Bowling foul detector

[RyanG]

I got this board from someone that got it from someone else. They want me to see if I can fix it. I think I know what the problem is, but I figured I would see what everyone here thinks. They said that it blows the main fuse(F1) every time it is plugged in. The fuse is in the black fuse holder below the transformer in the picture. Someone else originally worked on this board because the transformer broke off. They reconnected it by using all the wires jumped off of it, and epoxied the transformer to the board.

I checked everything on the secondary side, although I was fairly sure that wasn't the problem because the secondary fuses (F2 + F3) were alright. There were no shorts on the 2 separate secondary rails. I checked for shorts on the secondary side of the transformer, which has 2 outputs of 12v and 24v. One of them read around 160 , while the other read open circuit where I would have expected either half or double the resistance depending on which winding is which. I then checked the primary side, which read 0.3 between any 2 taps on the transformer. So, I am assuming that the transformer is shot because it should be able to accept 110v or 220v. Could it be anything else?

[Bratster]

You should get a lower resistance on the secondary side and a higher resistance on the primary side.
My guess is when that Transformer broke off whoever put it back on, put it on backwards putting Mains power on the low voltage secondary, which keeps blowing fuses.

And whatever Force caused it to break off may have fractured the connection between the Transformer pin and the winding itself, and that could be the cause of 1 winding open circuit.

I would disconnect all the wires off that Transformer and then take ohm readings off of it and see what you get.

Sent from my Moto x4 using Tapatalk

[RyanG]

I pulled the transformer off the board and desoldered the wires from it. On what was wired as the primary there was one winding with around 10 and the other with 0.3 . The other side read open and 160 . I pulled the tape off the transformer and the one pin had no wire connected to it. So, it looks like you were right about them putting it back on backwards and one of them being broken. I am having trouble finding a datasheet for the transformer. If anyone knows where to find one or what the part number might mean for a ST-5-2370 that would be a big help.

[floobydust]

Check Signal Transformer ST series pdf , but -2370 sounds like a custom part that is more than 6-pin, like a triple secondary part.
I wonder why it's installed upside down?
You could ask the bowling board manufacturer what the correct part is, or you would have to sketch a schematic of the board to estimate the voltages.

[RyanG]

It is an 8 pin transformer. It is labeled as 120/240v input with two outputs of 12v@0.5A and 24v@0.15A. I contacted Signal Transformer to ask them for info, but it looks like they won't be much help because they are asking for my business information instead of answering my questions.

[james_s]

Well you have all the information you need there to find a suitable replacement, anything with similar voltage ratings and equal or greater current capacity will work. Try the parametric search on Digikey or Mouser and see what comes up. You will likely have two separate 120V primary windings that can be connected in either series or parallel to set the voltage, then two separate secondaries.

[Cyberdragon]

If some daft dingus reverses the transformer and kept plugging it in, the transformer being fried is the least of the problems. Unless it has overvoltage protection on the secondary, it would have boosted the mains to insane levels and toasted it. I'm suprised the cap didn't become a bomb.

[RyanG]

I powered the 12v part of the circuit from another transformer I had around and everything seemed to work. I don't have a 24v transformer to try to hook the entire thing up. I might have two 12v around here somewhere though.

This transformer that I found on Mouser should work https://www.mouser.com/ProductDetail/Bel-Signal-Transformer/DST-5-24?qs=sGAEpiMZZMuKmRn7rpQYPW79jdBrHTAV%252bTfgpFz71P89OLHFadBeOQ%3d%3d. It is the same size according to the part number 5-2370 vs 5-24 since the 5 is the size according to the datasheet. The power rating is good. One question is about the secondary side. It says 24VCT/12V. Would that mean the windings are separate as the dual winding states or is it just 24V center tapped for 12V? Sorry, never had to pick a transformer out for anything.

[floobydust]

8-pin dual primary are the DST series, which have two isolated secondary windings.
Off-the-shelf transformers always have these two windings with the same rating. So a 12V and a 24V winding would be a real oddball. It should be dual 12V windings in parallel.

Can you check if the secondary windings are in series (pin 6,7 connected) or parallel (pin 5+7 and 6+8 connected) on the PC board.

When I look at your PC board, I see only one bridge rectifier, a buck SMPS and one extra diode.
Making the 12VDC relay coil voltage seems to be the most needed. U7 may be a 78L05 5V regulator IC.

There is fuse F1 so that is probably why no smoke happened.

[RyanG]

Here is a picture of the top and bottom together with the bottom mirrored. No traces on the top connecting any pins on the transformer.

[RyanG]

Could it be that it is just 2 12v windings and the rating on the transformer is for the series and parallel usage? The trace that runs up to the black wires goes to a buzzer labeled as 12VAC. So, that seems likely.

[Gregg]

It almost looks like the transformer has been replaced and isn't the same footprint of the original.  It looks like the original may have had pin terminals through the board, but the replacement wouldn't work without wires, which were inverted when installed.

[RyanG]

The transformer broke off the board. This is a foul detector for bowling, and they get hit by balls and people step on them often. When it broke off the pins broke so they flipped it over to solder it back on, but soldered it backwards. That is how I received it.

Attached picture of the label on the transformer.

[KE5FX]

Whoever replaced that transformer has entered a world of pain.  Was his name "Smokey?"

[floobydust]

Ah one winding powers the board, and the other winding goes to the relays to the buzzer?

It could be a label typo, it should read 24V 0.25A (series) if it's a "normal" part and bowling system uses 12VAC for lights buzzers etc.

I'd measure the transformer pins and confirm size, and get the DST-5-24 or Hammond 162G24 or Tamura 3FD-24 etc. as 12VA parts are a common size and footprint.

Hardest part is desoldering that mess

[james_s]

It's probably a custom transformer, I certainly have some in my junkbox that produce multiple different voltages, I think it was more common in older equipment. If you get desperate you could replace it with two separate transformers to get the voltages you need, or get a transformer with two 24V center tapped secondaries and use only half of one of them to get the 12V.

[RyanG]

I found the manual for this thing. Found the important info.

[RyanG]

I do think there is something else wrong with this though. I hooked up a 12vdc power supply to the board, and I can't get the IR detectors to work. The emitters are working. I used an IR receiver on a breadboard to check for that. I can't get the LEDs to blink, which is what the manual says is supposed to happen when the receivers detect the emitters being reflected back.

[Cyberdragon]

I do think there is something else wrong with this though. I hooked up a 12vdc power supply to the board, and I can't get the IR detectors to work. The emitters are working. I used an IR receiver on a breadboard to check for that. I can't get the LEDs to blink, which is what the manual says is supposed to happen when the receivers detect the emitters being reflected back.

As I said, it got blasted by HV due to the backwards transformer (the fuse only stopped a fire, not all damage). You might just have to replace the chips controlling the receivers (the diodes themselves should be fine).

[floobydust]

If the 5V and 12V rail is OK, I see two trimpots and two test points for setup.  R5/TP1 maybe for the LED driver, and R6/TP2 for the receiver.
We have no idea where the ribbon cables go.
Otherwise you'd have to troubleshoot measuring IC voltages.

[RyanG]

U1 is a TLC274 Quad Opamp. U4 is a PIC16C71-04. U5 is a ULN2003. The MCU has 2 outputs doing 50% duty cycle at 1.96Khz and 2 outputs doing 16.5% duty cycle at the same frequency. The 50% duty cycle goes out to the ribbon cables. That then seems to go to the IR emitter. The voltages for each IC are correct, but I don't know what voltage the onboard SMPS is supposed to put out. The 2 test points have nothing on them with or without the IR being reflected. I don't know what to do with it.

[james_s]

You'll probably have to reverse engineer a bit to figure out what conditions the IR signals. The fact that the PIC is doing something is a good sign, if that's dead then it's game over unless you want to re-write the firmware from scratch.

[RyanG]

The first thing I have tried to reverse engineer is the connection to each IR module. There are 4 wires in the ribbon cable. They are V+, GND, 1.96Khz connection to the ULN2003 to flash the emitter, and the last I assume is the wire for the signal of when the beam of light is broken. I have not been able to get that signal to change on either IR module when I reflect the light into the receiver. I even made a flasher with an IR LED hooked up to an Arduino at the correct frequency with no success. I even took each of the modules off and pointed them straight into each other. That didn't do anything either.

[floobydust]

Each IR module looks identical, it must be a reflective-type sensor covering a bowling lane on either side, with a mirror on the opposite end? I can see red alignment screws but no idea about focal length or how directional these are. It must have an analog output and LED pulsed out-of-phase to prevent crosstalk with the other lane perhaps.
Otherwise I can 't see why you need the quad op-amp. Can you give a pic of the IR module, I wonder if it's made by Sharp.

[RyanG]

They do have a reflector opposite them when installed on a lane. I just checked the outputs from the MCU and they are 180 degrees out of phase. Picture isn't the greatest for some reason. It isn't a Sharp module by the looks of it. It just has a TLC272 opamp, a diode, a bunch of passives, and obviously the emitter/receiver are on the other side. I've tried reflecting the light back at many distances and tried angling the mirror/reflector slowly to hit it in the receiver, but it never works. I fed the 5v into the inverting inputs on the quad opamp and I can get the LEDs on the board to blink, so I think everything is still working alright on that part. I really don't think that I need to stand the width of a bowling lane away from it to reflect the light back correctly, but I could try.