ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
I hope someone can answer this one for me. I am doing a capacitor replacement with a kit and instructions from Martin, very clear instructions so far. I am a ways into dis-assembly and I have just removed the top front aluminum panel and it reveals film type strips that are attached to what are the Bass Treble and Balance sliders. I notice that the film strips have a black linear pattern that slide when you move the sliders, under what I assume are plastic lenses that are lit from below. The black lines on all three of the film strips have the lines coming off it appears from the scraping that happens as they slide under the lens. What is the significance of these strips? Are these functional other than decorative? I have tried to attach an image with the areas circled in yellow.
Unrelated, I also found 3 small black (what appears to be plastic) threaded pieces when I removed the bottom plate that do not appear to go anywhere. They are hollow inside and are maybe 5mm wide and 11mm long. I was very careful with removing things and don't see where these came from. This is a beautiful receiver in excellent condition on the outside but these things have puzzled me.
The stripes on the sheets are decorative only. They are visible when light shines through them.The printing comes off due to the lamps heat.Later in production a different type of printing was used on the sheets, which handled the heat better.
The small rubber pieces, you describe, are the inner parts of what remains of the original rubber feet.It had a total of four, one in each corner. The wider outer parts wear off (or breaks off), leaving onlywhat's left inside the hole. That's what you find inside. Look again and you may find the fourth one stillin the bottom plate.
Martin
Wow, that was a fast reply Martin! I assume these are not replaceable at this point in time then? I will see if I can find replacement rubber feet however.
Thanks for the info!
jfrancis:I assume these are not replaceable at this point in time then?
I seem to recall somebody even posted ready templates you could laser print on a transparency!
That might have been in the now archived forum, though... maybe somebody else remembers better than I do.
--mika
Rubber feet, try Ebay or Home Depot, I found some in Home Depot here in Mexico, but there are several on Ebay.
Collecting Vintage B&O is not a hobby, its a lifestyle.
I did some tonecontrol sheets a couple of years ago, both the older and the newer patterns, but I don't recallposting about it so it probably wasn't me.Mine were reverse printed, in other words the printing was sandwiched between thin sheets of hardwearing foil.But I can't seem to find them right now. I will have to look closer.
tournedos:I seem to recall somebody even posted ready templates you could laser print on a transparency!
I have the same memory, there was a thread in the old forum,
Dillen:Mine were reverse printed, in other words the printing was sandwiched between thin sheets of hardwearing foil.
No Martin, it was definitely templates to print directly on transparencies.
It will wear off very fast if just printed onto a transparency. At least mine did when I played around with it.Print on one transparency and put a clear adhesive sheet over it to protect it. That may work if the heat doesn't spoil it.
I will scan mine from the BM 2400 next time I have it open, I have to go into the remote receiver as only one side works., I dont know if the 2400 ones are the same as 1900.
Søren Mexico: I will scan mine from the BM 2400 next time I have it open, I have to go into the remote receiver as only one side works., I dont know if the 2400 ones are the same as 1900.
There is a trimmer (R71 if I'm not mistaken) that oxidizes. It it goes bad, only the left side of the remotecontrol keys will work. That is Volume down, P1, P3 and PH.I've seen this fault four or five times now.
The later Beomaster 1900 and 2400 uses the same pattern.The pattern in Johns Beomaster is unique to the early Beomaster 1900.
Dillen:There is a trimmer (R71 if I'm not mistaken) that oxidizes. It it goes bad, only the left side of the remotecontrol keys will work. That is Volume down, P1, P3 and PH.I've seen this fault four or five times now.
Thank you Martin, thats my failure, but it will take some time before I get to it, PIB to open the 2400 and then the remote cover. I hope to get my smaller issues made this weekend (P45s and TX2) and then back to the BM 4400
Hello,
Some activity since I have been away regarding the issue of the plastic sheets for the balance, treble and vilume controls, and good to hear from you Soren. Regarding the stencils, I am a graphic designer and can reproduce the pattern for the sliders from the old ones I have. Question is how do I remove them? Does the brass or copper clip that holds them at the top just snap off or do you pry it up enough just to allow the release of the strips? I would be glad to share my stencils with the forum and to try and recreate Martin's sandwich approach.
I do have another question it is about accessing the boards to do the capacitor replacements, I have removed the programming section board. Do I need to unsolder wires to the boards to get them to where i can get access to the caps that I cannot get access to, or can I just remove the screws to the boards and pull them out enough to access the caps? This was not covered in the instructions that came with the bulb and cap kit.
Nothing broken so far by me so do not want to start now if possible. Any advice will be appreciated.
First of all, go here there you can see how I did my BM 2400, it should be more or less the same as the 1900, if not, Martin will chime in and punish me. As far as I remember there was only a couple of wires to unsolder
The copper clips comes of with placing a small screwdriver to one side of the clip, press against the middle and lift up, take them all way out and save in the box you of course have for all the screws and small items
Glad to hear that you are into Graphics, I´m in the printing business myself, your stencils will be highly appreciated, you should place these in the wikis with a small how to and material description.
Gutenberg is following this thread from his grave
Fantastic! Thank you for the link. I did a search for disassembly in the archives but put in BM 1900 so missed your posts.
As soon as I get the template for the transparent slider strips created I will do photos as well to show the process. Not sure how to put that in "wikis" however so you maybe can advise me.
Hello Soren,
Thanks for the post and the link. You second post does not contain images in it. Any chance you can fix that or send the images separately. I sent a post before this one that has not appeared in the forum yet saying I would be glad to document the process, my many thanks again.
John
You may have to download an app, Greasemonkey, to see the pics, I just checked and I see them all. do a search in the forum, Mika made the app and also explained how to get it.
As for wikis, I think its only for Goldmembers, but put it here and I will copy it into a wiki-
Thanks, Soren. The first post I saw showed the images so I thought it was a problem with the links. I will look at it on my computer and not my iPad.
I have the slider strips that Mika talked about (I didn't make them, though) but they are slightly off, which has been bugging me for a year or so now. I suppose they are for the later versions. Anyway, I have them in ai-format and you can have them if you like, for a template.
Would you mind sharing the strips with me when you've made them? I just don't have Illustrator anymore so making them is a real hassle for me..
Cheers
/ Johan
Hello Johan,
Of course I would be glad to share with anyone who would like copies of the templates. I think my receiver is a 1900 not a 1900 - 2 from what I can tell. Adobe Illustrator makes it relatively easy to do something like this, so as soon as I can get the strips off I will scan one of them for a template to draw on top of it. Soren has said I think he will help with the posting of the file to the site, but it will be a small file and I can email it as well.
Awesome! 1900 is what I need.
If you'd like the ones I have (that I believe are for the later versions), for whatever reason, let me know and I'll send the ai file to you.
I have just recreated the art for the transparency slider as a pdf document. My inkjet printer cannot duplicate the lines exactly and although the file looks like the lines are evenly spaced the print is off. My next step is to get a film copy made with better printing capability than I have. If any one wants a copy of this to check or give feedback please PM me.
I am in the process of replacing capacitors on my Beomaster 1900, first generation. I found something that makes no sense as to whether it should be a part of the circuit board or not. In the photo you can see a yellow circle around D19 showing something that is partly next to and partly under it.This located in the right rear corner of the board back by the cooling fins. It appears to be a really small coil of string that then just gets messy as it wraps around the diode.
Should this be there?
On closer inspection to the back side of the circuit board I see what appears to be a coil symbol for the mysterious object I refrenced in the last post.. It is still unclear to me why it appears to become a glob around D19, wrapping around the diode. I have down loaded the manual from this site to see if I can find a reference to the coil but do not see that in the schematic. I know there is a lot of expertise on this site and would really appreciate if anyone who is familiar with this receiver could comment as to whether I should be concerned about this or not. Thanks.
I have some receiver/amps but I have never seen anything like this, cant you push the white goo aside to see the symbol under there
Can't claim I know what it is, but I suspect it may be some mid production mod that may or may not be found in any particular schematic / service manual version you are looking in.
Seems like a coil that has been glued to the circuit board so that it stays in place. If the Beomaster works, leave the coil alone and forget about it.
Soren and Mika,
I sincerely appreciate your replies. I purchased this unit as a non-working one so wanted to find out if the mysterious what's it was a problem before I re-attach wires and reassemble. I have nine more capacitors to put in that I had to order from Mouser and then finish trimming down the film sliders I am replacing to finish the job.
Thanks for the input again.
Well, good news and bad news. When I got this on ebay I listened to see what the condition was by plugging in headphones and could only hear the right channel. Good news was at least one channel worked. I had hoped the cap and lamp replacement would fix the other the problems. Bad news is the left channel is still not working. I re-soldered the transistors that attach to the back cooling fins as recommended by Martin, when I replaced the capacitors.
I will take it apart again and look for any breaks in circuit leads but any other suggestions would be appreciated. I have a transistor tester are the main transistors in the back candidates for failure? Any other likely sources I should check? I have the transistor tester and a voltmeter that I can use for trouble-shooting.
Final good news is the film sliders I duplicated for the early version work great!
You can use a piece of wire to make a bridge between C219 and C319.
This way you see/hear if the absence of a channel is caused by one the output-stages of the amplifier.
Connect your speakers directly to the output of each amplifier. A common problem is malfunction of the switch at the bottom or the internal switch used with the headphone. Dirty contacts are to blame.
Thank you for the reply. I failed to mention I did connect my speakers up to the 1900 and was only getting output to the right channel's speaker. Would the malfunction of the switch at the bottom of the internal switch you mention still affect the channel dropping out? My guess is you were thinking based on my post, that it might just be the ear phones that were affected. Regarding your suggestion of running a wire from C219 and C319, does the one wire go to the positve end of both components or the negatives? Sorry to ask so many questions but do not wish to short the board.
Help me save a beautiful BM 1900! I really could use a little advice on what to do next to track down the cause of a dead left channel. Left channel was dead before a cap kit was installed and is still there. I have checked for visible signs of a broken wire or trace, read every thread I could find on the BM 1900 in the archives, and made some continuity checks with connectors with wire leads. Tried to check the main power transistors with a meter but have not been been sure of the results. The sliders all appear to be in working order, I assume that if the balance slider were broken I could see or feel that, that is the case. All the way up on balance gives me the right channel and as it slides down the volume disappears to where nothing is heard at the bottom position. I have hooked up speakers as well as ear phones and switched positions with the speakers.
Beobudy suggested I use a piece of wire to make a bridge between C219 and C319. He said way you I can see/hear if the absence of a channel is caused by one the output-stages of the amplifier. I wanted tO know if the wire should go from the positives of both or negatives of both before I tried that but received no reply. So greatful if someone could reply.
jfrancis: I assume that if the balance slider were broken I could see or feel that, that is the case.
I assume that if the balance slider were broken I could see or feel that, that is the case.
You can't.You need to take it apart, check and repair as necessary.
This is the time for an oscilloscope. It could solve your problem in 5 minutes - literally.
The signal path is very easy to trace in this machine.
Menahem
Hello and thanks for the replies, good to know people are still following this thread. I don't have an oscilloscope so will have to find a kind soul who might be interesting in checking this out or a repair shop which I have considered but not many are willing to look at it, no replacement parts usual excuse. I am investigating whether or not as Martin has suggested it is the broken potentiometer sliders that are the problem. I did take them all apart and the contacts were broken on several.I have super glued them back and got a partial signal in what was the dead left channel. So I am taking it apart again for another look to see if I have a dirty contact or not enough contact pressure. If someone can advise on what to use to safely clean the black coated strips that the coal contacts run on, I would appreciate it. Also is there anyway to visually identify the difference between the balance and treble sliders, they look identical and the back has the same info on them.
I used Iso alcohol to clean (used a pipe cleaner and scrubbed hard) and then with Deoxit, no spray, from a bottle, also clean the contacts with Deoxit. The Treble and Balance sliders are both 20K Ohms double, but have different parts numbers, check that they work properly with an Ohm meter. Check If they have the solder legs in the same position, or if a spare part number is on them, 5310061 is the balance and 5310060 is the treble
Sorry, for the late reply I didn't relalize there had been a post after my last one. Since I last posted I have gone back into the balance slider resistor and cleaned it a little more and bent the contacts for better contact with the rails and switched treble and balance thinking if they are different maybe I had accidentally switched them the first time. After reassembly the balance now works, HUURAH!
However when I slide the balance slider up for the right channel both treble and bass work as they should but when I slide down for the left channe neither work. Seems like quote a coincidence I seem to be having consistent issues with the left channel. Does the left channel signal for treble and bass come from the left channel balance slider and go into the other sliders? And I may have a problem with the balance slider or is it possible that I accidentally switched the two 20k sliders between balance and treble incorrectly? I had just switched them when it was not working before thinking that might have happened. Or would the balance not be working correctly as it does now if It is not in the correct place. Soren mentioned part numbers but both sliders have identical numbers, 13.359.00, as does the 50K bass slider. These are the sliders with the small black coals as well as metal contacts. Soren also mentions taking ohm readings, can you tell me where to take the readings?
Any thoughts appreciated?
This story has a great ending so bare with me.. It was one year ago today that I bought a BM 1900 on ebay. It was in excellent physical condition but was not working and had the usual issues with the lamps not working and needing new capacitors. So I got a kit from Martin with great instructions on disassembly and placement of parts and after a few months went by I installed the new parts. Unfortunately there were still problems with both channels working. Anyone who has one of these knows the resistor sliders often have problems with the contacts breaking off from their plastic mounts and this proved to be the problem with my 1900 as well. After much good advise from the forum I was able to take apart the resistor sliders and try to repair them but still was not able to get sound consistent in both channels, right was fine but left sounded dull and the bass slider did not function. Luckily I was able to find another very inexpensive 1900 recently on ebay and took the slider resistors off of it and took them apart and found two of them were working fine with no broken mounts. So I reinforced the mounts with epoxy and used one off of the original 1900 that had unbroken mounts to replace the defective ones. It is important to clean the slider rails well, this I did with advise from Soren and Martin here on the forum. The last 1900 was in pretty poor shape that I canabalized for the parts so I did not feel bad about using it as a donor for my better one.
I then put it all back together and now have a perfectly functioning 1900. I bought a BM 1900 in 1978, my first B & O component but it was stolen in a house robbery 2 years later. It is great feeling to have this unit working, like I got the original back after all these years.