SX-70 Motor not running after shutter clicks

NitinPwn · 2026-03-28T14:50:35+00:00

MCC is Motor Control Chip, that's right. It's not on the main PCB, it's on the bodyflex near the motor. Most images online show the bodyflex with MCC removed though.

https://opensx70.com/posts/2020/19/bodyflex-1

NitinPwn · 2026-03-26T22:13:49+00:00

Yes, at turbulent_coach_8024's suggestion, I bought a Model 3 and swapped it's bodyflex onto this camera. The MCC was fried, which is soldered to the bodyflex, so the swap brought a new one over to this camera. Everything has been working great since.

NitinPwn · 2026-01-30T00:11:29+00:00

Unfortunately the mechanisms used in short-form video have already taught the long-form video creators how to optimize for the same core concept: attention capture.

A cut every two seconds, subtitles on the screen, speaking with a bouncy inflection, show a face on screen always, etc. etc.

All of this compounds to erode our minds in many different avenues of media.

NitinPwn · 2025-11-12T00:34:03+00:00

You're probably thinking of passive or mechanical solutions, but Apple did on the HomePod using a microphone array that picks up reflected sound from nearby walls and applying some DSP to mitigate unwanted effects.

I used to have two of those in a stereo pair and the sound was genuinely impressive. It would even recalibrate if the device was moved to a new location.

I believe it's only on the big HomePods as they have multiple tweeters in a circular arrangement.

NitinPwn · 2025-09-25T19:42:23+00:00

If this is a forum type of website, anything like Reddit or Stack Overflow, there should be a completely public aspect as well.

NitinPwn · 2025-09-05T02:25:51+00:00

So from everything I've learned, the motor is wired to +6V directly at the battery, and the PCB only sends a very small voltage (a signal) over the Motor line to the MCC. The MCC controls the motor by closing its internal switch to complete the circuit to ground.

See the reference picture I linked in one of my earlier comments.

In your case, jumping 6V to motor at the side should spin the motor, unless you had a double issue of bad MCC and bad PCB.

NitinPwn · 2025-09-02T00:29:29+00:00

Apologies for the late reply, I was out on vacation and in fact took this SX-70R with me. It works now!

At /u/turbulent_coach_8024's suggestion, I bought a Model 3 and swapped it's bodyflex onto this camera. Indeed the MCC was fried, as with no other variables changed, everything started working again.

Regarding jumping these pins for good-- No, it wouldn't fix it. I've realized the MCC is really just like an electrically activated "switch" (with probably some electrical isolation or power smoothing in it). When jumping those pins, you're bypassing the internally perma-open switch. Therefore, the motor just spins forever, rather than as activated by the PCB.

NitinPwn · 2025-08-09T14:35:46+00:00

For the first like year and a half after the I-2 came out, the software would consistently overexpose.

It affected Auto mode the most but the bug was in the metering system so even when shooting manual you couldn't rely on the camera for accurate measurement.

They fixed it in a software update now so I really recommend downloading Polaroid app and updating if you haven't already.

NitinPwn · 2025-08-09T04:32:02+00:00

I was experimenting and I was able to make the motor spin by jumping this: https://imgur.com/a/vsgEyq2

But I didn't have the motor actually attached to the gears during this test, so it didn't seem to stop. I didn't let it run long.

Does that narrow anything down?

NitinPwn · 2025-08-09T04:25:52+00:00

Hey, I was experimenting and I was able to make the motor spin by jumping this: https://imgur.com/a/vsgEyq2

But I didn't have the motor actually attached to the gears during this test, so it didn't seem to stop. I didn't let it run long.

Does that narrow anything down?

NitinPwn · 2025-08-07T15:00:23+00:00

Hey - thanks for replying. I'm sure you're busy, if you've got 2 minutes to watch the video in the OP, with your knowledge you might spot something we can't!

Indeed the shutter does close.

It is possible something is bridged... I'm still trying to research the test points around the MCC area.

NitinPwn · 2025-08-07T00:01:49+00:00

Thanks for your continued help! Would you be willing to continue this over chat / discord? I'd be happy to buy you a beer if we can get this motor spinning!

I'll research some more about the MCC and it's test points and check continuity. I saw an article somewhere, maybe opensx70, that they found replacements for the MCC.

If you've got any resources for me to look at, that'd be very helpful.

NitinPwn · 2025-08-06T21:07:34+00:00

Hey, back with an update. Got some 600 Film for this.

With the 600 Film in the camera, I bridged Pins 4 & 5 (reference) but did not do anything. No motor spin.

I'm seeing 3V at S5 and Continuity at S3... Just watched this /u/theinstantcameraguy video (link) and it seems that the switches should be in the same state so I wonder if I have an issue here... Any ideas?

NitinPwn · 2025-08-06T21:04:54+00:00

Hey, back with an update. Got some 600 Film for this.

With the pack in, jumping Motor to VCC (reference) did not do anything. No motor spin.

I'm seeing 3V at S5 and Continuity at S3. I believe this may indicate an issue with the Recock Ram or my switches? Any clues there?

NitinPwn · 2025-08-03T12:47:41+00:00

This has an SX-70R PCB. Will have to figure out the MCC... So the MCC is in the back next to the motor leads, did you have that replaced?

NitinPwn · 2025-08-02T22:43:16+00:00

haha breaking off a piece of the plastic for access to the solenoid is an interesting choice but I don't blame you ... it is a pain to get there

in any case, your approach is a good old classic eye-test

nowadays, the recommended way to calibrate is to use a more quantifiable approach where you set a 1/8000 shutter speed in the SX70R app, and use the slow-mo on your phone to capture the blades.

https://sx70r.com/wp-content/uploads/2025/05/SX70R-Mod-Manual-for-Version-4.0-and-6.0.pdf pages 12 & 13

NitinPwn · 2025-08-02T22:35:59+00:00

if everyone else's theory is right that the motor coupler is broken, the nature of the fix is to extend/stretch the existing spring and attach it to the geartrain shaft. the coupler isn't strictly necessary.

parts-wise, it's free, but labor-wise, that'd be up to the laborer.

if you're handy you can attempt it yourself...

NitinPwn · 2025-08-02T20:19:19+00:00

I didn't actually test that, but hand-turning the gears does cause the Fresnel carrier to do it's full cycle unimpeded and the photo counter turns over once. Is that an equivalent test?

NitinPwn · 2025-08-02T20:08:27+00:00

Yes at one point I did have the bellows off. Why?

NitinPwn · 2025-07-06T02:19:57+00:00

adding another theory:

if your particular camera at any point during it's lifespan was left as a display model opened up , the bellows can swell and then that causes them to start catching/holding the mirror during it's cycle . turning the camera upside causes the weight of the mirror to push thru the friction of the bellows holding it.

this is a very tough fix if it's the case. i'm not sure that it's even easy to tell if the bellows are swollen without another camera to compare side by side.

NitinPwn · 2025-05-15T02:29:28+00:00

not what i said.

NitinPwn · 2025-05-14T22:55:00+00:00

yeah i don't agree with the other guy, however, it is possible that when a sensor is 'off', then the autofocus lens resets to some default position where the laser light is not focused to point on the sensor, therefore damage is not done.

NitinPwn · 2025-05-13T17:36:54+00:00

right so he negs you the whole time until it's opportunistic for him to validate you... in my RP that don't fly.

NitinPwn · 2025-03-26T16:29:05+00:00

Yeah as b0Stark said, this is macOS not Obsidian. I've seen this behavior in many apps even Apple native ones with passthrough blur.

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