Repairing Novak 4 esc _ what tools and what parts?

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Repairing Novak 4 esc _ what tools and what parts?

Post by JosephS »

Hello all,
For my 6 gear build I picked up 2 Novak 4s with the idea of making 1 that works.

I only have basic soldering experience.
What tools should I look into getting? What would be helpful.

I was going to get an soldering iron https://pine64.com/product/pinecil-smart-mini-portable-soldering-iron/

Is there a schematic for the nec4?
I was hoping to just order up parts in advance, such as like FETs, resistors and capacitors.

How transferable are FETs if I replace all of the FETs with the same kind could I use a different replacement part ?

I'm not looking to improve the performance, I just want chance to have a reliably functioning unit for stock motors.

I did a quick look and see 2 Fets that seem appropriate for a NESC4. Would the FETS from a T4 be a possible replacement as well?

Look at this thread https://www.rc10talk.com/viewtopic.php?t=48211

It seems that FETS that can work
BUZ11 it is for a Novak 1 Can that work in a 4 without modification.

if it is something else BUZ71 or BUZ10(discontinued with no stock)

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by JosephS »

Adding a question, Do I need a 4 cell receiver battery with the NESC4 or would it power the receiver?

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by jwscab »

generally yes, you can update the whole bank of FET's with appropriate replacements and it will work fine. However this is a little bit of a tricky job due to how compact the circuitry is and how well you can solder. So you definitely want to be careful and use your iron efficiently.

First and foremost, FET's are easily damaged by ESD when not installed in circuit, and can still be damaged by ESD or heat. The circuit board foil is also fairly delicate and the whole bank relies on a heavy application of solder for current capability.

You will likely need a little bit heavier iron than the one listed, because the idea is to heat with a really hot iron quickly to get the job done. an iron with not enough power will cause you to overly heat the FET and circuit board and allow the heat to flow down and potentially damage things.

You will want a solder sucker (solder vacuum) as well as desolder braid to wick away the solder from the traces. Get a good set of strong tweezers, and a vise of some kind to hold the board firmly.

the FET's you mentioned should all work OK, the Tempfets are (T4) are updated to include thermal protection, and the BUZ11 are a better FET than the original, but do not have the temp protecton.

Don't forget that the brake FET's are also different and sometimes there is a built in motor diode or regulator that may also have the same package as the forward fets. For a NESC4, I think it's just one brake FET.

the receiver can be powered through the BEC of the speed controller, as long as that is working as well. Also something that can be damaged and need replacement.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by JosephS »

jwscab wrote: Mon Aug 28, 2023 1:32 pm
You will likely need a little bit heavier iron than the one listed, because the idea is to heat with a really hot iron quickly to get the job done. an iron with not enough power will cause you to overly heat the FET and circuit board and allow the heat to flow down and potentially damage things.
How do I pick a soldering iron then? Is it on max temp or wattage? It seemed like the one I was looking at should have been enough, so I didn't research this enough. Also does solder matter?

jwscab wrote: Mon Aug 28, 2023 1:32 pm You will want a solder sucker (solder vacuum) as well as desolder braid to wick away the solder from the traces. Get a good set of strong tweezers, and a vise of some kind to hold the board firmly.
Would something like this https://www.amazon.com/dp/B0777LMVTT/?tag=tonytrip551-20 be enough, or is this not a good tool?

jwscab wrote: Mon Aug 28, 2023 1:32 pm the FET's you mentioned should all work OK, the Tempfets are (T4) are updated to include thermal protection, and the BUZ11 are a better FET than the original, but do not have the temp protecton.
What is a tempFET? I get that it stands for thermal protection.
Are there more modern types of protection fets that would work as drop in replacements for the Buz11?
When the FET has higher current rating does that mean it would handle more challenging loads as an ESC?


Are there any other parts that are likely bad in an old esc? Should I just replace the caps I find?

jwscab wrote: Mon Aug 28, 2023 1:32 pm Don't forget that the brake FET's are also different and sometimes there is a built in motor diode or regulator that may also have the same package as the forward fets. For a NESC4, I think it's just one brake FET.
It does look like a single brake fet. I was planning on using the same fet for all of them as they seemed similar enough.


Thanks for the guidance. It's a bit to think about.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by jwscab »

this iron is pretty cool, it's got a 'turbo' button for getting through tough solder areas, like heavy ground planes. funny that iron you listed has all of these specs but not the wattage.
https://www.homedepot.com/p/Hakko-20-Watt-to-130-Watt-Presto-Soldering-Iron-Pen-Type-980-V12-P/204215963

your link to the desolder equipment looks good.

if you can use leaded solder, it is much easier to work with, and has a lower melting temp, and would be what is in the older electronics.

the T series of esc's used a Tempfet, a trademark from a particular vendor. The BUZ parts if you can get them will be fine, no need to dig further.

The brake FET is different, you have to use the appropriate replacement part for that one.

if you are unsure on the FETs you want to replace or have a replacment, post up the parts numbers for both parts, and we can compare them to make sure the specs are close enough. Yes, in general FET's today will have better specs, mostly in the voltage and on resistance, which are good things. but you do have to watch certain specs can impact performance.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by WriteDean »

Where does someone purchase new fets that will fit the Novak 4 or 1?

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by jwscab »

Mouser digikey arrow Newark and many others. If you know who makes the part, such as Fairchild or ti or whoever you can often order direct.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by JosephS »

Finally getting around to trying this. I also picked up a 3rd Novak 4.

I stated with one with showed vary little signs of life.
IMG_4173.jpeg
IMG_4174.jpeg
IMG_4175.jpeg
IMG_4176.jpeg
I have buz-11a fets on order from china.

The wire is thinner than any I have around. It seems to be sightly bigger than 1/16" . It looks like that would be 14gauge wire.


The solder sucker is a great tool to have for rc. I started out cleaning up blobs of solder on motor that came in lots.

The tabs are folder over on the board and that is making it hard for me to pull off the fets. I got one out. I think I may be able to replace the fets but the middle of the board is a jumble to my eyes.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by JosephS »

My desoldering ribbon arrived today and I removed the remaining fets. I tore one of the traces but fortunately at the end of the row.

I’m not exactly sure what I’m doing but I tested all the fets that come off with a dmm diode test

They all measured around the same forward voltage of 5.0 expect for one that measured 2.2. I hope that was what was causing problems for the esc.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by JosephS »

So the replacement fets showed up last night. Compared to what I took out they behave quite differently so there is some hope that this can fix the esc.

One problem is that the leads on the new fets are the wrong size
IMG_4264.jpeg
The width increases as it get closer to the body. The original ones were a snug fit to the board.


Did I get the wrong package? Is there a way to spec parts with the same width lead from top to bottom?


The leads bent over after being mounted to the circut traces. I think the wider leads could cause shorts.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by 1911Colt »

I did a cross reference and yours are correct- BUZ11 replaces BUZ10A.

I don't think the leads will be a problem if installed with the correct amount of solder. It won't short unless the solder is globbed on. Before installing the case and applying power, measure for a short between the pins to verify they are not shorted. If you are saying they get "wider sooner", you could very carefully trim them down to size. Or you could put a couple for very small bends in the leads so they rest at the proper height to be level with the others. Honestly, though, I don't think they will be a problem if installed with the correct amount of solder. You can always remove and reapply the solder if you do get a short. If it does take multiple attempts, be sure to let the FETs cool between attempts.

Sorry if this is elementary stuff you already know.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by JosephS »

1911Colt wrote: Wed May 15, 2024 5:47 pm Sorry if this is elementary stuff you already know.
I don't know much about any of this at all. Any help or notes are appreciated. Since the only challenge I have is with the width of the legs as it gets to base I guess I'll try and shave them down with a drywall knife.


Speaking of not knowing things. When I test the fets using the diode tester on my multimeter I can only test once before I have to short all of the leads. then I can retest. Does it matter if they are 'reset' or not when I install them?

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by 1911Colt »

No, they will be fine. The meter is applying a voltage to them, that is why they do that.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by 1911Colt »

You could also remove one of the other FETs and use it as a guide to trim the leads on the replacement. Make them a close match and put them back on the board to verify that the tops of the built in heatsinks are even.

The trick to soldering is to get the lead and the trace on the PCB ho enough to accept the sold. The solder should "flow" into the area around the lead on its own. If it drips in and forms a "ball", that means it wasn't hot enough to flow properly. Also, a good connection will be relatively shiny. If it looks gray and rough, it is a "cold" joint, which is another indication that the solder did not flow properly due to a lack of heat.

If you are near southern Indiana, swing by and I can help. :D I am not good at very many things, but I can solder pretty well thanks to my vocational school teacher and the US Air Force.

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Re: Repairing Novak 4 esc _ what tools and what parts?

Post by JosephS »

My first attempt using a knife to shave the pin didn’t work
IMG_4272.jpeg
I used an Emory board to file down the legs and they fit easily
IMG_4273.jpeg
Folded over the leads. Did the ground plane pins facing the wrong way. Some of the pins looked as if they would cause trouble, so I trimmed them a bit shorter.

IMG_4275.jpeg
It looks pretty good from the other side. I really need to replace that brake diode while I’m at it.

Thinking about using 16ga wire to make it easier to route the wires though the case

IMG_4274.jpeg

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