Sandy Ganz RIB troubles

bellersley · Post by **bellersley** » Thu Feb 16, 2006 7:12 pm

I'm having issues with my "Sandy" RIB that I got a few years ago...I've only had one problem with it before and that was a bad solder joint (got the premade one from Radio Stew).

Anyway, it crapped out on my last night in the middle of programming an MTX. I tried using a different PC, programming cable and radio, still the RIB. My setup works fine with another RIB.

Jedi RSS gives me a "Bus data collision" error.

I tested all the diodes, no problems. Likewise with the voltage regulator.

Does anyone have experience with these things? Thanks!

mancow · Post by **mancow** » Thu Feb 16, 2006 9:30 pm

Are you getting +10 and -10 volts out of the inverter chip?

Hightower · Post by **Hightower** » Fri Feb 17, 2006 1:56 am

Check U2 (IC2) pin 1 for +5V, and check U1 (IC1) pin 5 for -5V

Make sure that second switch next to the Maxtrac (ethernet plug) is pulled away from the plug on the board.

Replace the on/off switch or bypass it. This switch has been known to build up some resistance on the contacts.

Replace your 9V

Check the junctions of all the transistors

If everything else checks out ok, then it's poaasble the op-amp U3 (IC3) is defective. These op-amps are sensitive IC - I think they are using CMOS technlogy on this IC, which is prone to static damage.

Good luck

bellersley · Post by **bellersley** » Fri Feb 17, 2006 2:59 am

Hightower wrote:Check U2 (IC2) pin 1 for +5V, and check U1 (IC1) pin 5 for -5V

I get -5V on pin 5 of U1 so that seems okay, and +5 on U2.

Make sure that second switch next to the Maxtrac (ethernet plug) is pulled away from the plug on the board.

Replace the on/off switch or bypass it. This switch has been known to build up some resistance on the contacts.

Replace your 9V

Check the junctions of all the transistors

I'll take a trip to the store later and grab another 3140 and see if that changes anything. From what I've heard, they can be the source of problems.

I'm going to place some of the blame on the crappy case design that comes with the Radiostew version, its very easy for something to cause a short. Perhaps I'll see about building it into something a bit more robust.

I'll post my results when I get a chance to work on it later!

bellersley · Post by **bellersley** » Fri Feb 17, 2006 3:00 am

Hightower wrote:Check U2 (IC2) pin 1 for +5V, and check U1 (IC1) pin 5 for -5V

I get -5V on pin 5 of U1 so that seems okay, and +5 on U2.

Make sure that second switch next to the Maxtrac (ethernet plug) is pulled away from the plug on the board.

Replace the on/off switch or bypass it. This switch has been known to build up some resistance on the contacts.

Replace your 9V

Check the junctions of all the transistors

I'll take a trip to the store later and grab another 3140 and see if that changes anything. From what I've heard, they can be the source of problems.

I'm going to place some of the blame on the crappy case design that comes with the Radiostew version, its very easy for something to cause a short. Perhaps I'll see about building it into something a bit more robust.

I'll post my results when I get a chance to work on it later!

kb0nly · Post by **kb0nly** » Fri Feb 17, 2006 9:21 am

My guess is that the 3140 is dead, so i'll agree with that, that's the number one problem i have come across.

bellersley · Post by **bellersley** » Fri Feb 17, 2006 11:46 am

I did some searching and came upon a post made by Monty a year or two ago about someone else having the exact same problem. He suggested changing the 3140 as well so for the 3 dollars it costs I may as well. Unfortunatly the original poster of that thread didn't post his results but either way it can't hurt.

I'm on my way to the toy store right now and was looking up the datasheets for the 3140 and it says it is a "direct replacement" for the 741 opamp. I've got experience with these and they seem pretty much indestructable. I wonder, since the 3140 is a pin for pin replacement for the 741, would I not be able to replace the 3140 with a 741?

kb0nly · Post by **kb0nly** » Fri Feb 17, 2006 12:55 pm

If it's a pin for pin replacement might as well try one! I'm going to put that in my RIB notes here and pick one up the next time i order some parts. Might be worth checking into if it's more durable than a 3140.

bellersley · Post by **bellersley** » Fri Feb 17, 2006 1:36 pm

I only went by what one manufacturer claims, I'd want to compare pin for pin on a datasheet before I drop one in. I'd hate to damage my computer, radio or RIB by using an incompatible chip!

BTW, whoever picks the lobby music for McDonalds should be hung

kb0nly · Post by **kb0nly** » Fri Feb 17, 2006 1:42 pm

LOL...

They always have the worst crap playing.

jackhackett · Post by **jackhackett** » Fri Feb 17, 2006 1:59 pm

A CA3140 and a 741 may have the same pinout, but they are not the same. The 3140 is a 4.5MHZ BiMOS device, it has high impedance MOS inputs and bipolar output, whereas the 741 is a 1MHz plain bipolar piece.

I would imagine they are using a 3140 for a reason, most likely they need the higher slew rate to handle the digital signals without rounding off the waveform. If they could get away with a 741 they would use one and save money.

If there wasn't the chance of bricking a $500 radio I'd say you could try substituting, but for this application I think I'd use the part called for to be safe.

bellersley · Post by **bellersley** » Fri Feb 17, 2006 5:10 pm

I think my balding is getting worse! I replaced the 3140 and 7660 chips, still no luck. I replaced all the diodes as well. Still no luck.

Its to the point now where I might just pickup a blank board and start from scratch, unless anyone has any ideas?

Will · Post by **Will** » Sat Feb 18, 2006 3:02 am

Too bad Monty is not here... He still is the master when it comes to RIBs.

I do repair them here.