S+ reels 'jumpy' on startup

[Jim]

that's what I said earlier in my post, you would have to extend wires from certain test points in order to measure them.

you can test +vb at the digital display board, it is present across the large electrolytic cap.C-4--15microf at 25 vdc,  the + vb should be around 10vdc.

Hope this helps

Jim

[Bob L]

I didn't realize the file system was there - thanks for pointing it out!  I have some things that tilt gave me a link to above, but I'll dig around in the file system some more.   

I think I might be able to verify the function of the other reel chips by just probing at the reel's themselves (although they're unplugged when I'm doing that).   

Based on  BadBaud's post, I'm concerned that the reel voltages aren't high enough.   The power supply diagram says 11.5 +- 1.5 volts when high, and that's what I see (10.8V to 11V), but BadBaud says it should be more like ~24V and ~15V.   A low voltage could explain the motors 'missing' a bit.   Still, the fact that the reels spin forever makes me wonder about Vb.  It also could explain the reels trying to spin forever on startup (if the reel sensors aren't working)  Thanks for the info on where to probe Vb Jim.  I'll also be able to look at that and for ripple on the 5V once I get the probes I ordered. I'm hoping it'll just be caps or diodes and not the reel drivers, but I did see some used stepper drivers for sale if needed...

Thanks for all the info!!!     The more I learn, the more I want to get another machine :-)

  Bob

[twinfire]

Hi, I've had an s+ double wild cherry slot for a long time and a month ago it wouldn't power up correctly.   I fixed the power connector with trifurcon connectors, and now when I start the machine, the lights come on, the bill acceptor self checks, and then all three reels do a 'jumpy' spin (moving mostly forward, but jumping backward randomly).   The reels continue this jumpy spin as long as it's powered on.

Just curious Bob, How was it acting prior to rewiring in a new replacement connector?

[Stayouttadabunker]

Here's how I repaired a S  reel driver more than once...lol...>>>

[Badbaud]

Are you watching the 24V with a scope probe on the metal tab of the TIP125 transistor? Look for excessive AC voltage waveform.
The main filter cap does go bad and need to be replaced to remove the excessive motor humping.

[Bob L]

Twinfire, I believe the reels weren't turning at all.   The displays were blank.  The first searches I did found the info about the burned plug and I saw the discoloration, so I fixed that.  After that, the reels became jumpy.   I didn't do a lot of analysis before fixing the plug because that looked like an obvious problem to fix. 

Bunker, thanks for the video reference.   I'm still holding out hope my reel drivers are ok because the couple outputs I looked at looked reasonable.

BadBaud, I should get new test leads today so I can check voltages while the board is plugged in.   Unfortunately, I won't be able to test in in the machine for a bit, as it's in a different location.  I'm hoping to get up there in a couple weeks.  I thought about moving the machine temporarily, but it's pretty heavy :-)  I've ordered some replacement diodes, and I may buy some extra caps just in case.  I will test the 24V at the butterfly when I get to the machine.

By the way, one thing I noticed when looking at the board is that all 4 large caps are 6,800 uF's (two are 25 V, two are 16V).  The schematic shows C23 as a 10,000 uF, but it's a 6,800 on mine.  I'm not sure if it was replaced or it's just different on my rev of the board.   I may just buy some replacement caps, and I'm wondering if I should get a 10,000 uF one for that.

[Stayouttadabunker]

Some of the older boards had those much larger caps
I noticed they went to smaller ones, in the later revisions.
I'd stay with the same size as the ones on the board presently.

[Bob L]

I decided to do a little more debugging on this at my brother's house (he's an EE) and I think we may have found the culprit.   

We decided to partially energize the board just before the LM317 (i.e. from the output of CR3/4 to the isolated ground with ~11V DC) to see how the voltage regulator was doing.   When we did this, we only got about 3V instead of the expected 5V, and we saw about 2.6 Amps were being drawn.  The voltage regulator was getting really hot (as expected as it's a 1.5A regulator). 

This seemed to imply that there was a short somewhere on the board so we tried to look for it by finding something 'hot' on the board.   We couldn't find any thing hot initially except near the LM317.   Thinking that maybe the LM317 was bad, we decided to desolder CR12 to disconnect the regulator from the downstream 5V, and it then stabilized right around 5V as expected.  This implied that the LM317 was still working, although with no load, and that the short was coming from downstream somewhere.    We decided to bypass the LM317 to be sure, and supplied 5V directly the 5V test point, and again we saw high current and the voltage was being dragged down to ~3V. 

We looked for a hotspot on the board again, and the only area that was getting hot was right near the LM317 - it looked like the ESD protection at D3 was getting hot.  We cut out one end of it, and then reapplied the 5V and everything looked good voltage wise on the isolated 5V circuit and the current was dramatically lower (I forget the exact reading). 

This says D3 was definitely blown (I measure about 2 ohms across it both ways).   It looks like the LM317 still works, and we're hoping nothing downstream was fried.  I could in theory plug in the board like this to check, but I'm going to wait until I find a suitable replacement for D3 and put it in (Mouser has a 1N5908 that has specs close to the original/obsolete ICTE 5 on the board) .  This may not fix everything that is wrong, but I'm actually optimistic it will.   Undervoltage on the 5V could cause all kinds of strange things to happen.

My theory is that when the plug went out, maybe it caused an arc or something that blew D3.  Hopefully D3 did what it was supposed to and protected everything else.   I'll order the part, install it, and see what happens next (fingers crossed).  It might take me a couple weeks to see if it works.

If anyone has recommendations for better matched replacement, let me know.

Just want to say thanks again to all of you for the continued help.  I'll post again when I have the results :-)

[Stayouttadabunker]

I can't wait to see your results.
I love the way you guys troubleshooted. 
You have to completely understand schematic diagrams to poke around like that.

BTW did you use a temperature gun to seek out heated IC components?

[Bob L]

My brother is a pretty smart  guy and he’s done this a lot. 

 We didn’t have a thermal camera, so we used an infrared thermometer to find the area that was heating up.  Then we checked with our finger. Pretty high-tech :-)