Hi All,

I've been suiting up for a deep dive on the first real issue with my Black Hole machine. My eyes were wide open when making the purchase and I knew that these could be bears to troubleshoot and resolve. I have no experience though I'm detail-oriented and can Google with the best of them - schematics are a weak point though.

That being said....

Current Issue:
All four topside flippers will be disabled intermittently. Sometimes they'll start out disabled; sometimes they'll flicker on and off over the course of play; sometimes nothing bad happens during a game. I can replicate it easily by bouncing the ball off of each of the trio of pop bumpers towards the top of the upper playfield. (The bottom bumper on the upper playfield does not appear to invoke the issue.) After I bounce the ball against a bumper after 5+ times while holding a fipper button, the flippers can fail energization briefly and may even go dead. Continually bouncing the ball against a bumper resurrects the dead flippers. Of note, the upper ring of the bumper might randomly drop 1/3 its travel distance after activation and stay there though none of the bumpers ever appear to truly die - I can always reactivate them.

Issue Months ago:
Once out of 10 times, returning from the lower playfield engaged the GI correctly though it didn't seem to engage the upper playfield flippers. I did not troubleshoot the issue thoroughly at the time and this quirk does not appear to persist.

The game came with:
Rottendog MPU
Rottendog PSU
Grounding Mod
Battery Mod

I've inspected:
The Q, T, and U relays under the main playfield towards the back - each appears to trigger manually. I did a generalized, [unprofessional] inspection looking for marks on circuit boards in the headboard and under the playfield, looked for mechanical obstructions to mobile pieces under the playfield, and read the instruction manual for a good long while. I did a self-diagnostic memory check - a 99 as a positive result. A switch check resulted in first a 15 and then a 25, though it achieved a positive 99 as a result after I juggled the ball trough contents.

I've read plenty of forums -many on pinside.com- about similar issues though none with identical symptoms. Based on the replicatable cause, I would have thought a mechanical vibration was causing a connection to come loose but I wanted to check with the experts before inadvertantly ruining something on a notoriously fickle machine. Does the community have a plan of attack or a general area of the pin that I should focus on? Thanks in advance for any help whatsoever.

Thanks for the speedy suggestions. I'll post an update later tonight.

Well, I don't know what to say. The machine is operating without major issue after my various probes and I've had a full thirty minutes of successful, strenuous testing and another hour of successful, uninterrupted play. I took the following notes before closing up the cabinet and screwing everything back together.

Good:
*All circuit boards in the headboard appear to be operating at a 4.95V - 5V apiece, aside from what I assumed was a transformer.
*All three pop bumpers had paired switches in the open position at rest with an appropriate amount of room between them and their respective halves.
*The rubber plunger on the solenoid shafts triggered the scoring switches correctly.
*All three relays (Q, T, and U) start in a closed position and appear to make good contact. There is enough space between leaves when activated.
*I traced some of the wires aimlessly and admit I didn't have too much direction. I surveyed the various areas and didn't spot damage or anything of note in the immediate area - wire bundles were clean and any attached connections lacked visible breaks or shears.

Anomalies:
*1 in 15 times or less, the metal rings hang halfway down a pop bumper after solenoid activation. Maybe the springs need to be replaced? With an additional ball hit, or a separate pop bumper activation, or flipper press, these rings always spring back to their normal location.
*The middle bumper of the trio will randomly energize when one of the other two does. I thought maybe the leaf switch was too sensitive though I wasn't able to violently shake or bang the playfield in such a way that the bumper activated without a ball present.

Bad:
*Some of the wire casings leading to the relays and a pop bumper had a small amount of burn or corrosion - not on the wire or the connection spot but towards the end of the plastic sheath. If you took a soldering iron and dabbed the plastic lightly, it'd look like that. I checked the immediate areas for something to cause a short or an external piece that'd rub up against it but didn't find any culprit.

Attached Pics:
*Bumper on the right is loosely "stuck" in a quasi-activated position.
*One of the three relays.
*One of the pop bumpers.

"Deactivating" the Bumpers:
These don't have molex wire connectors to disconnect so I just put a folded piece of sticky notes between the solenoid switches. I did not get a single instance of dead/dying flippers for about 10 minutes of testing. In fact after removing the sticky notes, I checked for a further 30 minutes on various parts of the machine, upper and lower, and didn't get a single instance of failure. This involved ricocheting the ball by hand between multiple bumpers, invoking multiplier lights, drop targets, and other features to turn on and I simply could not replicate any problem that might overload the voltage on any connector. The machine was being lit up like a Christmas tree while holding the flipper button down and the flippers didn't experience so much as a flutter this time around.

I'm at a loss for its mysterious nature, though I'm going to call this a win and consider myself extremely lucky. It looks like I might want to take apart the bumper solenoids at some point and replace the springs or in the very least be vigilant and hit a flipper when I catch that the metal ring has descended and won't ascend. (I hope the community will alert me if this is especially grievous.) The migratory symptoms had initially caused me to put a dust cover on Black Hole for months but I'm very appreciative of the quick and helpful support from this forum.

Thanks, all. I'll post again if I start experiencing confounding behavior from this esoteric pin. Game on.
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Today was a lesson in leaving well-enough alone.

I got home from work and enjoyed a good hour of uninterrupted playtime. I decided to make good on several suggestions from the forum just to get some sort of closure. My quick notes:

*I wasn't ever able to find the acronym TSB in relation to pinball and don't know if that update was done for my bumper boards.
*There is very little resistance on the down and upstroke of the solenoid cylinders. Applied torque and depression caused some resistance on the plastic shield.
*Manually depressing the metal rings -even at non-uniform angles- did not cause them to ever stick.
*Killing the machine while a ring was in a half-stroke position did not release the ring. Only hitting another bumper, that bumper, or a flipper would resolve.
*The downstroke of the plunger motion does indeed have a subtle 'groove' towards the end and a definitive stopping point within the solenoid.
*I considered that you might mean to put the cardboard on the outside of the stop housing. I tried this to no avail.
*The fasteners for those solenoids are so tight that I wanted to forego disassembling them unless there was an overwhelming need. (This would be required if you meant to put the cardboard between the coil and the stop, or if I was going to replace the springs).
*The springs, themselves, are wedging themselves into the bore hole where the plunger midsection meets it. I pried the springs out to increase the tension a bit though no measurable difference was recorded.
*I took note of the old vs new part advice for spring replacement (#21643).
*I was reading that you can demagnetize the plunger by: heating a solder gun and spinning it around the housing, striking it with a steel rod, a blowtorch and other methods I wasn't about to exert much effort on with a working machine. Those solenoid housings are in there TIGHT.
*I made a half-hearted attempt to clean the U, T, and Q relays.

After these tests and observations, I pivoted the machine to its place and realized in horror that the intermittent flipper issue had returned. I poked and prodded all the familiar spots but it seemed even worse than before for quite some time.

I took a doubled-up index card and ran it back and forth between each of the relay switches with a large amount of pressure. Fortunately whether it is the incessant physical jostling or a gaggle of 1980's malicious, voo-doo gremlins with my sanity in their clutches, the machine is back to working like earlier in the day. (Tested for 45 minutes with no issue.)

My final thoughts are.... the intermittent flippers were probably caused by light carbon buildup on the relays. The occasional laziness in the bumper rings might be purely mechanical and I'll order the suggested springs on my next Marco's run. Whether I'll soon risk angering the gremlins for something as benign as this issue, I'm not yet sure. (I can check for bindings and magnetization further when the time comes to disassemble them.)

Thank you sincerely to anyone that spent any amount of time trying to guide me through this. Everything helped.