Luckiestmanalive Posted January 14, 2015 Posted January 14, 2015 So I've finally got around to looking at the Beolab 1700 amplifier that Dsan gave me a couple of years ago. I've bought a couple of 5-pin to twin RCA socket cable adapters for interconnection and a pair of 2-pin DIN plug loudspeaker connectors and have it playing music again. There are only a couple of problems now to fix: 1. Balance slider is a little off (right is louder than the left). 2. Volume slider is connected to the dial attached to the PCB via a complicated pulley system but the string has come off and I have no idea how it is supposed to go back. I have had a go myself but I really could use some help from someone who has done this before or knows where I can find a diagram for the unit. My online search has been in vain. I'm looking for anyone who might have some experience in restringing a control like this or how to get a hold of a diagram for this model. I could provide a diagram of the pulleys to help. I also have a wiring diagram but I'm not sure what I need to do to fix the balance being off so advice on that would also be appreciated. Alternatively, I would be happy to pay for someone who is sure to know how to do it. Cheers LMA
Owen Y Posted January 15, 2015 Posted January 15, 2015 Volume - can't help with this but it sounds like vintage radios which had such string/pulley tuning dials. Balance - what is wrong, unbalanced when at centre? Is it a string arrangement again?
Luckiestmanalive Posted January 17, 2015 Author Posted January 17, 2015 Hi Owen - just unbalanced at centre - I have to slide it to -2 to centre the image. Luckily, there is no string involved!
Owen Y Posted January 17, 2015 Posted January 17, 2015 Caig have a spray product especially for pot wiper tracks, worth trying. Check out Tradetech.co.nz
Luckiestmanalive Posted January 17, 2015 Author Posted January 17, 2015 Cheers, Owen - I'll have a look. I've figured out how to string the volume control - wasn't so hard after all. I've attached a diagram for future reference - the numbers indicate whether the pulley is a single or double pulley.
Owen Y Posted January 17, 2015 Posted January 17, 2015 Looks like the Caig Faderlube Minispray might be your best bet. But maybe first check how the balance works - is it a conductive track/wiper type? Or is there some mechanism connected to a pot?
Luckiestmanalive Posted January 17, 2015 Author Posted January 17, 2015 I can't quite get the volume string working properly - there is too much slack in the string and it is hard to attach it tightly enough to the volume slider control. Given there is no string and it uses a slider the balance must be a conductive track/wiper? I can't get to it without removing the front panel by the looks of things and once done, I would have to restring the volume control, which is fiddly to say the least. Will have a wee think about it...
Luckiestmanalive Posted January 17, 2015 Author Posted January 17, 2015 Restringing the volume dial has made it a little frayed looking is some places. What should I use to restore it to its taut and slick self? Vaseline OK?
Luckiestmanalive Posted January 19, 2015 Author Posted January 19, 2015 OK - I thought some pics of the wee amp were in order. This is what it looked like before I started to work on it. This is the list of work I've done on it since the pics were taken: 1. Restrung the volume slider (a fiddly, hard job I hope I never have to do again because it takes many goes at it to get it right) 2. Desoldered the RCAs soldered to the wiring on the inside of the amp and pushed through a hole in the bottom of the chassis 3. Bought and soldered 2-pin DINs to speaker cables (cheap ones from Jaycar) 4. Bought new 5-pin DIN to RCA socket cables (just some cheap ones from surplus electronics) 5. Repaired the veneer on the lid, sanded it, and applied beeswax (looks a lot better now) 6. Cleaned black metalwork with slightly damp cloth with a little soapy water 7. Stripped remaining vinyl wood-like veneer from sides (there were only a few traces left anyway) Still to do: 1. Replace blown power lamp with an led and resistor (couldn't find anything like the old bulb online) 2. Find and install feet (it doesn't have any at present) 3. Sort out the balance issue I'll post new photos once I'm finished.
Owen Y Posted January 19, 2015 Posted January 19, 2015 Just a thought - you balance issue could be a vol control issue - ie. 1-ch volume could be slightly more than the other, esp if there is stringing connection - does one string control 2-ch's, on say the usual twin stacked, ganged pot with one shaft? Or could there be differences occurring betw L-R ch volume settings, eg 2 separate pots?
Luckiestmanalive Posted January 19, 2015 Author Posted January 19, 2015 Hopefully, the pics will come up now...
Luckiestmanalive Posted January 20, 2015 Author Posted January 20, 2015 Hi Owen - the second pic above shows the single shaft that the string winds around so it looks like the volume on both channels is from a ganged pot? Would the circuit diagram (attached in a post above) help? I've tried to decipher it but can't make out the balance or volume components...
Owen Y Posted January 20, 2015 Posted January 20, 2015 Yes it does look like a single 2-ganged vol pot. What is the Balance slider connected to?
Luckiestmanalive Posted January 20, 2015 Author Posted January 20, 2015 The balance slider is the first one on the left in the top picture. It is hard to see from the picture but there is another strip of PCB at right angles to the one you can see in the picture so I suspect it has tracks on it which the sliders touch?
Owen Y Posted January 20, 2015 Posted January 20, 2015 You may have to dismantle a bit more to inspect the front panel area.
Luckiestmanalive Posted January 20, 2015 Author Posted January 20, 2015 Yes - something I am loathe to do because it will mean having to restring the volume control. There is a sizeable gap on the front panel for the sliders to work in so perhaps a spray in there might work?
dsan Posted January 21, 2015 Posted January 21, 2015 Nice work & good to see you've made use of it. You're obviously a more patient man than me; I took one look at that string system then put the lid back on Good luck with the troubleshooting.
Luckiestmanalive Posted January 26, 2015 Author Posted January 26, 2015 Thanks, Dsan. You were right not to attempt the volume string. I became a little obsessed and nearly went insane! So I'm still working on a couple of things. I have feet on the amp so it doesn't scrape on the screws! But the resistor + LED did not work so well. It started to blink occasionally, then more and more, until kaput. Nor did the Caig deoxit and gold treatment fix the balance issue. I'll leave the balance issue alone for now but does anyone know where I can get a 32V tiny bulb cheap? I found an ebay link for a sylvania NOS 32V lamp but they want $US10.
Luckiestmanalive Posted January 26, 2015 Author Posted January 26, 2015 Found one! Hang on, I know it's coming from the UK but is't $102.30 for shipping a bit steep for a single bulb that is 5mm x 16mm??!!
Luckiestmanalive Posted January 27, 2015 Author Posted January 27, 2015 Yeah, that would be better - just need a clear one and not very bright. By the looks of things, the red perspex glows orange normally. The issue I've had is that it is a 32V circuit, which is hard to find. The design of the light fitting is a telephone slider. It slots into a hole that is about 7mm in diameter and is about that or a little more deep.
Luckiestmanalive Posted February 3, 2015 Author Posted February 3, 2015 OK - so after replacing the power on lamp with an led and resistor that works I've given it to my son and he is rapt with it! The only issue left to fix is the uneven balance but that can wait for another time. Here is how it looks now (apologies for the crappy pic but the camera on my iphone has lost the ability to alter its focal point). Thanks, Owen, for your input.
Owen Y Posted February 3, 2015 Posted February 3, 2015 Oh good,, still a good looker, well worth fixing. LEDs - you just need to get the R size right, to drop the Volts. (iPh camera - perhaps stand at the optimal focus distance next time & zoom in?)
Luckiestmanalive Posted February 6, 2015 Author Posted February 6, 2015 Yeah, good idea, O. Hopefully, the optimal distance is't over 4 metres!
MikeCB Posted February 3 Posted February 3 Hi Luckiestmanalive, my father-in-law has a Beolab 1700 that is in need of a re-string of its volume control. The string has broken but is mostly still in place, so I have some clues about how it goes. But actually replacing it looks hard - and sounds it too, from what you've said! I'd love to get some input from you as to how to go about this, if you can remember any of the details. In particular, how the string attaches to the slider, as I can't figure this bit out at all. Cheers, Mike
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