EEVblog #1301 - Arcade Machine Repair

[EEVblog]

Tragedy in the EEVblog lab as the arcade machine releases the magic smoke.
Claytons repair time.

[Ketturi]

As a arcade machine technician I can say that those arcade SMPS's are pretty much considered as a consumables. When a game comes to service, if there is any hint of power related issue or old PSU looks crusty, we will just toss it and put a new one in. Not worth of using any time to do in depth troubleshooting and repair on those as new ones do not cost anything compared to hour rate that would go to fixing one. Some rare systems are exceptions, like those used in Nintendo cabinets that usually do not fail, or just need new capacitors (or are otherwise made from unobtainium).
Swapping new power lead and possibly installing isolation 230v to 115v transformer are also common starting points with old cabinets, it just saves time and possibly lives. Feeling that 50Hz buzz when touching coin door is not nice when some yankee btard decided it would be good idea to snip that pesky earth terminal from plug. And power cords are constantly run over with pallet truck or otherwise damaged during transport.

Anyway, I find your lack of CRT disturbing

[EEVblog]

As a arcade machine technician I can say that those arcade SMPS's are pretty much considered as a consumables. When a game comes to service, if there is any hint of power related issue or old PSU looks crusty, we will just toss it and put a new one in. Not worth of using any time to do in depth troubleshooting and repair on those as new ones do not cost anything compared to hour rate that would go to fixing one. Some rare systems are exceptions, like those used in Nintendo cabinets that usually do not fail, or just need new capacitors (or are otherwise made from unobtainium).

Yep, doesn't surprise me. I wasn't going to reuse the crusty thing anyway.

Anyway, I find your lack of CRT disturbing

 

[james_s]

A lot of people put those disposable switchers into vintage games. I rip them out and restore the original linear power supplies. Yeah they run hot but who cares. Some of them are less than stellar designs but the ones that Atari and Gottlieb used in most of the classics are pretty solid. Once you clean up the ham-fisted repairs of rushed techs back in the day they're pretty reliable. In the case of Gottlieb I also replace the zener reference for the 30V supply to drop that down to 24V, there's no reason for the unobtanium audio amp to be run at the ragged edge.

[radix]

The 494-based designs (especially designs this old!) usually use BJTs for the main switching transistors. The power supply bootstrap sequence is quite weird and relies on the base drive transformer specifics. It's described on these two sites: http://ludens.cl/Electron/PS40/PS40.html, http://imajeenyus.com/electronics/20151028_smps_variable_voltage/index.shtml. I usually use one of these two schematics as a base when looking at similar PSUs.

[johnlsenchak]

My guess   at first was a  bad  Dio-Dee  on the ouput stage  that  does  the  DC  rectification


I think   that   power supply looks like  something out of  piece  of eighties medical  equipment.    Usually  in that type of  topology  you  find  a  opt-coupler between  the primary to  secondary for   feedback reasons   on the output voltage(s)  Why  don't  you  see that on that board, it has  no output  feedback ?

[duckduck]

This episode reminds me of the book that Atari published back in 1980 (known as "The BOOK") to help new owners of Atari console games repair them when they failed. Kind of an electronics-repair-tech-in-a-book book.

https://archive.org/details/atari_thebook/mode/2up

Ah, the old days...

[sean0118]

The isolation between primary and secondary doesn't seem great. 

Look at the creepage between the rectified mains and the heatsink / case mounting screw top right at 12:00. They could have added lots more separation than that.

[SilverSolder]

[...] Usually  in that type of  topology  you  find  a  opt-coupler between  the primary to  secondary for   feedback reasons   on the output voltage(s)  Why  don't  you  see that on that board  [...] 

This was the 80's, when men were still men, women were still women, and a measly zap across the fingers nothing to worry about! 

[Kleinstein]

This supply has the PE connected to the output for a good reason, so it can get away with less creepage distance and the transistors with just the thin isolation mounted to the case.

[wavebits]

Dave replaced a crappy throw-away switcher with an even crappier line cord bulge power supply. Spend 20 bucks and get a decent quality supply like a Meanwell and be done with it. Otherwise you will be back in a few years installing another, These sealed laptop type power supplies generally run hot (no ventilation at all) and are usually full of poor quality caps and dicey components. Some are downright dangerous.

[Wollvieh]

Is that power supply really a 1984 vintage?

I'm not a graduated archeologist like Jean Luc Picard, but during my expeditions in historic circuits I've never seen e.g. these transformers with the yellow tape around in anything before mid-90's. Also that black shiny 1 µF cap does not look much before 2000 to me.

Maybe I was cut off from this timeline, by just not getting the real hot stuff as in my experience 80's equipment was copper-iron-brick-style and baking tray-style heat sinks - black anodized, rarely blank - with TO-3 graveyards.

I'd appreciate any input, even to prove me wrong, as long as I get explicite pictures with it. 

[Nusa]

Is that power supply really a 1984 vintage?

I'm not a graduated archeologist like Jean Luc Picard, but during my expeditions in historic circuits I've never seen e.g. these transformers with the yellow tape around in anything before mid-90's. Also that black shiny 1 µF cap does not look much before 2000 to me.

Maybe I was cut off from this timeline, by just not getting the real hot stuff as in my experience 80's equipment was copper-iron-brick-style and baking tray-style heat sinks - black anodized, rarely blank - with TO-3 graveyards.

I'd appreciate any input, even to prove me wrong, as long as I get explicite pictures with it. 

Presumably 1984 is the major revision date of that PCB, not the date the board was actually made. In which case 1984 is only the earliest date that unit could have been assembled. For all we know the manufacturer used that version of the PCB for ten years, plus or minus. Unless you find newer dates on parts or labels, or a serial number that can be checked, we'll probably never know. So your observations may be correct, without being in conflict with what we see.

[thm_w]

It looks like its a specific "arcade style" supply: https://retroactivearcade.ca/products/arcade-power-supply
Maybe a clone/equivalent of this: https://retroactivearcade.ca/products/suzohapp-arcade-power-supply

Dave replaced a crappy throw-away switcher with an even crappier line cord bulge power supply. Spend 20 bucks and get a decent quality supply like a Meanwell and be done with it. Otherwise you will be back in a few years installing another, These sealed laptop type power supplies generally run hot (no ventilation at all) and are usually full of poor quality caps and dicey components. Some are downright dangerous.

They will run hot if the output load is high.

In this case his is 5V/2A, 12V/2A. I can't find much info on the jamma board, but most likely 12V supply is almost nothing and 5V is 1-2A or so?
If that is the case it would be running at ~30% of full load.

Presumably 1984 is the major revision date of that PCB, not the date the board was actually made. In which case 1984 is only the earliest date that unit could have been assembled. For all we know the manufacturer used that version of the PCB for ten years, plus or minus. Unless you find newer dates on parts or labels, or a serial number that can be checked, we'll probably never know. So your observations may be correct, without being in conflict with what we see.

Definitely, could be even longer than 10 years.
I think Rubycon BXA came out 1995-2000 ish? and ended in 2013. My guess is its made a few years before he bought the arcade machine, maybe ~2000.

[EEVblog]

Dave replaced a crappy throw-away switcher with an even crappier line cord bulge power supply. Spend 20 bucks and get a decent quality supply like a Meanwell and be done with it. Otherwise you will be back in a few years installing another,

I wasn't going to wait to order a supply when I had one available that did the job and got it back working immediately. Will likely last a lot longer than you expect. It's not being used anywhere near it's rated capacity, nor is it used in a hot environment.

[EEVblog]

Definitely, could be even longer than 10 years.
I think Rubycon BXA came out 1995-2000 ish? and ended in 2013. My guess is its made a few years before he bought the arcade machine, maybe ~2000.

Looks and feels at least 20 years vintage to me. There were no other identifiers.

[Zero999]

Definitely, could be even longer than 10 years.
I think Rubycon BXA came out 1995-2000 ish? and ended in 2013. My guess is its made a few years before he bought the arcade machine, maybe ~2000.

Looks and feels at least 20 years vintage to me. There were no other identifiers.

Don't forget the power supply had already been repaired before, so it's highly likely many of the parts will not be the originals, especially the capacitors which often go bad.

Anyway, thanks for doing the video. Of course it's not worth repairing, only for it to go wrong again, but there are often other reasons for repairing things than usefulness: educational, fun or making YT videos. I did a similar thing at work, when I had a couple of hours to spare, simply to pass the time and demonstrate to the boss I could fix it, if the replacement didn't come in time.

[Brumby]

One of the less obvious lessons is demonstrated here...

The one where you cut your losses and move on.  The commercial term is BER - Beyond Economical Repair.  Yes, we hobbyists redefine what "economical" means to us, but even in our own quiet world, there comes a time when you need to "call it".

[T3sl4co1l]

Haha, that schematic, always love it when my schematic symbols show up randomly.  That was back in the day when you were as well off with Paint as any other free schematic tool... not like today when the free ones are actually good.

The "official standard" for those curious: https://www.seventransistorlabs.com/tmoranwms/Elec_Circuit_Rules.html

Tim

[BurnedResistor]

"Dryer than a dead dingo's donger, who soldered that - Stevie Wonder?" has to be pretty high up the list of Dave 1-liners.

[EEVblog]

Don't forget the power supply had already been repaired before, so it's highly likely many of the parts will not be the originals, especially the capacitors which often go bad.

After the video was shot it did actually seem to hiccup again in some other way. It was brief, but it happened. Likely the solder joint(s) wasn't the only issue.
No way I was going to waster another second on it though, the joints caused the original fault so the video was done.