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 have just bought a secondhand beomaster 1700 (the one with the big belts)
it seems to work alright and then after an hour or so it starts crackling. (Well, the speakers start crackling)
Then stop again etc. very intermittent. its not when I'm adjusting anything. It does it whether I'm listening to the radio or via DAC plugged into the Tape input, so I suspect its something in the preamp or power amp sections
Any ideas on what might cause this behavior?
Aging capacitors would be my first guess.Is it in both channels?
Martin
Yeah it's in both channels. But I don't think it's in stereo if that makes sense, i.e. both channels crackle, but making different crackling sounds
Clean potentiometers, replace electrolytic capacitors.
Thanks Martin. I must admit I'm a bit confused what the potentiometer actually is on this model. Are the sliding belts part of it? The Box which the drive shaft is connected to only? Do I just try get some contact cleaner in there or can I actually open them up? Should I be looking at all the electrolytics or just the big ones? (Or just the small ones?)
They are the long ones driven by the bands, sandwiched between the boards.You cannot take them apart. The only way to clean them is to spray a good quality contact cleaner (I use Kontakt 60) down and then move the sliders back and forth a dozen times each.
Ideally all electrolytics. The larger ones will be the last suspects.
Thanks heaps, Ill get onto it
As my only real source of capacitors has quite a high shipping cost, should I be looking to replace anything else while im placing an order? Trimpots or anything?
I too, also aquired on of these beauties a few months ago, and after sorting out the lack of power (tiny spring broken in the power switch !), I connected it up and also got a lot of scatchy and random hissy sounds. I decided to replace all the capacitors and found the big ones OK but nearly all the small ones were out of tolerance, many by as much as 100% ! When they were replaced it was a joy to hear, no more scratchy hissy noise, this just left the clutches to fix.And here is my question (probably for Martin), I'm currently doing the volume, balance and tone control first, so I've dissasembled the cluth mechanism - do the components that make up the cluth assembly slide off the brass bar ? It seems that the "separators" are firmly glued in place, do they just need 'force' to remove them, or are they not meant to come off ? (obviously the cluthes are slipping and I need to replace/turn the rubber clutch plates).Tim
Use "controlled force" to slide the parts off the hexagonal shaft.
Thanks Martin. Do you or anyone else know of a suitable alternative or material for replacing the worn rubber clutch 'plates' ? (i was thinking of cutting up an old bicycle tyre inner tube, but suspect it may be too thick !). Thoughts anyone ?
Hey Tim, does the switch for your AFC switch stay engaged when you press it, or is it meant to be momentary? Mine is a different colour to the rest (Blue cap instead of red) and it doesn't stay in when you push it. Not sure if that's normal or not
Tim: Thanks Martin. Do you or anyone else know of a suitable alternative or material for replacing the worn rubber clutch 'plates' ? (i was thinking of cutting up an old bicycle tyre inner tube, but suspect it may be too thick !). Thoughts anyone ?
I reproduced them some years ago.PM or email me.
vindy500: Hey Tim, does the switch for your AFC switch stay engaged when you press it, or is it meant to be momentary? Mine is a different colour to the rest (Blue cap instead of red) and it doesn't stay in when you push it. Not sure if that's normal or not
The button itself doesn't stay down (it would look bad with a button not sitting flush).It merely moves the switch inside that triggers the AFC (and the AFC light) on and off for each pressing.
Sorry, yes the internal switch is what I meant. Mine doesn't engage, suspect the switch is broken
vindy500: Sorry, yes the internal switch is what I meant. Mine doesn't engage, suspect the switch is broken
- Or the whole assy needs adjusting closer to eachother.In severe cases it's necessary to glue in a small plastic sheet or similar to shoten the distance between the switchs plate and the buttons black actuator arm.
Do you mean like this?
http://imgur.com/a/24EQjot
Someone else had already done this, bit the problem seems to be in the switch mechanism itself, Ie. Even pushing the grey switch, it doesn't click in, it just pops back out again
An update
I cleaned out the left hand side potentiometers with some Servisol Clean and Lube NA-1012. I couldn't find anyone who sold the suggested brand in New Zealand. Outcome, they move easier and I got some very dirty cotton buds, but no change to the popping. . (side note, the resistor was missing from the Bass line. The LED doesn't work either (Unsurprisingly). Do you think its safe to just put a new resistor on and hopefully get it to work or is there a way to test the light? I assume it was removed for a reason).
I just finished replacing all the capacitors in the Tone section and the Power amp section. When I repowered it the popping started up again. I then played with it a bit (Not really sure what I did, I slid the balance pot up and down because I was noticing that the left speaker was crackling even when the audio was panned all the way right).
It seems to have come right after around 10 minutes of messing with it. Has been playing for around 30 minutes with no crackles, so Great!? (although I'm not entirely sure what actually did it)
Two of the power supply caps are on back order so I haven't tackled that yet. I also haven't touched the radio side at all yet. I ordered new caps for that so I guess I may as well change them out?
Meget tak for din hjaelp Dillen