My Paragon has recently become a bit unstable, occasionally locking up, and sometimes also blowing the playfield 1A solenoid fuse.

First happened back at Thanksgiving when people were over. I wasn't there when it happened; found the playfield fuse blown; replaced it; all good.

More recently, I've had it lock up on me in the middle of a game; or after sitting idle for a bit. Getting a bit more frequent.

Symptoms
- General Illumination remains on
- Displays go dark
- Controlled lamps go dark (any "thousands" score or other indicators)
- Cannot add a credit or start a new game
- Kickouts and flippers don't work
- Cannot go into test mode
- I can restart the game by powering off/on
- I have put it in test mode, and ran through all the solenoids for about 10 minutes
- a while later when sitting idle and solenoid locked on and blew the playfield fuse
- occasionally also locks up on power up, but rarely... it's usually after it's been played or sitting for a while
- assuming it's temperature or noise related
- other posts with similar issues have pointed to Solenoid Driver Board, or possibly power.
- I believe the solenoids occasionally locking up is secondary effect, since it doesn't always happen... assuming the MPU is sending out some random garbage when it hangs, and occasionally locks a solenoid on.
- On startup I get one flash, then 7 flashes, then green LED stays on but with lower visibility than flashes... when locked up, it goes completely dark.

Pictures of circuit boards attached
- MPU is TwoBits after market
- Other boards look original
- I've repaired the Sound Card (separate thread last year)
- I've replaced one of the power connectors (GI pins were cooked)
- compared to other peoples photos, it looks like the big caps on the Solenoid Driver Board may have been replaced?
- One resistor (R34) on the SDB looks like it was cooked and replaced at some time
- lots of harness wires have had electric tape added near connectors where insulation has become worn. I have some shrink tubing to eventually fix that, but up to now, it hasn't really caused me any problems.

Looking for feedback on
- possible root causes, based on symptoms
- opinion on locking solenoids being a secondary effect, or if they could randomly be locking (caps/diodes) and pulling down the MPU as well.
- Do boards look like they've had any "bullet proofing"... if not, point me in the right direction
- any other photos you want to see
- what to check when it's not locked up
- what to check when it is locked up

I'm a firm believer in diagnosing the crap out of an issue, and coming up with possible root causes that address all of the symptoms, before I start changing stuff. Not really a shotgun approach kind of guy for these old boards (and old skills!)

Thanks!

MPU
circuit 1 (resized).jpg

Switch Matrix

circuit 2 (resized).jpg

Sound card

circuit 3 (resized).jpg

Power Supply (front... never have taken it out)

circuit 4 (resized).jpg

Solenoid Driver Board with some closeups

circuit 5 (resized).jpg
circuit 7 (resized).jpg
circuit 6 (resized).jpg

TP5 on mpu is 4.56ish volts to both TP4 or the ground braid wire in head.

Will check the schematics to see which supply fuse is providing power but I only see a 5.5 volt on one of the fuses... so assuming that's the source.

Buried in my initial post. Lots of wires were wrapped with electric tape when i bought it. I inspected a few and underneath some of them wire insulation is worn off. I have some shrink wrap to make it neater, but so far I haven't really had problems so don't want to get into a job like that unless I'm sure it's causing a problem.

Concerned about old power board too, but still seems good, unless its affecting the levels... which I'll check into a bit more.

Thanks for input... gives me some direction for further investigation and things to retrofit in the future.

Thanks ... will dig up the schematics and trace some levels on boards and through connectors ... wouldn't have thought that the 5v didn't also come from the supply board so thanks for that direction. Will check 12v on the supply and 5v on the SDB.

Schematics ... gotta take the time instead of being lazy

Yup. Need to invest in a good crimping tool and wire stripper. I've tried to minimize connector fixes until absolutely necessary. Maybe with my Christmas or birthday money . Will start shopping in the new year. I may want to do a project pin sometime too so will be a good investment ... thanks again!

Good... will check that too. Thanks!

I found very very little slack when I was working around my soundcard. Some of the worn insulation could be an inch or so away from the connectors so I don't think I would have enough slack unless I cut past broken insulation and add extensions ... still need to shrink wrap but then I also lose the colour codes at the connectors too. Some of the wear appears to be where some tie wraps may have been ... too tight or something. Anyway will cross that bridge when I get there.

The taped wires look worse than they are. I don't think prior owner did them so they are really old. Hard to install in the first place if you ever tried to put electric tape around some individual wires in a bundle. The glue is dried now so some is coming apart. And the tape is often way wider than the small area of worn insulation they cover. I felt it was risky to start trying to pull them off until I was really ready to put shrink tubing on them which means pulling pins out of connectors ... which means might as well repin them at the same time....but like I said, they haven't caused problems (yet) so best to leave 40 year old wires alone until I have the tools to do it right .

All great advice peeps, and all on the list to do over time. For now gonna focus on seeing if fixing a couple pins helps rectumfy my 5v issue and hopefully that addresses my lock up problem .

I'll have this thread to drive my upgrades for the next couple years!!

Quick update. I seem to have stabilized the mpu resetting for now.
Voltages on the power supply seemed good (maybe a few of the higher voltages out of tolerance but nothing alarming)
5V supply on the SDB (TP1) was ~5.3V, but only 4.5V getting through to the MPU (TP5).

Turning off power and reseating some connectors to see if anything affected reading:

Reseating J4 on the MPU didn't affect the voltage on the MPU.
Reseating J3 on the SDB improved the voltage on the MPU, but not up to 5.3V.
I sprayed contact cleaner into the connector pins, and onto the header pins... did a bit of wiping the header pins with steel wool (probably better to use light emery or something else, in case you leave any steel wool threads that could short pins).
Inserted/removed/reinserted the connector several times to help clean the pins and contacts (probably wishful thinking, but it's gotta do sumthin right? )
I'm getting a consistent voltage on the MPU TP5 of about 5.1V now... so still losing some voltage through the pins, but 5.1V works for me.

Was able to cycle through the solenoid test lots of times, and play several games without it locking up on me.
I'm leaving it sit on for a couple hours to confirm it doesn't lock up after it's warmed up a bit.

So... good for now to play over the holiday; but looks like potential work to make a better long term improvement by replacing connectors (and maybe header pins).

In checking out some of the other voltages, things seem stable, but a bit off from the values on the schematics, especially some of the higher voltages. Nothing way out, but a few beyond the tolerances that are listed. Will dig deeper as time permits.

Thanks for everyone's help in leading me to a quick fix ('specially barakandl... again... helped me last year with soundboard!) , so's we can be playing Paragon for Christmas!

Have a great holiday everyone!

(...will be looking for people's opinions on quality wire strippers and molex crimpers in the new year!)

Ok... for you diehards who will read new posts even after it's resolved, here's your favourite wire stripper and crimper question ... what do you like? Looking for quality at a good price.

I have a basic wire stripper and crimper that looks like this. It usually requires "pull" on the wire itself to finish the strip; and the roundish crimps don't work on molex... to me this is essentially for house or motor wires with lugs crimped on.

IMG_1551 (resized).PNG

We had these wire strippers in high school which I thought were great; cut the insulation completely and did not require you to risk pulling on the wire itself since it separated the two pieces of insulation. I probably will get one of these.

IMG_1549 (resized).PNGIMG_1548 (resized).PNG

This is a newer style with self adjusting cutters, but I'm concerned about how it automatically sizes the cut...and it doesn't cut all the way around the wire... I see potential for incomplete cuts and nicking the wire... anyone use or like these? I prefer a solid cut all around the wire insulation.

IMG_1536 (resized).JPG

This is the type of crimper I think I need for molex.

IMG_1550 (resized).PNG

I'm looking for feedback on style of wire strippers and crimpers you use and like.. and what brands are good quality and price. Please post picture or links. Thanks!

Rationale? Accelerate corrosion? Damage to plastic molex connector? Something else?

From my background in semiconductors and circuit packs we used cleaner on edge connectors etc... usually "slide in" connectors, not necessarily square header pins with molex connectors .

So... good or bad ? Not dissing anyone, just want to understand why it's bad if it is ...

Bump for the new year... looking for peoples feedback on preferred wire strippers and crimpers for pinball connectors (check a few posts back for details as there were a few responses to initial request).

Probably going to order something online soon.

Happy New Year!