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This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
ok guys, I need some help please.
i just completed a full cap and lamp replacement from Martin. I also did the 2 large caps, and that seems to have remedied my muffled channel issue.
Now the problem.
When I install the touchpad panel, none of the "buttons" work. I've taken it apart and reinstalled everything multiple times. Quadruple checked that all pins are aligned and touching.
All inputs are functional and switchable with the remote. All inputs are functional and switchable when I use my finger, or touch the "fork" that rests against the pin with a screwdriver.
I have two functional 2400s, so I swapped touchpad panels. Both work exactly as they should on the other one, but neither function on this one.
WHAT AM I MISSING?
is there anything else that makes this function other than a strictly mechanical connection between the forks and the pins?
I feel like I'm going insane.
I've done some more digging, but haven't come up with anything
I have 12-13 volts at the collector of all the input selector transistors. But I don't have -6 at the base of TR22, which I think I need. On my working 2400 I have -6v at the standby pin and the base of TR22.
The non-working one shows 0 at the base. I've replaced it even though it seemed to test ok out of circuit.
I have 15v at the positive and 13v at the negative of c86, 13-14v at both ends of r128
15v at the positive of c71
nothing at either end of c87, the base of tr22, or the standby pin.
Can anyone smarter than me tell me where to look next?
i can't figure out why all the inputs work with my finger or the remote, but not the contacts of the touch pads.
Ok, I've replaced all the sensitouch transistors on the off chance it was disrupting the circuit. No dice. Same issue.
I've cleaned all the touch pins and forks, there is absolutely no issue whatsoever with their contacting cleanly and with tension.
Why in the world does this work with my finger, flawlessly I might add, but it is literally dead through the touch panel?
All caps and lamps per Martin have been replaced, so it can't be some weird lamp wattage nonsense.
I noticed in Martin's directions that the C71 polarity varies. I am 90% certain I put it in the same way, and it corresponds with the markings on the board, and I'm getting 15V at it. Is there any chance it should be installed against the markings on the board? I hesitate to switch it because I don't want to blow anything up, and I'm pretty sure it's in the right way. I was absolutely sure when I did it, but now that there's this weird issue it makes me question it.
Anyone?
Here's a comparison of readings from the working and non-working 2400s. Don't know if this is directly related to my touchpad issue, but it seems likely. If anyone can help me figure out why I'm getting different readings at the standby pin, I'd sure appreciate it.
I'd say a shorted B-E on the transistor, or the touchpads bronze-fork shorting to R129 (bent resistor).But keep in mind, that the emitter should have a 9V AC signal - not a DC.If the problem affects all sensitouch pads, then more likely a problem around TR7 on the volume control board.Is TR7 powered and oscillating?If so - perhaps a broken L1 on the volume control board - or no connection to it.
Martin
Thanks Martin. TR7 seems to be working, it reads the same on both machines.
New wrinkle that I've discovered. Everything seemed to be working fine before I replaced the 2 large filter caps, I used 6800uf 35V Nichicons.
Now it seems that the relay is stuck open (or closed). When I use my finger to select an input from standby, the relay really doesn't click anymore. It switches, but there's no click. The working one has a very audible click and visible movement.
ALSO, PROBABLY A MUCH LARGER ISSUE- In standby, the filter caps on the non-working one are reading and I think they shouldn't. The left is showing -31.5 and the right is reading 31.5.
On the working one the large filter caps don't read anything in standby. Once an input is selected, THEN the left shows -31.5, and the right 31.5.
I replaced the wires exactly as removed, and I replaced as I went along to make sure I didn't hose anything up. AND YET, I've hosed everything up.
Any brilliant insight?
How about a bad OD1 rectifier?
The 2 neutrals are each reading 23.4 AC at the rectifier, and of course at the relay. This is in standby as well as operating modes.
On my working 2400, they don't read 23.4 UNTIL it's out of standby.
Workable hypothesis?
Just to confirm I replaced the large caps right...
The yellow and blue wires go to the negative of the left cap, the red and orange go to the positive of the right cap, and the blacks basically bridge between the + and - of the two.
That's how it was when I took it apart, and how it is on my working example. It's just not functioning like it should anymore.
Went to look into your L1 suggestion...
Neither of my 2400s have an L1. They do have an odd looking TR21.
They're both the 3 IC versions, which unfortunately don't align with the schematics I have.
If it is still working if operated from the remote control - then it points to two faults at the same time.
TR7 on the early (1-IC) volume control version corresponds to TR21 on the later (3-IC). Check that it produces a nice AC sine.
With the amplifiers rectifier (+/- 31V) powered at all times and no relay clicking, the standby circuit must also be checked.It seems to be unable to cutoff power to the relay coil.Bad IC9, TR31, TR32, D55?Are the tonecontrol indicator lights on?Volume indicator lights on?
Checking the AC sine is going to be beyond my equipment and expertise unfortunately.
I will check IC9, TR31, TR32, and D55.
Yes, once out of standby, all the lights are operational.
So I'm using my working 2400 as a comparison, and it appears that all those components read about the same.
I figured out that LI is the same on mine... TR21 (TR7) checks out on both machines.
TR31 is what I replaced initially to get this one back up and running. It seems to be ok still. I pulled TR32, and it appears to be good as well.
IC9 returns the same results across both machines. Same for D55.
Argh.
Perhaps the relay itself.Are its contacts still closed with the Beomaster disconnected from mains?
It was the relay. I went to listen again, because I knew I could hear it trying to kick the relay over, and it was. I could hear it sending a signal to open/close the the relay. I was doing it a few times, trying to determine if I could see the contact move just the slightest bit, and then it popped open!
For the uneducated like me, is this something that needs to get cracked open and the contacts cleaned? It looks like there's just a plastic cover that can be taken off.
So it seems that the open relay issue has been solved, which brings me right back to the sensitouch controls not responding.
I put it all together again in the hopes that the relay issue solved my problem, but it didn't.
I can operate everything with my finger, and the remote control, but not with the control panel.
I've cleaned all the pins and contacts, and replaced all the transistors related to the sensitouch pins.
Since there's access from the front, where you can see that the contacts are all aligned, with the slightest contact on an input fork with the tip of a screwdriver triggers the input selections.
It's like there's an invisible force field between the cover and the pins.
More digging. Keep in mind I'm at least the 3rd person in here, and I suspect I may be 4th. So I'm working with the previous fixes, as well as working from the one IC volume board schematic instead of the 3 IC schematic, so that's making things tricky.
I think my issue is on the volume board, anybody chime in if this makes sense.
The checks in the images are the spots that I believe I'm pulling correct voltages based off my working comparison 2400.
The Xs are where I'm getting no signal, but I believe I should be.
The little power symbol in the upper image is where if I try to pull a measurement of either the end of R58, or the base of TR21, it triggers the system to power on.
The red line in the second image is if I run a jumper between those two pins, pulling a measurement of either of those two spots no longer triggers it on, but it gives what I believe is the correct voltage reading.
My inclination is that L1 is bad. Does that seem to make sense?
I am also not getting any signal to TR23 or TR26.
Irata: ... My inclination is that L1 is bad. Does that seem to make sense? ...
...
When I suggested that a week or two ago, your answer was': "Neither of my 2400s have an L1".
The circuit board looks like a war zone in that corner.Some heavy soldering has been going on there.At least one trace is broken or burned. Are all components still present in that corner - C21 etc.?
Yes, sorry, my apologies, that was confusion on my end. I was mistakenly thinking that TR21 was L1, since I didn't have a TR7, different volume board. When you clarified that TR7 is actually TR21 on my board, it dawned on me what L1 was. Then I got distracted by dealing with the stuck relay.
Now I'm back digging around.
yes, this board looks like hell, one of the previous owners managed to destroy some solder pads, and the wires are all over the place, hence my difficulty in working in there. I do believe that all the components are intact, but the black jumper wire may be taking a shortcut around the open burned-out solder pad.
Does the lack of power at the collector of TR7, and at TR23 and TR26 seem to indicate that L1 is bad?
Now it's YOU talking about TR7... :-)
See how much my head is spinning trying to get this little guy back up and running?
Knowing full well this will further cement my status as an electronics less-than-novice, what can I replace L1 with? There doesn't seem to be an easily identifiable part number in the service manual, like there are with all the transistors.
L1 is not that easy. It's a special component and it will need adjusting.Considering the general condition of that module, I would look in the dungeons for a complete replacement board.
That's what I was afraid of. I've been looking for a suitable replacement adjustable inductor, without any luck.
Fixed.
I unsoldered L1 last night, and ran an ohm meter across the leads. It showed similar resistance to the working version, and the leads were all connected as they should be, so my guess was L1 was still intact.
I took another look at the board, and went back to questioning why running a jumper was stopping it from triggering the system on.
It looked like one of the connections was bypassed. I am unsure if it was from the previous owner trying to make the LEDs in the tonecontrol board function, or if they were bypassing a burnt section of board. I think I assumed it was because of the missing solder pad, but since it worked before I corrected the bulbs, I think it may have been related to the LED modification.
At any rate, I reran all the connections correctly, with a few extra jumper wires given the condition of this board, and now L1 is giving the appropriate signal back to the sensitouch transistors.
I put the front panel back on, which I'm pretty good at now, and everything triggered as expected.
Argh. Fix one thing, something else goes wrong. This thing is really starting to test my patience.
Put everything together, the tuner stops working...
Any common faults for me to look into?
Good job, congrats admire your "never give up" way of working, an interesting thread that I have been following with great interest
Collecting Vintage B&O is not a hobby, its a lifestyle.
Good job, admire your "never give up" spirit, an interesting thread that I and others have been following with great interest
Excellent job on the volume board.The tuner stopped working - how?Silent or just static? No stations found?
Thanks guys. My never give up attitude is a blessing and a curse. :)
I told my buddy I'm smart persistent enough to fix most things, but too dumb to realize my limitations.
The tuner just stopped picking up anything but static. I've noticed if I put my finger on the board around C7, C8, it will start to pick up one very faint station. This station will not change when I adjust the tuner dial either. Just stays the same faint station from somewhere.
That's as far as I've dug in. I needed to take a little break after this morning's setback.
Check that the connectors to the tonecontrol/tuning presets board are correctly seated, not shorting or broken.Check if the tuning voltage changes as you travel the dial.
All three connectors are definitely seated correctly. I don't see any visible shorts or broken connections.
All 5 tuner dials increase in voltage when I go up, and decrease in voltage when I go down.
I've swapped out the upper PCB boards too, and they both work on the working 2400, and both don't on this one. So the issue must reside on the main board somewhere. Been looking for loose connections without any luck.
BACK IN BUSINESS!!!
After taking the 2400 mostly apart again, the red wire pulled away from the tuner box. There was my loose connection!
Resoldered it back in and the tuner came back to life!
Now I'm off to go put it together (AGAIN) and give those speakers some use.
Thanks for listening and giving advice guys!
Here it is, just in time for a Led Zeppelin weekend.
For my first non-speaker electronics project, I sure picked a doozy to learn on. Trial by fire I say.
Beautiful machine though, couldn't pass it up.
I feel like this is how the design process went:
Engineer: "Hey, if we made the cabinet taller, I could move the --"
Jacob Jensen: "No -- You make it thinner."
Irata: Engineer: "Hey, if we made the cabinet taller, I could move the --" Jacob Jensen: "No -- You make it thinner.", I want it flat, flat, flat, use your fantasy or a hammer
Jacob Jensen: "No -- You make it thinner.", I want it flat, flat, flat, use your fantasy or a hammer
Enjoy the music