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How Would You Fix These Traces?

Tincanalley

Experienced Member
Joined
Aug 26, 2019
Messages
176
Location
Los Angeles, CA
One of my Tandon TM100-2A motor boards had leaky caps, so bad they ate the solder and damaged the traces. I cleaned it up and tested the traces, but they are toast. What is the best way to repair them? I was thinking jumper wires from point to point until the circuits are complete. I have attached a pic with the proposed routes and points of connection.
 

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Jumper wires is the way to go.

However, I would suggest using an appropriate diameter of wire to cope with the expected current flow.

I would also tack the jumper wires to the PCB using small dabs of glue at regular intervals.

Another possibility is to gently sand away the top of the PCB track and solder the jumper wires very close to the damage. Isolate the damaged area of the tracks (by cutting either side of the damage). Ensure you catch all of the track (remembering through-holes and tracks on the reverse side). Make sure you protect any rework like this with a small coat of (say) varnish to protect the solder joints and/or bare copper track.

Dave
 
That would work--I use AWG 30 wire-wrap wire for such stuff.
That's pretty much the wire I have on hand. I've used it in the past to replace some damaged on the back side of a circuit board when it got ripped off. I'm thinking a little hot glue to keep it flush to the board.
 
Tincanalley,
I've repaired several of those RPM boards for the Tandon TM-100 Drives.
I have Hollow rivets to insert in the PCB holes that allow the Cap to be mounted
in the rivet. I patch the removed traces by adding jumpers to replace the missing
PCB traces. I also insert two new Caps, and set the RPM to 300 RPM (assuming I
have the drive).

If you would like, I can repair that RPM board for you, and return it and you can set the
RPM to 300 RPM. If you want I can install it on my Drive and test to be sure it
regulates at 300 RPM.

If you have other Tandon TM-100-XX Drives, I'd check the RPM boards on those drives too.
They likely need fixed too.

Larry
 
Tincanalley,
I've repaired several of those RPM boards for the Tandon TM-100 Drives.
I have Hollow rivets to insert in the PCB holes that allow the Cap to be mounted
in the rivet. I patch the removed traces by adding jumpers to replace the missing
PCB traces. I also insert two new Caps, and set the RPM to 300 RPM (assuming I
have the drive).

If you would like, I can repair that RPM board for you, and return it and you can set the
RPM to 300 RPM. If you want I can install it on my Drive and test to be sure it
regulates at 300 RPM.

If you have other Tandon TM-100-XX Drives, I'd check the RPM boards on those drives too.
They likely need fixed too.

Larry
I'm still debating on whether I want to repair it myself, and am leaning towards that. Out of curiosity, what would your service cost? I've recapped one and will be testing today, but the other is in pretty bad shape.

Is the RPM setting thrown off by recapping? I replaced a third cap, that tested good, just in case. It was the 1uf 50V cap.
 
Tincanalley,
You can't beat the Price anywhere, even Walmart! Cost is actual USPS Postage back to you
with Tracking.

The Copper Hollow Rivets from Sweden will run you around $40 USD with Postage, and are
much better than any from China. Plus, the Rivets allow you to change the Caps again down the road.

My Kaypro Drives were off several RPM, and I adjusted them. Doesn't take long to adjust the RPM.

Larry
 
If it was like the last three I recently repaired, a good portion of the PCB traces are completely gone.

Larry
 
Are they actually gone? They just look corroded. Using a fiberglass brush you can wipe away the corrosion to bare copper and plate with solder. https://www.amazon.com/gp/product/B07S3RCTGZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Yeah, for the most part, they are gone. I've attached a closer up image. It's a little hard to see, but where the traces are, close to the mounting holes, you can see the green of the board as the copper trace is gone. I really want to know how this happened as the liquid in the caps is supposed to be non-corrosive.
 

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Tincanalley,
You can't beat the Price anywhere, even Walmart! Cost is actual USPS Postage back to you
with Tracking.

The Copper Hollow Rivets from Sweden will run you around $40 USD with Postage, and are
much better than any from China. Plus, the Rivets allow you to change the Caps again down the road.

My Kaypro Drives were off several RPM, and I adjusted them. Doesn't take long to adjust the RPM.

Larry
So you are writing that the repair is "free" and I pay for shipping, only?
 
I really want to know how this happened as the liquid in the caps is supposed to be non-corrosive.

Wrong. Capacitor electrolyte is VERY corrosive, especially if power is applied to the PCB with leaked electrolyte on the board. If capacitor electrolyte wasn't corrosive, we wouldn't have bombed Apple boards from leaking electrolytic caps.

Those traces look intact to me, it just looks like the solder mask has lifted up from the copper oxide rust jacking the coating off. I'd suggest using something like Krud Kutter rust inhibitor on a cuetip and scrub the trace to get rid of the oxide, then tin the trace with solder.
 
Tincanalley,
There is another problem with the Tandon TM-100-x Series Floppy Drives. It's the Door Hinge
part that breaks if there are two small White Nylon Pins in each side of the Hinge Part. You can
easily see if there are two small White Nylon Pins versus one long Brass Rod for the Hinge, but
looking a the Open Door and seeing if there are two Small White Nylon Pins. If there is not a
full length Brass Rod in the Hinge part, it needs to installed ASAP. I have some SPARE Brass
Rods and Hinge Parts if our Hinge is broken.

Larry
 

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Tincanalley,
There is another problem with the Tandon TM-100-x Series Floppy Drives. It's the Door Hinge
part that breaks if there are two small White Nylon Pins in each side of the Hinge Part. You can
easily see if there are two small White Nylon Pins versus one long Brass Rod for the Hinge, but
looking a the Open Door and seeing if there are two Small White Nylon Pins. If there is not a
full length Brass Rod in the Hinge part, it needs to installed ASAP. I have some SPARE Brass
Rods and Hinge Parts if our Hinge is broken.

Larry
I wish mine were this simple. The pic you show has full circular ears for the bar on the door. Mine are not full circles and have openings in the front of them so it snaps onto the door. These "ears" broke off one drive. I took a door off another drive that I scavenged parts from because the black upper frame broke the attachments to the cast metal bottom and I could find no way to reattach and have it stable. So I took all usable parts from it.

You can see in one pic the broken "ears" and the missing rod from the drive door. The other pic is the salvaged door and you can see the rod of the door snapped into the "ears".
 

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Wrong. Capacitor electrolyte is VERY corrosive, especially if power is applied to the PCB with leaked electrolyte on the board. If capacitor electrolyte wasn't corrosive, we wouldn't have bombed Apple boards from leaking electrolytic caps.

Those traces look intact to me, it just looks like the solder mask has lifted up from the copper oxide rust jacking the coating off. I'd suggest using something like Krud Kutter rust inhibitor on a cuetip and scrub the trace to get rid of the oxide, then tin the trace with solder.
I ordered some of the fiberglass eraser pens and will see about cleaning up the traces. I'll then flux the points and tin them.
 
Well it seems these two capacitors on the drive board are a real issue. I just inspected my other spare drive and both are leaking. All surrounding components are showing signs of corrosion, but it hasn't migrated to the trace side of the board. I'm going to clean it up, remove the caps and install new.

I know am paranoid and will be taking out the main drive from the 5150 and inspecting the drive board on that one. Anyone know if the earlier drives used in the TRS-80 Model 4 have such drive boards or other issues I should be looking into for preventative maintenance? The work perfectly, but then so did the drive that just died and the board is really bad. I have no idea how it continued up til now in such bad condition.
 
Okay, here is board 4. I removed the bad caps, as well as the 1uf. I used vinegar and a toothbrush, but this is as clean as I can get it. The back side and traces are fine, it's just the legs of these resistors, cap and transistor. I see a little green on some legs, so I know that has to go. But I doubt the black will clean off. So should I just concentrate on getting all the green corrosion? If so, what is stronger that won't hurt the board?
 

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