beogram 5500 turntable repair, gear disassembly?

[ummagumma]

 I want to remove part 1609 which is catching on the arm movement, as documented here:

https://archivedforum2.beoworld.org/forums/t/40664.aspx

But I can’t figure out how to get all the gears apart? What’s the best way to get access to that thing? Thanks!

[ummagumma]

PS I have the service manual. Hoping things don’t go flying when I try taking apart the gears, as there are springs and wires with tension on the parts.

[ummagumma]

Ok I managed to get part 1609 out. It is bent just like the other pics in that thread. Dis- and re-assembly was a pain in the ass. I have not powered it back on yet: the arm gets stuck halfway thru travel, when I slide it manually. In both directions. The gears seem to be stuck there, and I’m wary of breaking something. Does it matter how the gears are oriented, relative to each other? I did not see anything about that in the manual.

 

Thanks for any advice

[ummagumma]

I may have figured it out….pulled it all apart again, part 1608 appears to have popped off the shaft it’s supposed to sit on, when I removed 1609. But now the C-clip holding 1634 has flown across the room & may be gone for good!

[ummagumma]

 

Powered it up, hit “turn” to get the platter spinning, it ran for a bit & then the arm moved across about halfway, the platter jolted to a stop & I can’t even get it to power on now. I wonder if the internal fuse tripped once it hit some resistance?

 

The arm slid freely, but now it’s difficult to move manually. If I pull the platter & mess with the drive gear that has the white plastic slider, the arm frees up again. But the TT will not power on.

[ummagumma]

I think I know what happened: because I lost the C clip for part 1634, it wasn’t pressed all the way down. A clue would have been I noticed the platter looked like it was rubbing on the top of 1634, before I powered it up.

 

So something down in the gears wasn’t right: when I powered it up and the motor hit that resistance, it might have killed the solonoid piston, which is why it won’t  even power on now that I’ve seated 1634 properly. I can’t find the C clip either: I knew something was going to fly off despite being careful: this is such a fiddly POS to work on.

 

Unless I have the gears installed wrong & there is a switch stopping the circuit from starting. I saw reference to gear installation the 3rd time I looked thru the service manual. Will check it out tommorrow, I don’t feel like pulling this apart again tonight.

 

Hopefully this log is useful for someone else.

[ummagumma]

Captains log, stardate 2022:

 

There are notes in the 2nd half of the SM that explain orientation for installing some of the gears. Easy to miss, as you need to skip past all the other language versions of part 1. Usually manuals have each language’s contents organized together?

 

I pulled it all apart & installed the gears according to the manual, x2 checked with pics I took before disassembly.

 

Fuse is still good, so I suspect I need to rebuild the piston, using condor audio’s doc for reference.

[ummagumma]

Is there anything other than a dead solonoid that will show symptoms like this?

The unit doesn’t even power on anymore. As I said, the fuse is ok.

I might check transistors 4, 5 as they are in the same circuit as the 2 relays/solonoid.

[ummagumma]

Pulled it apart & checked the solenoid, both coils appear to have continuity, so I don’t think it burned up.

Also removed & tested diodes 3,4 as they are in the solenoid circuit. Both tested good.

Very impressed with how serviceable B&O makes their stuff. Clear labelling on the PCB’s, and hinged cases for access. I discovered the lid support wire at the back, which is convenient. I had been propping the lid up with a hook screwed into the wall earlier.

Connector P6 is the most awkward thing I have ever seen though. By the time I wriggled it off, I had to resolder all the connector points under the board since some of the pins came loose.

 

5500 turntable still won’t power up.

 

Am I posting this in the wrong section? Surprised no one has replied? Has nobody here repaired one of these before?

 

Thx

[ummagumma]

Forgot to mention: the reason I reassembled it was I noticed switch #2 was jammed, and thought maybe it, or the loose connector P6 might have been the reason it wasn’t working. No such luck though.

[Mark-sf]

If you are getting 12v at the anode of D1 then pressing Play should cause pin 10 to go high and turn it on. Please confirm you see 5v on that pin.

[ummagumma]

Thanks for the tip! Will check it out

[ummagumma]

I’m not getting any voltage at the anode of D1. Well, I get some millivolts. I checked my multimeter on a 1.5v battery to make sure I was using it correctly, thought maybe my range setting was off.

 

R26 right beside it goes to ground, and also R2. I measured from the anode of D1 to ground. Cathode to ground gave me nothing, as expected.

 

But this coincides with the symptoms of the TT , as it won’t even power on.

 

Is there another safety device in the 5500 TT besides the fuse? I wonder if the mechanical gear resistance took something out.

 

I plan to replace caps C2 ( 470uF 16v ) and C28 ( 2.2 uF 50v ) but need to order them.

 

I’m curious about the solenoid: pics below. It appears to be ok to me? The inside piece with 2 plastic ends & magnet in the middle is intact & slides freely. So I don’t think I need to rebuild it? Unless there is something else in there?

Thanks again

 

[ummagumma]

pics

[Mark-sf]

It appears you are not getting DC voltage from the regulator on PC Bd #2. I would disconnect  connector P3 and measure the DC voltage on the input and output of the regulator, IC1. Either C3 or C4 could be a problem but id the fuse is not blowing, I would expect the regulator has opened. It’s not likely the solenoid unless you hear it activate when simply plugging in the power cord. Then either TR4 or 5 could be shorted.

[ummagumma]

Thanks again! Will investigate

I have also been testing it with the beomaster set to “phono” in case it makes a difference whether the TT is simply on, vs activated by the system to play

[ummagumma]

Hmm I’m getting 0.17 volts across the red & black wires @ IC1. Their source points on the PCB2 regulator board. P3 is disconnected from the control board PCB1, so there should be no load on it.

Maybe I need a new regulator?

I Never even noticed C4 hidden down there!

And that big clip-on capacitor C3 @1000 uF, can you still buy those?

*edit* hang on, I just realized those points depend on the state of C4, I do need to measure before & after the regulator. I don’t see the voltage listed before the regulator on the SM though.

 

 

[ummagumma]

Allright I’m sick of editing that post…sorry for the mess.

It looks like the regulator is readily available, at least:

 

https://www.digikey.ca/en/products/detail/stmicroelectronics/L7812CV/585973

[ummagumma]

I can’t even get that board PCB2 out. The regulator has an aluminum heatsink wedged on top of it, that is quite difficult to pry out & holds everything down. I’m wary of breaking something else. It’s awkward to get probes in there otherwise & if I need to replace anything, PCB2 will have to come out.

[Mark-sf]

It’s easiest to remove the power supply whole as it’s carrier is secured with screws from the bottom.

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