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inside a MRD


gianmarko
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hi all

not sure is the right section, but i thought you might  be interested in seeing whats inside a MRD and what justifies the top dollars required to buy one

so one colleague shooter, after the advice of other colleagues shooters in italy (and against my advice) and who swore these MRD were top quality, bought a couple of these "made in japan"  Benthley TSX6 red dots.

https://www.erreditrading.com/red-dot/1210-red-dot-aperto-tsx6-con-illuminazione-regolabile.html

 

they look very similar to the nikko stirling pro t4 diamond and they were priced around 250 euro apiece. according to the italian guys, they were the same MRD but sold unbranded. the T4 diamond is the MRD coming as standard on top of the BUL SAS II
the two red dots failed quite soon, but were replaced for free by the shop which sold them. they currently still work.  for mysterious reasons, he bought a third one, that failed pretty soon, and i got it to attempt a repair
the symptoms are that randomly the red dot would shut down, usually after a couple shots.

when i got it, it was working ok,  banged it several times on the table and was still working, then it died completely. 

here below you can see how the MRD looks like from the outside (please ignore the horrible mess on my workbench...) 

1.jpg

2.jpg

 

3.jpg

 

 

4.jpg

 

the body of the MRD is milled aluminium, quality looks ok
cant tell what material is the lens, but it looks of ok quality and looks properly installed in the body of the MRD

 

 

inside i found a small PCB with a nameless chip, a capacitor, a limiting resistor to drive the LED, and a small PCB mounted 90 degs with the  main PCB, carrying the two switches and the clip to hold the battery drawer.
the small PCB is soldered to the main PCB with a very liberal dose of solder. 
the led is temporary for tests
10.jpg


11.jpg

 

 

 

the LED module is mounted on a mechanism that allows it to be set and then locked. the mechanism looks ok-ish, and has tiny sprung ball bearings that will make the screws "click" when they are turned.  

 

5.jpg

 

the module looks ok, wires seem well anchored and it project a small and somewhat weak red dot on the glass

 

13.jpg

 

once i had the module in hand, the led started working again, but touching the PCB it would flicker and randomly turn off
after having redone all soldering, the problem was still there.
then i found out that the ground wire on the pcb was cracked in correspodence with the large solder blob, as shown here after the repair

12.jpg

 

 

the crack was not visible even with the microscope, i repaired with a little copper wire and more solder.

so it looks like the small side PCB, under the stresses of the 200lbs monkey fiddling with the tiny buttons, and of the battery being knocked about by the recoil, makes the large solder blob move, and the ground copper strip will eventually crack generating this problem.

 

the PCB has no conformal coating, and from the red dot hole in the MRD body dust, sweat, water, oil and crap can get in, so i expect the PCB and solder to eventually corrode and fail.
also the led module wires were badly soldered and there was only a tiny amount of glue to fix them, so that would have also eventually failed.

in short, the quality of the electronics is CRAP and smells chinese from miles away. further confirmation of the chinese origin is the fact that the red dot module wires are swapped, red is negative and black is positive. 

 

i might get hold of a couple failed Cmore MRD's and im curious to see whats inside

 

one thing is for sure, if the MRD has to last, the battery is a very weak point. if you look at how a slideride is designed, the battery will not stress the contacts or anything else under recoil, and thats am excellent design.

is probably not easy to have such solid design in a micro red dot, due to space constraints and the need to install a 3V battery

 

for those who find their MRD red dot too weak, rather than using 2 batteries, id install another resistor in parallel with the standard limiting resistor, or replace the resistor with one of lower value. that would be a safer option than doubling voltage

 

 as the mechanical part of this MRD is ok, it would be rather simple to produce better electronics and perhaps pot them,  and devise a better arrangement for the battery. 

 

 

 


 

 

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That's basically the exact same board you'll find in an RTS2 V4 and earlier. The chip is an ATtiny13A. The are multiple failure points that crop up over time and the battery contacts are rarely it. Yes, unfortunately, it's all electronics you'd expect to find in a cheap child's toy.

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8 hours ago, theWacoKid said:

That's basically the exact same board you'll find in an RTS2 V4 and earlier. The chip is an ATtiny13A. The are multiple failure points that crop up over time and the battery contacts are rarely it. Yes, unfortunately, it's all electronics you'd expect to find in a cheap child's toy.

if thats the case, is really incredible considering the price of a RTS2

 

producing a proper electronic board would not be that expensive, a few design changes and conformal coating or potting would go a long way towards reliability

the contacts themselves are ok, the problem is the mechanical and electrical interface with the rest. 

 

the chip in this specific MRD is not an attiny, unless it was scrubbed of the markings. 

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15 hours ago, gianmarko said:

if thats the case, is really incredible considering the price of a RTS2

 

producing a proper electronic board would not be that expensive, a few design changes and conformal coating or potting would go a long way towards reliability

the contacts themselves are ok, the problem is the mechanical and electrical interface with the rest. 

 

the chip in this specific MRD is not an attiny, unless it was scrubbed of the markings. 

 

They do tend to scrub the markings. Most of these dots all come from the same place that's why they're so similar. The v5 board in the RTS2 is finally an entirely new construction with improvements, added complexity, and still yet to be long term tested so we'll see. 

Edited by theWacoKid
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16 minutes ago, theWacoKid said:

 

They do tend to scrub the markings. Most of these dots all come from the same place that's why they're so similar. The v5 board in the RTS2 is finally an entirely new construction with improvements, added complexity, and still yet to be long term tested so we'll see. 

Wife's V5 dies after about a month. 

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  • 4 weeks later...

i got a RTS2 to fix and opened it

 

as already stated by others, it is identical to the generic MRD i already showed here. only difference is that the microcontroller is marked atmel and is an attiny13 

 

all the rest is absolutely the same

 

i was at a gun show saturday and had a look at the sig romeo3, and it also looks very similar with only small differences in the aluminium enclosure. would be curious to see it inside, but i wouldnt be surprised to find out it is the exact same thing with just a slightly different milled enclosure. all screws and controls are in the same position

it was on "offer" at the equivalent of USD550

 

i wont bother posting more pics as it is exactly the same MRD except the markings outside

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1 hour ago, BoyGlock said:

It validated my preference for slideride and serendipity

they are good red dots, very well designed and built. they have some weaknesses but they are cheap and super reliable

 

im still trying a DPP on top of my czechmate, see how it goes.. at any rate, it looks much better built than these chinesium SRT2 and the such, and i can source them for around usd 450, which is relatively cheap

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  • 4 weeks later...

my friend's Nikko Stirling MRD failed. it is almost new, maybe 4-5000 rounds, and bracked mounted of top of an open gun 

as expected, it is identical to the "made in japan" TSX6 and to the CMore RTS2

 

this failure is nothing short of shameful. the resistor that drives the led just detached from the PCB. see picture.
easy to fix, but this should not happen. quality is just crap.

 

WhatsApp Image 2019-12-30 at 09.05.23.jpeg

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On 12/30/2019 at 10:57 AM, gianmarko said:

my friend's Nikko Stirling MRD failed. it is almost new, maybe 4-5000 rounds, and bracked mounted of top of an open gun 

as expected, it is identical to the "made in japan" TSX6 and to the CMore RTS2

 

this failure is nothing short of shameful. the resistor that drives the led just detached from the PCB. see picture.
easy to fix, but this should not happen. quality is just crap.

 

WhatsApp Image 2019-12-30 at 09.05.23.jpeg

 

You mind measuring that resistor while it's off?

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unfortunately the resistor detached by itself and then found its way out of the red dot so we dont know what it was

but we can safely assume is the same as in the other various versions, which is 330 ohm

as this red dot was not very bright i replaced it with a 280 ohm, slightly brighter now.

 

 

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  • 1 month later...

must rectify what i said about the resistor. is a 33 ohm not 330, and i replaced it with a 28 ohm

 

sorry for the mistake

 

i have designed a 3d printable battery drawer for this style of red dots, as they break very easily and i bet they dont come free.

is better than the original as it doesnt break so easily and is basically free.

 

if anyone interested drop me a line

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10 hours ago, 38super said:

Try coating with clear coat paint.  It was also provide a mechanical retention for those pesky SMD's.

yes, some sort of conformal coating would certainly help. 
the mechanical construction is actually ok. the led module seems to work fine and i have not heard of any failure. if the driver circuit was properly designed and built, these would be very reliable. 

 

is a pity, they could have built good units just sacrificying  a couple bucks per unit. 

Edited by gianmarko
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1 hour ago, parvusimperator said:

 It makes me wonder how hard it would be to get them built right, 

not that hard

the hard part is the mechanical part, the glass, the led emitter. and that part is reasonably well built. 

the electronics, i could have made a better one in my kitchen....

 

 

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3 hours ago, parvusimperator said:

They definitely could. It makes me wonder how hard it would be to get them built right, 

 

It's not hard to get them built right, it's just more expensive.  

3 hours ago, parvusimperator said:

market something that actually works reliably like the AMG labs timers guys do for their timers.

 

you mean like Trijicon? 

 

Nolan

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2 hours ago, Nolan said:

 

It's not hard to get them built right, it's just more expensive.  

 

you mean like Trijicon? 

 

Nolan

Yeah maybe. I think there might be enough good experiences with the SRO for me to take a look. I'd need a new mount though.

 

The changes mentioned in here don't seem like they'd add all that much more to the cost.

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