Mackie 1202 Gain Pot Replacements

[doorunrun]

Hello all,
I bought a first-gen Mackie 1202 mixer which seems to be working well but some of the pots are a bit wobbly and I'm looking around for replacements.

So far they don't seem to be scratchy and I haven't pulled the main board to see if there's a way to cure the wobble. The ones I'd like to replace right away are Mackie part number 130-061-02, a dual pot, with a value of 50k with 6 in-line pins. These are out of stock as far as I can tell.

Searching online it seems like the form factor is still used and there might be some suitable candidates. Has anyone found good replacements for these?

Thanks!

 

[Ricardus]

I have an early US made 1202 also, so I'll be watching this thread.

 

[doorunrun]

This looks like a possible replacement from AliExpress:
https://tinyurl.com/229d8uuv
It's described as: "2PCS/LOT ALPS alpine RK12L1230C2N double 6 pin potentiometer B50K axis long 23MM midpoint"


I had the circuit board out of my mixer and got approximate measurement of the shaft length from the top of the pot's 'body' and got ~23mm. I didn't measure the distance from the bottom of the pot to the end of the shaft, but I think 30mm is pretty close.

I haven't purchased through AliExpress, price and shipping seem reasonable.

Thoughts?

Thanks!!

 

[Whoops]

This looks like a possible replacement from AliExpress:

I would get it from a better source than Aliexpress.

Search Mouser, farnell, digikey
try to choose a good well known brand

you don't want to replace a wobbly pot by another pot that will be wobbly very quick

 

[doorunrun]

Search Mouser, farnell, digikey try to choose a good well known brand you don't want to replace a wobbly pot by another pot that will be wobbly very quick

Point well taken. I checked all the usual suspects without any luck of finding the right size, value, or stocked.

I went ahead and ordered some from AliExpress. Caveat Emptor, as they say...
Thanks!

 

[doorunrun]

Replacement ALPS pots arrived from AliExpress. They are good quality with smooth movements; values are ~43k. Physically, they are a perfect fit.
Here's a comparison view side by side with an original:

What keeps the shaft anchored is a small pin at its bottom that extends through the pot's base. The wobble is caused when that pin gets sheared through an excessive side to side bump. Below is one of the original wobbly pots taken apart, sans pin in shaft, but still in the base:

The replacements have larger shaft pins.

Getting the old ones off the mainboard is not too bad. It's a little tight around the Master and Headphone level control area. I used a couple of sizes Solder-Wick to get them freed up and out. Expect a lot of solder to flow when wicking the mounting tabs.

A weakness, if you want to call it. with the mainboard are the plated through 'eyelets' used to secure the pot's mounting tabs. There's no foil on the top or bottom of the PB board to help keep them attached.

Consequently, I pulled out some of the plate-throughs probably with too much heat or not enough 'wicking. My fix, in order to keep the replacement pot mechanically stable was to solder short pieces of solid hookup wire to the tabs on the underside of the PCB.

Just for reference here's a view of the mainboard:


So far, the replacements work quite well. Fingers crossed!

Good luck!

 

[thomasdf]

Thanks for sharing ! Love this little mixer, so gnarly and fat we used properly Sometimes I wish I had a rack of 8 pre and EQs to take on tour with me in a convenient package.

 

[rock soderstrom]

Love this little mixer, so gnarly and fat we used properly

+1

1202 is a musical powerhouse with a small footprint.

 

[doorunrun]

Thanks for the replies!

I haven't been inside any of Mackie's subsequent models (a.k.a. VLZs and up) but I'll bet they are much harder to work on. The density of switches and controls seems daunting.

Not that I wouldn't mind having their extra features from time to time; I just don't need them for the voice tracking I do.

 

[Ricardus]

So is the link above the same pot you ordered?

How many did you have to replace?

I might order a few just to have.

I want to recap and rebuild the power supply in my1202, and possibly swap out the opamps.

 

[doorunrun]

So is the link above the same pot you ordered?

How many did you have to replace?

I might order a few just to have.

I want to recap and rebuild the power supply in my1202, and possibly swap out the opamps.

Hello Ricardus,
1. Yes that's the link to the pots at AliExpress. I think it took about 2 weeks to get them delivered.
2. So far I've replaced 4. Gain pots on the first two input channels. The Master Gain (Output) and Headphone controls.
3. I think it's a good idea to have some, given their cost, long term availability and use of the mixer.

4. Recapping thoughts...I was hearing hum in the headphones and found a tip here to replace the PS caps that are hung on the outputs of the 15V regulators (22uF-25V??) I did that using some I had on-hand of slightly larger capacitance. They cured the noise.

I then replaced the larger input caps on the PS board. But, the originals I pulled out had very good ESR values. My conclusion: chances are the rest of them on the mainboard are still good. If it ain't broke...

5. Op amp replacements...the originals are 9-pin SIPs. There are adapter boards available, but IMO the originals come pretty close to NE5532s at least on paper. Given the rest of the circuit topology and parts used I'm not sure of the advantages. But, YMMV!

A couple more ideas about these replacing these pots...
1. consider the use of something like Chip-Quik or low melting point solder when removing the old ones. I'd wick as much solder off the mounting tabs as possible and then add a little of the Chip-Quik and wiggle the pot out.
Otherwise, sacrifice the part, not the PC board. Cut the pots leads and mounting tabs at the base of the pot, if possible. Then remove the pieces one at a time.

2. The control knobs fit a little tight on the ALPS pots' shafts. Might be a good idea to lightly wet-sand one down just a little with some fine grit paper and see if it's better before installing.

I haven't tried finding a suitable replacement for the other pots, the 3-pin ones.

Hope it helps!

 

[Ricardus]

Hello Ricardus,
1. Yes that's the link to the pots at AliExpress. I think it took about 2 weeks to get them delivered.
2. So far I've replaced 4. Gain pots on the first two input channels. The Master Gain (Output) and Headphone controls.
3. I think it's a good idea to have some, given their cost, long term availability and use of the mixer.

4. Recapping thoughts...I was hearing hum in the headphones and found a tip here to replace the PS caps that are hung on the outputs of the 15V regulators (22uF-25V??) I did that using some I had on-hand of slightly larger capacitance. They cured the noise.

I then replaced the larger input caps on the PS board. But, the originals I pulled out had very good ESR values. My conclusion: chances are the rest of them on the mainboard are still good. If it ain't broke...

5. Op amp replacements...the originals are 9-pin SIPs. There are adapter boards available, but IMO the originals come pretty close to NE5532s at least on paper. Given the rest of the circuit topology and parts used I'm not sure of the advantages. But, YMMV!

A couple more ideas about these replacing these pots...
1. consider the use of something like Chip-Quik or low melting point solder when removing the old ones. I'd wick as much solder off the mounting tabs as possible and then add a little of the Chip-Quik and wiggle the pot out.
Otherwise, sacrifice the part, not the PC board. Cut the pots leads and mounting tabs at the base of the pot, if possible. Then remove the pieces one at a time.

2. The control knobs fit a little tight on the ALPS pots' shafts. Might be a good idea to lightly wet-sand one down just a little with some fine grit paper and see if it's better before installing.

I haven't tried finding a suitable replacement for the other pots, the 3-pin ones.

Hope it helps!

I have a desoldering gun so I'm not worried about pulling parts from any PCBs.

Yeah, the original OpAmps are SIP and they're palindromic. You can put them in either way and it's fine.

I already made boards to replace them. I get that it's probably not even worth it, but I'm crazy and it's just another fun thing to try. Someone on here already did the 5532 update and it worked. I guess they draw a little more current so the PSU will work a little harder.

It's a great little utility mixer so I'd like to get it up to 101% again.

 

[neowalla]

Great little mixer. I bought mine at Guitar Center in 1994. i use it mostly now for testing new mic builds but I suspect my son will in time inherit it for his band. I remember at the time these came out there was talk in the recording magazines about the quality of the mic preamps in this series of mixers from Mackie. Bang for buck, quietest pres in this class of mixer, and some such.

 

[k brown]

I encountered one of the world's top Classical engineers, Marc Aubort, using a 1202 just for it's mic pres on a string quartet CD many years ago.

He could tell I was giving it the 'side eye'; he simply said: "They sound great". Had it plugged directly into his SADiE, since it was a simple 2-mic job. I didn't notice at the time but I imagine he was coming out of the pres' insert jacks.

 

[JohnRoberts]

I am not a fan of Mackie but they were serviceable value mixers. The inexpensive op amp technology was already quite good by then.

Speaking of ALPS pots, when I was buying them directly from ALPS the minimum order was something like 1,000 pieces per value. Perhaps some middle man is stepping up and buying commonly asked for replacement parts. The mark up can be quite good, if they can get enough business to turn over the inventory in a reasonable time.

JR

 

[doorunrun]

BTW, I pulled the three electrolytics used in the phantom power supply, a 100uF@100V and two 47uF@50V. They all had ESR values ~1 Ohm; not bad in my book considering their age and use.
The replacement Panasonics measured 0.3 and 0.7 Ohms respectively.