hi. to make a long story short, i pulled all the carbon type resistors from this tube tester. installed metal film resistors. now tester test all tubes as being perfect. even bad ones.??? why??? and there is now way to calabrate this tester.

Not to insult you in any way, but the first thing comes to mind, is that you may have made an error in reading the color codes. Or connection. A resistor carbon or film type should not make any difference. If it was working well before, it still should now.

not stupid. i have the manual for this tester and it tells you what value the resistors are. plus i can read the color code. the tester read low before i fooled with it. yes i changed the rectifier too. thank you.

:not stupid. i have the manual for this tester and it tells you what value the resistors are. plus i can read the color code. the tester read low before i fooled with it. yes i changed the rectifier too. thank you.

Paul: I said before I do not ever try to insult anyone.
I don't know anything about you, or what you know and don't know. Was for help only. <> Warren <>

:hi. to make a long story short, i pulled all the carbon type resistors from this tube tester. installed metal film resistors. now tester test all tubes as being perfect. even bad ones.??? why??? and there is now way to calabrate this tester.
:
:
:Hi! Paul,
Check your email, I sent you a link for your TC-2 tube tester calibration.If you didn't receive it ,just google (heathkit tc-2 calibration) then click on the (Tube Sound blog).At the bottom of the TC-2 section you can click on the (Knight 600) for calibration instructions.Apparently the Eico 625, the TC-2 and the Knight 600 have basically the same circuit.I just repaired an Eico 625.And just as the above blog says, the line voltage was too high and I ended up installing a 25watt 40ohm power resistor on the hot side which gave very good line voltage adjustment.The 50 ohm resistor they recommend might be better than the 40 ohm I put in.I also ran into the same problem as you did with bad tubes reading good.I found a wire, that went from the load pot to a tube socket,broken.Everything looked O.K., until I probed with a small stick,and a wire that looked perfect, moved away from the socket, revealing the break.My problem was isolated to one socket, so it was only one type of tube that was reading faulty. Hope this helps. Bob Masse
:
:

::hi. to make a long story short, i pulled all the carbon type resistors from this tube tester. installed metal film resistors. now tester test all tubes as being perfect. even bad ones.??? why??? and there is now way to calabrate this tester.
::
::
::Hi! Paul,
:Check your email, I sent you a link for your TC-2 tube tester calibration.If you didn't receive it ,just google (heathkit tc-2 calibration) then click on the (Tube Sound blog).At the bottom of the TC-2 section you can click on the (Knight 600) for calibration instructions.Apparently the Eico 625, the TC-2 and the Knight 600 have basically the same circuit.I just repaired an Eico 625.And just as the above blog says, the line voltage was too high and I ended up installing a 25watt 40ohm power resistor on the hot side which gave very good line voltage adjustment.The 50 ohm resistor they recommend might be better than the 40 ohm I put in.I also ran into the same problem as you did with bad tubes reading good.I found a wire, that went from the load pot to a tube socket,broken.Everything looked O.K., until I probed with a small stick,and a wire that looked perfect, moved away from the socket, revealing the break.My problem was isolated to one socket, so it was only one type of tube that was reading faulty. Hope this helps. Bob Masse
::
:: thank you very helpfull

The original diode was a copper oxide unit. If you replaced it with a silicon diode, the tester will be goofed up. The original copper oxide diode should still be good.

Also, the original Heathkit schematic shows the diode installed backwards, at least by modern graphical standards for showing polarity.
Doug

One more thing. My TC-2 could not be zeroed with the modern line voltages. If you encounter this problem, I can give you a simple fix.
Toug

:One more thing. My TC-2 could not be zeroed with the modern line voltages. If you encounter this problem, I can give you a simple fix.
:Toug
:
:
:
:Hi! Doug,
I would be very interested in hearing what your simple fix was for getting the line voltages down.I'm always happy to learn. tks. Bob Masse
:
:

Refer to the TC-2 schematic or the pictoral wiring diagram. Find the black wire connecting Terminal 2 of of the voltage adjusting pot. It goes to the "100" terminal of the primary winding of the power xfmr.

Disconnect either end of this wire and tape it. Leave a note inside the TC-2, explaining what you did (for the benefit of others that may come along later).

This will allow the zero-adjust to work with modern line voltages. No additional power resistors needed.
Doug

::One more thing. My TC-2 could not be zeroed with the modern line voltages. If you encounter this problem, I can give you a simple fix.
::Doug
::
::
::
::Hi! Doug,
:I would be very interested in hearing what your simple fix was for getting the line voltages down.I'm always happy to learn. tks. Bob Masse
::
::
:

Correction: I said to disconnect either end of the wire. Well, one end is a permanent pigtail lead from the xfmr. So, disconnect the end that is connected to Terminal 3 of the pot, leaving the pigtail in place.
Doug

:Correction: I said to disconnect either end of the wire. Well, one end is a permanent pigtail lead from the xfmr. So, disconnect the end that is connected to Terminal 3 of the pot, leaving the pigtail in place.
:Doug
:
:
:
; Thanks for info! Much appreciated. Bob Masse
:
:

Hi,

I have the TC-1 model and a Superior TV-11. If your link is good for me, I would like you to send it to me please.

:
:I have the TC-1 model and a Superior TV-11. If your link is good for me, I would like you to send it to me please.
:
;
;
:Hi! Check your email.If you didn't get the info let me know. Bob Masse
:
:

Thank you!

ok guys, the line voltage zeros out fine. i have plenty of pot left to zero with. the diode was changed. i did install it right. if its backwards the meter works backwards. the ressitors were all replaced with metal film types. yes they are the correct value and in the right places. im going to try the replace the 1200 ohm resistor with a pot. maybe i can get it to work that way. also checked the wiring to make shure it was wired properly. also my line voltage is at 120 volts ac.

The forward voltage drop for a copper oxide diode is three times that of a silicon diode (if that is what you used for a replacement). I tried using a silicon diode, and the tube checker was completely goofed up, so I reinstalled the original copper oxide diode, and all was well again.
Doug

:the diode was changed. i did install it right. if its backwards the meter works backwards.
:

Or, you can try putting three silicon diodes in series.
Doug

:The forward voltage drop for a copper oxide diode is three times that of a silicon diode (if that is what you used for a replacement). I tried using a silicon diode, and the tube checker was completely goofed up, so I reinstalled the original copper oxide diode, and all was well again.
:Doug
:
::the diode was changed. i did install it right. if its backwards the meter works backwards.
::
:

i was told that i would have to change a resistor to make the diode work properly. i have no idea what resistor to change or to what value to change it to. funny though i did chage the diode in the other tc-2 and that seems to work fine..