Leader 3216 AM/FM signal generator Repair

[Richard P]

I just finished repairing my second Leader 3216 and could never find much info on them so I thought I'd post a quick summary for anyone searching.

I purchased my first one off the auction site a few years ago as a working unit, but it wouldn't boot up when it arrived, so the seller gave me a very healthy discount to keep it. I contacted leader and they sent me all the manuals they had, which was very helpful. Basic troubleshooting uncovered 2 of the 4 power rails were dead - the +15VDC and one of the +5VDC. Neither rail was shorted, so I surmized the regulators were bad - testing confirmed this. The 7815 regulator is located on the right side of the frame and connects to the main PCB by a wire harness so it's easy to replace. There are 2 - 7805 regulators - one next to the 7815 and the other mounted directly on the main PCB. My dead one was on the PCB so it was not as easy to replace, but the board has connectors so it comes out pretty easily, although desoldering is a bit of a challenge. With both of those replaced, the unit fired right up and frequencies/output levels were all spot-on. I've been using that one ever since with no issues.



The second 3216 also came from the 'bay but this one was sold as 'no output' 'needs repair' and was priced attractively because of that. Knowing what I did about the first one, I took a chance on it . . . This one only had a dead 7815 regulator so a quick, easy fix. Like the first one, the frequencies and voltages were all correct . . . . now I have 2 which is probably 1 too many, but . . .

FWIW, I communicated with a guy a while ago who repaired his non-functional 3216 by "replacing a couple of resistors on the RF board that had drifted significantly". He mentioned that they were located near a transistor that runs hot but didn't provide any more details.

Hope this helps someone.

 

[dlucy]

Excellent work!



Leader 216 standard signal generator for CW, FM/AM modulation, and FM stereo modulation from 100 kHz to 140 MHz.

User manual (English and German) and service manual for Leader 3216 https://www.lost-manuals.com/en/manufacturer/leader/3216

 

[alonsojar]

Hi Rich,
Congratulation for your double success.
I've also got a Leader 3216 in fairly good conditions that is working fine with the exception of some cpu problems (I'm still looking for a clean eprom code because I suspect mine is corrupted causing cpu hunging from time to time). I really love its building quality.
A couple of recommendations if I may, first is to change the mains EMF filter. Mine exploded (big noise, terrible smelling smoke, house protections tripped, wife complaining etc) and this looks to be the typical behavior of old Schanffer filters sooner or later (google a little and will see). I replaced it by a new model same brand (ref FN9222-3-06). The other is to check or replace the NiCd backup battery in the cpu board to avoid leakage and keep memory settings longer. Mine was not leaking but was dead so I replaced it by a same format nimh one.

I also attach, if it may help, an excel file with a table and some formulas to convert the displayed output of the 3216 that is EMF (no load) dbuV to any impedance and also to more common dbm units. Not sure it's 100% free of errors (I built it on my own and I'm not an expert in that matter), but it helps me setting up the generator to roughly follow the alignment instructions in service manuals.
J. Alonso

 

[Richard P]

Great info @alonsojar . Thanks for sharing your experience. I'll have to open them both up and check the batteries and capacitors as soon as I get back in town (in Florida for some R&R). Your conversion table is also helpful. I created a similar spreadsheet but didn't take into account that the output was calibrated for an open circuit. I'll have to update mine to reflect that.

 

[alonsojar]

It's curious but device impedance is 50 ohms, but the display only shows EMF. Of course the usable value will vary with the type of connection in every setup, but I think this is not very common and for instance HP devices had many selectable units calculated under 50 ohms PD if I'm not wrong .
Regarding capacitors I couldn't find anyone faulty. My device is from 1991 or at least this is the most recent date on the IC's I can see. The capacitors are of course of good brand (Panasonics perhaps), so probably not a lot of work for you either. It's odd that both yours had the regulators toasted. Did you check that the voltage selection in the primary transformer connections is right for your supply? I changed it from 220V to 240V (we have 235V usually in this area). That helped to reduce the heat dissipation on the 78xx and 79xx.
Enjoy your holidays
J. Alonso

 

[arts]

https://www.lost-manuals.com/en/manufacturer/leader/3216

That is a really good site, lots of oddballs

 

[Richard P]

Mine was factory wired for 120VAC and operates on an input voltage range of 108 ~ 132 VAC . . . Connections match that.






I stumbled across a guy who had a boot issue with his that turned out to be a couple of drifted resistors on the RF board. Have a look at the comments below this video if you haven't seen it already:

Leader 3216 Boot Issues

 

[targeteye]

I thought I’d share my experience with a Leader 3215. To add to the knowledge here a bit.


For those who may not know, the 3215 does not have built-in stereo modulation — it requires an external stereo modulator when that function is needed.


I picked this one up at an estate sale of a ham radio operator (of all places) and was surprised to see it there. After bringing it home and powering it up cautiously the way one should with old equipment, it worked perfectly right out of the gate.


Several months later it simply quit. Investigation showed a shorted main power transformer. The fuse was still intact, so the transformer had apparently drawn just enough extra current to cook itself without blowing the fuse.


I recently decided to try repairing it rather than hunting for a replacement (and taking the chance of getting another marginal unit). Further troubleshooting revealed that a shorted tantalum capacitor on the input side of the remote-mounted 7815 regulator was the real culprit. That short had overloaded and destroyed the 18 V secondary winding of the transformer.


Instead of buying an entire parts unit just for the transformer, I ordered two individual transformers from Mouser and modified the layout to fit them. The input voltage to the regulators is higher than what the schematic indicates, so I ended up choosing a higher VA rating than necessary. It’s still well within the regulators’ ratings, and after hours of running on the bench nothing is getting hot.


Space is tight, but I got them in. I had to relocate the input filter to the center area just below the GPIB connector.


Next up is dealing with the battery on the CPU board. I’m leaning toward simply removing it and leaving it out — I don’t really need the memory/preset function, and that eliminates one more potential future failure.


Heads-up to anyone working on one of these: you might want to proactively replace those tantalum capacitors.


Steve

 

[El Rubio]

I have an LSG 215A and a few years back I tried to find a service manual for future use and calibration instructions.i emailed Leader Support and a fella there emailed me a pdf copy. I uploaded it to the digital docs section here. I had the same luck reaching out to Krohn Hite once as well. They said if I had contacted them a few months earlier, they would have sent me their remaining spares that ended up in the dumpster. Never hurts to ask.

 

[Richard P]

Leader is very good about providing manuals. They've sent every manual I've needed including owner's manuals, parts manuals, schematics, service manuals, GPIB manuals, etc. . . .

BK Precision has been good as well.