Macke

I'll do my best to get a full write up of tests performed tonight, but that means I'll probably have it done Sunday It works though! Full range of speed, even made my first bowl on it today in the rain because I couldn't wait

I ordered two of each 20k, 50k, 250k, 1M and 5M (5M because it's $.80). I know that the low speed is a 1M, the part number for it lead to the 201UR105B I linked above, but I ordered the 20K because if on the off chance the stamp on the back of the red (high) trimmer is the code created by CTS rather than the 250k value, the 250 would indicate a 20kohm trimmer. I'll start with the 20k and if it slows the wheel down enough on the top end I'll keep it, otherwise I'll be installing the trimmers with higher resistance until I find the spot I like. I ran it as just the slide pot for testing, so I'm not worried about damaging anything with the 20k test first.

Ordered new trimmers from digikey, they show up between Tuesday and Thursday next week, and I took this afternoon to make a 3D printable version of the plastic tray that they mount to since I had the tray stripped down and could get good measurements off of it. I'll be doing some trimmer assembly once they show up to run a few tests and will share my findings then, as well as the file for the tray once I get confirmation that there's no design issues with the file. I think I'll do my best to do a final write up of the tests I ran through, POSSIBLY a video of the steps taken, and links to components I purchased and replaced.

https://www.digikey.com/en/products/detail/cts-electrocomponents/201UR105B/98359 This link goes to the blue one (low side) and the part number leads to a 1M ohm 0.2W trimmer The high side is the "250k" one. I tried adjusting the dial on them during measurement and there was no resistance across any of the posts in any position, it's like they're completely shot. The plastic tray definitely smelled like hot/burnt electronics as well. If I had to guess, when the cap went bad it probably took this out with it?

Slide pot works great on its own! I HAD A VARIABLE SPEED WHEEL!! Turns out it doesn't work worth a hoot with the trim pots and I can't get any reading off of them, so I'd say it's safe to assume the trim pots are bad. I pulled them off of the plastic tray (I'm going to see if I can recreate it in a way that would allow for 3D printing a spare). One of the single turn pots has "250K" stamped on it, so I think it might be 250k ohms, but would that mean they're both 250k?

I have one of those slide pots waiting to order, but just in case it was one of the trim pots that went bad, with the slide pot being 1Mohm, should I be ordering 1Mohm trim pots too? They don't test well with my multimeter which is why I suspect trim pot issues over slide pot, but since they don't test I can't get a resistance reading in them.

The yellow capacitor was bad and wasn't providing any capacitance, which is why it fried the new resistor I had put on so quickly. Once I replaced both of those it didn't fry the resistor again, but I think it changed the flow of electricity when the resistor went out and was bypassing the pedal. Reinstalling the components seems to have redirected the flow (correctly) through the pedal again, which is why I assume bad pot, but I'll confirm that tonight.

Ok, been awhile since I've given any update on this. The new capacitor I had installed was good, the resistors all checked good, diodes were ok. With some guidance from a friend I bypassed the PCB and pot/pedal, I also installed a 500w $15 work light in place of the motor to test that the bridge, switch and fuse were good. The light turned on, so I connected the motor in that configuration instead of the light and it ran full speed again (hooray!/?) Now I've narrowed it *back* down to the PCB and pot, so tomorrow when I get home from work I'll run a jumper across the terminals for the potentiometer and see if it gets full current and spins full speed that way. Hopefully it does, then I'll only need to track down a replacement 60 year old slide potentiometer. Worst case scenario, I know how to turn it into a ceramics themed night stand/lamp combo Once I get it figured out I'll try to post a circuit diagram so anyone else that doesn't want to spend the money on a new control board has some sort of reference material

Ok, so the good news is that nothing exploded, overheated, popped, smoked or otherwise damaged new components. Soldered in a new capacitor, resistor, thyristor and bridge rectifier. The bad news is that the wheel no longer spins - period. Got a late start today and lost the light, but back to more testing tomorrow Not even sure where to start now, but one piece at a time as best I can I suppose. Wish I had more experience with the testing side of things edit: I have my suspicions that the capacitor is bad, I just checked the second capacitor in the pack and didn't get any sort of reading from it, almost like it's not completing the circuit with the multimeter

The replacement I ordered was NTE56022, it also says TO-48 isolated. I'll have to look up how to test em but the NTE cross reference said it was a direct replacement. Looks like almost everything will be here Friday, so I'll update this weekend. All this waiting is giving me plenty of time to get my gardening done at least

I ordered a new thyristor and a new bridge rectifier, going to be a few days for new components. Will probably look into a new controller if this fails and hope that the new one doesn't blow up immediately after installation Thank you all for your help through this!

I meeeean. It did work. Briefly. I haven't properly adjust the potentiometer, which is why I think it was spinning with the pedal all the way back, but the capacitor checked out and so I put it all back together. Got 3-4 slow revolutions out of it before it stopped and started smelling funny. Forgot to put in the magic smoke plug I guess. Back to square one. Ordering a new capacitor because they're fairly cheap, but not sure where I would find a replacement for this thyristor thing.

Just to follow up on this, I lifted both halves of the resistor today and it VERY much looked like brown-black-black-silver/gold which would indicate 10ohm, so I pilfered a 10 ohm resistor from work today and I'll be installing the board again tomorrow to see what happens. I'm not ready to pay for a new board just yet, but then again the "I'll do it myself" attitude is what got me into pottery in the first place. It was also the much more expensive way to get the bowls and plates that I wanted Will report back at some point tomorrow though!

Hello, I've been doing some searching and digging trying to find another thread with this specific question and was unable to. I just bought an older Brent b that I was told needed a whole new controller (the wheel spins full speed regardless of pedal position) but upon inspection I found a resistor that was fried. Unfortunately it's blackened enough and split in half, so I can't measure resistance and I can't match colors to determine what I should buy. Does anyone have a similar wheel or know of a place I could get a circuit diagram? Amaco/Brent was utterly unhelpful and just told me "we don't know" and "we don't have any circuit diagrams for any wheels". Does anyone else have an old Brent b with the same controller to compare to?