sp 210 help

[W9JCM]

Just picked up a super pro. Brought ps and radio up slow with variac no smoke. But not getting and audio nor can I tell RX. Funny thing is when i switch avc to manual the meter pings to the right. I found 5 dead tubes that were replaced also and someone had a 12SJ7 where the 6SJ7 was so that was put back. Where do I go from here ? Any super pro experts on the forum? FYI I see all the org caps are still on the underside also but I see no leaking. I do not want to be a parts changer and want to do this logically.

tnx
N9AMI
(formerly w9jcm)

[Todd, KA1KAQ]

W3JN has a lot of experience with these beasties, he'll probably wander through at some point.

Symptoms you described could have any number of causes from a bad coupling cap to missing voltages etc. Start with the power supply, give it a thorough going over before proceeding. Burnt transformers are a pain to repair or replace.

Also be aware that these receivers were the subject of numerous 'improvement' articles which involved tube substitutions and other circuit changes. Don't assume the tube you found is 'wrong'; it could just as easily be a modification done some years ago, documented or otherwise.

Best thing to do would be a complete schematic comparison to confirm any changes to your receiver. Once you're satisfied you understand the current situation, get some new caps installed, check for damaged components and out of tolerance resistors, tubes, etc, check voltages, then do a complete alignment. They are excellent receivers when working right, you won't be disappointed with the effort expended.

I'll let John warn you about the hidden snakes inside waiting to bite since he's been there.   

[W9JCM]

Just took some voltage readings from the power supply some odd stuff. I will write them down and post so maybe I can get some ideas but looks like there is a issues with ps and that would explain a lot!

[W9JCM]

Ok here we go on the voltage readings as per manual

Terminal 2 6.3V AC    =  0 AC Reading

Terminal 4 +140V  = 396V Reading

Terminal 5 +270V = 480V Reading

Terminal 6 +385 = 484 Reading

Terminal 7 -50V = -67V Reading

Terminal 8 and 9 are AC 110V
Now with switch off the RX off I get a proper 117V AC
With the switch on I get Zero Reading  Possible bad switch? Not sure on that.

[w3jn]

^^ No, the 117 VAC readings are correct.  Only ONE leg of the 117VAC goes thru the PS umbilical cable, thru the ON/OFF switch, and back to the PS.  So 0V across the terminals when the switch is on is correct, as those two terminals are shorted.

You have some serious issues with the power supply, perhaps an open voltage divider resistor (these are multisection resistors riveted to the chassis of the supply).  Straighten those out first.  Then we'll tackle the radio.

I just went thru a SP-110LX and that PS was hammy hamboned to the max - no way it ever would have worked the way it was.  Also Todd's statement about hammy hamboned radios would be well heeded - very seldom will you find one of these that hasn't been modified and/or butchered to some extent.  Check it out, compare with the mil manual (available on BAMA) to see how it's been screwed with.

On the bright side, when you get it going it'll be one of the best boatanchors ever for 160/75/40 AM use.  It's defnitely worth the effort!

[Todd, KA1KAQ]

One other thing to keep in mind when playing with these particular rigs: even though the receiver is off, the terminals across the back are still live. Not a big deal if your receiver and PS have the protective terminal covers in place, but a VERY big deal if they're missing (and they often are). Reaching around the back or even brushing against them accidentally could provide a very rude awakening, or worse. Unplug it, and if you have to work on it while energized, provide plenty of space to work around and behind it with full visibility.

[W3SLK]

Todd said:

One other thing to keep in mind when playing with these particular rigs: even though the receiver is off, the terminals across the back are still live. Not a big deal if your receiver and PS have the protective terminal covers in place, but a VERY big deal if they're missing (and they often are). Reaching around the back or even brushing against them accidentally could provide a very rude awakening, or worse. Unplug it, and if you have to work on it while energized, provide plenty of space to work around and behind it with full visibility.

Wow! Thanks Todd. I never knew or considered that fact. I have a BC-779B which is a military version, (sort of) of the SP-210. Great radio for listening on AM. It was the first radio I ever did an alignment on and it worked smoothly.

[K8WBL]

This might be a dumb question, but check the power supply model numbers, there is a large variety of different power supplies made for these.  Also be sure to check the chokes on the receiver deck, they leak.

73, Tim K8WBL

[Todd, KA1KAQ]

Power supplies are basically interchangeable, excluding the need for the field coil winding on SP-10s, 100s, and early pre-war 200s. Military supplies were a bit beefier and utilized oil filled filter caps through most of the war, and also offered a dual-voltage 120/240V input version, the RA-94. RA-84 is the more common, single voltage version.

As John said, it's likely a bad component in the PS that is skewing the voltages so much. Increased line voltage will only account for a minimal increase. Getting the PS sorted will make going through the receiver a whole lot easier and methodical. 'JN is Super Pro Zen Master in my book. Much of my SP knowledge comes from his experience.

At nearly 70 years old, it's amazing so little is usually wrong with these old rigs. Pretty easy and straightforward to work on too, provided they aren't severely hacked.

[W9JCM]

Ok guys a little update in comparing the power supply to the 210 manuals i have downloaded its different. I will post a picture of what I have here maybe it was modified is what I am thinking. I will take a few pics this weekend and maybe you guys can steer me the right way. I do not see and markings on this P.S. There are no terminals on the back either as pictured in the manuals. I know there are a few different models but maybe this is way off. Starting with the easy stuff and moving on. I am going to take some more Voltage readings on the ps also. John N9AMI   

[w3jn]

Might be a hammy hambone homebrew PS. 

The PS isn't complicated at all for the SP; there's 2 rectumfriers (1 for B+ and 1 for biass), a couple of voltage divider resistors, and some capacitors. 

Another thing that's suspicious is lack of fil voltage...

Post the pics, should be able to tell easily if it's a HB or Hammarlund PS.

[N3DRB The Derb]

no term strip anywhere on it? bet hambone molested it or it's hambone JS.

[W9JCM]

Power supply pics

[W9JCM]

underside

[w3jn]

WOW!!!  THat's one humongous power supply!  Defnitely not a Hammarlund PS

OK, here's what you need to do.  Compare what you have with the PS schematic for the Hammarlund PS.  The B+ values should be similar, as should the bleeders and voltage dividers.  Trace down the fil line and see why you're not getting any filament voltage.  I presume that the dial lights on the radio aren't lighting?  They're powered by the same filament line.

You need to correct any wiring errors, bad components, design flaws, etc., in that PS before you go any further.

[W9JCM]

I been wondering if it would be easier to put out a want for a proper PS for the receiver instead of using a bastardized one from who knows where.

[w3jn]

It's possible, but not likely.  No reason you can't get that one working!

[Todd, KA1KAQ]

I agree with John - that supply is basically a Plus-sized SP supply. No reason it can't do the job just fine. Are the tubes 5Z3 and 80, by chance?

Check the wiring and components as John suggested, measure your voltages, and go from there. Original supplies do show up from time to time, but seldom cheap when you factor in the shipping costs due to their density and the number of folks looking for them.

Weird thing is - I have a supply either just like this, or very, very similar. Got it in a load of stuff years ago. Figured it was salvaged from some WWII surplus transmitter that was otherwise-useless to hams at the time. If yours is HB, they did a nice job.

[w1vtp]

Just picked up a super pro. Brought ps and radio up slow with variac no smoke. But not getting and audio nor can I tell RX. Funny thing is when i switch avc to manual the meter pings to the right. I found 5 dead tubes that were replaced also and someone had a 12SJ7 where the 6SJ7 was so that was put back. Where do I go from here ? Any super pro experts on the forum? FYI I see all the org caps are still on the underside also but I see no leaking. I do not want to be a parts changer and want to do this logically.

tnx
N9AMI
(formerly w9jcm)

The meter pegging in manual mode may mean you have a RF front end prob.  That's normal for that kind of "S" meter.  It monitors the plate current to the IF's.  Try injecting an IF sig near the IF section and see if you have something.  In the manual mode that meter should vary as you adjust the RF gain.  I had one of those beauties and my PS certainly wasn't like that.  If you don't have a schem.. get one and check out the PS voltages etc.

Al

[WU2D]

Great on the SuperPro

Boy are you ready for fun...and tickles. After you are happy with the power situation, do yourself a favor and put some electrical tape over the terminals on the back - ouch!

Once you have verified the voltages from your power supply:

350 - 385 VDC on the plates of the audio tubes
250 - 270 V or so on the rest of the tubes plates
140V or so for the screens
-50V for the bias
6.3 VAC for the FILS

Work from the audio output stages backwards. Inject audio at the grid of the AF Driver then the 1st AF stage then at the top of the AUDIO GAIN POT. Check the cathode bypass cap - It is likely that it should be replaced. The cathode resistor may be burned up. Replace it with a suitable cathode resistor. All of the bias for the triode-connected push-pull stages come from this resistor. The two single ended 1st AF and Driver are biased from the voltage divider off the bias voltage. Much can be accomplished by getting these stages biased correctly and installing good coupling caps. Many feel that the resulting restored SuperPro audio system is the best of the best, as far as receivers go. She do run HOT as class A push pull will.

Mike WU2D

[Todd, KA1KAQ]

The variable IF combined with the stout audio section can't be beat when listening to the BCB or conditions allow the thing to be opened up for amateur use. A conversation some years back with 'JN and 'HUZ about this very topic is what really spurred my interest in learning more about the SPs and giving them an honest try. I'm forever grateful for that conversation. What a receiver. WELL worth the effort.

[W9JCM]

UPDATE:  Well guys She Lives!  Going through the supply I really didn't find much wrong from my meager tech knowldege. So I had on order a new set of rectifier tubes for it 6x5wgt/5r4gy. Now first of all what i was told if they light up they should be good but I did not believe that. So with them replaced everything went back to normal got the 6.3 fil and all the voltages went down to very close to where they are supposed to be. And I was very very impressed on the AM AMI wed listening to 12/16K wide. I had a flex and I will say even with the crappy speaker it was at least as good audio if not better. So I am going through it all replacing all the nesc caps on the underside/hidden areas etc.. checking the resistors etc etc.. And then she will get a nice chasis clean up and be put into a rack. Thanks for the help much appreciated. Now i need a BC transmitter for 75 

John N9AMI (former w9jcm)

[steve_qix]

I have a bunch of these receivers, and they are very good.  My main receiver is the military version - the BC1004.

The audio output section is, in my opinion, not good - OK, but not great.  Lots of unnecessary transformers.  I would suggest picking the audio from the wiper of the audio level control, and feeding an external hi fi amplifier and speaker system.  You will be rather pleased by the improvement in the sound !!  And, you can take out all the audio tubes for a cooler running unit.

That being said, these receivers, with the variable bandwidth IFs, are fine high fidelity receivers.

I ended up completely rebuilding (removed every part except the IF transformers and front end transformers & tuning cap) from my receivers and converted them to solid-state, which is not an easy process because you are designing a new receiver from the ground up, but are restricted to existing components (IFs, RF components, etc.).  It was a great project! 

But, I finally ended up with 2 very high performance, high fidelity receivers that I can leave on 24x7, and they only consume about 15 watts of power !

I'm sure you will enjoy yours 

Regards,

Steve

[w3jn]

John, congrats!  There are a few bypass caps that are kind of hard to get to in the front end compartment, also there's a few hidden INSIDE the IF cans.  The IF can covers come off easily, no need to unsolder wires to do these caps.

If you're doing an IF alignment, make sure you check the IF frequency for your particular radio per the manual.  The SP-210, BC779, BC1004 are 465 KC IF, NOT 455 KC.  I think every one I've had has been hammy aligned to 455 so the crystal filter doesn't work, and the frequency readout doesn't track.

When you're doing the IF alignment remember that there's B+ on some of those trimmer capacitors.  Use an insulated tool, or be sure not to grab the shaft of the screwdriver when tuning.  Ask me how I know this 

As far as the audio section goes, it ain't perfect but it's better than just about any other communications receiver ever made.

[Steve - WB3HUZ]

I would suggest picking the audio from the wiper of the audio level control, and feeding an external hi fi amplifier and speaker system.

This exact tap is available on the back panel terminals labeled phono (if your version of the 200 has such).