Taito Power Supply for Qix

VectorJunkie

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I picked up a Qix project today and had a question about the power supply. Are these original supplies worth rebuilding? I know allot of folks will just say throw a switcher in there and be done with it. If the original power supply can be made reliable, I will probably be interested in doing that instead. That is of course if something like the two large caps are going to cost me more than a switcher and adaptor. :)

Thanks for any information on the Taito hardware.

-VJ
 
I picked up a Qix project today and had a question about the power supply. Are these original supplies worth rebuilding? I know allot of folks will just say throw a switcher in there and be done with it. If the original power supply can be made reliable, I will probably be interested in doing that instead. That is of course if something like the two large caps are going to cost me more than a switcher and adaptor. :)

Thanks for any information on the Taito hardware.

-VJ


I have done both (not a FULL rebuild though, just enough to get one working). The switcher was easier and more reliable, but obviously not original. I am sure you could replace nearly everything on the original Taito PSU and make it bulletproof though. Tough call. I say rebuild it, then test it and get me a parts and price list for my next one.
 
I have done both (not a FULL rebuild though, just enough to get one working). The switcher was easier and more reliable, but obviously not original. I am sure you could replace nearly everything on the original Taito PSU and make it bulletproof though. Tough call. I say rebuild it, then test it and get me a parts and price list for my next one.

Well that is encouraging... I will probably just try to get the existing one working since it sounds more like a cost/time trade-off issue rather than the linear ones being a fire hazard or something similar. I will certainly keep a repair log on the rebuild.

This Qix needs some love... It is beat, but complete. It really needs to live again.

Thanks Phet,

-VJ
 

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Looks to be in pretty decent shape if you ask me.
 
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Looks to be in pretty decent shape if you ask me.

Deceptive CL resolution photos... :) I will document the current state before I start with some high-res photos for the before and after pics. It needs to be sanded down, given a little bit of that wood hardener in places because the edges are fraying a bit, and the back door needs to be replaced. I probably overpaid at $80, but it is the first Qix I have even seen since I started collecting and it is worth restoring to me.

I just hope it ends up looking at least half as good as your Elevator Action restore.
 
Original Taito linear power supplies are total crap IMO. Once in a blue moon you will get a good one.

Best bet here is to replace with a switcher.
 
They are a MF'r to get working sometimes! I have fixed several of these and alot of times they will just need a 7805 , a bridge, or a pot, something simple. You should not have to replace the big caps on it. Then occasionally you will get one that takes days to get working.
I think I still have a couple parts boards if you want them. I also Have a complete working power supply/brick assembly. If you install a switcher you will need the adapter that has the reset circuit built into it.
 
They are a MF'r to get working sometimes! I have fixed several of these and alot of times they will just need a 7805 , a bridge, or a pot, something simple. You should not have to replace the big caps on it. Then occasionally you will get one that takes days to get working.
I think I still have a couple parts boards if you want them. I also Have a complete working power supply/brick assembly. If you install a switcher you will need the adapter that has the reset circuit built into it.

Thanks for the parts boards offer. Let me dig into it a bit a see what i have first. The board was not mounted in the cabinet since the guy was trying to use a switcher. The board is a little dirty, but the components look to be in good physical shape with nothing looking burnt. I'm going to try cleaning it off tonight, getting it mounted and seeing what it outputs. If it looks pretty bad across the board, I will probably ping you about those parts boards. :) Either way, it sounds like a rebuild will be worth while, but possibly a PITA.

Thanks,

-VJ
 

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You cant simply wire a switcher straight up on these, it wont work.

The pots are quite often flaky because the way these mount they see alot of dirt and dust. What voltage(s) are missing? Like I said, the 7805 goes bad on these alot so suspect that first on the +5v. Easy to test it but just as easy and cheap just to throw a new one in.
 
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You cant simply wire a switcher straight up on these, it wont work.

The pots are quite often flaky because the way these mount they see alot of dirt and dust. What voltage(s) are missing? Like I said, the 7805 goes bad on these alot so suspect that first on the +5v. Easy to test it but just as easy and cheap just to throw a new one in.

He had the adaptor for the switcher from Arcadeshop. I just didn't want to buy the switcher and adaptor from him. I have not fired it up yet. Tonight I should be able to see what's up and post back. There is a good chance it even works and something was just disconnected or something else stupid was wrong. I didn't get the feeling that he could really diagnose anything and was what I would call a "part swapper".
 
You cant simply wire a switcher straight up on these, it wont work.

The pots are quite often flaky because the way these mount they see alot of dirt and dust. What voltage(s) are missing? Like I said, the 7805 goes bad on these alot so suspect that first on the +5v. Easy to test it but just as easy and cheap just to throw a new one in.

Ok, I had to replace all of the fuses since none were the right values. I hate when people do that. LED 2, 3, and 4 light, but not LED 1. So the +5V can only be adjusted to about 1V. So as you suspected there was a problem with the +5V line. What is a 7805? I'm not seeing a part with that in the name. Is that a replacement part for one of the components? I was thinking maybe the problem was with the voltage regulator for the +5V (U3) which is a UA723CN.

Also, there is a diode (D18) missing from my board which says it is revision C. When I look at the revision C schematics it and parts list it does not have a D18 that I can see. It does show the D18 in the component diagram too. I am wondering if this is supposed to be populated and if so with what? I have been looking through other Taito manuals to try and figure that one out.

Thanks,

-VJ
 
7805 is a voltage reg.

LM723 is the voltage reg that you have. They do fail pretty regularly. Bob has them for $1.

The two are NOT interchangable as the LM723 is an IC chip and the 7805 is a Transistor type.
 
Must have been the 7905 I was thinking of. Not sure, just remember that I had to replace a to-220 regulator on several of these boards.
 
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7805 is a voltage reg.

LM723 is the voltage reg that you have. They do fail pretty regularly. Bob has them for $1.

The two are NOT interchangable as the LM723 is an IC chip and the 7805 is a Transistor type.

Thanks Dokert. Not sure that I have enough on my list for a Bob order yet. Might just throw an NTE part in there for the time being and get a couple from Bob to have on hand with my next order.

Must have been the 7905 I was thinking of. Not sure, just remember that I had to replace a to-220 regulator on several of these boards.

I thought maybe you meant the 7905 as there is one, but it regulates the -5V line. Either way, I'm hoping that is all that is wrong so I can move onto the game board and monitor. :)
 
Taito power supplies are trash...

Throw in in ATX w/ converter board and be done with it...
 
While waiting for the new voltage regulators to arrive I thought I would hook up the power supply and go through it as much as possible with the meter.

Then, I decided to RTFM and it talks about not being able to bring the voltage enough and that you should adjust the current limit to half. Needless to say that next thing I know the LED 1 is glowing but is pretty dim. Adjusted the +5V pot and low any behold +5V and a nice bright LED 1.

It is a good thing that I found the voltage regulators for $.30 since I don't need them. :) Anyway, will probably have more questions / issues as I work my way through this game... Looks like the board test is stopping on one of the ROMs.

-VJ
 
How is the main board, any acid damage on it? Those ribbons loose connection sometimes and need to be reseatted.

The main board looks pretty good. It has had some work done in the past. There are a couple jumper wires and whatnot but still pretty good. The power supply also had an Eldorado Games tag on it too.

I had the same thought and did just that earlier tonight and did reseat all the connectors. Needless to say it is now playing blind! :cool2:

Now I need to do something with the monitor. The guy gave me two chassis with it. Both are K4600s. Is it just me or is that one ugly chassis? All the daughter cards and wires everywhere makes it look more like a prototype than production product. Anyway, hopefully one has signs of life and I will just rebuild that one.

-VJ
 
I personally dont like the 4600 either. They are decent monitors once working.
Hook the monitor up to something else and see if maybe its just a connection issue in the game.
Check the ribbon cable/connectors in the area where the battery is, they get corroded. Usually reseating them a few times does the trick but in some cases you will need to scrape the pins to get the corrosion off.
 
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