My first post and the sub cat may be wrong. Apologies.
I mashed the Philips socket on one of the speed control trim pots on a B&O RX turntable control board. If I can find one or two that would be great. If I have to buy a dozen… I’ll have to think about it! Thanks Photo attached.
Welcome to the forum.
Here’s a search result to get you started, it shows all the top adjust, PCB mount, single turn trim pots.
You will need to further filter the results for resistance value then choose one that fits the PCB.
Paul,
thanks for the reply. I had found those pages but, frankly, I was hoping that the old pots on my board might still be available. Seems not, or perhaps they are an item you don’t carry.
That said, I’m a tech ignoramus. I’m sure if I had the parts that I could do the soldering. Picking the right one is not in my skill set. The service manual for the turntable is unavailable to me so determining resistance values is beyond me.
I don’t want you to go to any heroics, but is there a way you could get me into a smaller ball park? Would having a pic of the backside of the PCB help? There is no writing on that side…
Thanks for your help
Dave Kunath
Sent from my Chamberlain garage door opener…
If you like this email, you can keep it…
I do text… I don’t Tweet… I don’t blog
2 + 2 = 4 the/she/it
Hello Dave
Well to get close to the part we would need more information the Resistance, wattage, and lead spec s(o it can fit on the board.
There is marking somewhere on the existing trim pots. It is not readable in the photo (at least to me). If you could transcribe the markings that would help narrow down the choices.
If you can also measure the trim pot or include a scale (ruler) in the photo that will help.
Paul.
That photo is from a vendor’s advert. I have no reason to suspect it’s not the correct one so I’d have to dismantle my unit to get an accurate measurement. I was hoping that some sort of relative size could be inferred from the other bits on the board.
That said, I’ll see if I can find some additional info.
Thanks!
Dave Kunath
Sent from my Chamberlain garage door opener…
If you like this email, you can keep it…
I do text… I don’t Tweet… I don’t blog
2 + 2 = 4 the/she/it
Hi @dpaulku ,
These look like an ‘old-school’ thumbwheel potentiometer. I used to have some of these exact types back in my radioshack tinkering days. It appears these types are not really around much as they mostly went away, and the ones remaining are much smaller surface mount style which are typically now used in radio tuning circuits, instead of through-board.
It is hard to know what resistance value they would be, as they are in direct relationship to the transistor circuitry design of the board, which would also depend on what type of transistor bias is being utilized. Below is a small list of potentiometer resistances that may work, please review datasheets. I do not foresee harm done in selecting any of the below values, but more so finding the value that produces the correct linear motor speed & resolution to the potentiometer position.
https://www.digikey.com/en/products/filter/thumbwheel-potentiometers/77?s=N4IgjCBcoEwCxVAYygMwIYBsDOBTANCAPZQDaIcYAzABxUAMIAuoQA4AuUIAyuwE4BLAHYBzEAF9CAVhoBORCBSQMOAsTIhacGjOZtOkHv2FjJIALQJoitFjyESkcrOrMz5mAqX8ArmsfkUm6E5vLW3nx%2BDhoQTOJmnk4gUjC4bkA
You may also want to remove the pots from the board and verify these indeed are the issue with a multimeter, at the very least you may be able to get a full resistance reading of what these values are, since alot of the time potentiometer issues are with the wiper and not with the entire resistance. Getting a pack of Micro Grabbers 461-1038-ND also work great if you were to remove the pots, and try various pot values without having to solder each one since you can hook these to the solder pads and swap pots out until the right one is found.
Ryan,
Very helpful. I’m not surprised that these are “off the books” these days.
I’ve got a feeler out to shop in Texas that services B&O tables. I basically threw my self at their mercy! I’ve not heard back yet if they have any numbers for me.
A thought just popped into my little head… could a guy find small surface mount pots that have hand knobs which might be relocated to a more accessible spot on the machine?
Hummmm.
If I find any info that will help, I’ll surely be back.
Thanks so much.
Dave Kunath
Sent from my Chamberlain garage door opener…
If you like this email, you can keep it…
I do text… I don’t Tweet… I don’t blog
2 + 2 = 4 the/she/it
Thanks!
Dave Kunath
Sent from my Chamberlain garage door opener…
If you like this email, you can keep it…
I do text… I don’t Tweet… I don’t blog
2 + 2 = 4 the/she/it
1 Like
Ryan,
I stumbled on a service manual that the forum boys suggest might apply to the RX table,
the Beogram 1800, 2000 & 5000.
(The layout and controls seem to me to be the same as my RX.)
As far as I can determine, the trim pots are referred to as Resisters R43 and R44 on the image
I grabbed out of the data sheets. (I’ve attached relevant docs.)
R43 is 100 kohm +/-20%
R44 is 25 kohm +/- 20%
Still no help on the size.
I’m a bit fuzzy on the pin configuration. Perhaps you could lend your best guess?
Your parts list, shortened linked here, ( http://bit.ly/3yNlbfL ) seems to suggest only two configurations,
and what I can’t see, I don’t guess about.
The original manual is a .php scan of the original document that I opened in LibreOffice. It’s not a particularly good scan
but If you can’t use my screen captures and can/want to deal with it, I’ve sent it along.
Thanks so much for your help and patience.
Dave Kunath
Sent from my Chamberlain garage door opener…
If you like this email, you can keep it…
I do text… I don’t Tweet… I don’t blog
2 + 2 = 4 the/she/it
B&O RX service_v2.php (2.91 MB)
Hi dpaulku,
I wonder if this is the correct schematic, or a revised schematic at the least as the board reference designators list R9 & R7 as the potentiometers.
If the schematic is correct then it looks like R43 is 100 kohm +/-20% closest option from aforementioned link would be 3352E-104LF-ND and R44 is 25 kohm +/- 20% would be 3352E-253LF-ND.
Ryan
I can’t say for sure. You made the same leap that I did. The photo of the RX board indeed does not present any R42/R43 options, but we’ve been “assured” that the other predecessor machines shared essentially the same the trim pot values.
Your choices of likely candidates, although I don’t see your “ND” designation in the tables.
Do these all share the same data sheet? The pin configuration from the table for these part numbers are not the same as the data sheet’s. I get it if the topology is the only difference.
If there’s no minimum order I’ll pick up a couple. I’m weighing this option against locating a parts doner on e-bay for the whole board…
Heck, I still have to get the thing dismantled!
Thanks so much for your assistance and patience.
Dave Kunath
Sent from my Chamberlain garage door opener…
If you like this email, you can keep it…
I do text… I don’t Tweet… I don’t blog
2 + 2 = 4 the/she/it
Hi @dpaulku ,
They are a little different but I would think they would work fine (according to the resistance specifications provided). But of course, no guarantees!
Good luck
Datasheet links can be found within these product pages, and they do share since they are of the same series:
3352E-104LF-ND
3352E-253LF-ND.
If you could work out the pin spacing within a fraction of a mm then I suspect something from the Piher PT15 line will fit nearly perfect. It is also large and sturdy to withstand a lot of hard adjustment.
However the pins used on the Piher are like the ones in the photo and can not be bent even sligthly without risking breaking the pot. So you need very accurate measurements of pin spacing.
The Bourns parts @Ryan_2724 suggested have nice flexible leads so they can be bent plenty without risk of damage so, they should be easy to fit in the existing holes. They are little smaller so they won’t take as much hard adjustment so use a lighter touch when turning them
Paul,
I’m going to try the Bourn options first. I’ll keep your suggestion in mind.
The only thing that I have trouble with in the Piher options is that I can’t see what they look like.
No pictures in the catalog and the data sheets suggest that they might not be happy being twiddled with a screwdriver.
You guys have been a great help for me and my little project.
These may be just the tip of the iceberg approaching!
Take care!
Dave Kunath
Sent from my Chamberlain garage door opener…
If you like this email, you can keep it…
I do text… I don’t Tweet… I don’t blog
2 + 2 = 4 the/she/it
1 Like