Suitable Replacement Potentiometer (pics) - Page 1
Forum section: electronics / beginners

author: thared33
author_rank: Contributor
timestamp: July 25, 2022, 02:02:19 am
content: I'm working on a cassette deck. All is refurbished by this point and the only thing left is to replace the 'Record Level' pot. The service manual for the CTW600R seems to only list the small PCB it's attached to and not the part # itself so I'm having trouble figuring out which replacement to get.https://ibb.co/9VCvpbxhttps://ibb.co/1d0w6R4It says Alps Japan on one side and the other says 902Y 50KA. I'm guessing it's a 50k pot due to the 50KA part pot but I'm unsure of which taper to get (linear?). It has 5 pins to solder with two extra big legs for strength. I can't find one on Mouser with that arrangement.

author: eugene
author_rank: Frequent Contributor
timestamp: July 25, 2022, 01:44:01 pm
content: On Asian and US made pots an Ausually- but not always - means log taper. Some people call it audio taper for obvious reasons.If you have a DMM then you can measure the resistance and determine the taper experimentally.With 5 pins it's a safe guess that one of them is common ground. The other 4 are separate 'hot' and wiper for the two stereo channels. Set the shaft half way between the two extremes. Assuming the pots are functioning (there are two of them in one package), you will likely find 50k ohms resistance between the common and hot pins and a lower resistance between common and the remaining two pins, which must be wipers by process of elimination.If the resistance between common and wiper is close to 50% of the resistance between common and hot, then the pot is linear taper. If it's something less, like 25%, then the pot is log taper.Incidentally, log taper is rarely actually log taper. It's typically closer to a few linear sections pieced together.I can't help find a replacement with the same mounting, shaft, and footprint. What makes you think it needs to be replaced?

author: thared33
author_rank: Contributor
timestamp: July 25, 2022, 04:53:06 pm
content: Quote from: eugene on July 25, 2022, 01:44:01 pmI'll test with my multimeter later tonight to find out if it's 50kohm and its taper, but the pot won't work without some help. The left channel works fine, but the right won't work unless I put pressure on it (pushing it from below). I've cleaned it very well so it isn't dirty, it's a physical issue.

author: andy3055
author_rank: Super Contributor
timestamp: July 25, 2022, 06:52:32 pm
content: Those Alps pots are very reliable and durable. However, if it is old, it is possible the wiper is either bent or broken (unlikely). If you are careful, you can remove the cover by opening up the 4 tabs and inspecting it. If necessary, you can bend the wiper ever so gently, with a fine, needle nose pliers. If all fails, you may be able to get one of these and modify the wiring to match what you need. No idea what the 2 extra contacts of this 7 pin version are for.https://www.ebay.com/itm/275360672883?hash=item401cc66c73:g:q6MAAOSwKXZitP8hThe emoji was selected by my granddaughter who is watching me typing this!

author: thared33
author_rank: Contributor
timestamp: July 26, 2022, 06:54:33 am
content: Hi again Andy. Tell your granddaughter I said HelloI took apart the pot and bent the wiper ever so slightly, cleaned it up and reinstalled it. It's not working at all now. It'd be much easier to just replace it. Just have to find a suitable replacement because I can see a total failure (on my part) about getting the wiring correct. After searching for the numbers written on the pot I can't find much information on the original part.

author: andy3055
author_rank: Super Contributor
timestamp: July 26, 2022, 10:25:39 am
content: See my PM in a bit.