hi all,

(1) one of my bm1000's has an issue w/ its right channel.

it has appreciably lower output than the left on either spk1 or spk2

i have the mans / schematics...

also, the main light is out... specs, availability?

thanks in advance,

There are two bulbs in the dial, one in each end. The originals are 6.3V 300mA E10 bulbs - I don't know what they are called on that side of the pond, but here they are known as "flashlight" bulbs. 6.3V is off to specialty shops but 3V flashlight bulbs are available in every corner shop, so if you don't tell anyone, I'll reveal that I have modified my BM1000 and two 900K's to have the two bulbs in series instead of parallel so I can use the 3V bulbs Of course, then both will go out when one burns...

Regarding the weak output on one channel, I can't think of any obvious reason. You might want to check the test point voltages first, or just wait until Dillen gets here

There can be several reasons for a weak channel.
I would concentrate on the two large capacitors on the main board first.
Then the balance and volume potentiometers and/or sound source switches.

I have suitable lamps in stock, also for the MPX (stereo) indicator if you can't find any locally.

Martin

thx for the replies!

i had a chance to open it up last night, and briefly do a look over.

everything looks fine, but i ran some of the factory tests across the (2) resistors and clearly the right channel is lame. if i offset the balance to the right, it sounds ok, but clearly not correct.

i also notice quite a bit of heat build up on the front plate in proximity to the radicator and the tuning knob area. after a while of running (2 hours) the radicator quit functioning. after power on/off it did come back...

i think that there is more going on than meets the eye... i have sourced some 3000uF 25v's but they are radically smaller in size than what is present on the board... i am missing something? the balance pot seems to be fine... could just replacing the 3000uF's be sufficient?

all (3) bulbs are shot -is there one also in the radicator dial? i don't think so...

i will likely have to take this completely apart, something i am not looking fwd to doing, though it is not *that* complex...

any thoughts before the grand dissection?

Hi!

I had a similar problem on my beomaster 1200, problem was a bad transistor. I compared the voltages on the pins of the transistors in the good channel with the voltages on the transistors on the bad channel. Mine had a transistor in the preamplifier that had 0 volts somewhere, was obviously no good! Swapped the transistor from right to left channel and from left to right and the problem switched channels, so it was obvious for me! Changed the transistor and now everything is fine. Maybe your problem is the same!

The smaller size of the 3000 uF caps is normal, they can make much smaller elco's these days... It's good as long as the voltage rating is the same or higher.

Good luck!

Premiumverum:

I had a similar problem on my beomaster 1200, problem was a bad transistor. I compared the voltages on the pins of the transistors in the good channel with the voltages on the transistors on the bad channel. Mine had a transistor in the preamplifier that had 0 volts somewhere, was obviously no good! Swapped the transistor from right to left channel and from left to right and the problem switched channels, so it was obvious for me! Changed the transistor and now everything is fine. Maybe your problem is the same!

i recall reading about that when i started in on this project -and now i can't find the thread! arrgh! -i'll keep looking.

are you referring to the transistors encapsulated on the bottom of the beomaster towards the front plate? they ought to be easy to swap around...

thanks!

++++edit++++

found it!

Nice to hear you recall my very first post here!

I'm not familiar with the beomaster 1000, But before swapping and desoldering anything, I'd take the readings on the pins with the multimeter. Sounds like the encapsulated transistors you are talking about are the power amp transistors, in  my beomaster they are also located on the bottom of the beomaster. Start with the ones on the pre-amp board, they're probably located near the pots for volume control (don't pin me on that though, never seen a bm1000). Did you already clean the pots btw? First thing to do in case of these sort of problems.

Be careful not to create a short between transistor pins with the multimeter tip, might easily blow one up! (Gives cool sparks and smoke though)

Good luck!

Check also the fuses in the supply to the amplifiers. The holders oxidize and a fuse can be blown.

Martin

Dillen:

Check also the fuses in the supply to the amplifiers. The holders oxidize and a fuse can be blown.

Martin

unfortunately, i swapped the fuses and the problem remained in the right channel... was hoping it would be that easy!

i have iced this project a bit, but i am still having difficulty finding everything i need cap wise (located axial rather than radials for the 3000uF 25v).

@martin: have you ever put together a cap kit for a bm1000? i would be interested in pricing for one to include the (3) bulbs as well. PM me if you have -i have bought from you in the past.

now i just need the time to get back to the project!