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
The film sliders that attach to the controls for bass, treble and balance can deteriorate over time from the heat of the lamps underneath. This problem I understand was fixed in later versions of the receiver. Below is an example of one of the film sliders with the black lines coming off.
I took the damaged film slider and scanned it, flipped it vertically (I will explain why in the next post.) I then placed the scan into a vector drawing program (Adobe Illustrator) to use as a template to draw on top of. I drew the outside contours of the slider and then the bars and lines of the original. I then duplicated the outside contour and aligned it so that it and the original drawing with the bars and lines shared and edge. The art work was grouped at this point and duplicated 6 times so I had some spares. The file was then sent to the only place in Boise that still has what is called an image setter. Image setters were before digital printing what was used for film output for lithographic printing. Below is the film positive output. The color is from the different lights used to make the photo, the image is clear.
I cut around one of the pairs and then very carefully with a sharp Xacto knife cut around the contours. I cheated a little and did not conform to all the round curves of the original film. Then I took the knife and from the back side of the film cut just a little down the center line of the two halves being careful not to cut too deep. This is so you can fold the the two sides together with the back ending up on the outside and the emulsion of the image setter is on the inside. This protects it from getting scratched when it slides under the plastic lens.
I folded the film along the scored edge and then pressed it flat with a small transparent protractor. With narrow double sided tape that I got from a craft store the two halved can be held fairly flat in place. A really sharp blade is key here and taking your time with the cutting. The six copies allow for mistakes and redo's. I will see if I can get my drawing to someone who can put it on the site if possible or the pdf can be sent by me to anyone interested.
Good job (and photos) jfrancis, have you tried it in the bm 1900 ?
I am still in the process of replacing the capacitors in the BM 1900 but I did assemble the plastic lens over the board to see if the sliders will indeed slide as they should, they do. The reproduction of the art is as accurate as I could possibly make it so don't think that will be a problem. Anyone who would like to get a copy of my file and try it out as well is welcome to.
John
ps. If anyone can take a look at my other older post regarding the "BM 1900 Restoration Question" I have posted it would be much appreciated.
I did an LED mod for the BM1900 and BM2400 a few years ago, which solves the problem of heat damage on these plastic films.
If anyone's interested, let me know, and I'll look through my notes for the details. It involved quite a bit of work, because under each of the Bass, Treble, and Balance panels, 2 LED's had to substitute for one lamp to disperse the light over the whole area.
Menahem
Hi Menahem,
As I have several of these 2400's I would like to test and try to implement the led substitute to these plastic film sliders.
Thanks a lot
Alain
I have removed LEDs from two Beomaster 1900s during the last year or so and put back in lamps.The standby circuitry depends heavily on the load on the 15V rail.The load is used to bleed the 15V rail when the electronic switch is commanded off.If the load is not correct (if too many tonecontrol etc. lamps are burned) the Beomaster canbe difficult to put into standby (and particularly problematic by remote control, it seems).
If you replace the three tonecontrol lamps with LEDs, at least make sure to get the total load correct by introducing asuitable parallel bleeder.
Nice work, John !And no worries regarding the heat.Almost any DIY job will be better than the original printing in the earliest Beomasters and it's not THAT hot anyways.
Martin
Thank you for the explanation Martin.
Now I understand why he reluctancy to replace by Led's as there is an obligation to be very careful with an equivalent current consumption.
If anyone needs copies of the files for the film sliders I created I am glad to share.
Does anybody have these films or files to create them available?
Thanks in advance, John
Hello
Hey john,
this is probably a long shot, but do you still have the files ?
best,
Ian