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(Topic ID: 182683)

DE 520-5047-00 PS and Hot R15


By stangbat

3 years ago



Topic Stats

  • 11 posts
  • 5 Pinsiders participating
  • Latest reply 3 months ago by vec-tor
  • Topic is favorited by 1 Pinsider

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#1 3 years ago

This is regarding the DE power supply for the small DMD games. I have someone asking me about this issue. Seems like a lot of people have had this problem and nobody has posted an answer. I've never run across it myself, but I know someone that has. The common problem described is that the 68v is low, usually about 20v low. People rebuild the PS or work on it and then R15 gets hot. Most people seem to give up and buy a new replacement board.

Okay, so they did shoddy work or installed something backwards, right? But why are so many people encountering this? Is everyone bunging up their boards in the same manner? Seems unlikely. Anyone know what is going on or what part is commonly installed incorrectly or is faulty and makes this happen? Is it a bad DMD causing the issue?

Some examples. Do a search on RGP for "hot R15" and you'll find four posts and no answer:
https://groups.google.com/forum/#!searchin/rec.games.pinball/hot$20r15
Some more searching will find even more cases with people asking about this with no answers.

A search on Pinside brings up these posts and no answers:
https://pinside.com/pinball/forum/topic/data-east-power-supply-cn5-pin-4-low-voltage
https://pinside.com/pinball/forum/topic/super-hot-capacitor-after-5-secs-of-power-on
I could probably find more if I did some more creative searching.

I'd like to be able to investigate this myself, but I don't have a suspect power supply on hand and I don't have access to a small DMD DE game. So I'm asking for others to see if anyone has the answer to this problem that seems somewhat common.

#2 3 years ago
Quoted from stangbat:

This is regarding the DE power supply for the small DMD games. I have someone asking me about this issue. Seems like a lot of people have had this problem and nobody has posted an answer. I've never run across it myself, but I know someone that has. The common problem described is that the 68v is low, usually about 20v low. People rebuild the PS or work on it and then R15 gets hot. Most people seem to give up and buy a new replacement board.
Okay, so they did shoddy work or installed something backwards, right? But why are so many people encountering this? Is everyone bunging up their boards in the same manner? Seems unlikely. Anyone know what is going on or what part is commonly installed incorrectly or is faulty and makes this happen? Is it a bad DMD causing the issue?
Some examples. Do a search on RGP for "hot R15" and you'll find four posts and no answer:
https://groups.google.com/forum/#!searchin/rec.games.pinball/hot$20r15
Some more searching will find even more cases with people asking about this with no answers.
A search on Pinside brings up these posts and no answers:
https://pinside.com/pinball/forum/topic/data-east-power-supply-cn5-pin-4-low-voltage
https://pinside.com/pinball/forum/topic/super-hot-capacitor-after-5-secs-of-power-on
I could probably find more if I did some more creative searching.
I'd like to be able to investigate this myself, but I don't have a suspect power supply on hand and I don't have access to a small DMD DE game. So I'm asking for others to see if anyone has the answer to this problem that seems somewhat common.

Untitled (resized).png

An active device is likely shorted consuming lots of current.

When you see a power schematic drawn like this, the line in the middle is 0v / gnd and the upper part is the positive voltage and the lower stuff is the negative voltage. Since the resistor is in the top section, I would investigate all the diodes and transistors in the positive voltage section side.

#3 3 years ago
Quoted from barakandl:

When you see a power schematic drawn like this, the line in the middle is 0v / gnd and the upper part is the positive voltage and the lower stuff is the negative voltage. Since the resistor is in the top section, I would investigate all the diodes and transistors in the positive voltage section side.

Yes, I've basically pointed this out and told the person this, and told him what to investigate. I'm just trying to find out what the culprit usually is for this situation. Lots of people seem to report it, nobody seems to have answered what is commonly causing it. Maybe I'll get my hands on the PS and be able to investigate it.

#4 3 years ago

I'm wondering if there is an incorrect silkscreen on the PCB and people install a diode backwards. Just seems weird so many people have this problem after working on the board.

#5 3 years ago
Quoted from stangbat:

I'm wondering if there is an incorrect silkscreen on the PCB and people install a diode backwards. Just seems weird so many people have this problem after working on the board.

Resistors burn open on WMS games too with a similar circuit when actives short out in the hv section. The circuit is pretty simple and I doubt there is any quirky issue with the PCB.

#6 3 years ago

I repaired a lot of these..... There is 1 common issue with the the HV section at these power supplies: it is the brown 330uF cap above the MJE3x0 transistors. It is prone to leaking, spitting its crap on the MJE's legs causing a lot of sparking and in the end a failing HV section. Sometimes even with holes in the PCB. And if you don't clean the PCB thoroughly after such an event the problems will return.

#7 3 years ago
Quoted from MarAlb:

There is 1 common issue with the the HV section at these power supplies: it is the brown 330uF cap above the MJE3x0 transistors. It is prone to leaking, spitting its crap on the MJE's legs causing a lot of sparking and in the end a failing HV section.

I've seen this and dealt with it. Doesn't really explain the hot R15 and low 68v issue though.

#8 3 years ago
Quoted from stangbat:

I've seen this and dealt with it. Doesn't really explain the hot R15 and low 68v issue though.

A resistor only gets hot when there is running current through it and it is getting too hot when something is drawing too much current. The resulting voltage drop over the resistor will cause a lower outputvoltage. Could be a bad display. Disconnect it and see if the 68V is returning to its normal value. Could be a bad transistor/component or even a short between transistors legs caused by a leaking capacitor. Or sometimes, as I experienced a few times, by people who replaced the MJE3x0 transistors by MJ150x0. The cicuitry is pretty straightforward and I never encountered faulty silkscreens. Only faulty components, leaking capacitors, defective displays and human error.

#9 3 years ago
Quoted from MarAlb:

A resistor only gets hot when there is running current through it and it is getting too hot when something is drawing too much current. The resulting voltage drop over the resistor will cause a lower outputvoltage. Could be a bad display. Disconnect it and see if the 68V is returning to its normal value. Could be a bad transistor/component or even a short between transistors legs caused by a leaking capacitor.

Yes, I realize this. I was just asking in case someone had found a common mistake that people are making when rebuilding this PS. Sounds like there isn't one. Based on the information given to me I'm guessing the display is bad and is causing the issue. I've told the person this. Unfortunately I don't have a 128 x 32 display on hand to help with testing, nor do I have access to a game that uses that display.

3 years later
#10 6 months ago

I realize this post is 3 years old now, but I am encountering this exact issue with a Star Trek 25th.

Has anyone found a solution?

I've replaced every component on the 68V side of the circuit.
With the DMD disconnected, I measure 28VDC and it quickly drops the longer the machine is on.

2 months later
#11 3 months ago
Quoted from SarverSystems:

I realize this post is 3 years old now, but I am encountering this exact issue with a Star Trek 25th.
Has anyone found a solution?
I've replaced every component on the 68V side of the circuit.
With the DMD disconnected, I measure 28VDC and it quickly drops the longer the machine is on.

I had a problem with a Hook display power voltage... It was a short in between the transistors that
turned the PCB into a carbon resistor... I had to cut the PCB between the solder pads to "Break" the contacts.
I think I had to go completely through the board...The one power resistors got VERY, VERY, HOT! and I burned the tips
of my fingers...The solder pads to the voltage regulation transistors are too close together.

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