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
Hi,
I'm Chris and I'm new to this forum.
I have already restored a Beomaster 1200 and a Beomaster 3000-2, but I need help with my Beomaster 6000.
I completely swapped all of the capacitors. Two of the indicator Lights (Volume Control) 2x 3,6V and 100 Ohm Resistor for each LED at Anode.
The old trimmers are still original and will still be replaced. The values of the trimmers on the circuit board 9, however, are correct.
The IC's of the circuit board 9 would have to be replaced because they make crackling noises while listening to music but the Heatsink is not hot. Thats my fist problem with this Beomaster IC's: 9IC102 / 202 / 103 / 203 are BDV65A and 9IC104 / 204 / 105 / 205 are BDV64A.
My next Problem is the Power Supply. The Heatsink gets very hot and the Voltages are not correct.
I read in another forum that I have to swap the transistor and IC's 16TR2 / 16IC1 / 16IC2. I noticed that under two resistors the board is black. So I think that these resistors 16R1 and 16R12 are burned.
Now my Questions:
1. Did I replace the lamps with the LEDs correctly or does that lead to the malfunction in the power supply?
2. Can I replace the IC's BDV65A and BDV64B with BDV65B and BDV64B?
3. Would you recommend me to replace the transistors and IC's 16TR2 / 16IC1 / 16IC2 in the power supply?
4. The resistors 16R1 and 16R12 are normal 47 ohm 1/2W right?
I'll try to attach photos tomorrow morning. Many Thanks.
Chris
Hi CHris
1.
As I look to the service manual the volume lamps are parallel at 6,5 Volt so the limiting resistor for your LED's seems a liitle bit too low (about 60mA with 100 Ohm)
300 Ohm should work too regarding to you LED's current.
If you are not sure that these LED's have impact to your powersuply voltages just disconnect them and measure the voltages and let us know.
2.
The "A" and "B" at the power transistors gives information about the max B-C ( C-E) Voltage. With a "B" it's '100 Volt with "A" it's 80 Volt.
Both should work, but my question is what makes you shure tha the "crackling noise" comes from these transistors.
First exchange the old trimmers with new multiturn potentiometers. Measure and align the quiescent current and the zero adjustment of the left and right poweramp as described in the service manual.
Check for cold solderjoints.
3.
No if the transistors are still ok
4.
Yes, if the values are still ok leave them or solder new ones in with a 0,5 cm gap to the PCB
Best rgegards
Christian
sorry for my late reply. I measured the voltage again and get these voltages: 53V, 6,8V and 15,3V. If I listen music over TP1 the Power Supply gets warm but if I switch to radio than the Power Supply gets hot.
It doesn't matter whether I have built in LEDs or lightbulbs. I have tested it.
I have changed the cables between the Beomaster and Beovox MC120.2 and the crackeling noises are gone.
I'll be looking for solder joints today.
I took photos of the power supply.
Hi Chris
Haha yes the speaker cabels and the plugs are a common problem when they get older and pick up corosion and dust, maybe you buy some new ones or new plugs.
The issue with the power PCB is quiet normal as the tuner board is drawing a lot of current from the power board for the signal LED's and the tuning center lightbulbs and other stuff.
Can you imagine how hot the cooling fins get, can you still touch them with tuner on?
They get really hot, but If you can touch them for more than 30 sec. we talk about under 50° C I think.
One thing I just saw in the picture, did you connect the 3 ground tabs from C1 and 3 ground tabs from C10?
I Always take the ring of the old caps and solder them back into place to make sure I didn't forgot.
If the board not smelling and no smoke comes up In would think it's ok with sight from my armchair in north Germany 😉
When you run the amp keep an eye on it for the first couple of hours.
Just saw in the picture that you did not use the metalring from th e old C1 and C10, did you connect the ground tabs from the trace side?