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
Hello All,
I purchased a used and non-functioning Beomaster 2400 last year and have been slowly cleaning it up and diagnosing various issues. The initial problem when I got the unit was that there was either no sound or occasionally a very quiet whisper of audio when either speaker outputs or the headphone jack was used.
I took the unit to a local repair shop and they diagnosed it with a bad LDR volume circuit and quoted me several hundred dollars to do the repair. I declined and decided I would try and fix it myself.
After some research I was able to reach out to Martin on these forums back in April and get a replacement LDR volume daughter board and I went about replacing it. I got the unit all back together and turned it on with my dim bulb test setup and it worked, but instead of no audio all I got was that same whisper of an output. I went back through all of my soldering points and lade sure there were no bridges bad soldering mishaps.
After about two days of looking at this thing and trying various fixes, I put it all together and it worked... for 10 seconds. Then the audio went back to a whisper. Out of frustration I gave it a little smack, and boom it sounded fantastic. Another tap and it got quiet. Well to not go on too much longer about the steps of troubleshooting why that was happening, I did end up finding out how to get it to play.
I discovered that removing the board with the standby light and program lights (called "Program-Indication" in the manual) fixed the issue completely. Now this board when installed functions fine, as in all the lights are functional, but with it installed it kills the output. Playing around a little more I found that there are two pin plugs (P3 6 PIN and P3 8 PIN) on the board and unplugging either one of them will allow the audio output to operate just fine, they just cannot both be plugged in at the same time.
So I ended up leaving the one that shows the active function (T, P, 1, 2, 3, 4, 5) unplugged and left the one that controls the standby light plugged in and hooked it up and started using it. The only other issue that I was aware of with the unit was that the equalizer bulbs were blown. Doing some reading on the forums I saw mention that these are more than just lights and are used as resistors in other parts of the unit. So I ordered some replacement bulbs and hoped this would fix the Program-Indication board issue.
I replaced the bulbs (with appropriate voltage, wattage, size, incandescent) and powered the unit up and the equalizer lights up fine and everything works, well except for when I have both the the 6 PIN and 8 PIN plugged into the Program-Indication board.
I am using the unit on a daily basis and it sounds so good and am really enjoying it. I am just out of ideas on how to fix that Program-Indication board so I can have the unit "100%" functional. Hoping someone has some advice to offer. I have attached some images of what that Program-Indication board is in case my description of what it is isn't clear.
"I replaced the bulbs (with appropriate voltage, wattage"
Appropriate as in per the servicemanual or as in correct?- Because the servicemanuals give wrong info.
Check the muting signal. It can be held active if wrong lamp(s) are fitted to the source indicators.
Martin
It was my understanding that the service manual was incorrect with the 12V specification and that the proper part should be a ~15V 1W bulb.
This is what I replaced the 3 EQ bulbs with: https://www.arrow.com/en/products/2182/jkl-components
That was the closest I could find available and they are 14V 0.08A bulbs (1.12W). I did only replace the 3 blown EQ section bulbs and I left the original functioning Program-Indication bulbs alone. I have lots of extras, so it it is suggested I replace them all to fix this issue, I can. I did figure leaving the original functional bulbs in place made the most sense since they are very easy to access and replace if they blow. The replacements fit in the lamp holder clips pretty well, they just do not have that little girdled part that the originals had for that perfect fit.
I will work on checking the muting signal. That can probably be checked at the base of TR206 and TR306 I imagine (or maybe there is a test point somewhere for it).
As always Martin, thanks for your help. I love your diligence in helping people keep these vintage units going. I know I am a new poster, but I have lurked and read lots of past threads over the past year or more for a wealth of information.
- David S.
daveys93: I will work on checking the muting signal. That can probably be checked at the base of TR206 and TR306 I imagine (or maybe there is a test point somewhere for it).
TR6 on the volume control board.Note how it senses the current flow of the source indicator lamp(s) to introduce a brief muting while switching source.If the original lamps are still fitted, and working, they can be ruled out as the reason, but 1,2W is to much for the source indicators. It will keep TR6 active constantly.