开云体育

agree 100% the Chinese connectors are junk and can damage the instrument.

Get a real USA made, search "used" on ebay

Jon

If they are SMB they should BUT, repeat BUT at $1.34 each I wouldn’t touch them. Adapters that work properly and don’t inject their own silliness cost money. Save the hassle and buy one from Mouser or Pasternack.

Regards,

Stephen Hanselman
Datagate Systems, LLC

After searching the archives, I didn’t find the answer to my question. So here it is.
I found these on Fleebay. It’s supposedly an SMB to BNC female adaptor. However, they don’t look like they’re gonna fit the male SMB connectors on my DC505. What am I missing...?
Should I just change the connectors on the DC505, or is there another alternative?

Thanks great advice,
I put everything in a small metal box with two BNC connectors (input / output). On the 75 ohm side I put a 75 ohm BNC connector.

On Fri, Mar 12, 2021 at 05:08 PM, EB4APL wrote:

You can build it at home, it is just a 2 resistor pad. Google for minimum loss
adapter.

The following will do fine: At the 50 Ohm side: 91 Ohm to Gnd. 43 Ohm between 50 Ohm and 75 Ohm signal lines.

Raymond

You can build it at home, it is just a 2 resistor pad. Google for minimum loss adapter.

Regards,

Ignacio EB4APL

--
El software de antivirus Avast ha analizado este correo electrónico en busca de virus.

Hello everybody,
I would like to calibrate a VHF band pass filter using the tracking generator TR503 (converted to TR502) and the SA 7L13 in the mainframe 7613, but I have the problem that they have a characteristic impedance of 50 ohm while the filter has input and output impedance of 75 ohm . How can I do ?
I have seen on the internet a 50 to 75 ohm BNC adapter (5.7 dB attenuation) but it is quite expensive.

Thanks for the attention
-- Cheers
Attilio

I've no idea what I should be looking for and those pins are mighty small
and close together.

Oh yes, thats not easy.

I was thinking about checking if the lines are totally stuck or are looking normal, i.e. change state every now and then.
Or if a line is moving a little when you switch below 400us... things like that, to confirm or not if the ASIC really has a problem.

cheers
Martin

Eight of them - I've checked everything now using the stereo microscope.

D.

I've no idea what I should be looking for and those pins are mighty small
and close together.

Just one more thing... (Columbo)

Can you check the suspect lines with a another scope?
Do they look stuck? Is there any correlation with good/bad behaviour of the TDS?

cheers
Martin

How many Tantalums did you replace on that board?
How sure are you that there is no problem with a solder joint on or around one of these?

cheers
Martin

I have no clue as the IC's in question are custom ASICs.

Hi David,

were you able to verify the type of pin that you shorted, or presumably shorted? I mean if its a supply line (low impedance), or inputs or 3 state or whatever? In my experience digital logic is rather robust and it was rare to cook a chip just by shorting one of its pins to another, even to GND or VCC.

cheers
Martin

And the bad news is - it's still broken ?

D.

I'm waiing a delivery from Mouser including 2N3565 transistors, 1N4152 diodes and capacitors.

Will get back when I'll receive it and change CR1539, CR1534, C1537, Q1544.

Jose

I went in and checked over and partially redid the cleanup under the
microscope yesterday pm. Still need to put back together and test.

D.

I've since removed the splatter but now any horizontal sweep rate faster

the

400uS breaks up into a mess, and autoset doesn't work right. I'm thinking
I've probably killed it >:(

Are you sure you got *all* the solder?

-- john, KE5FX

If you look at the fourth image in the photo album where the bottom right 'button' is active then the artifact appears on the very top line of the scan, presumably displayed on the following field. The artifact is also triggered by the symbol for the rotary control knob but only where the approximation to the circle extends to the very last pixel on the scan line.

This suggests a way to reliably look at the video signal where it is displaying the artifact. You can trigger from FSYNC or VSYNC, it would be interesting to see if the artifact was on all four fields or just one. You then use delayed sweep to select the first scan line and depending on the polarity and timing of the vertical sync pulses you may need to change the delay for the different trigger options. So now you can trace the video signal from the RAMDAC through to the output of the video amplifier at the clipping diodes CR560, CR568. The video amplifier has a lot of high frequency peaking including a few inductive elements so there is plenty of opportunity for it to ring because of a fault or an incorrect video drive signal.

Good hunting!

Regards,

Roger

Im still struggling with this power supply

If I remove the A5 board from the scope the power supply voltages return to normal and can be adjusted to spec by adjusting R938. As soon as I plug the A5 board back in the voltages drop to the following levels: and R938 has no affect
+5.2=4.3
+8.6=7.4
-8.6=-7.3
+30=+25.8
+100=+87.8

Also when I adjust the Scale Illumination knob the with of the trace shrinks

Any and all suggestion would be appreciated

R A