Here's my new tube tester. I made this video a few weeks ago. A few people said they wanted to see this video. (I mentioned it in another video) so here it is. Happy New Year everybody!
Type 43 filament draws 300 mA at 25V and was used in some of the earliest transformerless sets with 25Z5 rectifier and a few then-standard 6.3V 300 mA tubes such as 6D6 in a series string. You'd still need to dissipate 50V at 300 mA so 15 watts which is a lot for a resistor, so you often instead see either a ballast tube or a resistive line cord.
Great video on the Eico 625, I have 625 that is still used today in my work space and I have to go through and check resistors and the caps, but the tester works like new. This was a kit built back in 1956 by a friend of mine that had become an electrical engineering professor at Akron Unv, in Akron, Ohio. Thank you again for sharing this video with all of us.
If you are interested: This procedure will make your EICO Model 625 filament voltage capable of being calibrated. In order to calibrate filament voltages the EICO 625 a few modifications needed to be done. R6 the 95K 1% need to be replaced with a variable 100k pot. I put it next to the 6H6 rather than have it on the face panel where it could get bumped. Next find the point where you can read the 250vac across the secondary windings. R1 2.5K 5w one its legs is a good spot. The negative side I used the return on B1 and B2 for my return test point. Install wire to your test points. Next insure the lever switches 1- 10 are all in the “CENTER” position. Insert AC into your TESTER. Turn on TESTER. Measure your test points. 250Vac should be seen on your connected DVM. If not adjust line voltage until you have 250Vac at your test points. After getting this adjust your new R6 variable pot for the needle to be on the line mark on your TESTER’s meter. Once you have the 250Vac and the line meter adjusted. Check your filament voltages. Place the lever #1 in the “DOWN” position. Place your DVM to check your four pin tube filament slot pins 1-4. Rotate the “FILAMENT” switch while observing your DVM. All the voltages should be fairly close.
On all basic emission type tube testers the ONLY alignment you have to do is the line adjust. On this unit you put a tube in a socket and turn it on. On the selector switch that says 1,2,3,4, line adjust. Set that to line adjust. You are supposed to set the needle for top center i.e.mid-range of the scale. You then turn the pot on the left that says " Line Adjust" to get it there. You can then test a tube.
Hey that's great I am in the middle of restoring a 1957 Precision Model 660 tube tester on my channel.I had to take the roll chart out of mine and re-roll and reset it to the start position boy was that a job and a half. I still have to go through and check out the resistance values and even has a large single plate selenium rectifier that is probably not working but it keeps me busy. Thanks for going through the tube tester and giving me more ideas. Oh and I have an Eico model 636 that works perfectly.
Make me want to have a tube tester like your ,the problem being it wouldn't get much use some .I like how simple they are inside ,amazing .I guess if you have to restore one that would be the one to get .nice save finding that loose connection.
Enjoyed the video. I have had this same model for many years and it is my go to unit I have never went through it but should. This video will help. Thanks again. Enjoy your channel.
I also like old radio's and I have a few. I also like repairing them it is just a hobby wich I enjoy very much. I was interested in buying a tube tester but overhere (Netherlands) they go crazy on the price 300-400 euro's. I don't want to spend that much money. I guess they never be able to sell it to any hobyist. I looked on ebay and over in te USA the go for as much as 100 dollars now that is reasonable. But then you have to add shipping costs and customs, and then the question is in what kind of condition it will be after the long journey. But I see now there is not much inside that van brake. Thanks for the opload, great video!
I have the Eico 625 and would like to replace: miniature bulb (Part#2 /symbol B3 / #42 OVERLOAD) + miniature bulb (Part#3 / symbol B4 / NE-51 SHORT IND.) Someone knows what are the values needed and where I can find these bulbs? Thanks
Like all your videos this was very good and very helpful. Just got one of these today, but like yours needs some resistors. I do have the Eico schematic which denotes R1 as a 5W but the others have no designation, R2, R4 and R8 all appear to be larger resistors. What size did you use here 2 Watts? Thanks for any help you can provide.
