Pioneer PL-510A Turntable Repair - Suspension Screw Inner Thread Repair

[evanbalthaza]

Hi hello!

I recently replaced some foam in my turntable and discovered a stripped internal thread in reassembly. The other three screws tighten completely and hold suspension on the spring, but the fourth screw's spring spins once "fully" screwed in and doesn't hold the motor assembly high enough to avoid platter grinding.

I've purchased other suspension screws to ensure it's the internal thread and have tried using JB weld to repair the threads using the screw as a guide, but this hasn't worked. As a result of overtightening I've also driven through the plastic faceplate under the platter, so I'll need to plug that as well.

I just wanted to post and garner some opinions or thoughts on the best move to take next. After researching internal thread repair, it seems like the only option short of retapping would be a helicoil so if I can determine the right size and find the correlating kit I might try that. Is it worth trying or does it seem likely to damage / crack plastic?

 

[painttoad]

can you pull that plate and use a screw and nut? nut on the foot side?

 

[evanbalthaza]

can you pull that plate and use a screw and nut? nut on the foot side?

I can pull the plate pretty easily, but it would need to be on the platter side of the thread and I'm not sure there will be room. It's an interesting thought though, maybe if I could source a similar but slightly longer screw and have the clearance below the platter that could work.

 

[Govany]

The problem wasn't the threads or the screw..you didn't tension your spring after you installed the screw..that black plastic part is an adjustable spring tensioner..just push down the lower part & twist to get the tension you need..but if the threads are stripped now won't work.
Also make sure you put the springs back where they came from.

 

[evanbalthaza]

The problem wasn't the threads or the screw..you didn't tension your spring after you installed the screw..that black plastic part is an adjustable spring tensioner..just push down the lower part & twist to get the tension you need..but if the threads are stripped now won't work.
Also make sure you put the springs back where they came from.

Hi, I've adjusted the spring tensioner to it's highest setting and have tried other tensioners on that screw to confirm it's the inner thread. The screw will also occasionally slip through the thread with the spring tension at it's highest point. Thank you for your observation though.

 

[JSMATT]

Hi, I've adjusted the spring tensioner to it's highest setting and have tried other tensioners on that screw to confirm it's the inner thread. The screw will also occasionally slip through the thread with the spring tension at it's highest point. Thank you for your observation though.

What kind of fastener is it - sheet metal screw or bolt/machine screw?

If it is a sheet metal screw, you could put a larger one in.

How thick is the material into which the fastener is trying to bite? Just sheet metal or ???

 

[gadget73]

yeah I think we need a good view of what the screw goes into and what the screw itself is.

 

[evanbalthaza]

I'd be inclined to call it a sheet metal screw, but I'm not sure in a technical sense. Below is a picture of the screws and spring assemblies. These fasten directly into the plastic housing of the turntable, about an inch or so of screw/thread contact. I'll try to get a better picture of face of the thread without the screw in place, probably will upload that tomorrow.

 

[JSMATT]

I'd be inclined to call it a sheet metal screw, but I'm not sure in a technical sense. Below is a picture of the screws and spring assemblies. These fasten directly into the plastic housing of the turntable, about an inch or so of screw/thread contact. I'll try to get a better picture of face of the thread without the screw in place, probably will upload that tomorrow.

View attachment 3174962

Yes, sheet metal screw. OK.
You indicated these screw into a plastic base. Please take a photo of the back side of the plastic base. Need to.see.how.much 'real estate' is available for something to augment and support the fastener threads.

 

[evanbalthaza]

Looking at it again, I'd say it's more like a half inch of screw/thread contact. Below are some pictures- I'd rather not pull the black suspension plate for reference, but for repair it's not too much of a pain. I should have plenty of mobility if retapping is necessary and viable.

 

[painttoad]

if that was mine. i think i'd cut the riser flush. go to an autobody supply store with the screw and match it up to a retainer like these



i'd also cut off and throw away the part of the clip that does not have the threads

...or i'd nut and bolt it like i said before.

 

[evanbalthaza]

Thanks for the thoughts painttoad, cutting the riser flush would definitely make space for a nut or clip like that. I think I'll end up doing that and will share an update once hopefully patched together!

 

[JSMATT]

Thanks for the thoughts painttoad, cutting the riser flush would definitely make space for a nut or clip like that. I think I'll end up doing that and will share an update once hopefully patched together!

I second PT's recommendation.

Mixing some JB Weld to keep the threaded piece in place may be a consideration as well. Just clean the area thoroughly to help assure the max adhesion.

 

[Powertech]

If there is sufficient material in the raised stub you can carefully drill it out and glue in a thread insert - epoxy resin is best. This will give you a female machine thread to take a machine screw. They are available in a variety of sizes. At least then it will still look original.

 

[evanbalthaza]

Trimming the raised thread and using a slightly longer screw with a couple jam nuts did the trick!

I tried using a helicoil kit (5521-2) to rethread it and ended up cracking the plastic, thankfully just the threaded column though. I tried the JB weld again to create solid medium to rethread, but even after curing for a week this didn't hold. I was pretty careful with it, but maybe it was user error? Idk.

At this point I figured aesthetics aside, the nut was the best bet to make it work. I used a trim saw to cut the threaded column flush and a for a <$1.50 purchased a 1.5" 8-32 screw with a couple matching jam nuts from Ace. A quick note that a 2" screw is over clearance, but 1.75" might be alright. Seems to be holding fine, it was a huge relief after the failed rethread. I would definitely recommend a U clip or nut to solve this problem unless you're working on a collectible / complete refurb. I'm not planning on selling it and the fix lives under the platter so this solution works great for me.

Balancing the platter had it's own headache (a lot of rebalancing as the spindle drops with pressure), but a small level helped keep this quick enough.

Thank y'all for your help!