo – look, I must seem really dumb re the swell pedal – that’s because the swell pedal I have for my Nord just plugs in to the back of the keyboard and has no other inputs, I see that the swell pedal you suggest can be plugged inline, which answers that question… Sorry… Still interested re my Hammond pedal – so my question now is – will any competent electronics guy or gal be able to diagnose the problem on my pedal and fix it with standard parts?? Thanks for that, sorry again for time-wasting questions re in-line pedal.
Hi Bill,
great to hear from yet another happy B250 owner! You are not alone in the world. ;-)
The original volume pedal circuitry consists of just a few parts, and they are all standard; no rocket science. Check the wiring first. From your description, I would suppose IC1 (TL081 op-amp) to be bad. You should also check and maybe replace the capacitors C1 and C2 while you are at it. The parts are easy to get and cost just a few cents each. Let me know how things go!
All the best,
Hajo
Fantastic, Hajo. Looking at the details you have provided, there aren’t that many parts to go wrong! Now I need to ask around at work – maybe one of the physics shop guys can help… Somehow my B250 got to London, England… Who knows what road it travelled down… I got it secondhand (of course) for the equivalent of $400 – worth every penny. It works absolutely fine – maybe someone had put new capacitors in before I bought it… One point I am interested in – the „keyclick“ and 2nd and 3rd percussion buttons don’t have any discernable effect – is that typical? Also, the „warmth“ which you describe as overdrive has very little effect, to be frank – is that typical too?
Hi Bill,
as for the percussion, see this thread. Both the „warmth“ effect and key click became stronger or rather recovered on my B250 after the cap replacement. The key click is however not that strong as one may know this from other organs, but it is surely discernable. So, yes, to some extent it is typical.
All the best,
Hajo
Hi Hajo – your circuit diagrams for the pedal etc were just what the doctor ordered! Our techie was able to re-connect, basically some of the wires had become detached from the plug possibly because the other end of the wire wasn’t securely anchored within the pedal. All the parts were fine. She said it was clear that the same job had been done a couple of times at least before it came into my possession. Thanks again, I am pedalling away which really adds to the control of the beast! Keep up the good work – you’ve saved me from buying a new pedal and, more importantly, kept it all authentic! Buy yourself a drink from me!
Hi Bill,
thank you for your kind feedback and the drink (I took it yesterday). „Always check the obvious first!“ is the motto ;-)
All the best,
Hajo