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 PHONO input of the Beolab 5000.
If you are NOT using the PHONO input in your Beolab 5000 a small click can change this input to an extra AUX input.
From the Beolab 5000 manual:
This means you can actually adjust PHONO HIGH to a level for high output CD players up to 4V – for CD players the level is about 1V or 1,5V.
/Frede
Here you can “click” to change the PHONO input.
Very useful Frede, thanks for sharing.
More and more people seem to be migrating back to vinyl, including many younger people fed up with tunny sounding mobile device music. Black is back.
Have you had any response to the new MC box you are going to build or the 'new' version of the stereo width box?
Dave.
I still use a Beogram 4000/20CL with my Beolab and I find the phono preamp really superbly musical and detailed!
Jacques
The exact same combination as I use Jacques! Wonderful to hear isn't it?.
Hi.
Is the Phono and the Mic input crossing signals on the priamp?
I have changed all electrolytic caps(not tantilum) and transistors, but after playing vinyl for 30 mins, i get some awful distortion in the right channel.
Sounds like a camp fire in the speaker. The speaker is OK.
If I turn the volume down, it's gone. The higher the volume, the higher distortion. Suddenly it can be quiet for several minutes, before it starts again.
The MIC input has similar noise, AUX and TUNER is perfect.
Did you fit low-ESR capacitors?
Martin
I used mostly general electrolytic capacitors. But sure, you are onto something I didn't think of. I understand you are NOT supposed to use to high spec capasitors, right? All values are directly replacements, with some higher voltages, but all uF has been swapped with same nearest value.
I have used some Nichicon FW Gold Muse caps from 3-100uF. Are they to low-ESR?
Great tip Martin!. Thanks
BR
Frank
Frank Solem: I have used some Nichicon FW Gold Muse caps from 3-100uF. Are they to low-ESR? Great tip Martin!. Thanks BR Frank
In which circuits?
Hi Frank,
I would also recommend you to check the following:
1.
Do you hear the noixe in both channels?
This is to indentify the source of the noise.
2.
A possible point could be - the polarity of the replaced electrolytics.
Please check that in the 2 pre-amps
If the noise is on both channels - perhaps the problem is in the power supply filters for the 2 pre-amps.
Dillen,
Since the problem is in the phono stage and Mic only, I'm thinking is has to be a problem with preamp 1 or amplifier 2, right side. I have used the gold muse caps on that whole board, exept the four bigger caps,
2x400uf(142&182). There I used 2x 390uF Nichicon, but I cannot see the type.
2 x 160uF(63&89). There I used 190uF Nichicon, cannot see the type.
I have used the same capacitors on right/left side. Only right side has the problem.
I can see now that I haven't changed the two transistors 86 & 87 in amp 2(Nor the 64&82 left side). in mine they are BC-transistors with TO-18 metal casing.
I will replace those two transistors pr side and give it a try. Of course, now as I am fiddling with it, it have had no symptoms for one hour... Crystal clear , perfect sound
Thanks for the inspiration, I really value the help. I was getting stuck, but now have found new inspiration :)
Thanks to Classic also, for valid points :)
Check the level setting switches. They can cause problems.
Thanks, but the fault comes at the same time on Phono and Mic. So it has to be a common component. It has been playing flawlessly for 2,5 hours now, until the bonfire just returned.
The bonfire is thinner in Mic than on Phono, but pretty much the same pattern. But it is a much thinner sound compared to the rich crackling in the Phono. Strange..
I don't think it will help, but I'll try replacing the transistors, and will be back :)
Edit, I also did check the level switches. Together with cold solder joints and all other switches. But you are right, it does sound like a dirty switch. I have operated them all, and there is no easy indications of a dirty switch.
I'm no quitter, but I find the schematics for this amp hard to read.
There is something wrong in my pri-amp. Now I have the same sparkling noise on all inputs. A weak ago it was only phono & Mic.
On the right side, I measure OK on transistor 41 & 56. But on 86 & 99 the voltages are too high. Tried to replace them, same result.
On transistor 86 I get 33V on collector, 22V on emitter and 14V on base.
On transistor 99 I get 33V on collector, 22V on emitter and 33V on base.
Transistor 171 and 180 measure according to schematics.
Any expert on reading the diagram that can guide me in the right direction.
I'm hoping the dispair at the moment will make he love my Beolab even more when done