Announcement

Collapse
No announcement yet.

Considerations when replacing GZ34 with 1N4007's

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Mick Bailey
    replied
    The socket fitted looks like the Chinese ones I referred to in #18. The type was originally used with transmitting tubes but as usual they get cheapened. For some reason the UX5 types I use for 807 tubes have always been fine, but I gave up early on with the Octal bases because even when new there wasn't much engagement. The rivets can be expanded slightly if loose and the flared end soldered to the contact. I quite like the backing spring that maintains the contact pressure and I guess in the original versions they worked fine and there were no problems.

    Leave a comment:


  • nevetslab
    replied
    That looks like what's installed to me. The point of pin engagement by the terminals does look a touch further than traditional sockets, but not such that there would be no mating as in this case. Now, if there's any additional spacers placed between the socket's built-in spacer and the chassis, then it would set it further down....but, assuming the tube base mates with this ceramic base, I don't see why there would be the problem described..

    Leave a comment:


  • glebert
    replied
    Originally posted by Enzo View Post
    Would love a photo of the empty socket from the top side.
    Wondering if it is one of these. https://tubeworldexpress.com/product...rt-122-228-200

    Click image for larger version

Name:	1_5de4346d-2969-4679-8433-17c7899ebcd4.jpg?v=1571439005.jpg
Views:	108
Size:	94.5 KB
ID:	936186


    Click image for larger version  Name:	1_7d34b52a-fc68-4aa1-b058-39835b716d9d.jpg?v=1571439005.jpg Views:	0 Size:	164.1 KB ID:	936185

    Leave a comment:


  • Enzo
    replied
    Would love a photo of the empty socket from the top side.

    Leave a comment:


  • nevetslab
    replied
    Originally posted by Mr_bibbles View Post

    Ah how true this was.

    SO back in the shop today, confirmed what I knew; the pins did not even REACH the little "grabbers" on the pin socket bottom, so tightening them would yield no results!

    WHAT I DID NOT KNOW was that the eyelets holding the grabbers had become a little loose over time, letting the "grabbers" travel about a MM or two lower than they should, and the "grabbers" themselves were bent upwards slightly. So, carefully flattening the edges of the eyelet, the "grabbers" dropped back down a smidge, close but not perfect. Then I VERY carefully bent the "grabbers" down a little bit and re-tensioned them as I normally would any socket.

    This was as humiliating as it was effective.

    Looking back at last week, my landlord sold the property so I've been filling out housing applications all week, one of my best friends was moving to New York, my partner started a new job, our band coordinated our first show in 2 years, and our shop was finally returning to full 40 hours for amp work so I was already a bit stressed out and definitely absent minded... thank you guys for getting me "up in that front seat".

    Here's a pic of the socket (after doing the eyelet press / re-tension):
    I've never seen one of these sockets before. Now, seeing brass rivets on this side of the ceramic base, I'd have to believe there would be substantial space between the opposite side and an additional insulator....or just plenty of space so there's sufficient spacing between Ground (chassis) and any of the pins at their elevated AC voltage/DC voltage. So, does it seem longer pins are needed on any rectifier tube inserted, due to that space requirement between live rivet heads and the chassis surface we're seeing in this photo? It looks like a good quality socket. I'm guessing a Russian connector?

    Using a wooden Q-tip shaft or something similar, see what the length is needed from the top surface of the connector to passing thru/past the contacts. How much longer is it than the typical octal pins on any of the octal tubes you have.

    How thick is that ceramic base? Can you get any photos showing more of the thickness/height of that ceramic base? Very interesting connector

    Leave a comment:


  • Mr_bibbles
    replied
    Somehow I have this mental image: we are sitting in the back seat of the car, and our feet don't reach the pedals. We think of extending the pedals, or maybe extending our feet with heels. Or maybe making remote controls for the pedals. Maybe the car was built wrong? Lots of solutions xcept why are we not sitting up front?
    Ah how true this was.

    SO back in the shop today, confirmed what I knew; the pins did not even REACH the little "grabbers" on the pin socket bottom, so tightening them would yield no results!

    WHAT I DID NOT KNOW was that the eyelets holding the grabbers had become a little loose over time, letting the "grabbers" travel about a MM or two lower than they should, and the "grabbers" themselves were bent upwards slightly. So, carefully flattening the edges of the eyelet, the "grabbers" dropped back down a smidge, close but not perfect. Then I VERY carefully bent the "grabbers" down a little bit and re-tensioned them as I normally would any socket.

    This was as humiliating as it was effective.

    Looking back at last week, my landlord sold the property so I've been filling out housing applications all week, one of my best friends was moving to New York, my partner started a new job, our band coordinated our first show in 2 years, and our shop was finally returning to full 40 hours for amp work so I was already a bit stressed out and definitely absent minded... thank you guys for getting me "up in that front seat".

    Here's a pic of the socket (after doing the eyelet press / re-tension):
    Attached Files

    Leave a comment:


  • Leo_Gnardo
    replied
    Originally posted by Mr_bibbles View Post
    1. It is the ONLY socket of this STYLE in this amplifier IIRC; the other sockets are much more traditional, this one is wacky: A floating octal base where pins travel through to a wafer type socket, ground rails attacked to chassis mounts.
    2. I believe it is the "Wafer" type socket, at least on the pin fittings, which could account for the lack of depth due to manufacture mistake. The pins are not internal, but floating above the wafer socket.
    Wafer socket - only seen them on super cheapo very obsolete gear. Sounds like a very dicey improvised setup. Not the kind of thing we would expect on a jewel like the Lumley. Maybe a repair done by a person who had a limited supply of parts and/or knowledge? Photos may help us decide.

    3. I have also considered extending the leads, or even hardwiring the tube in. The customer is familiar with this sort of work and could be understanding, but it seems, for lack of a better word, "Janky".
    "Janky" = Irish slang for "half assed." "That grease monkey put a janky fix on my motor, now it's totally banjaxed." Very appropriate!

    Looking forward to getting the janky socket out of your banjaxed Lumley, and a proper one installed so you can listen to the indescribably awesome tone of a single ended 300B amp. Or so I've been told...

    Speaking of Lumley, does anybody remember Enid Lumley? She was an Absolute Sound commentator who looked & listened to the world from a unique angle. For instance she reported a certain hi fi preamp sounded better when it was turned upside down. Good ol' Enid. Now who would think of that? Maybe she should right-side-up the preamp & listen whilst standing on her head and report on that. It's only fair. Of such things are snooty hi fi publications made.

    Leave a comment:


  • Enzo
    replied
    Somehow I have this mental image: we are sitting in the back seat of the car, and our feet don't reach the pedals. We think of extending the pedals, or maybe extending our feet with heels. Or maybe making remote controls for the pedals. Maybe the car was built wrong? Lots of solutions xcept why are we not sitting up front?

    Leave a comment:


  • Mr_bibbles
    replied
    Oh no! THE SUN GOD! HE'S COMING!....

    Oh hey, look, he's actually kind of cute.

    These are all great responses, sorry for the delay time as it's been a crzy holiday weekend. I have a phone in my hands now, fully prepared to take some pictures and eat crow once we found out what I've overlooked! A couple takeaways;

    1. It is the ONLY socket of this STYLE in this amplifier IIRC; the other sockets are much more traditional, this one is wacky: A floating octal base where pins travel through to a wafer type socket, ground rails attacked to chassis mounts.

    2. I believe it is the "Wafer" type socket, at least on the pin fittings, which could account for the lack of depth due to manufacture mistake. The pins are not internal, but floating above the wafer socket. It's possible someone re-tensioned them incorrectly at one point?

    3. I have also considered extending the leads, or even hardwiring the tube in. The customer is familiar with this sort of work and could be understanding, but it seems, for lack of a better word, "Janky". At first 1n4007 struck me as an elegant workaround but....

    4. I think the consensus is that 1n4007 could be totally safe... or cause a lifetime of problems. So, now the we know the sun god is all talk, I'll try to solve the issue rather than to circumvent it... sometimes a weekend helps clear your head.

    So I am heading into the shop soon, I'll take some pictures and we can see who was closest without going over. Thanks for all your expert attention and patience,

    -Matt
    Attached Files

    Leave a comment:


  • glebert
    replied
    Originally posted by nevetslab View Post

    Wouldn't this give you the same length pins as we already have? Which are said NOT to engage the socket terminals.
    My thought was to harvest the pins out of the tube base to make pin extenders. Don't know of it would work or not, as others as have said this all makes little sense without pictures.

    Leave a comment:


  • nevetslab
    replied
    Originally posted by glebert View Post

    I would try extending the pins using the pins from a tube base like this.

    https://tubedepot.com/products/8-pin...base-only-deep
    Wouldn't this give you the same length pins as we already have? Which are said NOT to engage the socket terminals.

    Leave a comment:


  • The Dude
    replied
    Originally posted by Enzo View Post
    ......I swear we are missing something.
    A picture.

    Leave a comment:


  • Enzo
    replied
    We can think of all manner of technician fixes to solve the immediate problem, but that overlooks the amp should not have the problem in the first place. I swear we are missing something.

    Leave a comment:


  • glebert
    replied
    Originally posted by nevetslab View Post


    I know this is going out on a limb, but, having had to re-solder octal tube pins periodically in hopes to restore the operational state of an output tube in a set of power tubes, many times with success, that lends credence to perhaps scavenging a set of pins from some bad octal tubes, or similar source, heating up the pins in the 5AR4, inserting a suitable contact lead, such as 20AWG buss wire, and trying to add additional pin length to what's on the tube. Obviously the full length of the second set of pins would be too long, but with careful slicing of pins with a Dremel fitted with carbide discs for slicing, one could cobble the extension of the pins on a good 5AR4 so the longer pins DO engage the socket terminals. Hard to really see if this would work, NOT seeing the physical tube socket as you have there. I too am bewildered with this problem-induced tube socket as has rendered this amp non-functional.

    I would try extending the pins using the pins from a tube base like this.

    https://tubedepot.com/products/8-pin...base-only-deep

    Leave a comment:


  • nevetslab
    replied
    Thinking more about your tube socket.....is it possible the socket contacts have been pushed out of their original detented positions as they appear to be on the preamp tube sockets? If the tube socket body is the same, I can't think how else the tube socket pins won't engage the sockets.

    Leave a comment:

Working...
X