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
Thanks for the information!
Yes that is what I was afraid of too, making parts units of my two working ones. They are functioning at a high level and the little annoyances are not a huge deal to me right now.
Good idea on the parts machine, I'll tinker around with it some. I don't even have a good soldering iron so I won't be doing any of that anytime soon.
I do have many years experience fixing PCs and building them. So I have a little handyman in me.
I pulled that mute relay/din socket part. It had a metal shield over a yellow rectangle shaped part. I was expecting some kind of mechanical switch.
Also how do I pull that circuit board that is under the push buttons?
- It looks like it slides out from these plastic clips. I am not sure if I take the top button plate off first of the board first.
- Also not sure how that black power box comes out. I don't want to force anything.
You can see the control button plate open here. You do have to be gentle and careful with the removal but basically, you pop it open from the top then it slides off the bottom (front of the Beogram). The top part is held in place by plastic tabs. You can see one in the picture. The transformer pops off its connector by pushing it up from underneath the Beogram. When you look underneath you can see the rectangular base of the transformer (middle of the page here).
I did push that transformer box from underneath but could only get the far side to come up because the board is blocking me from pushing it up evenly on both sides. And it looks like the transformer has to come out first in order to slide the board out from the thick plastic clips.
I was pushing on the outside edge of the lid from below but not directly on the power box. I did not want to push on the transformer in case the lid was to come out first to unhook something.
So can I just push on the transform part and it and cover will just pop up? I'm just cautious because its pretty tight fight and do not want to break that old plastic if I can help it. I appreciate the guidance.
the front end of the transformer is where 12? heavy terminal pins grasp the main board; that is the area you need to push up on; I don't think anything else retains it. Other than the pins and the lid, I don't think anything else restrains it, but I could be wrong. I remember having to push fairly hard and on the terminal end of the unit to get it out.
I took a photo of the inside of the Mute relay. Is that a seal unit, if its bad is it fixable?
pfcs49: the front end of the transformer is where 12? heavy terminal pins grasp the main board; that is the area you need to push up on; I don't think anything else retains it. Other than the pins and the lid, I don't think anything else restrains it, but I could be wrong. I remember having to push fairly hard and on the terminal end of the unit to get it out.
Right, there is a connector on the transformer that slides right onto the pins of the main circuit board. The whole transformer assembly slides up and out the top. It does fit fairly tight but if you keep applying pressure to the base with your thumbs it should start to move. After that, it is a little tricky getting the circuit board assembly out with the control panel attached but it can be done if you go slow and are careful. Once out, I re-attach the transformer when I want to run some tests.
-sonavor
@sonavor-I hope you are a quick learner! You may need to learn some basic electrical stuff to be effective here.
That is the relay; all that I've opened had clear covers. If this is the turntable that develops a weak channel, you could try removing the cover (I coached you somewhere how to do this-AK?) and treating the contacts or perhaps slipping paper between them to see if the problem resolves.
One diagnostic possibility is to read and understand wiring diagrams, understand things like relays and resistance, and basic circuitry, understand Ohms law and it's implications; then to apply simple logic to see ways to diagnose problems like this one with a VOM (volt/ohm meter) Failing that, you really will need a "self-healing" Beoggram! or you will be in a real quagmire!
Thanks, yes I am slowly doing a refresher on basic circuits. Hands on is totally different than on paper. Right now I am just trying to get it apart without breaking anything. That photo is from my parts unit not the one with the weak channel.
I don't think it was me you coached on AK, I was not even to the point of removing the cover. But I can use it now.
I am not even close to soldering anything. I am asking questions to get a better understanding of how it works. I have no idea how that mute relay works right now. Even If I knew exactly the problem I would not fix it yet. I don't even own a decent soldering iron so I am light years behind you Obi Wan :)
I guess what I meant was are the parts in the little relay generic? Lets say that little yellow box is bad, is that a replaceable part? Or is this more about broken wire, bad solder or resistor (which are generic parts) I think I only saw two resistors on that relay.
I appreciate the help.
there's scores of relays and many differences, but this one is very simple. One magnetic coil (with 2 terminals) pulls the 2 pair of relay contacts (one pair per channel) apart when un-muting, which separates the + & - signal circuits/wires from their formerly joined/shorted/shunted muted state.
But if the relay or associated circuitry is the fault, it is a tricky one! The circuit is relatively high impedance/resistance (the resistance of the cartridge) while everything else in it is very low resistance. To cause such a roughly halving of signal strength requires a fairly high resistance fault, and that is not likely. But if this is truly a fault between the DIN socket and the cartridge plug, and NOT the cartridge or the stuff downstream of the DIN socket, (interconnect and amplifier) then it is somewhere between those points. And if it is, an ohmmeter is your best friend! As I alluded to, you could remove the plastic....wait-I'm checking....yes, here is my response to you on AK:
Sorry for the frustration but I don't know if I ever read that post. I left AK long ago and have not been back.
Oh that part was very appreciated. I do not work on this every day. I have kids, house cottage etc. Its something I get around to when I can.
Reading comprehension? What are you referring to? Memory probably, I have recently had a few bouts of encephalitis which did affect my short term memory. I do remember you sending that clip but no recollection of the above post. Its not intentional. Sorry.
This: (Maybe I should have said memory instead of comprehension)
Hey thanks for digging that up. I have a vague recollection of the first post but not the second.
I do own this multimeter. Is this one good enough?
Now cool it down boys. @rajod, if you want to know if your DMM is good, look for reviews on the net, also how to use it, As Dillen once told someone, we dont educate technicians or electricians, we do like to help, but the basics you must learn somewhere ells.
When I started out, I had to do my homework, hours on the internet, and then i did my first one a BM 901, and went from there.
Collecting Vintage B&O is not a hobby, its a lifestyle.
Soren, thanks for the suggestions.
I think the issue was his frustration over my memory issues on some old posts. Which I can appreciate.
But I was never close to being heated in this discussion so I think you might be reading too much into it.
I fixed the problem with the intermittant channel drop out (knock on wood)
I was hesitant to open up that beogram because its working and all the plastic pieces are like new intact.
As I said before the DIN socket felt loose, not the connection but the housing. So I did not want to pull on the plug in fear of pulling the entire socket out, same thing with pushing it in.
Today a channel dropped and it would not come back up even with the power on/off trick.
The issue was so simple. The Din socket was tight but one of the pins must have not been inserted all the way. Once I knew how the socket inside was held down I was not afraid to push it in too hard. It pushed in maybe 1/4" further. As soon as I did that the channels are both up. Been fine all day too. When it went out before jiggling it made no difference because the the DIN cable and socket were moving as a unit. The connection was still marginal.
I still don't understand why powering it on/off made it work before though. One of the pins was not making enough contact which would drop the voltage of one channel by maybe 50 percent but only intermittent.
Anyway happy that its fixed with no soldering needed.
A resurrection!
Well done!
Jacques
Oh it was too good to be true. A few days later it started acting up again. I pulled it apart and lubricated it, remounted the power supply (the top was no snapped in) Also found the ground to the inside of the case was off. Left channel is still low. So It probably is the mute relay that just so happen to begin to operate properly when I reseated the plug.
It could be the cable itself so I am waiting on a replacement cable. If its not the cable. There are a few things I can try.
1. Pop open the plastic mute relay switch and Spray it out with contact cleaner.
2. Cut the wires that operate the mute relay. Not sure which ones.
3. Replace the mute relay (if I can find the part)
I like your foot, but I don't like the solder joints at all...
Agree with Jacques, and are there components missing on the PCB ?, and where do you get your pedicure
I still have the new cable on order but I had another cable to check it with. It works! again Knock on wood.
I checked the cable for continuity with my multimeter and was getting nothing through the left channel. It must be a pulled wire near the din socket on the cable. It was getting about 1/2 signal through while on the TT. My guess is the previous owner unplugged by grabbing the cable vs the head of the DIN connector and probably partially pulled the left wire out of contact or so it was barely connecting.
The strange thing is I never heard any static when wiggling the cable during play. I've had other TTs with a bad RCA jack and they always sounded static like if I moved the cable during play.
LOL, Yea I should have cropped that ugly foot out.
Well I did not take a picture of the actual unit, that is a photo of my unworking parts machine and yes it does look to have been re soldered at some point, it even looks like it overflowed to the next pin.
The unit in question is still the stock soldering and it looks ok. A new cable seems to have fixed it for now.
i was hoping someone here could take a crack at answering this puzzle.
I compared the working and intermittant cable and found that three pins of the din are used.
pins 2,3,5 and outside ring is the phono ground.
R RCA CENTER PIN ------ DIN 3
L RCA CENTER PIN ------ DIN 5
L & R RCA OUTER ------ twisted together at DIN 2 pin grounds or neg.
On the faulty left cord the neg/ ground is not connected to the outer coller of the left RCA JACK.
So basically the left channel is not getting the ground.
i checked with multi meter.
So why would it work at all?
and why would turning the power on/off fix it for a few hours?
Answer?
- left channel can play wo ground somehow
- weak ground caused left coil of cart to decrease output?
I realize a fix is new cable i just would like to understand the why of it.