Freestyle Troubleshooting Questions:

[D56VillageNut]

I finished up my Freestyle and am having a problem that seems similar to two others I've read about regarding getting power past the rectifier and Vreg.  I followed the troubleshooting steps in the manual.  On step 1 it says to check the voltage across the small cap to the left of the PIC.  I'm only getting about .98 volts here.  It says to go to step 4 which states to check the + pin on the rectifier. 

Question 1:  I know that the positive or red lead from my meter goes to that spot on the + pin of the rectifier but where should I put the negative lead.  I don't want to zap something inadvertantly.

I also looked at the following posts You are not allowed to view links. Register or Login and You are not allowed to view links. Register or Login prior to building my Freestyle so I was trying to be aware of potential problems but it seems I am heading down a similar road.  My initial power up was done with the board installed in the CG-1500 case so the issue of shorting things on the back should not have been an issue.  I did note that both the rectifier and the Vreg heatsink got very warm very quickly when I powered it up.  Per the previously mentioned threads I verified that the AC cord is wired with smooth to the HOT side of the terminal block, that the + on the rectifier is near the + on the pcb, that pin 1 on the transformer is in the right spot, and that the caps are in correctly.  I've checked and can't see any obvious solder bridges and I've only applied AC power in short bursts to do the troubleshooting so my rectifier didn't "pop" or bulge but I'm at the end of my skill set on this one.

I'll try to attach pics. 

Any help is greatly appreciated.

Notes on the pictures:  The two dark "smudges" on the back of the pcb are blue dots from a fine sharpie to mark the pins for voltage checks.

The dull solder joints on the rectifier in the larger backside pic occured after power up.  It looks like this area was getting pretty warm to me.  Not sure though.

[KeithTarpley]

Greetings,,,

As to Question 1:  The negative lead goes on the connection diagonally opposite the + pin of the rectifier.  See if you get 10 to 12 volts DC with that reading.

Keith

[D56VillageNut]

Greetings,,,

As to Question 1:  The negative lead goes on the connection diagonally opposite the + pin of the rectifier.  See if you get 10 to 12 volts DC with that reading.

Keith

Keith,

I'm getting about 7.25 to 7.28 V DC across the + and the pin diagonaly across from it.  In just the short time I powered it up for the test the rectifier got almost too hot to touch.

[KeithTarpley]

Greetings,,,

I'd pull the voltage regulator and check the same points again.  Trying to divide and conquer the possibilities.

Keith

[D56VillageNut]

Greetings,,,

I'd pull the voltage regulator and check the same points again.  Trying to divide and conquer the possibilities.

Keith

Keith,

I took out the Large Cap to get to the bolt on the Vreg and Heatsink.  I removed the Vreg and the checked the voltage across the same pins on the rectifier and got about 9 Volts.  Is my Vreg bad?  Also I think I might have pulled the copper out of one of the vias for the large cap when trying to desolder it.  Not sure but that may be a different problem.  I also noticed that the rectifier did not seem to get hot.  For now I'm with you on the divide and conquer idea.  Your thoughts.

Alan

[austindave]

Hi D56VN,

I think I see the problem. Looking closely at the photos, it looks like half your IC's are installed incorrectly. Looking at the manual, it looks like half the 74HCT273's should have pin1 to the left and half to the right. It looks like all yours are installed pointing to the left.

Take a close look at the alignment notch on the silkscreen under the sockets - make sure that pin 1 for each of the devices points that same way.

Hope my eyes aren't deceiving me (which is quite possible - I'm looking at a pretty small screen) and I'm not sending you on a wild goose chase...

Hope this helps.

--Dave

[KeithTarpley]

Greetings,,,

Yep, that would definitely cause a problem.  And shows the output side is an issue, not the input.  Good catch.

Keith

[ponddude]

Dave is correct.  The bottom half of the flip flops are installed the wrong direction.

[D56VillageNut]

Hi D56VN,

I think I see the problem. Looking closely at the photos, it looks like half your IC's are installed incorrectly. Looking at the manual, it looks like half the 74HCT273's should have pin1 to the left and half to the right. It looks like all yours are installed pointing to the left.

Take a close look at the alignment notch on the silkscreen under the sockets - make sure that pin 1 for each of the devices points that same way.

Hope my eyes aren't deceiving me (which is quite possible - I'm looking at a pretty small screen) and I'm not sending you on a wild goose chase...

Hope this helps.

--Dave

Dave is correct.  The bottom half of the flip flops are installed the wrong direction.

Thanks for the catch.  I've reinstalled them correctly.  Would this have caused the power issue?  Might I have fried some of the flip flops?  Should I reinstall the Vreg and the large cap and give it another try or is there anything else I should check first?

Thanks for the help on this everyone.

Alan T

[KeithTarpley]

Greetings,,,

Unless you can see an obvious bad solder joint under the cap or regulator, I would try it and see.

Keith

[D56VillageNut]

Greetings,,,

Unless you can see an obvious bad solder joint under the cap or regulator, I would try it and see.

Keith

Keith,

I'll give that a shot after dinner.  Thanks again to everyone who pitched in with assistance.  We'll get this thing working yet.

Alan T

[austindave]

Thanks for the catch.  I've reinstalled them correctly.  Would this have caused the power issue?  Might I have fried some of the flip flops?  Should I reinstall the Vreg and the large cap and give it another try or is there anything else I should check first?

Hi Alan,

Yes, this definitely would cause the power issue. The TTL devices being in backwards would each provide a direct short (pretty much) between Vcc (5v) and ground.

It's *possible* that some of the devices are fried, but maybe not. Those old TTL parts are pretty robust. And I *think* if any of them have fried, they'd be "open circuits" on the power supply (meaning the bad chips just won't power up) - even failed, they shouldn't "crowbar" the power supply - they probably just wouldn't work.

I'd go ahead and install the vreg & caps & give it a shot. Again, brief power "on" and see if you have excess heating of the bridge rectifier. If not, then you can check all the outputs. While checking outputs, if you see bad behavior on some of the channels, that might be due to a dead flip flop chip. Swap it with another one & see if the problem moves. If so, you'll just have to replace that one chip.

Good luck!

--Dave

[D56VillageNut]

Thank you everyone.  We have SUCCESS.  One down and Oh So Many to go!!!  Again THANK YOU to everyone here on DLA.  

Alan T

[austindave]

We have SUCCESS.

Good deal... Glad to hear it! And congratulations!
--Dave

[wbuehler]

Congrats