I recently purchased a 1957 Berlant reel to reel drive unit with 2 mono TWA-1 recording amplifiers all built into red Berlant carrying cases and a unknown built 6v6 push pull stereo amplifier that is built into a very well-done reproduction of the Berlant cases, these itemns are in superb physical condition but am having a problem with the custom amplifier, it uses all Stancor transformers and vis a 2 channel 6v6 push pull that has 2 x 6v6 1 x 6J5 & 1 X 6SJ7 for each channel but in-between the in an empty socket for a rectifier ? im guess but wondering what would be the correct or at least safest to put in there once im ready to put it on a variac and see what happens. First two photos are the recording system third photo is the home brew amplifier designed into a look alike case, next is to show what tubes are where and what is missing then the inside of the chassis then the bac of the amp with connections. I not very knowledgeable about this part of enjoying audio, just enough to get myself into these situations and any help or ideas on what tube is missing it would be greatly appreciated, Thank you.
The smart thing to do would be to trace the wiring of that socket to see where it goes. Is there a heater coming to it? Is it connected to the power transformers and reservoir capacitors? I wouldn't just plug in a tube and hope for the best.
Jan
Jan
Yes, trace the wires first. Anyway, I suspect this ain't no tube socket at all, but an assortment of test points instead, or a speaker terminal or a terminal to connect a preamplifier or...
Best regards!
Btw, congrats to these decent, almost immaculate units
!
Best regards!
Btw, congrats to these decent, almost immaculate units
!
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You might expect that an octal socket for a rectifier will use the 5T pinout, with pins 4 and 6 for anodes and 2 and 8 for filaments. Easy enough to measure resistances to test: anodes will be somewhere in the tens or maybe a little over a hundred Ohms apart, and the filament winding will look like a pretty hard short.
All good fortune,
Chris
All good fortune,
Chris
Yes, I was just re-thinking it while having taken my morning shower and came to a similar conclusion. If it's intented to take a tube indeed, the only possibility would be a rectifier due to the lengthy wires and the resulting immense parasitic capacitances and inductances.
Best regards!
Best regards!
Take care with those electrolytic multiple section cans. One of them may be shorted and this burnt the (lost) rectifier. I almost sure that was a 5U4. Verify trafo resistance as above suggested and if you can, check the heater voltage.
Thanks for taking the time to help out, soi would i be checking these with the amp powered up, might sound like a stupid question, probably because it is, but i have to start somewhere. Thank you.
Before powering up, you want to check with a resistance meter as Chris suggested in #4.
In the meantime, I'm also sure that the rectifier tube is missing. Note that red wire running from one of the lugs to the capacitor at the right.
Best regards!
In the meantime, I'm also sure that the rectifier tube is missing. Note that red wire running from one of the lugs to the capacitor at the right.
Best regards!
Resistances are always measured with power off, preferably after also draining each of the power supply caps with a short. Safety first.
If this stuff has been sitting unused for a good while, you'll need to re-form the electrolytic caps. Actually, you should do this anyway, just in case. Un-formed electrolytics will quickly destroy themselves, and often take other parts with them. The procedure is all over diyaudio.com, but the basic idea is to remove all the valves, make a temporary rectifier with a pair of 1N4007s, and to bring up the mains voltage very slowly on a variac, observing mains current draw and waveform on the first power supply cap. Could take several hours, but it would be a shame to damage such a pretty piece.
All good fortune,
Chris
If this stuff has been sitting unused for a good while, you'll need to re-form the electrolytic caps. Actually, you should do this anyway, just in case. Un-formed electrolytics will quickly destroy themselves, and often take other parts with them. The procedure is all over diyaudio.com, but the basic idea is to remove all the valves, make a temporary rectifier with a pair of 1N4007s, and to bring up the mains voltage very slowly on a variac, observing mains current draw and waveform on the first power supply cap. Could take several hours, but it would be a shame to damage such a pretty piece.
All good fortune,
Chris
I tested the socket and t looks like it is for the rectifier so tacked on the loose lead from the cap attached a power cord and noticed two loose wire one each coming from each of the transformers on that side of the chassis that were tucked in with all the other wires. I am at he point now that wish there were someone to take it too to get it fixed as its sort of the only part I wanted out of the system however there is no one that could do something like that for 250 m8iles and shipping it there and back with no estimate or guarantee makes it a non choice for me
The loose leads from the output transformers are coming from the same side as the secondaries, so may be either a 32 Ohm or a 70.7 Volt output. That would look like a couple Ohms to circuit ground. If so, just cap off with shrink-wrap.
Pictures so far haven't shown a line (mains) fuse, which you must have. The missing mains cord should be 3-wire, with hot going immediately to mains fuse, switch following fuse, and PE (safety ground) going immediately to chassis with a dedicated screw, lockwasher and nut.
All good fortune,
Chris
Pictures so far haven't shown a line (mains) fuse, which you must have. The missing mains cord should be 3-wire, with hot going immediately to mains fuse, switch following fuse, and PE (safety ground) going immediately to chassis with a dedicated screw, lockwasher and nut.
All good fortune,
Chris
There is a possibility it is not for a tube, but for linking to something else, like the UX4 sockets in old radios.