Omni VI+

OK, here's an interesting one to ponder...

Tonight, I was loaned an Omni VI+ to consider for permanent placement in the shack.

It has a very unusual problem...

Receives great, until you switch in one of the CW filters. Then, sometimes the signal completely disappears, other times it goes way down, almost to nothing. (No problem with the 1.8 kHz narrow SSB filter, only the 500 & 250 Hz CW filters)

The current owner swears (and I believe him) that until about a year ago, everything worked fine. That was when he started having problems with 10 meters, sent it out for repair. The person repairing it took almost 8 months... suffice to say he had issues. The rig came back with 10 working, but the filters fluky.

I haven't done anything with it yet; first chance I get, I'm popping the filters out and making sure all the contacts are clean. Any other thoughts?

Have the schematics for the IF/Passband Board?

Have access to a scope or DVM?

First thing is to verify voltage at the header pins which control selection of the filters.

Schematic I have. I have to find my DVM.

Don't worry about it Fred. The rig has more problems than I first thought. The meter implies it's transmitting, but the external Daiwa SWR/watt meter doesn't move, at least on 40. (And I know the meter's good, since it works fine when I switch it to the O7). I'm beginning to suspect that the last two people who "fixed" the rig for Bill secretly used a golden screwdriver.

I'm going to make time over the weekend to look everything over very carefully, make sure we don't have something jostled out of place, or a switch bumped somewhere. Also make sure that my PS is working correctly, just to dot all the T's and cross all the I's. Unless I find something obviously amiss though, the rig's going back home to it's current owner.

Bummer.

Well, I was asked to take another look at the Omni VI before returning it. No change.

Then I got an email from someone with some suggestions on what was wrong with my original one. He asked me to verify it had power output, so I swapped rigs... And no power output. So I suspected something wasn't right.

Bad patch cable. Turns out both rigs put out 100 W on tune.

Worked a few guys in the Salmon Run this afternoon with the "eval" O6. Works great. Just not switching in the CW filters correctly.

So I may just keep the rig after all. We shall see. Still have to track down the filter switching issue.

FINALLY found someone who is familiar enough with the Omni VI+ -- my original one, that suddenly died on me, not the loaner (which I still have) -- who was able to take a look at it.

He got the rig today, and gave me an update tonight:

"I found that the VFO PLL was not working. It was stuck on one frequency and very unstable.

This radio does not produce an out-of-lock signal so it was able to produce output power in spite of the fact that the thing was way out-of-band.


I traced things around and find that the MC145156 PLL chip is ignoring data from the CPU. I know that the CPU is producing the control signals because I was able to put an Omni 5 board in and get it working."

So that's the bad news. The good news is that the chip isn't expensive -- Surplus Sales of NE is selling Motorola NOS chips for $5 each, and eBay sellers (of course, who knows what you're really getting with some of these guys) go from $.99 to about $3.50 each.

Including 2 hours bench time (between diagnosis and repair) I'm looking at about $175. He also says he can pull the chip from the Omni V board he mentioned, but since that would make the board useless, it would be another $25. He's ordered the chip from the UK. Take a few days to get here, but there's no immediate rush, and that's better than destroying the board.

This is not something that I would have ever diagnosed. Oh, I'd probably have figured out the board wasn't working right, but not that far. Needless to say, the next time I hear of someone parting out an O6 as a reasonable price, I'm going to try and stockpile a few spare boards.

I really miss using the O6. Nothing wrong with the O7, but the "feel" of the rig is different enough that it just seems like, well, that it's harder to use sometimes.

We shall see.

Following this thread and our initial dialog on the matter, the true problem with that radio was waaayyyy removed from an IF related issue.

Did the tuning ever work when the radio was returned from the first service trip? If not...that person may have damaged it when poking around inside the rig. Or - given the fact that CMOS devices are susceptible to failure due to substrate migration - the part simply died of age.

This is why I've been building up a stash of components for all of my favorite rigs. All ICs used therein are at the top of the spares list.

This reminds me to fire up my Pegasus, have not turned it on in four years. :ashamed:

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Originally Posted by N8YX

Following this thread and our initial dialog on the matter, the true problem with that radio was waaayyyy removed from an IF related issue.

Did the tuning ever work when the radio was returned from the first service trip? If not...that person may have damaged it when poking around inside the rig. Or - given the fact that CMOS devices are susceptible to failure due to substrate migration - the part simply died of age.

This is why I've been building up a stash of components for all of my favorite rigs. All ICs used therein are at the top of the spares list.

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Ah, Fred, my bad here. You're confused. My doing, not yours.

This thread was originally about the Omni VI+ that W3WH loaned me. This is the one that had been sent to KJ4WS for what should have been a minor repair (issues with output on 10 meters), got waylaid for quite a long time, and came back working as a rig, but with the filter switching issue.

My update was not about THAT O6, but my original one (the one that I traded a TS-480SAT for a few years back). THAT is the rig currently in MO. I went to turn it on, and no receiver -- now I know why.

I was in a rush last night, and for some reason, thought this thread was about my rig, not the loaner.

The loaner still has the filter-switching issue, and yes, I'm convinced that Wade accidentally did something he shouldn't have done. Without the narrow filters, it's kinda useless on CW -- but for SSB, not an issue.

Bill & I have talked about the rig. For now, at least, once I get my 6 back, he's probably taking the loaner back and will get Gary to look at his as well. I think Bill's plan is (if all goes well, repair-wise) to keep the 6, along with his TS-990, IC-7300, and KX3. But he still has more radios in inventory than he's ever going to use on regular basis, which is why the Paragon and Scout are listed for sale. (I am VERY tempted by the Scout, but to be honest, I'm also in the more-radios-than-I-need boat, and unlike a certain SoCA Islander we all know, I have no plans to open a museum)

Again, sorry about the confusion.

And yes, I'm going to start stocking some spare parts. I believe that the new Ten Tec is able to do basic repairs on the Omni V & VI now, but when it comes to things like these NOS chips...

Quote:

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Originally Posted by W3WN

..which is why the Paragon and Scout are listed for sale. (I am VERY tempted by the Scout, but to be honest, I'm also in the more-radios-than-I-need boat, and unlike a certain SoCA Islander we all know, I have no plans to open a museum).

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If a Paragon, I would agree with the sale. A Paragon-II? If I had to sell most of what I own, my two P-IIs, the Herc-II amps and the 253s are what I would keep. Heck, all the vintage Ten-Tec gear I have for that matter. Of course, it would be very hard to let all of the Drake 7-line stuff go, as it would certain Kenwood and Cubic gear. A lot of the stuff I've bought over the years is "tinker material". That is: Get it fixed (or modified), use the equipment until someone makes me an offer I can't refuse then send it home with them. The P-IIs, Omnis, Corsairs, TR7s/R7s and others have earned their spots in the lineup. I wish I had enough space to put them all out at once...as it is, I rotate the stuff in and out.