Date
1 - 20 of 22
Unknown Type 547 add-on circuit.
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Chuck Harris
I am certain that is true, however, I have never found a connector
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where it would work. It does a nice job with CRT deflection socket pins. I used to use an ordinary set of pointed pliers, but they only grip the pin in two small points, which turn into pivots if you apply any pressure. Bending the CRT pins is all but a certainty. -Chuck Harris william_b_noble wrote:
almost certainly either insertion or extraction tool for connector pin in a connector such as a 38999. very handy if you have to work on those connectors, lasts longer than the plastic ones
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william_b_noble
almost certainly either insertion or extraction tool for connector pin in a connector such as a 38999. very handy if you have to work on those connectors, lasts longer than the plastic ones
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Chuck Harris
Just imagine a pair of pointed pliers where when the points
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are closed, they form a tube about 3/32" in diameter, and 1/4" long. -Chuck Harris Roy Thistle wrote:
On Sun, Jul 12, 2020 at 09:24 PM, Chuck Harris wrote:If you have a chance... a pic ... or perhaps... a reasonable facsimile thereof... from Google images.. for the imaginally chalanged and CRT deflection pin breakers among us (me!)
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Morris Odell
I imagine... silver filled polyurethane?... but could of been carbon or metal?I don't think it was anything as fancy as that. It was some black goo sold labelled 'conductive glue' by the local electronics emporium down here in Australia. It should be pretty obvious to the naked eye so so no label.
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Hi Martin. I see I have 4 of the little buggers and there seems to be only 2 in the 549. If you use my email address books4you4 at mail dot com I will test them and send you a pair. Stay safe. John
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Maybe for driving an x-y plotter?
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John Gord
Martin,
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From what I can see of the board, it may be an output buffer board: It may provide deflection-voltage-derived X and Y output to some external device, probably at fairly low bandwidth. --John Gord
On Mon, Jul 13, 2020 at 05:49 PM, Martin Hodge wrote:
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I've carefully traced the topology of this board and I can say fairly certain it is not an input circuit. The crt pin leads connect through about 300k ohms of resistors to the _bases_ of NPN transistors. I've applied +-12.6v and a signal to the board at several points and the signal always shows up at the XLR plug. Sorry, but the mystery remains.
Dave, thanks for the warning regarding the hv transformers, I had read up on that before I started on the 547 and it appears to be stable at the moment. I was reading only 7600v at the anode for a while, which concerned me. But it turned out the 1M ohm resistor on the anode capacitor was open. After replacing it I had the expected 8200v. The 549 hv circuit went out with a bang before I got it. The 220ohm 2w resistor on the primary side of the transformer was exploded and charred the inside of the housing. It looks like the driver tube, a 6gf5 if I remember, popped and shorted out the resistor. Replacing both the tube and resistor brought back the hv circuit with good voltage readings and a nice bright trace. The storage circuit appears to be working. I can draw on the tube with the horizontal and vertical position knobs like an etch-a-sketch and press the erase buttons to clear it. Both sweeps on the 549 are stuck in hold off though. The 547 sweep 'b' had the same issue. The problem there was the 5.9meg resistor to ground on the grid of the first stage of the hold off circuit had opened. A 4.7m + 1.2m in series to replace it was all that was needed to get it running again. These scopes are so easy to repair I'm confident I can get the 549 running again if I can get ahold of those 8608 tubes. John, that's very kind and generous of you! I dont mind paying a reasonable price + postage for those tubes if you have them. Thank you!
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Roy Thistle
On Sun, Jul 12, 2020 at 09:39 PM, Morris Odell wrote:
I imagine... silver filled polyurethane?... but could of been carbon or metal? filled 2-part epoxy? Did you add a label to slow down any pliers welding pin-braking posterity?
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Roy Thistle
On Sun, Jul 12, 2020 at 09:24 PM, Chuck Harris wrote:
If you have a chance... a pic ... or perhaps... a reasonable facsimile thereof... from Google images.. for the imaginally chalanged and CRT deflection pin breakers among us (me!)
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Albert Otten
Hi John, works fine here with Firefox. In such cases I click Photos at the website and set "Sort by created" arrow down, i.e. new to old. It will be one of the first albums.
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Albert
On Mon, Jul 13, 2020 at 03:11 AM, John Griessen wrote:
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Dave Seiter
Yeah, I know all too well; fortunately, I only have one that's marginal, the rest of 547s are ok (so far!) I've rewound HP solenoid coils and a few other items, but never tried a transformer.
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-Dave
On Sunday, July 12, 2020, 06:07:53 PM PDT, Dave Wise <david_wise@phoenix.com> wrote:
Beware that the 547 and 549 are susceptible to a high-voltage transformer problem. Tek switched to an epoxy-based winding impregnant which has become lossy. The symptom is loss of high voltage, sometimes after a short time on the order of minutes to a couple hours. Chuck Harris is working on an industrial-grade rewinding operation, or you can try my low-tech DIY approach documented in topic and album titled "453 HV Transformer Rewind". The 547 transformer winding spec is available at TekWiki, w140.com . Dave Wise ________________________________________ From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Dave Seiter via groups.io <d.seiter=att.net@groups.io> Sent: Sunday, July 12, 2020 5:55 PM To: TekScopes@groups.io Subject: Re: [TekScopes] Unknown Type 547 add-on circuit. A nice haul! I have a 549 around somewhere that I've been meaning to restore; thanks for reminding me! -Dave On Sunday, July 12, 2020, 05:03:39 PM PDT, Martin Hodge <mhodge@innocent.com> wrote: Actually the total bill was $60, for a 535a, 547, 549, 575, 585a and a little Heathkit scope. I was very pleased, but the suspension on my van was not. I was really after the 575. I'd been wanting a curve tracer and the other units were gravy. The 585a and the heathkit were unfortunately rotted away far beyond saving. But I've got the 575 and the 535a working nicely and calibrated. The 547 I've just finished but haven't calibrated yet. The 549 storage scope is going to have to wait, it needs two 8608 tubes in the vertical amp (gassy) which are very expensive. The 535a has a beautiful, bright and razor sharp aqua colored trace and is completely transistor free when equipped with a Type 53/54K. I feel like a bolt of lightning could hit it and it would keep right on ticking.
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Morris Odell
Good advice from Chuck Harris about care in removing wires from the CRT pins. On a related note I once was asked to repair a 535 scope that had damaged resistors in the VA because the wires had slipped off the CRT pins and come in contact with the chassis. This destroyed the non inductive resistors in the plate loads of the output tubes. As part of the repair I put a a dab of conductive glue on the connection to make sure it couldn't happen again.
Morris
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Chuck Harris
The 500 series scopes all (?) had ports on the left
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side for direct connection to the deflection plates. This allowed the user to gain faster sweeps and deflection than was available from the scope's circuitry. And, it had the side benefit of allowing all of the bias circuitry, and anode voltages to be provided by the host chassis. For your purposes, you will probably want to remove the modification, and reconnect the deflection wires to the CRT. Don't break the CRT pins sticking out of the neck. The socket pins should slide on straight and easy. I find that using a usual set of pliers to grip the socket pins lets them pivot too easy, and invites catastrophe. I have a pair of needle nose pliers that have semi circular tips (like a piece of tubing slit down its sides), about 3/32 inch in diameter that are perfect for gripping the socket pins. -Chuck Harris Martin Hodge wrote:
Can anyone identify the circuit shown in the photo album? It's in a Type 547 I got off craigslist for $10.
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John Griessen
On 7/12/20 8:00 PM, Dave Wise wrote:
Can anyone identify the circuit shown in the photo album? It's in a Type 547 I got off craigslist for $10. I can't get that to show in firefox or chrome. I'm logged in, but that URL redirects to https://groups.io/g/TekScopes with no mention of albums anywhere...
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Dave Wise
Beware that the 547 and 549 are susceptible to a high-voltage transformer problem. Tek switched to an epoxy-based winding impregnant which has become lossy. The symptom is loss of high voltage, sometimes after a short time on the order of minutes to a couple hours. Chuck Harris is working on an industrial-grade rewinding operation, or you can try my low-tech DIY approach documented in topic and album titled "453 HV Transformer Rewind". The 547 transformer winding spec is available at TekWiki, w140.com .
Dave Wise ________________________________________ From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Dave Seiter via groups.io <d.seiter=att.net@groups.io> Sent: Sunday, July 12, 2020 5:55 PM To: TekScopes@groups.io Subject: Re: [TekScopes] Unknown Type 547 add-on circuit. A nice haul! I have a 549 around somewhere that I've been meaning to restore; thanks for reminding me! -Dave On Sunday, July 12, 2020, 05:03:39 PM PDT, Martin Hodge <mhodge@innocent.com> wrote: Actually the total bill was $60, for a 535a, 547, 549, 575, 585a and a little Heathkit scope. I was very pleased, but the suspension on my van was not. I was really after the 575. I'd been wanting a curve tracer and the other units were gravy. The 585a and the heathkit were unfortunately rotted away far beyond saving. But I've got the 575 and the 535a working nicely and calibrated. The 547 I've just finished but haven't calibrated yet. The 549 storage scope is going to have to wait, it needs two 8608 tubes in the vertical amp (gassy) which are very expensive. The 535a has a beautiful, bright and razor sharp aqua colored trace and is completely transistor free when equipped with a Type 53/54K. I feel like a bolt of lightning could hit it and it would keep right on ticking.
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Dave Wise
That was an unbelievable deal. I'd be pinching myself to prove I was not dreaming it.
That mod was available on most (all?) of the 500-series scopes, it gives direct access to the CRT vertical deflection plates so you can bypass the built-in vertical amp and drive them at frequencies far above spec with external equipment. Dave Wise ________________________________________ From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Martin Hodge via groups.io <mhodge=innocent.com@groups.io> Sent: Sunday, July 12, 2020 4:17 PM To: TekScopes@groups.io Subject: [TekScopes] Unknown Type 547 add-on circuit. Can anyone identify the circuit shown in the photo album? It's in a Type 547 I got off craigslist for $10. https://groups.io/g/TekScopes/album?id=250335 It's only connections are a 4 pin xlr socket mounted thru a hole in the left cowling and 4 leads that clip directly to the CRT deflection plates. Apparently some kind of interface, but for what?
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Dave Seiter
A nice haul! I have a 549 around somewhere that I've been meaning to restore; thanks for reminding me!
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-Dave
On Sunday, July 12, 2020, 05:03:39 PM PDT, Martin Hodge <mhodge@innocent.com> wrote:
Actually the total bill was $60, for a 535a, 547, 549, 575, 585a and a little Heathkit scope. I was very pleased, but the suspension on my van was not. I was really after the 575. I'd been wanting a curve tracer and the other units were gravy. The 585a and the heathkit were unfortunately rotted away far beyond saving. But I've got the 575 and the 535a working nicely and calibrated. The 547 I've just finished but haven't calibrated yet. The 549 storage scope is going to have to wait, it needs two 8608 tubes in the vertical amp (gassy) which are very expensive. The 535a has a beautiful, bright and razor sharp aqua colored trace and is completely transistor free when equipped with a Type 53/54K. I feel like a bolt of lightning could hit it and it would keep right on ticking.
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Nice buy Martin! Wow that is a dream. I checked vacuumtubes.net and they are $25 each new. I am going to check and see how many spares I have. I will let you know if I can help. John
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Actually the total bill was $60, for a 535a, 547, 549, 575, 585a and a little Heathkit scope. I was very pleased, but the suspension on my van was not.
I was really after the 575. I'd been wanting a curve tracer and the other units were gravy. The 585a and the heathkit were unfortunately rotted away far beyond saving. But I've got the 575 and the 535a working nicely and calibrated. The 547 I've just finished but haven't calibrated yet. The 549 storage scope is going to have to wait, it needs two 8608 tubes in the vertical amp (gassy) which are very expensive. The 535a has a beautiful, bright and razor sharp aqua colored trace and is completely transistor free when equipped with a Type 53/54K. I feel like a bolt of lightning could hit it and it would keep right on ticking.
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