Realistic 113 Tube Tester Question Help (Precise 111 or 111M)

[moondogtn]

I picked up this Realistic 113 several months ago. It is supposedly a great tester which I plan to restore but I have a few questions. I have tested a couple of tubes just to see how it works and seems fine. I still plan to go through and deoxit and replace a few parts.

Naturally the first tube I want to truly test ( 7189 ) isn't listed on the chart that I have found.

1. I don't see the 7189 tube in the tube chart unless I am missing it. This seems odd unless it is listed differently.
2. I plan to replace the electrolytic caps and the molded paper. There were three.
3. The carbon comp resistors will be replaced with metal oxide or metal film depending on availability or values.

Thoughts?

Bill

 

[Dave451]

Definitely replace the caps. Be sure to replace resistors with comparable or better tolerance ratings. MF/MO are fine. The 7189 tube is a higher voltage capable and higher plate dissipation version of the 6BQ5/EL84 tube. It is pin compatible. EXCEPT pin 6 in the 7189 is tied to the screen grid and not in the 6BQ5/EL84. That probably won't make a different in your tester, but check to be sure, otherwise use the same settings for the 6BQ5/EL84. Transconductance and other values are the same for the tubes. Conventional wisdom is that a 7189 or 7189A is a suitable replacement for a 6BQ5/EL84, but not vice versa.

 

[moondogtn]

Dave451, thanks for the info.
I had considered testing as EL84/6BQ5 but wasn’t sure.
When you say check for my tester to be sure, what exactly do you mean?
Confirm that pin 6 of that socket isn’t tied to something else ? Or? Thanks again.

Bill

 

[Dave451]

Yes, check for any pin 6 connection when the tester is in the configuration for testing the 6BQ5. For info, I've checked 7189's at 6BQ5 settings without issue on my B&K 707 tester. I expect it will be OK.

 

[tubeactive]

The 7189 and 7189A are extra rugged and will usually test very high as a 6BQ5/EL84. In the mil-spec TV-7 testers, a 7189 test uses less negative bias (lower numerical #) plus the testers get lowered in their sensitivity setting. That results in a tougher test, also more centered on the tester meters. So, to further illustrate in the TV-7, for a 6BQ5 /EL84 test:

EV2-7930...bias = 30...shunt = 0...sensitivity = C. A new tube typically reads 100...Minimum = 50.

For the 7189 and 7189A:

EV2-7930...bias = 10...shunt = 0...sensitivity = D. A new tube typically reads >60...Minimum = 46.

As you can imagine, the "spread" in meter movement is very different. A great test for a good 6BQ5 in the TV-7 is to try it with the 7189 settings. This is because the 6BQ5 test usually shows okay tubes to read high, while the tougher 7189 test proves strength. For longevity testing (AKA:Life Test), lowering the filament voltage from 6.3V to 5V while testing, will either have the meter reading droop quickly, slowly or barely at all. A close to new tube will barely budge.

I hope this helps with your acquaintance of the Precise Realistic tester. Perhaps, there are other tube charts in the Precise 111 family which utilize a tougher test for you to try. Although, with some experimenting, you can probably figure it out. For all testers, the "Life Test" is a great way to predict strength and longevity....

If you ever run across a reasonably priced Sencore TC-114 to TC-162 emission tube tester, the Sencore "Shorts" and "Grid Leakage" tests are perhaps the most sensitive in the vintage tester world. I have found "good" tubes on TV-7s and Hickoks, which when retested on the Sencore read bad grid leakage, essentially a "shorts test under duress." For opt tubes, any intermittent short or leakage during use can cause impending doom of amp parts.

 

[moondogtn]

Thank you both for the replies and expansions. I will have to look into it further but what you are both saying is if I can actually test the 7189 it won’t be a good test without some modifications to the settings.
I’m busy with a couple of classes at the moment but will try to dig into it as time permits.
So, for starters, I can test a 6BQ5 to see if I have anything on pin 6 or am I misreading what was suggested above?
Or, In that configuration, with it powered on, tube not inserted? Just asking to clarify.

Bill

 

[Dave451]

Bill,
My B&K 707 checks the 7189 on a different socket than the 6BQ5, also with a different sensitivity setting compared to the 6BQ5. Checking a 6BQ5 first on your tester is a good idea. Checking the 7189 in the same socket as is used for 6BQ5's will, as tubeactive says, give you a different reading from the same settings, but you can sort this out with experience by comparing known good 6BQ5's against known good 7189's.

As for the pin 6 situation, after you check the 6BQ5, pull the tube and check the voltages at each pin and note them. Heater voltage is AC and the bias voltage (on the control grid pin) will likely be AC (check with the test button pushed in). Check the pin 6 voltage and see if anything is present when set for 6BQ5. If not, you're probably OK to test the 7189 but the tester may show a short at pin 6, depending on how it's wired. You can also check the schematic of your tester and, at the 6BQ5 settings, see if you see anything that will happen around pin 6. Without the schematic in front of me, there's not much more I can tell you but to give it a try.

Google the tester and you'll find some useful rehab threads that may help you (especially Precise 111 or 111M).

Dave

 

[moondogtn]

I finally got the electrolytic caps replaced. The one behind the meter was a bit of a challenge to access. I also replaced the 330 Ohm resistor using MF 1%. NE51 short bulb was also replaced. I have powered it up but need to work on calibration procedure. I will need to read over procedure again but recall the first step said something about turning all pots in power supply section full counter clockwise...talked about which were facing certain ways....seemed confusing at the time but don't recall exactly why. I also remember not having the exact tubes needed for the calibration but can get them....seems like a 6C4 and ???

Bill

 

[moondogtn]

So, I finally picked up a 6C4 tube and a 6L6 to run through the cal procedure. It seemed fine until it asks to place it in tube test mode. The needle swings over to full scale on 3K. It then says to switch to 6K span and adjust P5a to read the same. I haven't made any adjustments as something doesn't seem right.. That tube should read 1300 as good. This basically pegs out the meter in 3K setting. Any ideas or do I just have a heck of a good tube. Also, the line adjust is up about 3/4 of the way to center the meter. I am not familiar with tube testers so just wondering if something is off? I quit for tonight but thought I would see if anyone had any thoughts.

Bill

 

[moondogtn]

I was able to get through the Gm calibration perfectly.
The Em calibration is another story. It appears that P11, a 30ohm wirewound pot is no longer working. I removed it and attempted to clean up but still nothing. I am going to be looking for a suitable replacement. It is the shunt pot. I am not sure what power rating to look for...there is a 1 watt ohm resistor in the same circuit so maybe anything above that? If anyone has suggestions here, let me know. Thanks

Bill

 

[moondogtn]

I found a 27 ohm clarostat in my parts bin and was able to get this completed. I ran through the entire process to make sure it all worked as expected. Everything seems to work properly so I buttoned her back up!

Bill

 

[DARRYL JONES]

Bill,
My B&K 707 checks the 7189 on a different socket than the 6BQ5, also with a different sensitivity setting compared to the 6BQ5. Checking a 6BQ5 first on your tester is a good idea. Checking the 7189 in the same socket as is used for 6BQ5's will, as tubeactive says, give you a different reading from the same settings, but you can sort this out with experience by comparing known good 6BQ5's against known good 7189's.

As for the pin 6 situation, after you check the 6BQ5, pull the tube and check the voltages at each pin and note them. Heater voltage is AC and the bias voltage (on the control grid pin) will likely be AC (check with the test button pushed in). Check the pin 6 voltage and see if anything is present when set for 6BQ5. If not, you're probably OK to test the 7189 but the tester may show a short at pin 6, depending on how it's wired. You can also check the schematic of your tester and, at the 6BQ5 settings, see if you see anything that will happen around pin 6. Without the schematic in front of me, there's not much more I can tell you but to give it a try.

Google the tester and you'll find some useful rehab threads that may help you (especially Precise 111 or 111M).

Dave

Greetings, I am searching for the Heater, Socket and Sensitivity for 7189 testing with the BK 707 tester. Thank you...

 

[Dave451]

Darryl,
The 7189 is tested in the 'emission only' section of the B&K707. Settings:

Heater: 6
Socket: 39
Sensitivity: 33
Switch settings: 5-4-1-2
Test:1
A notes says shorts are normally observed on positions 1-3-6-9 (I don't always see them there)

Dave