(Topic ID: 191559)

Stern Solenoid Driver High Voltage Issue

By Shredso

4 years ago


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  • 18 posts
  • 5 Pinsiders participating
  • Latest reply 2 years ago by JT-Pinball
  • Topic is favorited by 4 Pinsiders

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#1 4 years ago

I've been working on a Hot Hand. I bought a handful of components to replace on the solenoid driver. A couple resistors and diodes were bad. The header pins looked fine so I reflowed them. I will probably replace them just in case. CR21 and R35 both give me odd readings in circuit even though I replaced them. With the board installed I can get the displays to turn on by finding a sweet spot on the potentiometer. This sweet spot is letting the full 240v to the display. The pot seems to test fine other than a few odd spots in the sweep. This doesn't make sense to me, hopefully replacing it solves my problem. I have a few questions.

Could a bad pot be causing me to get weird readings on the diode and resistor?
Are there any other parts I should consider adding to my order in addition to the pot?
How long can I run the displays with full voltage before I damage them? I was hoping I could run it for a few minutes at a time to troubleshoot some other stuff.

#2 4 years ago

I also did the 2 capacitor ground mods and the TP 1-3 mod.

#3 4 years ago

My humble opinion is to just go thru the board and replace the 5v regulator and the 190v. Did you replace the capacitors at c23 and c26. If original they should be replaced. Hot Hand. My favorite game! My uncle had the machine, played when I was a kid, when he passed it came to my house not working. Works now! .

#4 4 years ago

Unsolder and test the 3 transistors in the the high voltage section. 1 or all 3 is shorted. Allowing the pass transistor on the heat sink to run wide open. When this happens a resistor will burn up.

#5 4 years ago
Quoted from JT-Pinball:

My humble opinion is to just go thru the board and replace the 5v regulator and the 190v. Did you replace the capacitors at c23 and c26. If original they should be replaced. Hot Hand. My favorite game! My uncle had the machine, played when I was a kid, when he passed it came to my house not working. Works now! .

I should have added I did replace those 2 caps. Not sure what you mean by 5v regulator and 190v. I'll do some more research.

#6 4 years ago
Quoted from pinballdaveh:

Unsolder and test the 3 transistors in the the high voltage section. 1 or all 3 is shorted. Allowing the pass transistor on the heat sink to run wide open. When this happens a resistor will burn up.

The 3 transistors tested fine in circuit. I will try them out of circuit. Might as well add them to the next order either way.

#7 4 years ago
Quoted from Shredso:

How long can I run the displays with full voltage before I damage them? I was hoping I could run it for a few minutes at a time to troubleshoot some other stuff.

I would unplug them for now.

Good the filter caps are problematic if the old ones are on the board. They are past there life expectancy you and should be changed. Here is the standards for a solid working sdb that will not have you chasing issues.

5.7.6 How to Rebuild the Bally/Stern Solenoid Driver Board
The Solenoid Driver board is critical to the operation of the electronics of the game. The Solenoid Driver Board (SDB) comes in several types for Bally and Stern, and are completely interchangeable for any game of the 6800 MPU type. The SDB supplies the game with the voltages for the MPU, coils and high voltage for the displays. Recommendations are given below for replacing components to ensure proper operation and reliability. In all cases, do the ground modifications as shown in another part of this Wiki.
Minimum Recommendation for a Working board
At a minimum, replace both large capacitors on a working or non-working board, especially if they look original. Original caps are often metallic blue or metallic silver, and are at least 30 years old and due to fail, owing to the electrolytic chemicals in the capacitor drying up. The capacitor at C 23 has a factory value of 11,000 uf and 20 volts, but these values are not easily found these days. An electrolytic capacitor of between 11,000uf and 16,000 uf and 25 volts or greater can be safely substituted. A screw terminal capacitor makes for a easy installation, but a snap cap with leads can be used as well. Recent prices for screw terminal caps have increased greatly so this may be a factor in your decision.
The high voltage capacitor at C26 has an original spec of 160 uf and 350 volts and is an axial electrolytic capacitor. Once again, this part is difficult to encounter with these exact specs, but an axial or radial cap from 150uf to 180 uf and at least 350 volts can substitute. 400 v or 450v caps can be had in a radial format and size that will fit. With a radial cap you will have to make leads that bend back to the negative (-) solder pad.
Preferred recommendation for a working board

Clearly fractured .156 header pins on a Bally single sided driver board
Besides the above, replace ALL the .100 and .156 molex header pins and the connector terminals in the nylon housings with Molex TRIFURCON Phosphor Bronze tin plated crimp terminals (Molex Part# 08-52-0113 for 18-20 ga. Wire, and 08-52-0125 for 22-26 ga.) for the .156 connectors, and Molex .100 tin plated Phosphor Bronze crimp terminals, (Molex Part#08-52-0123). Do NOT skimp on this step and just do one or the other. The receptacles can be re-used if not burnt. If replacing the receptacles, the locking or non- locking ramp type are fine. Often, the connector at J5 does not cover the last few pins. I don’t like this personally, although no harm can be done if the key is in place.
Check every resistor that is usually covered by the plastic shield between the two big heat sinks for correct value and no sign of burn. Replace any that are suspect. Use the diode function on your multimeter to check the zener diode at VR1 and the 1N4004 diode. The zener diode can be difficult to source. See below for recommendation.
Gold Standard for Working or NON-WORKING board
It doesn’t make too much sense trying to trace down the exact problem and replacing only the bad components on a NON-WORKING board. Better to replace every possible bad component and start fresh. To ensure long life and proper operation of a working board, in ADDITION TO THE ABOVE, it is recommended that the components below are replaced regardless. Below is a list of components that effect the HV and +5 volt logic circuits on the SDB. Replace them all! * The Stern Revision J board is rather different, & a component list for that board follows. It can be identified by the extensive silk screening of each component and its function as seen in the 4th photo above, and by the HUGE 2 Watt and (2) large 1 Watt resistors. It is most often found on late date Stern games like Flight 2000 or Viper, etc.
Component replacement list for Bally AS2518-16 or -22 and Stern SDU100 SDBs, except * revision J
Resistors
R51 22k ohm 1/2Watt
R52 390 ohm 1/4 Watt
R54 8.2k ohm 1/4 Watt
R55 1.2k ohm 1/4 Watt
R56 82k ohm 1/2 Watt
R35 100k ohm 1 Watt
Diodes
CR21 1N4004 400PIV 1 amp or better (1N4007, etc.)
VR1 Zener diode 1N5275A 140 volts, 1/2 Watt. Can Sub 1N5275B or NTE 5099A
Transistors
Q21 2N3584 250volts, 2 amp, TO-66 NPN
Q22&23 2N3440 250 volts 1 amp TO-39 NPN
Q20 LM323K (original 78H05KC or LAS1405)
Capacitors
C27&28 .01 uf 400 vdc metal polyester capacitor
RT1 25k ohm potentiometer (2 types) a 15mm black one, Piher Part# PT15LH06-253A2020 or a 6mm blue one BournsPart#3306P-1-253

#8 4 years ago

I have complete original schematic for this. If you need something let me know.

#9 4 years ago

Try just replacing the pot with a middle valued resistor if you have one on hand.

#10 4 years ago
Quoted from zacaj:

Try just replacing the pot with a middle valued resistor if you have one on hand.

I was considering this. The pot is 25k. I must have something in the 12k range lying around just to test it.

I would put the resistor on the center lead and whatever lead had resistance. Would I need anything in the 3rd hole? I'll have to see if I can make some sense of the schematic.

edit: Looks like I need all 3 legs of the pot, so I assume that means I would need 2 resistors? I wish I understood schematics a little better.

#11 4 years ago

I just ordered 3 transistors and the pot. That means I'll have just about every part on hand. Hopefully one of those will fix me.

1 week later
#12 4 years ago

I replaced the 3 transistors (I think they were fine) and the diode at VR1 (almost sure this was my culprit). I can adjust to 170v and all my displays light up. I wish I understood a little more about the schematic. I'd like to know why VR1 was causing R51 to heat up 2 6,000 degrees and make a perfect resistor sized burn on the tip of my index finger. Now to figure out why the big flipper stopped working.....

Thanks for the input!

#13 4 years ago

Simply put the diode keeps the current only flowing one way. Like a check valve on a pump line that keeps the water from going back down the line. If the diode shorts out the current can now go both ways and then over loads the next thing in line. Usually a resistor.

#14 4 years ago

Rotating flipper issue turned out to be a disconnect I missed. Every once in awhile it's something easy! I think this game will be ready for Pintastic! Now to get working on the other 2 games I promised to bring......

#15 4 years ago
Quoted from JT-Pinball:

Simply put the diode keeps the current only flowing one way. Like a check valve on a pump line that keeps the water from going back down the line. If the diode shorts out the current can now go both ways and then over loads the next thing in line. Usually a resistor.

Thank you. I do understand what a diode does, I just wish I could follow the chart a little better. I replaced VR1 because it was the last thing I might not have replaced. I don't want to always take the shotgun approach. I wasn't getting anything at the potentiometer. I guess I could work backwards and the next thing is the VR1 diode. I'll get it one of these days...

#16 4 years ago

Some items I take shotgun approach and some I take the let's figure it out approach. Just depends. On stuff like the SDB, I go shotgun! The 190V components and 5V components are OLD! Without proper 5V the game will never run reliably. If the 190V goes bad it can fry displays. The connections to the driver board affect almost the entire game, so old header pins here all go. Now, just because I have a locked on or weak driver circuit dose not mean I replace all the driver transistors. But I would replace the resistor and diode in that instance.

#17 4 years ago

R51 burns open when the HV transistors short. When the zener goes out, you usually get low, but adjustable voltage.

Can usually look at a bally driver and if you see R51 burnt, you know the HV section is shorted.

1 year later
#18 2 years ago
Quoted from barakandl:

R51 burns open when the HV transistors short. When the zener goes out, you usually get low, but adjustable voltage.
Can usually look at a bally driver and if you see R51 burnt, you know the HV section is shorted.

Ok so I am working on a 190 v section on a driver board. TP 4 and 2 had 240V and R51 was shorted. I replaced R51 C27 and 28, q22 and 23 as well as both diode. Put back in burn 51 again. So I change the 3584 and R51. Now I have 50 v at tp 4. But the zener is still good and R51!gets hot but isn’t blowing. Bad q22 or 23 out of box?

Hey there! Got a moment?

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