Hi All,

Sorry, I forgot to add some useful information regarding the Triac in the motor controller.
Initially I thought the original G-loc Triac was faulty. When testing with my "universal" tester, it showed as a resistor  :(

So I bought a replacement Triac which was a little higher rating: BTA10-600C
It has a metal tab, but it's still insulated like the original. 

Before installing the new Triac, I tested, and found it to measure the same as the original:

I thought the new Triac was faulty from the shop 
But then I thought the tester was faulty.
I found an old Triac which I had from another project, TIC226, and the tester detected a good Triac:


Now I begin to think the original Triac and the new BTA10-600C were faulty, but before I complain to the shop, I have to be sure what I'm talking about. Could it be that the tester cannot correctly test sensitive gate Triac's ? The old TIC226 was not a sensitive gate Triac, so that makes me think that there's a design limit with the tester 
I need another way of testing a Triac. A Google search shows there are lot's of simple (low voltage) tests, but I wanted something which would test the Triac under a greater load, but still reasonably safe to operate.

I had a GE3020 (same as a MOC3020) opto-coupler which has a Triac output and can trigger a larger Triac, and the input is isolated, so it's reasonably safe.
Here's an extract from the MOC3020 datasheet:

I built the sensitive-gate version, with a jumper to short out the 2.4K resistor to test older Triac's which need greater trigger current. I used a 390ohm resistor for Rin, so I can use 5VDC to trigger the tester. I also connected a 3mm LED to the input as an indicator so I can confirm when 5V is connected to the input. I also have a small socket for the Triac under test. With this circuit I can test almost any Triac with mains voltage and a few amps of current if I like.
Here's what it looks like:

By the way, we have 240VAC mains in Australia, so the 220VAC on the circuit is good. Those in Japan or USA will need to adjust the 180ohm and 2.4K resistors - check the datasheet for the opto-coupler.

With my tester, all Triac's worked, including the original G-loc Triac 
Even the old TIC226 tested perfect in the sensitive gate configuration of the circuit.
I put the original G-loc Triac back in the motor controller 

In the end it was a very good learning experience. I found that some test equipment cannot test what might be expected, and so have to build my own test gear.

Cheers for now.

Hi all,
Sorry it's taken a while to get back to you.

I finally put in the triac, as well as the OP-AMP and 5V regulator for the logic circuits.
I don't think I mentioned previously, but I removed the solder jumper which connects the 380VDC to the main output MOSFETs.
After I apply power, all voltages are correct. The red LED comes on also. I think it's all working.

I didn't have access to the G-Loc machine, but I still wanted to test the H-bridge. Here's how I did it:

• Ensure that the solder jumper is removed from the 380VDC and the MOSFETs. Scrape a little to widen the gap, and test with a multimeter. Make sure it's open circuit and there's a clear gap of maybe 2mm. Use a magnifying glass to make sure it's safe !!!
• Find a small motor. I used a 12VDC motor from a tape recorder, and connect to the H-bridge output CN2
• Obtain a PWM generator. You can use a 555 timer as a PWM generator, or buy one. I have the LCD version of this one: https://www.ebay.com.au/itm/PWM-Signal-Generator-Module-Adjustable-Pulse-Frequency-Duty-Cycle-Square-Wave/282732060828?
• Power the PWM generator from a separate +5VDC supply
• Connect the output of the PWM generator to pin 6 of CN3
• Connect the +5 for the PWM generator to pin 7 of CN3
• Connect a free wire to pin 5 of CN3 (this is the direction control)
• Connect a DC voltage (eg. 12V) which matches your motor to the H-bridge
• Use an isolation transformer (240VAC in, 240VAC out) to power the motor controller

If the PWM generator is set for 50%, then the motor should run at about 50% speed, but probably not, as the reduced power and load are not matched to the H-bridge. Adjusting the PWM duty cycle from 0% to 100% should vary the speed of the motor, from full speed to stopped. The LED on the G-loc motor controller will also vary in brightness, but it's not a linear device, so it will change from full bright to dark with only a few percent (%) change in duty cycle.
If you ground the free wire (pin 5 of CN3) to the PWM generator ground pin, the the motor will change direction.

When you're satisfied that everything is working as expected, power off, remove the PWM generator, small motor, 12V power supply for the motor, etc.... and re-solder the bridge connecting the 380VDC to the H-bridge. You're now ready for action 

I realize that the above test is not a full test, but I wanted to see if the H-bridge can actually operate a motor's speed and direction. Using a small motor of maybe 12V is also safer than the high voltage/current which can come from the H-bridge. It's true that it could fail with the original motor from the G-loc, but I didn't have access to it. Also, I didn't test the over current circuit as I was running out of time  :(

As it happens, this G-loc motor controller belongs to a friend of a friend of mine. It was installed back in to the G-loc by my friend, and I suggested that he replace the small capacitors, as you might remember I had trouble with them.
When my friend opened the other motor controller, he found that a mouse or rat had eaten through the "F" wire from the L2 transformer !!!!! Even worse, the wire was eaten close to the transformer, and also at the other end where it goes into the PCB.
Luckily there was enough wire sticking out from L2 to make a full repair 
The capacitors were replaced and everything was put into the G-loc, along with the motor controller I had repaired with Per's replacement L2 
The machine is back to life     It works like new.

I was trying to post a video, but I can't figure it out just now

Thank you again, Per. Without your generous help there would be no hope for us, and thank you to all in the Forum for helping keep these machines running 

Cheers for now.

Hi all.

Yes, ordinarily we might get 17Vdc from 15Vac, but we have half-wave rectification, and not a sine wave. Plus it also depends on the load...... But you will see below it's all much simpler....

Per, I was thinking about the 15V windings on your transformers. In theory, all 15V supply windings should be the same, right?  So why does the 15V-delay supply provide about 18Vdc before the zener-transistor regulator... This is what I want from the other 15V supply windings after rectification, so the 78L15 regulators (IC5 and IC6) can function correctly.
What's different ?

If I measure, with the multi-meter, the cathode of one of the (low) 15V supplies, I get 15.1Vdc (as my last post shows).
BUT now looking at the waveform with the Oscilloscope shows something quite wrong:

...there's about 8V of ripple 
The 15V-delay supply has a 470uF capacitor. So I temporarily connected a 470uF capacitor across C30 in the low 15V supply. It gave 18V 
Now I begin to wonder about the original capacitor, C30   
I took out C30 which was supposed to be 47uF but it measures a few hundred pF 

It's almost as if there is no capacitor !!!!
No wonder there is so much ripple !
(I tested at 10KHz, as the supply is switching at about 90KHz, but the tester does not go higher in frequency. A new capacitor measures correctly at 10KHz)

I replace C30 with originally specified 47uF low ESR and get very little ripple:

As you can see, there is about 250mV ripple, which is acceptable 

More importantly, I get almost 18V before the 78L15:

Of course the 78L15 regulator IC6 is now giving 15V as expected 

I did the same on the other 15V supply, and checked C28. It was also a few hundred pF   
I replaced C28 and everything is good 

In summary, it seems that the L2 transformers from Per are good 
Thank you again, Per, for getting the transformers made and sending some to me. I can't thank you enough 

The golden rule is to check the filter capacitors, or just replace them if there is any doubt. I found out the hard way, and spent a lot of time looking for a problem which turned out to be quite simple 

It might be worth checking or replacing all of your small electrolytic capacitors (eg. C13, C28, C30, C25, C26, C27, C19, C20, C21, C36, C18), it might solve (or prevent) all sorts of strange problems 

Next step is to put the triac back in, as well as the OP-AMP and 5V regulator for the logic circuits.

Cheers for now.

Hi Per.

Thank you for the transformers 
You are so kind to send them so quickly !

You mentioned that the first batch of transformers had low 15v. So you had another batch made.
I have a copy of the "Specification for approval" for the first batch.
What exactly was made different in the second batch of transformers ?

Cheers.

Hi all.

Thanks to Per and his very fast shipping, I have received 3 beautiful new L2 transformers


After testing EVERYTHING else, I installed the new L2 and tested.... No smoke or burning 
The main 12v supply is perfect 
The 15v "delay" supply is perfect   
It seems though, that the other 15v windings are still not enough. In theory, as they use a 78L15, we need at least about 17v on the cathode of the rectifying diode (eg. D11). The 78L15 has about a 2v dropout voltage (depending on the manufacturer), so we need 15+2=17v.
I adjusted trim pot (marked "VR2 +5v") on the 12v rail up to 12.6v, as it's the reference, and I can now get 15.1v on the cathode of D11 which is still not really enough to supply the 78L15  :(

The 78L15 gives out about 14.5v  :(
I've not tested anything else.

Where to from here....?   
Maybe find a low dropout 15v regulator as a replacement for the 78L15 ??
Does anyone have any ideas ?

Cheers for now.

Yes. Quite right about other devices failing which might be unrelated. I found IC2 was dead, and it's not directly part of the low voltage power supply using L2. I tested IC2 with the OP-AMP tester I built for another repair project (vintage drum synthesizer) which had dozens of OP-AMPS:


For now, I put the G-Loc project aside, awaiting your L2 transformers 
When I install the new transformer, I'll have to check EVERYTHING very carefully before I turn it on.

Cheers for now!

Hey that's a nice game room !

My boards already have aluminium heatsink tabs bolted to Q20 and Q22   



While I'm waiting for the L2 transformer from perjmolsen, I was trying to understand what went wrong in the first place.
He's how I see it: TR1 (triac) failed and put 340v on its gate, this caused the 78L05 to short and blow out IC2 (dual opamp), D3, C13, Q1, D5, ZD1, Q2, ZD2 and L2, in that order !  Of course I'll never be certain, but my theory seems to match the circuit layout for which I congratulate gc339 - thank you for your fine work 

Speaking of circuit layout, I found a small error. gc339 has drawn R23 and C15 in parallel when they are in series (at least on the 2 boards I'm looking at). Note that the layout shows another C15 across D6: It is actually C16.
Also the collector of PC1 was incorrectly drawn connected to the node of R22, Q2 and R27. The collector of PC1 is actually connected to the node of ZD2 (cathode), R23 and pin 1 of L2.
Similar to this layout extract:

It's hard to see, but note the collector of PC1 connects to the node of the zener, transformer, and resistor. The emitter of PC1 goes through a diode to the base of the transistor.

Here is my corrected version of gc339's  low voltage power supply:

Note that the capacitor across D6 is marked as C15 - it should be C16.
I think also that the markings for the beginnings of each winding of L2 is incorrect: I believe the dot shown is indicating the END of each winding.

Hello there.
I'm new to this forum, and I've been following the adventures of repairing the Sega motor controller with great interest. You all seem to be the only people on Earth who are really serious about keeping these machines alive - congratulations.
I'm a technician in Australia and I've been working on repairing one of these units.
The chopper FET (Q1) shorted and burned the PCB track between pin 6 and the emitter of Q2. Possibly Q2 failed and then killed Q2. Many other things burned which is not too bad, and I can replace. But my worst fears have been realized: The little L2 transformer is dead. The winding between pins 1 and 6 is open.
Did perjmolsen ever try one of the China re-build transformers with success ? I Would like to buy 2 of them.

Thank you in advance.