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
Nederlands/Dutch:Beste lezers,
Ik ben nieuw hier op het forum. Recentelijk heb ik een 2e hands Beomaster 900 K, 2233 Serie 4 kunnen kopen. Het exemplaar is werkelijk waar net als nieuw. Ongelooflijk hoe goed de staat is waarin het verkeerd. Vanmiddag heb ik echt nog het plastic beschermplaatje wat er in de fabriek op is gedaan af gehaald. Die zat er gewoon nog na al die jaren op. Alles functioneert goed, hij klinkt goed, hij ziet er echt goed uit.
Al om al, ik ben er enorm blij mee.
Er is echter 1 probleem, ik ontvang geen FM.
De handleiding (gevonden op het internet) gevolgd. Als ik op FM druk, gaan netjes alle lampjes branden (op het groene stereo lampje na). Als ik het volume harder zet kan ik horen dat er spanning op staat. Oordelend naar de staat van het apparaat zou het haast niet moeten kunnen dat er iets kapot is. Maar ik ben bang dat dit wel het geval is.
Is er iemand die mij hier wat meer over zou kunnen vertellen? Weet iemand misschien wat het kan zijn? Of doe ik zelf stomweg iets verkeerd?
Engels/English:
I am new here on the forum. Recently I was able to buy a second hand Beomaster 900 K, 2233 Serie 4. The Beomaster is just like new. Unbelievable how good the condition it is in. This afternoon I really took off the plastic protective plate that was put on at the factory. It was still there after all these years. Everything functions well, it sounds good, it looks really good.
All in all, I'm very happy with it.
However, there is 1 problem, I am not receiving FM.
I followed the manual (found on the internet). When I press FM, all the lights come on nicely (except for the green stereo light). If I turn up the volume I can hear that there is power. Judging by the condition of the device, it should hardly be possible that something is broken. But I'm afraid this is the case.
Is there anyone who could tell me more about this? Does anyone know what it could be? Or am I just doing something wrong myself?
Check the IF-transistors.They are known to develop tin whiskers and short from the die to the casing.
Martin
Thanks for you response Martin!
I'm a bit of a novice when it comes to repairs. What is the best way to check the IF-transistors?
DC readings or continuity from emitter/collector/base respectively to ground, would be the easiest.
How do i do this easiest? As I said before, I'm not that technical and would be very sorry if I accidentally did something wrong. Just to be clear, am I supposed to screw it open?
(sorry for the late response, I was very busy)
Yes, of course.You cannot measure, diagnose or repair anything from the outside.
When I unscrew the back of the Beomaster. Where do I look for and how do I recognize if a part is broken and should be replaced?
You don't unscrew the back of the Beomaster.You take the four dial knobs off, losen the screws at the bottom of the cabinet (either two or four) and push the chassis out of the cabinet.You can push on the four spindles where the knobs sat.If your Beomaster has built-in speakers, their internal connecting plug must be disconnected when the chassis is apprx 8-10cm out.
With all due respect - and don't get me wrong, but from what you write, I don't think this repair sounds like a job for you.
As a matter of fact I have already removed the four large buttons once. This was to remove the protective plastic that was still on it from the factory. So I already have experience with this, and I am capable to do this again.
Then carefully sliding the chassis out should also not be a problem. My problem, however, is that I have no experience yet and don't know what to look for once I have pushed the chassis out. If you could describe that to me, then I would most sertainly be able to do it. As for the speakers, they are built-in so I would have to disconnect them.
I don't plan on opening the radio until I know what to look for and what to do. When this indeed turns out to be beyond me, I know how to find my way to a B & O dealer or refurbisher. Then I will then contact them to see if they can do something about it.
You will be looking for bad transistors in the IF-stages.Check for continuity/shorts, particularly from the screening pin to the emitter, collector and base pins.You can also measure the DC voltages on the pins and compare to the readings in the service manual.If bad, they must be replaced. Don't use the original type again - they will all be bad by now, even if from unused old stock.
Keep in mind, that Beomaster 900 has positive ground/chassis.Martin