Decode pot numbers

[Rigormortis]

I'm trying to decode numbers on the back of a small potentiometer so I can put in a replacement:

70-133-01

137/7850 ROC

It's a normal, cheap pot with just the three legs coming down and spearing into the circuit board. The back is about 5/8" across (actually 19/32). It's for a Crate 1x10 solid state guitar amp.

I'm sure many different ones would do. Anyone know what the replacement should be?

[Jerry]

The 70-133 number is Crate's part #. 137 lets you know that it's a CTS pot and 7850 tells you that the pot is from the 50th week of 1978.

[Enzo]

70-133-01 right away I recognize that as a Crate part number. In fact I have them in stock. The center number often decodes like a color code... but not on this one. This is a 50kB. B for linear. Shaft is green?

ANy 50kB pot will work fine, but using the Crate part will fit the holes and the knob.

It is not 5/8" nor 19/32", what it is is 16mm. That is a common pot size.

137/7850 is a code that means CTS made the part (137), and it was made in the 50th week of 1978. That is a 30 year old part, and the Crate folks may or may not have them around any more. Call Loud Technologies and ask, what the heck.

I would sell you one if you want, but please check with a dealer first. Or stick any 50k pot you like in there.

Oops, Jerry got in there while I was writing this.

[Rigormortis]

Thanks for your prompt and helpful replies!

Yes, the stem is green. And it's a pretty wimpy stem at that--the reason for its demise.

I guess this one lasted a while. But I would like something a little more sturdy. The knob is gone anyway--so no use matching it perfectly.

50 k huh? Sure, I would like to find something that fits in there. I'm good at soldering and all that, but I don't have any supplier here but Radioshack. So Enzo, if you want to give me your contact info, I'll take you up on your offer.

[Enzo]

OK, the part I have is the exact factory part new. I don't have any Crate knobs to fit at the moment. On your own there.

You can email me at the address below for further details, I accept paypal.

tmenzo at msn dot com

[Rigormortis]

Will do.

The knob style isn't particularly important for me. Do you have anything that would fit on there? What is it, a 3/16"?

[Enzo]

I am sure it is metric, but yes, 3/16 it is. I don't know that I do have a knob to fit in my bins.

[Rigormortis]

Thanks! This will make it easy, rather than trying to put a pot in there that needs to be modified to fit the board and faceplate.

I'm surprised how hard it is to find that little potentiometer through internet searches. You would think it would be very easy to find a pot, since they are in so many appliances.

[Enzo]

No, that pot is custom made for Crate.

There are lots of 50k pots.
There are lots of 16mm pots.
There are lots of pots with small shafts.
There are lots of pots where the small shaft is round and knurled and plastic.
There are lots of pots with that size and thread bushing.
There are lots of pots that have no mounting bracket.
There are lots of pots with that pc board terminals spacing.

But for the most part, all those other products that use a 50k pot don't also share all those other things. it is easy to find an equivalent pot, but not one the same. Pots are almost always custom made.

[Rigormortis]

Got it! Thanks, Enzo.

It's an identical replacement; but you knew that already.

Now I can fix that channel. With the Mackie coming for vocals, the little Crate will go to our bassist. He likes it for his acousitic bass with pickups.

[Rigormortis]

LOST IT!

In my pants pocket, I had the little white box, with the pot inside in a little ziplock, and while I was struggling with a large piece of cargo in a snowstorm, the box must have popped out into the snow.

White box, white snow storm. So sad!

[Enzo]

Oh geez.

Look, you payed me more than I asked anyway, so send me your address again, and I will replace it. I probably still have the address, but I am not near my shop now to look.

[Rigormortis]

That's super of you.

I'm still kicking up the snow where I was working. Hope glimmers. It was well protected, as long as we didn't stomp on it. I can't believe it happened. I was so protective of that little box--hence the reason it was in my pants pocket. I should have just left it on the dashboard or in the pile of junk mail on the seat.

I have this theory that the more important something is, the more likely it is to get lost. I once had a complete, original, hand-drawn house plan disappear, yet in my folders I still had all the little scraps of paper cash register receipts from that job.

[Rigormortis]

Found It!

One of my co-workers found it. The box was a bit dented, but the pot was fine. I put it into the amp and got everything working.

So hold off on that second pot, Enzo. Get yourself a beer instead.

[Enzo]

Oh cool, I came in a boxed one up after reading emails that had gathered all week. Now I won't send it.