# Router repair - speed control board



## Relative (Apr 24, 2008)

I have a Trend T4 that only works when switched to max speed (definite 'click' on the speed dial). Soft start is also non-functional.

Investigating the circuit board I found the SCR (BT151) shorted and the gate diode (possible zener) shorted. 

Substituted a NTE5558 SCR but cannot identify the diode. I cannot find a schematic for the board (labeled B/230-12/4 110V) and Trend does not reply.

Can anyone help?

Thanks,
Mike


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## jschaben (Jun 21, 2009)

Relative said:


> I have a Trend T4 that only works when switched to max speed (definite 'click' on the speed dial). Soft start is also non-functional.
> 
> Investigating the circuit board I found the SCR (BT151) shorted and the gate diode (possible zener) shorted.
> 
> ...


Hi Mike - Sorry can't help you but I'm interested in case the same thing pops up with my T4. It's just possible that Trend may not even be able to help either. So many companies these days just farm components like a circuit board out with just performance and physical size specs and the design is done outside. 
Good Luck


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## Relative (Apr 24, 2008)

Failure of this board was fairly common at one point and I have hopes that someone with a little more electronic experience has figured out the board and can give us some answers. Otherwise, a replacement board is available, but there are so few components on it, it is easy to replace parts if you know what they are.

Mike


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## Cherryville Chuck (Sep 28, 2010)

If you can't fix it, just hook it to an external speed control. That won't help with the soft start but the router will be functional at least.


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## del schisler (Feb 2, 2006)

It may be this one ? 5KP110A 5000W 110V Transient Voltage Suppressor Diode. ? If so ebay 110v diode | eBay

I was in repair for 50 yrs lot's of diode's for different apps. ? It is probly a ziner diode to keep voltage at 110 ?? The band on the diode went to ground ?


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## Relative (Apr 24, 2008)

This is a very small (about as small as I've ever seen one) blue-colored component about 2x as thick as the wires coming out of it and it has a label of C702 printed on it along with a band at one end. Searching for C702 on the internet hasn't helped one bit.

It is connected to feed the gate of a T151 SCR.

Mike


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## Mike (Nov 22, 2004)

I messaged Harry to jump in on this one. I think he has one of these routers and is pretty good on electronics.


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## jschaben (Jun 21, 2009)

Relative said:


> This is a very small (about as small as I've ever seen one) blue-colored component about 2x as thick as the wires coming out of it and it has a label of C702 printed on it along with a band at one end. Searching for C702 on the internet hasn't helped one bit.
> 
> It is connected to feed the gate of a T151 SCR.
> 
> Mike


Hi Mike - A "C" designation on a circuit board is usually indicative of a capacitor. The 702 is probably a numeric reference to a component number on a schematic somewhere. The question then becomes the capacative value and the polarity. I believe the band would indicate the positive (+) terminal. Can you make out any other numbers? 
The good news is I believe it is a very common component and should be easily secured once the values are determined.


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## harrysin (Jan 15, 2007)

Relative said:


> I have a Trend T4 that only works when switched to max speed (definite 'click' on the speed dial). Soft start is also non-functional.
> 
> Investigating the circuit board I found the SCR (BT151) shorted and the gate diode (possible zener) shorted.
> 
> ...


Hi Mike, I'm not familiar with your router and have only ever repaired one tool speed controller in my scroll saw, BUT, I've repaired numerous touch control light dimmers, I even started such a thread: http://www.routerforums.com/lobby/12826-how-repair-touch-lamp-etc.html
I don't ever remember seeing such a diode.The original device is a triac whereas you have fitted an SCR, which doesn't contain the internal diode that the triac does for bi-directional firing. Because of the tiny size of the diode, I'd be inclined to try a small signal diode or possibly two in series. Let's face it, there's no way that you can damage the router itself. I hope this is of some help Mike.


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## Relative (Apr 24, 2008)

harrysin said:


> The original device is a triac whereas you have fitted an SCR, which doesn't contain the internal diode that the triac does for bi-directional firing.


I found the tech sheets for both the T151-500R and the NTE5558 and both are called 'passivated SCRs. Main difference (other than manufacturer) is the T151 is 500V and the NTE5558 is rated to 800V and is 6x more expensive.

I also found an application note that shows the T151 in a similar circuit to the T4's circuit and D2 in the 3rd illustration on the PDF page I printed and attached is the little jewel in question. The actual circuit in the T4 is more complicated, but R1, D2, R4 and BT151 seem to be exactly as drawn on the pdf page.

The 'diode' is physically destroyed while taking it out and what I thought was a band on one end isn't really there. I suspect the 702 is the end numbers of the diode but don't have a clue why there is a 'C" in front of it.

Mike


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## harrysin (Jan 15, 2007)

Relative said:


> I found the tech sheets for both the T151-500R and the NTE5558 and both are called 'passivated SCRs. Main difference (other than manufacturer) is the T151 is 500V and the NTE5558 is rated to 800V and is 6x more expensive.
> 
> I also found an application note that shows the T151 in a similar circuit to the T4's circuit and D2 in the 3rd illustration on the PDF page I printed and attached is the little jewel in question. The actual circuit in the T4 is more complicated, but R1, D2, R4 and BT151 seem to be exactly as drawn on the pdf page.
> 
> ...


Perhaps if you draw the circuit it might make more sense Mike. Here are data sheets that show the BT151 as a triac/thyristor and the NTE5558 as a Silicon controlled rectifier, similar devices but not the same!


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## Relative (Apr 24, 2008)

On the road for about a week at the moment. Will attempt to reverse-engineer the PC board when I return next week.

Data sheets???

Thanks,
Mike


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## montague (Jan 5, 2009)

Dear Sir,

Please be advised that Trend takes any and all warranty issues with our products seriously. I have checked our our customer service department and no one is aware of a recent problem with a circuit board. Perhaps your are using contact number/e-mail from our headquarters in Kentucky which closed in December, 2009?? Please do contact us at (877) 918-7363 or you may e-mail us at [email protected]. 

We look forward to hearing about your problem.

Thank you,

Jamie


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## del schisler (Feb 2, 2006)

Relative said:


> This is a very small (about as small as I've ever seen one) blue-colored component about 2x as thick as the wires coming out of it and it has a label of C702 printed on it along with a band at one end. Searching for C702 on the internet hasn't helped one bit.
> 
> It is connected to feed the gate of a T151 SCR.
> 
> Mike


the c702 is a capator the (C) indacate's a condenser on the pc board . Like a R123 is a resistor just made that up but that is what they use. The band is the ground end. and went to ground. You won't find nothing with a search of C702. You need a schematic and than you can look up the cap and find just what it is. That may be a little electrolytic cap. and still the banded end goes to ground. good luck


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## montague (Jan 5, 2009)

Mike,

We are here to help if you are in need of assistance. My concern was that you stated that Trend does not reply. Please do contacvt us in the USA as we pride ourselves on customer service and we will do what we can to address customer service issues.

Thanks,

Jamie


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## Relative (Apr 24, 2008)

Jamie,

Sent a PM to you.

Mike


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## harrysin (Jan 15, 2007)

I think that we all await the result with interest.


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## Dmeadows (Jun 28, 2011)

*parts*

NTE5558 is only couple dollars more than the control board!

Trend T4 Router Spare Parts | Miles Tool & Machinery Centre(cant post link!)

However, don't know if they ship to USA!


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## Relative (Apr 24, 2008)

Dmeadows said:


> NTE5558 is only couple dollars more than the control board!
> 
> Trend T4 Router Spare Parts | Miles Tool & Machinery Centre(cant post link!)
> 
> However, don't know if they ship to USA!


Looks like may be $20-$25 plus shipping. Sent them a note to ask. Couldn't find a US site with the pc board as a part.

Still would much rather have the schematic with parts designations so as to repair quickly.

Mike


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## Relative (Apr 24, 2008)

Reply from Miles says they don't ship to the USA.

Mike


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## bobj3 (Jan 17, 2006)

Hi

Why not just remove or by pass the control device and use the item below, you could call it a ext.cord with a switch on it.. 

Don't make things harder than they need to be..

Router Speed Control

=======


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## Relative (Apr 24, 2008)

bobj3 said:


> Hi
> 
> Why not just remove or by pass the control device and use the item below, you could call it a ext.cord with a switch on it..
> 
> ...


Mainly because it says "Will not work with soft- or slow-start motors."

And if you have used a slow-start router, you will not want to give up that feature.

I use one on an old Makita D-handle workhorse and it's fine for that one, but I really like a slow-start feature.

Mike


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## bobj3 (Jan 17, 2006)

Hi Mike

I have the T4 also and it's nice but once you by pass the device on the T4 it's just a full speed router motor  they are cheap now days ,you can always just get one more for about 100.oo ,can't have to many routers..but working on the T4 is like works on a watch .. you can just end up with a pile of parts...  best of luck with yours..

========



Relative said:


> Mainly because it says "Will not work with soft- or slow-start motors."
> 
> And if you have used a slow-start router, you will not want to give up that feature.
> 
> ...


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## Relative (Apr 24, 2008)

*Update*



harrysin said:


> I think that we all await the result with interest.


Just a quick update. I'm back home now and yesterday sent email to Trend support requesting a schematic of the pc board. Received a 'wire diagram' of the router setup (not a schematic of the pc board). However; after an exchange of emails, my request for a schematic has been forwarded to a "Trend UK technical office" - but the really good part is a pc board is on its way as of today.

Once installed, I will feel more comfortable tearing into the bad pc board - it has a black epoxy covering some of the components making it difficult to figure out.

Mike


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## jschaben (Jun 21, 2009)

Relative said:


> Just a quick update. I'm back home now and yesterday sent email to Trend support requesting a schematic of the pc board. Received a 'wire diagram' of the router setup (not a schematic of the pc board). However; after an exchange of emails, my request for a schematic has been forwarded to a "Trend UK technical office" - but the really good part is a pc board is on its way as of today.
> 
> Once installed, I will feel more comfortable tearing into the bad pc board - it has a black epoxy covering some of the components making it difficult to figure out.
> 
> Mike


Good deal Mike... Looks like perserverance paid off


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## jw2170 (Jan 24, 2008)

Great to see some brands that back their product.

Being on this forum may have helped as many thousands of members and non members would be watching with interest...


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## harrysin (Jan 15, 2007)

A good outcome Mike, for Trend, it's very cheap advertising, considering how many members we have here.


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## Relative (Apr 24, 2008)

*Fixed!*

New circuit board arrived in today's mail and the T4 is back to normal operation. Can't say enough about the service support from Trend!

Now, if they would only respond with the schematic I requested....

Mike


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## harrysin (Jan 15, 2007)

I'd take bets that they don't have a schematic, a faulty board gets replaced, Their landed cost probably from China would be peanuts. I base this on the fact that today I ordered from China a hard drive A/V recorder with a 1 Tb hdd, 8 A/V inputs, plus SIX colour day/night cameras, plus SIX mains plug packs, plus SIX 20metre power/A/V cables. The cost including postage via Hong Kong post?........................................$A106.00!!!!!!!

Edit: I've just remembered it also has 2 x USB ports and supports VGA. 2 cameras are dome type and 4 are weatherproof, each contain 22 LED's


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