Rohde & Schwarz SMIQ03B with Error 110 Output unleveled; IQMOD: ALC failure

[zmetzing]

Yep, that was the video that I watched before bidding on this unit. He replaces the final output device, which did not fix the issue on my unit. I'll be replacing the two drivers before that final device after I get the parts from Germany.

Final device is a SHF-0189, purchased from link in the i-hobby video shown in the previous message, but can also be found on eBay.
The two drivers in the chain before that are SHF-0186 devices, currently available on eBay from seller "rici61".

[smgvbest]

Did you check out the repair that DaJMasta and I did.   there's allot of information in those posts
I also produced a spreadsheet to record all the TP's in the diag section to help zero in on the issues.
you would just run your's up to the 3Ghz instead of the 6Ghz we did

this is DaJMasta
https://www.eevblog.com/forum/repair/rohde-schwarz-smiq06b-repair-log-6ghz-board-alc-error/msg1193985/#msg1193985

this is mine posting
https://www.eevblog.com/forum/repair/rohde-schwarz-smiq06b-repair-6ghz-board-level-preset-error/msg1240640/#msg1240640

[zmetzing]

I did check out those posts and they were very informative. I'm keeping my eyes open for a 6GHz extender board and the FM modulator board (although this could be done externally by feeding the proper I/Q signals).

I await the SHF-0186 devices from over the sea, and then I'll remove the 100 tiny screws from the IQ Modulator board again. :-)

[zmetzing]

Well, the entire output stage has new amplifiers, but this was not the problem. So, I've stopped shotgunning it and started tracing the signal path.

I performed the CW leveling procedure IQCON 7.4.4.4 and found that the output from that module was ~2dB low. That has been rectified, but that wasn't the issue, either. Note: The SMIQ03 will run without the IQMOD module installed ("Press SELECT to simulate hardware"), so that R495 can be accessed when the front panel is removed and rotated out of the way. I have my SMIQ on it's side, which seems to work the best for keeping things out of the way but still accessible.

I then traced down the signal from the input connector X247 (FIQFIL) [schematic page 17] toward the FAM3300 off-page arrow. I see the amplifiers doing their thing along the path, with a selected frequency of 450.1 MHz and +13dBm selected. My analog o-scope only goes up to 470MHz, but the levels seem reasonable until I hit the Pi-attenuator R966/R120/R113. On the C593 side of things, the signal looks great (1.070V or 4dBm, just what we expect). On the C343 side of the path, the signal drops to something very low, and doesn't look like the 450.1 MHz signal I was tracing. I found R966 to be 51 Ohms, R120/R113 to be 100.0 Ohms, and there was a C590 piggy-backed across R966 which seems to be 1pF. This does not agree with the 1084.9800.01 schematic, but my board has a .08 revision, so maybe that's ok. This would be a 8.5dB attenuator, without the effects of the capacitor, which would allow a high-frequency bypass path for better leveling, perhaps?

I went ahead and replaced R966, but no joy. I can only think that something with the D_SWITCH circuitry is effectively grounding out the signal.

Next, I plan to lift C343 and see if the problem persists, to better isolate the problem.

[zmetzing]

I've repaired two SMIQs with that same error and the problem(s) were always caused by either RF amplifier(s) (MMIC or final FET) and RF switches (old Hittite parts). It seems R&S decided to drive the control voltajes a bit harder to improve isolation between ports, which has an impact on the part's life. I replaced them with something similar and modified the resistor networks to trim the control voltajes down to safer levels. I believe I have some of those parts still somewhere...

I seem to have the same issue with the switch S2 (SSW124). I removed C343 and observed a reduced amplitude, but still good, 450.1 MHz signal on the hot end of R113.

Replacing C343 and then breaking the signal path at C333, terminating that leg into a 47 ohm resistor, results in a garbage waveform of not much amplitude on R113. So, it looks like S2 has bit the dust. I'll be PM-ing you, EB4EQA, to find a suggest replacement part.

Postscript: Doing the math, I see that R&S is putting nearly -10V on those switch inputs, which are nominally -5V. I may increase the value of R36 substantially, perhaps to 4.7k, to reduce the voltage on those lines to something closer to -5V. Any thoughts?

[zmetzing]

I've made a first-order identification of a part which might work: HMC284AMS8G HMC270AMS8GE

Differences:

• The package is smaller -- not a deal-killer
• RF input pin is on wrong pin -- solvable with small wire
• Control inputs on wrong side of chip -- annoying, still solvable

[zmetzing]

Appears that others have gone the same route with the HMC270 device:

https://www.eevblog.com/forum/repair/rs-smiq-ssw124-gt-hmc270-replacement-(_alc-failed_-error)/

Thanks, Roberto, for the helpful information!

[zmetzing]

I replaced S2 (SSW124) and boy was that a bear. Another situation where hot air plus the Metcal got it out without damaging the board. Definitely not for the faint of heart. Note: In the pictures, I swapped the control lines, which was wrong. The lines should go straight across (2nd pad to top left pin, 3rd pad to 2nd left pin) for the RF to be routed properly. I didn't take a new picture, but you get the idea.

Partial success! The message "ERROR: CW: ALC_ON voltage oot" is no longer generated, and 7.4.4.5 test point 2108 is now ~3.3V, P54 is ~2V. I can trace the signal all the way to V144.

However, I'm now getting "maximal level oot" from the calibration routine, and the bias on V144 looks all wrong. The manual says the drain should have ~4.5V, whereas I'm measuring ~1.2V. Definitely not going to work very well without some more drain voltage. Drain current appears to be set by V6 (BSP31 device) along with some circuitry around it. I'll have to confess that I'm not quite sure what it is doing .. I'm not an analog engineer. V143 is a 5.1V Zener reference, R1301/R14 combine to a 14 ohm resistor, but I don't see what it's actually doing.

Note that I replaced this device with a "new" one from an eBay seller. I wonder if it is toast and drawing too much current from the current source (if that's what it is). I may try replacing it with the old device.

P.S. I replaced R1151 and R1150 with 1.5k resistors to decrease the negative voltage on SWITCH_A and SWITCH_B. The HMC270 part cannot tolerate much more than -5V.

P.P.S. You'll note that I didn't reconnect the signal path after putting the new switch in. Limiting the causes of down-stream failure is always a good thing when replacing components.

[zmetzing]

"That's no small moon."

On the path toward a working SMIQ, we last learned that the bias on V144 was wrong.

While probing around on the bias circuitry, I found 0.8V at the junction of V143 (5.1V Zener) and R644. As the +7V5A rail was at the proper voltage, I was very suspect of the diode, and with good cause. Examining the diode under the microscope, I noticed that the cathode band was pointed at ground! This is definitely wrong. Also, it looks like this device was re-worked at some point, possibly in an attempt to fix V144.

I found a replacement 5V1 Zener in my SMT parts bin -- the last one in a lone ESD package, picked up by chance from someone dumping a load of remnant board build kits. It is a little lower wattage rating (375mW), but the bias circuit isn't drawing that much current (~40mA). Fitting it in, the bias on V144 is now correct, and it appears to be amplifying!

The LEV PRESET calibration gets a little further, but still no joy. The new message is "nominal level oot", which is different from the "maximal level oot" that I was getting before this fix.

We continue to follow the signal ...

[zmetzing]

Getting very close here, folks. Re-reading the service manual pointed out that I should close up the resonator chamber M while running the bare board. Given that I don't have a cover handy, I re-installed the B-side shield with two screws over the M chamber and four in the corners.

With Level 2 Debug ON, CALIB -> LEV PRESET gets to the full bar graph like it will complete. but then says "maximal level oot" and the debug info says it failed at 2.8GHz. So, perhaps still not quite enough gain at the high end?

P.S. Telling the unit to "Continue calibration on errors" seems to get it through the CALIB -> ALL path, and the 110 error disappears! However, the IQMOD-CW LEV PRESET table definitely shows a trend on the high-end toward +128 numbers, which appears to be the maximum. Does that mean it was trying to add power (reduce attenuation) at the high end?

I'm considering changing R1226/R411, which are currently selection II, to selection III (edit:corrected). That should boost the overall gain of the final PA.

Would anyone be able to post a picture of their IQMOD-CW LEV PRESET table, specifically the > 2.2 GHz frequencies?

P.P.S. Even though my unit shows a front panel of "SMIQ03B .. 3.3GHz .. 1125.5555.03", attempting to enter a frequency over 2.2GHz (with no errors present in the system) says "Out of range". Did someone sell me SMIQ02B innards with a SMIQ03B nameplate? Or am I missing a setting?

[zmetzing]

P.P.S. Even though my unit shows a front panel of "SMIQ03B .. 3.3GHz .. 1125.5555.03", attempting to enter a frequency over 2.2GHz (with no errors present in the system) says "Out of range". Did someone sell me SMIQ02B innards with a SMIQ03B nameplate? Or am I missing a setting?

Well, it looks like I've been taken by an eBay seller who says "I’m pretty sure that gear run until 3.3 GHz", which isn't true of the SMIQ02B.

I doubt changing the batteries in the CPU unit would have caused it to suddenly think it is the lesser version.

Not sure if it's worth filing an eBay claim.

Anyone know if there's a way to change the model to SMIQ03B via software incantation?

[zmetzing]

Fixed (I think)! I let the unit warm up for about 30 minutes, then re-tried the calibrate without any debug options turned on. It completed successfully!

Now, if I could only figure out how to fix the bit-flip that made it go from a SMIQ03B -> SMIQ02B. The seller has pictures of the unit, complete with all the S/N and external markings, showing that it, at one time, went to 3.3 GHz.

What is the "Factory Installation Key" on the back? Would that turn it back into a SIMQ03B, if entered into the appropriate software or into the instrument itself?

[zmetzing]

did you ever managed to fix the 'IQCON no convergence' error?

Based on my experience, this is caused by a failed S2 (SSW124) on the IQMOD board (schematic page 18, PDF page 52). I got this when I had the SWITCH_A and SWITCH_B lines reversed, so it was sending the FAM3300 signal off to the wrong path.

[teknut]

Would anyone be able to post a picture of their IQMOD-CW LEV PRESET table, specifically the > 2.2 GHz frequencies?

Hope it helps if still required

[zmetzing]

Thanks! Could I beg another couple of screen shots for the IQCON table? Specifically, I'm interested in the values as they head toward 3.3 GHz.

I don't have my power meter hooked up, as the unit has a power supply problem. However, power appears to be approximately correct, given that I have 1 meter of RG-174 between the SMIQ and the Anritsu SA.

(That Anritsu will be the topic of a future repair, and possible custom TFT LCD upgrade!)

[little.tesla]

What is the "Factory Installation Key" on the back? Would that turn it back into a SIMQ03B, if entered into the appropriate software or into the instrument itself?

The Factory Installation Key defines/enables the model (e.g SMIQ03, SME03 etc) in the software, since the software is generic for all generators SME, SMT, SMIQ (exception is the fast CPU option). To my knowledge it's entered after a blank software install. I don't know if it can be changed once entered or how it's entered. Hope this helps a bit.

[zmetzing]

The Factory Installation Key defines/enables the model (e.g SMIQ03, SME03 etc) in the software, since the software is generic for all generators SME, SMT, SMIQ (exception is the fast CPU option). To my knowledge it's entered after a blank software install. I don't know if it can be changed once entered or how it's entered. Hope this helps a bit.

Indeed it can be, and I thought about this around lunchtime. The trick is to unlock LEVEL 3 access, and then a new option appears under UTILITIES -> INSTALL -> FACTORY INSTALLATION KEY. Make sure to set "FACTORY OPTION TO INSTALL..." to SMIQ03B.

I now have a fully-functional SIMQ03B! Hope this narrative helps others.

(Now I have to eat some crow and apologize to the eBay seller for suggesting that he/she sold me the wrong unit.)

[RecursiveLogic]

I've been working on a SMIQ 03 (non B) model. It's been interesting following your thread, and working parallel to your progress. Currently I am trying to resolve the issue with IQCON no convergence during calibration. The only error I'm dealing with is Error -313 Calibration Memory Lost; LEV PRESET run internal calibration.

There are some differences with the IQ-Modulator board... most notable S1 and S2 are populated with YSW-2-50DR. Has anyone else encountered these chips, and is the HMC270 a valid replacement, or am I better justified going with an M3SWA-2-50DRA+ as a possible recommended replacement?

I've also included an example of a previous repair made on the board, most likely to correct an Error 110, which I've had to fix for obvious reasons.

[zmetzing]

is the HMC270 a valid replacement, or am I better justified going with an M3SWA-2-50DRA+ as a possible recommended replacement?

The YSW-2-50DR looks to be logic-level control with 3.3V positive logic (0, +3.3), so the HMC270 chip, which uses 0V and -6V, would not be the appropriate choice.

The M3SWA chip looks like it would work, with a few flying wires, with the small caveat that it doesn't go all the way to DC (0.3MHZ or 300kHz). If the signal it switches stays above this lower limit, which it might if it's the first switch out of the IQCON block, it'll work just fine.

Good luck, and, yeah, it looks like someone tried to use a branding iron to install that transistor. :-)

[techneut]

I've been working on a SMIQ 03 (non B) model. It's been interesting following your thread, and working parallel to your progress. Currently I am trying to resolve the issue with IQCON no convergence during calibration. The only error I'm dealing with is Error -313 Calibration Memory Lost; LEV PRESET run internal calibration.

There are some differences with the IQ-Modulator board... most notable S1 and S2 are populated with YSW-2-50DR. Has anyone else encountered these chips, and is the HMC270 a valid replacement, or am I better justified going with an M3SWA-2-50DRA+ as a possible recommended replacement?

I've also included an example of a previous repair made on the board, most likely to correct an Error 110, which I've had to fix for obvious reasons.

Any luck with the "IQCON no convergence" error? I have SMIQ 02E with the same error and also the same switch. Unfortunatly is the board different from the SMIQ-03B so I can't use those schematics and testpoints.

[Ick]

Late reply to this thread as I spent quite some time reparing a similar  (bult older, SMIQ02 - without the B) unit.

Any luck with the "IQCON no convergence" error? I have SMIQ 02E with the same error and also the same switch. Unfortunatly is the board different from the SMIQ-03B so I can't use those schematics and testpoints.

Please mind that the calibration error message (1) "IQCON no convergence" is very different from (2) "maximal level oot" and the detailed asociated debug info "IQMOD fail at frequency.."

(1)The former points at an issue of the IQConverter board: The unit is unable to set/tune or measure the RF level during Level Preset calibration. This points to an error anywhere on the HF path between LO Driver (just before the mixer) and ALC detector near the output of this board. So everything that is bypassed in CW mode (in case CW mode works without errors). Level Preset on the IQConverter is only used in Vector mode (so heterodyne path over mixer is active).
Issue sits with either of the overall ALC control loop (e.g. detector diodes or OpAmps - albeit not very probable if this is the only error, because the same components are also used for CW ALC), PIN diode errors switching the HF path, the Level Preset DAC U5 (DAC08) in combination with N1 OpAmp prducing the bias voltage, the respective current source circuitry V11, V18-V24 +V8/9 current mirror, asociated biasing or the three filters paths (750-1800;1800-2500; 2500-3300) (containing the preset PIN diodes in later board releases). In these filter paths there are MMICs that also can go bad.

(2)The latter - which is described here by zmetzing - points at the IQModulator board: e.g. here with the error on the S2 HF switch, preventing the level preset for CW in the final amplifyer stages of the IQModulator.

@techneut: In case 7 month response time are not too late - focus at the IQConverter board, not at the IQModulator board with this issue.
The IQConverter comes with two main board revisions. The schematics available over the links posted here are for the older revisions, so is the service manual. The principle remained the same and the schematic is also the same in big parts. However some important details like amplifyer stages and filters have changed with the newer revision.

[Antonio Borda]

Good evening,
have you found the firmware to start your smiq, I find myself with the same situation after buying a smiq03b
Boot eorom version 1.26 hx
Cpu board var 8 rev 2
ram 2048k
WIS D 115200.8, e, 1
I restart with winflashpro 1.2.27 with 5.93 it displays error in the middle of the loading it is stopped. I see quit there are other users with the same type of failure, as you have found the solution. Thanks for your help

[drhex]

So am resurrecting a dropped SMIQ03B, after putting in a new screen (still looking for the outer glass/perspex), I have the dreaded 110 Output unleveled. S2 was broken, I replaced that with a HMC270 and now have output, but the ALC still complains. @zmetzing, how did you set debug to get more information? Am I interpreting your posts correctly in that the board has to be closed up to calibrate?
Some photos of the failed switch innards:

[drhex]

OK, replacing the last output FET got it to work again - bit of a bother as R&S decided to solder a little sub assembly across source and drain which needed careful wrangling. Output looking good now, what I can test with my limited resources seems to work fine. Need to find an outer screen now and this is done. Please ping me if you have one kicking about, even if yellowed or such as that would be better than none :-).

[zmetzing]

Congrats! These are great units that can be had for a fraction of what they cost new.

If only I could find a 6 GHz module and a fading simulator module, and then figure out how to convince the software to use them. :-)