I guess we have a partial success with the possibility of complete success.  But I'm not holding my breath.

Yes, exercising the 33 pot led to a full range of much too slow to much too fast speeds.  However, exercising the 45 pot led to a range of much, much too slow to almost the correct speed.  I could just get to the correct 45 speed if the main board pot was fully set CCW (or left, IYP) and the adjustment on the control panel was fully set to the right at "3."

But the 33 speed is not staying constant.  I'll set it while a record is playing, then maybe 1.5 to 2 minutes later there will be a noticeable slowing in the speed.  I'll adjust again, and it may play fine for five minutes.  Then I'll hit stop.  Wait a half minute, hit start, and the record will start at the beginning too fast.  I haven't been able to play a full album side at a constant speed - correct speed or not.

I'll give it a rest, exercise the pots some more, and try again.

Is there anything else I can try besides replacing the pots or board?

Oh, and pardon my poor manners.  Thanks everyone for the help!  It is deeply appreciated.

Neither speed will stay stable.  Going to try to source the parts for replacement.

So I've been walking my wife through all this - not that she's all that interested, but she understands what it means to me.  And I'm on the web sourcing replacement trimmers, and she says, "Did you try Radio Shack?  That's where you went to get the capacitors to fix the TV that one time."

So I went on Radio Shack's web site, and lo and behold, they have a reasonable approximation of the trimmers.  And, turns out they're open until 8:00 pm on Sunday nights.  Long story short (too late!), I've already replaced the trimmers.

One of the all time easy desolder jobs.  Can these old trimmers be reconditioned with Deoxit or something?  Or should they go in the souvenir bin with the MMC4 my toddlers thought would be fun to grind down to nothing?

So far I've tried out the new trimmers on a single LP side.  The speed was not rock solid stable.  I'll play more records and see if a burn-in helps stabilize the speed and report back.

Meanwhile, I'm sure I can get better trimmers than the ones I got tonight at Radio Shack.  Any suggestions?

Hi Rich, Mouser are superb :-)

Tbh doesn't sound like the trimmers are at fault if replacements haven't cured the problem... You maybe need to start by checking if you have a nice stable supply. Does the motor run freely?

Hmm also have the replacement trimmers mean't the 45 setting can now be adjusted to its proper speed and beyond? Is 45 stable at all?

Have you replaced the original capacitors yet? I would. Even though they look good doesnt mean they are. is there a can or two right off the transformer main / power supply.

Unstable speed culprits are normally :

- Trimmers
- Relay contacts (if your version has the speed selector relay)
- Capacitors, electrolytics and tantals
- Motor cleaning and lubrication

While playing, tap the motor lightly with a pencil or similar. If it changes speed it
will definitely need cleaning etc.

Martin

Thanks again, for the help and suggestions.

This morning I started off by playing an LP.  The speed (33) started too fast.  I did no adjustments, and eventually the speed settled down to pretty close to the correct speed after half a song (1.5 to 2 minutes).  I adjusted with the new PCB trimmer, then restarted the LP.  It seemed OK for about a half a song, then went slow.  I adjusted again, but this time let the LP play for about 10 minutes.  The speed stayed very close to correct, but would wander from a little slow, to OK, to a little fast, back to OK, to a little slow, etc. 

I then tried a 7" single (45).  After about 3 plays through the song - I purposefully chose the (for this situation anyway) ironically titled "Hey Hey What Can I Do?" - I came to the conclusion I don't have enough "range" in the 45 trimmer to get up to speed.  It's just a hair too slow.  Of course, it isn't stable, either.

And now, specific remarks to Olly, Eugene, and Martin to follow.

Step1:

Hi Rich, Mouser are superb :-)

Tbh doesn't sound like the trimmers are at fault if replacements haven't cured the problem... You maybe need to start by checking if you have a nice stable supply. Does the motor run freely?

Hmm also have the replacement trimmers mean't the 45 setting can now be adjusted to its proper speed and beyond? Is 45 stable at all?

I think you're right about the trimmers, and based on how the 33 speed is wandering, isn't it safe to say the motor isn't getting a stable supply?  The motor seems fine (see below).  As noted above, I can't get to 45 at all.

Eugene:

Have you replaced the original capacitors yet? I would. Even though they look good doesnt mean they are. is there a can or two right off the transformer main / power supply.

I have only replaced the two speed trimmers so far, as well as both belts.

Here's a picture of all the guts.  Just south of the transformer is a fuse box and further south is just one can.

And a closer shot of the NW quadrant.

Dillen:

Unstable speed culprits are normally :

- Trimmers
- Relay contacts (if your version has the speed selector relay)
- Capacitors, electrolytics and tantals
- Motor cleaning and lubrication

While playing, tap the motor lightly with a pencil or similar. If it changes speed it
will definitely need cleaning etc.

Martin

I tapped the motor (a lot!) and did not have any speed changes.

Is this a speed selector relay?

Do you have a capacitor kit for a BG4002 Type 5513?

It is just me Rich, but whenever I have a fault on a piece of equipment over 20 years old I suspect caps and trimmers. If your TT was on my bench I would set to work on replacing every single electro. you have already replaced the two speed trimmers. There probably are a couple more that may need checked.

Yes you can try deoxit on trimmers but my experience is that only works about half the time and no more than what a timmer costs why not simply replace it if you suspect it may be losing contact.

Radio Shack may be a bit of a joke in some ways but what little product they do stock is of good quality. N need to re- replace your trimmers.

But thats just me. If you can trace the circuit to the motor there should be a cap right in from of the motor power supply. It could also be a failing motor or a very dirty one !

BTW, where did you get your disk and strobo kit.

Yes that is the relay! Remove the plastic cover and wipe the contacts using a thin piece of folded paper dipped in isopropyl (carefully press the contacts together and pull paper between contacts) and see if there is any improvement...

Step1:

Yes that is the relay! Remove the plastic cover and wipe the contacts using a thin piece of folded paper dipped in isopropyl (carefully press the contacts together and pull paper between contacts) and see if there is any improvement...

 

Thanks, Olly.  Will get her back out tomorrow night.  Right now, I've got some peeps over for the Independence Day soiree and I've got half a buzz going.  Thank you, Newcastle Brown Ale.

Eugene:

BTW, where did you get your disk and strobo kit.

Here.  Part way down the page.

Rich:

Is this a speed selector relay?

Do you have a capacitor kit for a BG4002 Type 5513?

Yes and yes.
That relay is a known trouble-maker. I suggest you check it before you
replace the trimmers again.
Tap it gently while playing, just like you did the motor - or just replace it.

Martin

Step1:

Yes that is the relay! Remove the plastic cover and wipe the contacts using a thin piece of folded paper dipped in isopropyl (carefully press the contacts together and pull paper between contacts) and see if there is any improvement...

 

Doing this seemed to do the trick...but....

Leaving the relay soldered to the board, I took the plastic cover off and did as Olly directed.  This is easy on the side closest to the board edge, next to impossible on the other side without removing a resistor or two (which I did not do).  So one side should have improved contact, the other, maybe.  The side with improved contact leads directly to the replaced trimmers.  The other side...well...I didn't trace the circuit very far because I wasn't sure the other side is even in the circuit.

And of course I got impatient to try it out so stopped tracing the circuit and put the turntable back together.

33 seemed to work all right through two songs.

Checked 45 and now I had a full range from too slow to too fast.  So that was improvement for sure.

Went back to 33.  Had to adjust a bit again, which took about 30 seconds.  The speed was solid for the rest of the album side (20 minutes or so).  I flipped the LP and played the other side.  The speed was solid into the 4th of 5 songs then abruptly fell a bit slow and stayed there.  After waiting a minute to see if the speed would go up "on its own," I adjusted back up again.  The speed was solid again for the rest of the LP (5 minutes or so).

Played a 45 again.  Speed had to be adjusted up a bit but stayed solid after the bump up.

SO CLOSE!  Man, after I flipped the LP and the speed was solid for a song, I thought the collective wisdom of this forum had licked another problem!  Well, I guess we have.  It's the relay.  Should I just desolder it, remove it from the board, try to clean it even better, then solder it back in?

Or should I just replace the relay?  If this is the better option, can anyone suggest a suitable replacement?  If I'm reading the "tacho control" schematic in the service manual right, it looks like the relay is a single pole double throw.  (Never messed with a relay before.  This is a new one on me.)

Well, I'm heading back to try another LP.

We interrupt our regularly scheduled program to make an important announcement.

During all this testing of the BG4002, I've come to realize my Beomaster 1900 makes a superb headphone amplifier.

And back to our program.

Went back to the BG4002 to find the 45 still on the table.  So I played it.  Before the stylus even touched down I could tell the platter was spinning way too fast.  Made an adjustment on the main board and it played fine and stable the whole song.

Put an LP on and played through all of side 1 at perfect speed with no adjustment.  Took a break to pour a whiskey and make this post.  Now I'm off again to play the other side.

Let's all cross our fingers, shall we?

And side 2 played perfectly.  More listening tomorrow on the bench, I guess.  Don't want to jinx the whole thing by putting the 4002 back into the main system just yet.

(Almost) well done!

Those relays are nothing but trouble... On my Beogram CD3300 the same relay poses the same problems. Even after a good cleanup the problem reappears. I haven't been able to source any so far (the flat ones with the same pinout disposition).

Should anyone here have a reliable supply source, please let us know!

I guess you could wire a different relay somewhere else if a replacement that fits on the PCB cannot be found.

The other contacts in the relay switch between the two resistor chains for speed control, and the other contacts switch between the 33/45 marker lamps. I believe you could just disconnect the relay and connect a jumper wire in place of the speed selection contacts to have the speed fixed at either 33 or 45 - that should prove whether the problem is in the relay or somewhere else...

tournedos:

I guess you could wire a different relay somewhere else if a replacement that fits on the PCB cannot be found.

That's exactly what I do.
The flat Siemens type relays come up for sale occasionally but I wouldn't rush to buy them.
They will be of the same vintage and they will have oxidized contacts too.

Martin

Came home this evening and the speed checked out again.  Let's all keep our fingers crossed again because the BG4002 is back in the main system!

Thanks everyone for help, suggestions, guidance, etc.  This truly is an exceptional group of people, and I am very happy to have found Beoworld.