On my TDS220 I changed the backlight lamp to a LED strip.
??? Mark Jordan, PY3SS
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On 24-Feb-25 16:50, Bob Kendrick via groups.io wrote: Hi All
Anyone know what the correct voltage is at the input of L6 on the Power Supply. Its the supply circuit for the display CCFL. I'm getting -4.6v.
My display is a dull shade of orange with no detail. A new display did not fix it. The output CCFL voltage is reading 768v pk-pk. Manual says is should be 1270v pk-pk. The other power supply voltages are correct.
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Hi All
Anyone know what the correct voltage is at the input of L6 on the Power Supply. Its the supply circuit for the display CCFL. I'm getting -4.6v.
My display is a dull shade of orange with no detail. A new display did not fix it. The output CCFL voltage is reading 768v pk-pk. Manual says is should be 1270v pk-pk. The other power supply voltages are correct.
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Hi Gerald,
after several years, it seems I found the right help for my 2784 Tektronix Spectrum Analyzer.
I would be very interested in your Processor Extender Card with serial Port.
Please let me know, if I can buy one from you. If you sell only a PCB with the connectors, it is also ok for me.
Hope for contact.
Regards
闯ü谤驳别苍
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Re: 278x Spectrum Analyser
Hi Gerald
I am repairing a Tektronix 2784. Therefore i'm searching for the Processor ExtenderBoard with the SerialPort or a Circuit Diagram for this.
I know it's a 85C30 Dual Serial Interface from Zilog and it uses &0100 to &010F to communicate.
Thank you for help. That's the first Time I'm using groups. I have some files with circuit diagrams, also Module Level Service Manual
Regards
Juergen
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Hi all,
I am repairing a Tektronix 2784. Therefore i'm searching for the Processor ExtenderBoard with the SerialPort or a Circuit Diagram for this.
I know it's a 85C30 Dual Serial Interface from Zilog and it uses &0100 to &010F to communicate.
Thank you for help. That's the first Time I'm using groups.
Juergen
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Re: Is there an alternative to the 151-0703-00 NPN's from the 492 power supply board?
Thank you Mark.
I can actually source these locally.
Looking at the board, the pin layout isn't as obvious as I thought and I haven't been able to find any kind of schematic for the 492 PSU so I'll just assume that the TO-61 pinout is standard to all TO-61's.
James
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Re: A bewitched voltage divider?
I tried simply using two VOMs. The presence of the HV probe does not change the read value at U1540 pin 4 even one millivolt.
So there are two possibilities: the HV probe does not say the truth or the presence of a high ripple changes the measurement (or both). Probably at Tektronix took that in account, so they asked to check pin 4 (which has a capacitor to integrate the ripple) and not directly the voltage.
What do you think?
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Il giorno 24 feb 2025, alle ore 00:28, David Knight via groups.io <david@...> ha scritto:
Greetings, all.
It occurs to me that maybe this is a simpe loading problem.
The HV probe is likely to have a resistnace of the order of 100M. With 1600V, the current is 16uA — not insignificant.
So was the procedure like this?
1) HV measurement taken using HV probe, and a multimeter: 1510V
2) HV probe disconnected from’scope and DMM, then DMM used ot measure low-end voltage: 1.6V.
If that was the procedure, the two circuit conditions are not the same.
Its a simple matter to leave the HV probe attached to the ‘scope (but disconnected from the DMM), then use the DMM to measure the divider.
Just a thought,
David K
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Re: Is there an alternative to the 151-0703-00 NPN's from the 492 power supply board?
James,
A BUV48A will work and is heavier capacity. Mouser has these in stock for $6,76.
Mark
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Re: Is there an alternative to the 151-0703-00 NPN's from the 492 power supply board?
An NPN is an NPN is an NPN, no?
Therefore, it must be possible to use a more common package of transistor and bodge a solution to this unobtainium nonsense?
Ok, we don't know the Gain, but we do know it is 10A and 450v and I'm sure I can figure out which terminals are the B,C & E.
This TO-61 package is the 'bolt and nut' type and was attached to a fat heatsink, so why can't a couple of different NPN's be used instead? Maybe TO-247's laid flat on the heatsink instead of passing through it?
Surely this has been done before?
Unless of course these chips aren't 'normal'...
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Is there an alternative to the 151-0703-00 NPN's from the 492 power supply board?
Hi all.
Can't seem to find these anywhere.
According to Sphere, these are,
'HARD to find 49xP Series Inverter Transistors! - 2N6587, TO-61, NPN, 10A/450V' - (SOLD OUT)
Is these a feasible request, or shall the 492 be stripped and sold for spares?
James
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Re: A bewitched voltage divider?
Greetings, all.
It occurs to me that maybe this is a simpe loading problem.
The HV probe is likely to have a resistnace of the order of 100M. With 1600V, the current is 16uA — not insignificant.
So was the procedure like this?
1) HV measurement taken using HV probe, and a multimeter: 1510V
2) HV probe disconnected from’scope and DMM, then DMM used ot measure low-end voltage: 1.6V.
If that was the procedure, the two circuit conditions are not the same.
Its a simple matter to leave the HV probe attached to the ‘scope (but disconnected from the DMM), then use the DMM to measure the divider.
Just a thought,
David K
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THANKS!
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Il giorno 23 feb 2025, alle ore 22:35, zenith5106 via groups.io <hahi@...> ha scritto:
On Sun, Feb 23, 2025 at 09:30 PM, Gianni Becattini wrote:
Sorry, my fault. It works.
It is still important that an 11300 non-A with F/W 3.1 is treated as an A-scope in CATS.
/H?kan
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On Sun, Feb 23, 2025 at 09:30 PM, Gianni Becattini wrote:
Sorry, my fault. It works.
It is still important that an 11300 non-A with F/W 3.1 is treated as an A-scope in CATS. /H?kan
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Sorry, my fault. It works. I was running in the wrong directory.
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Il giorno 23 feb 2025, alle ore 20:23, zenith5106 via groups.io <hahi@...> ha scritto:
On Sun, Feb 23, 2025 at 07:54 PM, Gianni Becattini wrote:
Has someone a more recent version of TekCATS or must I reinstall the old
firmware?
Select 11302A and ignore the error message and it will work.
/H?kan
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Thank you Hakan,
I tried but its still says “LOG ERROR-> CAN’T FIND EIS RCS VERSION NUMBER”
Actually this is not set and the EIS RCS control variable says NOT SET.
Is there a way to set it?
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Il giorno 23 feb 2025, alle ore 20:23, zenith5106 via groups.io <hahi@...> ha scritto:
On Sun, Feb 23, 2025 at 07:54 PM, Gianni Becattini wrote:
Has someone a more recent version of TekCATS or must I reinstall the old
firmware?
Select 11302A and ignore the error message and it will work.
/H?kan
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On Sun, Feb 23, 2025 at 07:54 PM, Gianni Becattini wrote:
Has someone a more recent version of TekCATS or must I reinstall the old
firmware?
Select 11302A and ignore the error message and it will work. /H?kan
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Hi, it's me again... :)
I was going to go on with the 11302 checking and tried to connect to TekCATS 2.19, but in the meantime I had updated the firmware to the 3.1 version and TekCATS refuses to connect to it.
Has someone a more recent version of TekCATS or must I reinstall the old firmware?
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Re: Tektronix 145 PAL test signal generator - repair (oven control circuit and maybe more)
The capacitors are fine... I did change the ones on the PSU board, but left the large cans be. However, there was an open diode in the bridge rectifier circuit which was the cause of the ripple on the 10V rail I also made a mistake and do have all the colors, it was a setting on the monitor. Now there is still ripple on the 3.6V line which appears to be caused by the 3.6V regulation going into current limiting. It looks like something on the A3 field timing board, though nothing appars to get hot. The A3 board is quite complex.... /g/TekScopes/photo/296482/3889932
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Hi all,
So last year my venerable old 2465A developed a weird intermittent fault. After some time - arbitrary and not temperature related - this fault would arise whereby the screen would become *really* bright with some spurious artifacts showing up as well. When this happens, the screen brightness control fails to have any effect and I cannot turn that dazzling brightness down.
Now, from what I've read, I need to monitor TP73's voltage ('grid no. 1' to the CRT) and see if it changes when the fault arises. So I've stripped the casing away and removed the HV safety/warning shield from the HV supply board A9 and attached a scope probe to TP73. The service manual provides a diagram of how the waveform on TP73 should look so I'm all revved-up waiting for the fault to materialize (which it invariably does when I try to use it to check anything). Guess what? I've had the damn thing on now for 5 hours and it's not missed a beat! Behaving perfectly normally with no sign of any screen issue at all. Bloody intermediate faults. I hate 'em!!
Jinxie
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James55
zenith5106
Jinxie