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    TDR Relay with Tube Rectifier

    jimmeq
    jimmeq

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    Post by jimmeq on Sat Oct 10, 2020 5:17 pm

    I didn't want to hijack the ST-120 Problem post.

    For reasons I don't remember I thought the TDR Relay was to let the output tubes "warm" a bit. I have the TDR, and like to use a tube rectifier; and so far so good.

    Would it be reasonable to remove the TDR to continue using a tube rectifier? I don't have a problem replacing a rec. tube now and then but is it possible that with the tube rec. and TDR it could cause damage elsewhere?

    Jimme
    Bob Latino
    Bob Latino
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    Post by Bob Latino on Sat Oct 10, 2020 5:46 pm

    jimmeq wrote:I didn't want to hijack the ST-120 Problem post.

    For reasons I don't remember I thought the TDR Relay was to let the output tubes "warm" a bit. I have the TDR, and like to use a tube rectifier; and so far so good.

    Would it be reasonable to remove the TDR to continue using a tube rectifier? I don't have a problem replacing a rec. tube now and then but is it possible that with the tube rec. and TDR it could cause damage elsewhere?

    Jimme

    If you have a TDR and want to use a tube rectifier, all you have to do is BYPASS the TDR. See below ...

    1. Unsolder and remove the two wires that are now connected to pins 4 and 6 of the rectifier tube socket at the rectifier tube socket.
    2. Remove the two RED wires that come from the power transformer and go to the TDR board at the TDR board.
    3. Connect the two RED wires from the power transformer to pins 4 and 6 of the rectifier tube socket (S)
    4. The TDR is now bypassed and high voltage AC now goes from the power transformer directly to the rectifier tube socket.


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    Hops

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    Post by Hops on Sat Oct 10, 2020 7:33 pm

    If you are going to bypass your TDR, I would suggest doing the "Yellow Sheet Mod" at the same time. I think there is a sticky on that.
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    nmchiefsfan

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    Post by nmchiefsfan on Mon Oct 12, 2020 6:46 pm

    FWIW, I have been running with a tube rectifier and TDR for about 7 years. I started with the Weber solid state rectifiers but they kept getting hot and burning up. I have had the same Tung-Sol tube rectifier running for about 4 years now...at least 2000 hours on it. Since it had been so good to me I ordered a couple more from Jim McShane about 3 years ago but haven't had to change it yet. I am running at about 53mA per tube. Running KT-120s and driving some 100 dB Klipsch speakers so the amp isn't working very hard, even at moderately loud volume.

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    DavidR
    DavidR

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    Post by DavidR on Sun Oct 18, 2020 11:38 am

    I too have a TDR in my ST120 and use a tube rectifier (that's how it came). No problems that I'm aware of.

    Bob, what would we expect to see as far as negative effects from using a TDR with a tube rectifier.

    As far as I know the TDR first gives current to the filaments allowing them to warm up a bit and 20 seconds later the plate voltage is applied.
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    monkuboy

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    Post by monkuboy on Sun Oct 18, 2020 11:46 am

    I've been using a tube rectifier with a TDR since getting my ST-120 in mid-2016. No problems until I saw this thread, so it must be a jinx. Yesterday I turned on the amp and the rectifier put on a light show. I quickly turned off the amp. The fuse had blown so I replaced that and put in a Weber copper top that I had purchased to use as a spare. Thankfully it started up and played fine, but after reading so many comments about the heat of that "tube" I'd like to use another tube rectifier (I have a couple of spares but used the Weber instead) but am hesitant because of Bob's warning.

    I did write to Bob when this thread first appeared and asked if I should take the TDR out of the circuit since I was using a tube rectifier and he said if it is working okay then just leave it in. So I guess I jinxed it by asking, haha.
    Bob Latino
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    Post by Bob Latino on Sun Oct 18, 2020 12:00 pm

    DavidR wrote:I too have a TDR in my ST120 and use a tube rectifier (that's how it came). No problems that I'm aware of.

    Bob, what would we expect to see as far as negative effects from using a TDR with a tube rectifier.

    As far as I know the TDR first gives current to the filaments allowing them to warm up a bit and 20 seconds later the plate voltage is applied.

    Current is given to the 5 volt AC rectifier filaments all the time when the amp is turned on. What the TDR does is to switch on the two high voltage AC lines from the power transformer to pins 4 and 6 on the rectifier socket after all the tube filaments in the amp have been on for about 17 seconds. If you use a tube rectifier, you don't need the TDR because a tube rectifier will not pass any high voltage to pin #8 until the tube rectifier is warmed up. (15 - 20 seconds)

    Bob
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    nmchiefsfan

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    Post by nmchiefsfan on Sun Oct 18, 2020 12:28 pm

    It was my understanding that the TDR also helped with short cycles on the amp. I thought for sure that after I bragged about my rectifier lasting so long that I would have fireworks when I turned the amp on this weekend but...and here I go pressing my luck again...the amp powered right up and played for about 8 hours yesterday while I was working around the house. I have had no issues and will leave my amp as it is.
    Bob Latino
    Bob Latino
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    Post by Bob Latino on Sun Oct 18, 2020 12:45 pm

    Yes - You are correct .. The TDR also prevents the amp from "short cycling". Sometimes a quick ON/OFF/ON can take out a rectifier tube. The TDR does prevent this .. If you don't have a TDR and you do live in area where quick ON/OFF/ON short cycles occur, you can also use a manual reset GFCI. (Ground Fault Circuit Interrupter) A manual reset GFCI cannot deliver power unless you manually push in the white button to reset the device after a power failure. Amazon link below ...

    GFCI on Amazon.com

    Bob

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    DavidR
    DavidR

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    Post by DavidR on Sun Oct 18, 2020 2:35 pm

    That's exactly the GFIC device I use.

    It saved my amp at least once.
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    monkuboy

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    Post by monkuboy on Sun Oct 18, 2020 3:45 pm

    Question - I replaced my blown rectifier tube with a Weber solid state but I've read mixed comments about them, some saying they got too hot and fizzled out. Can that cause damage to the rest of the amp? I'm wondering if it would be safer to use another standard rectifier tube (I have a spare Genalex GZ34).

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