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Check the supply circuit of back light itself.

Hello,

Does anyone have the electrical diagram of the Mitsubishi AA084VB02 LCD screen?
I have found the service manual, but not the schematic.
The screen is black, there must be an internal problem on the supply chain of the screen, i think.
it's on Agilent 54810A
The motherboard works, my keyboard is good, and on the outside screen, I can handle the bios.
(Hard drive is deconnected for now, backup to be done)

cdt

Hello Lehane,

I was trying last year to send Iban EB3FRN an email but I cannot really
find his email address. I am watching his blog site and also his youtube
channel but I don't see how to get in touch with him.

Can you help me with his email address?

73!
Razvan

On Tue, Jun 25, 2024 at 06:45 PM, W4PJB wrote:

......

One thing I did discover this evening is the red LED on my A6A7 YTX Current Driver is lit. Not very brightly, which is probably how I didn't see it until this evening, but it is lit. I haven't had any time to dive into that yet but I suspect it isn't helping. But I'm also getting a proper, full amplitude signal to the LO OUT, perhaps this isn't affecting anything regardless. To be determined another evening.?

=====
Red LED says heater is working hard to bring up temperature of YTX. It should turn on bright at power up, and turn off when YTX temperature is within target. I just checked on my 8566B, red LED was on at power up and was out in less than 1 minute. On your unit does it start bright and get dim later or is it always dim?

As Jeff wrote LO output signal doesn't need YTX. However, if YTX is not working high band will not down convert input RF to IF.?

In case it helps your debug: I measured resistance of YTX pins to ground on a spare YTX of unknown state. ?

pins 2 and 5 are two coils in series ~ 60-ohms across
pin 3 heater drive: 238-ohm to ground
pin 4 heater sensor: 455-ohm ground

Ozan

Hi All,?

Thanks again for the suggestions. I'm calling it a night, but I wanted to update this thread before turning in.?

I have already run the test on the LO OUTPUT, and I do get a mixed 321.4 MHz s + my center tuning frequency at the proper amplitude. For example, a 3 GHz input signal, with center tuning at 3 GHz, yields a 3.3214 GHz output on an SA. I did just quickly try putting a short 3 inch SMA jumper to the IF In/Out and there was no change in performance.?I will run the other checks tomorrow.?

One thing I did discover this evening is the red LED on my A6A7 YTX Current Driver is lit. Not very brightly, which is probably how I didn't see it until this evening, but it is lit. I haven't had any time to dive into that yet but I suspect it isn't helping. But I'm also getting a proper, full amplitude signal to the LO OUT, perhaps this isn't affecting anything regardless. To be determined another evening.?

I really appreciate all of the ideas, and I am testing every theory as time allows. Thank you!?

A message posting requested by Artek Manuals:
Artek Manuals will on vacation from June 27th through July 5th, returning to answer questions, process orders on Thursday July 6th.

regards, Ron
-

Follow this sequence:

Right next to the 1st LO OUTPUT connector (front panel) is the IF jumper. Remove the jumper and check it for continuity. The one in the picture on EEVBLOG does not look like the factory original, so maybe someone made a replacement and it's open.
Connect your troubleshooting SA to the "IF OUTPUT" SMA connector. Is the 321.4 MHz signal present?
If you still have a good 321.4 MHz signal there, reconnect the jumper. Does the IF signal make it through the 1.5 GHz low pass?
If it does, and you are sure the cable between A16 LPF and A4 SECOND CONVERTER is good, then the problem is in or around A4 Second Converter. That microcircuit contains a switch. Check the d.c. drive signal to the switch by changing between low band (0-2.5) and high band (2-22). Every time you change bands, the control voltage should do something.
If the control voltage is working, and you have a 321.4 signal going into the second converter microcircuit, then I would suspect the switch inside.

Vladan

Thanks everyone, I tried running the Preselector Peak Routine, no success. Also, just for kicks, I swapped out the YIG with a supposed "tested good" unit. Also, no change, although I didn't expect this to be the issue.?

The SA works perfectly on the low band. There are no errors such as YTO unlock, PL1/PL2, REF Unlock (except when the Oven light is on), M/N unlock, HET unlock, etc. It simply gets a very, very weak signal on the high band. Like -94 dB weak. So it's something in this path for sure. My signal generator only goes to 6 GHz, but now that I think of it, I have an Anritsu SA with TG that goes to 7.1 GHz. Perhaps I can try injecting a 7 GHz signal with the Anritsu to see if it works on the next band up.?

I tested the RF switch with another SA with TG to 7 GHz, there is no attenuation in the switch on either band. I should also add, I did put another SA on the "1ST LO OUTPUT", set a really narrow sweep span on the 8566B (might have been 0), set attenuation to "0", and was able to measure my input signal (3 GHz) + the 321.4 MHz signal, at full strength from the LO OUT. So we've got? great signal at least to there.?

Hello Massimo,

Thanks for the tip with the patents!

As for the heater I already have some left over power resistors so I can
build something similar to yours.

I will most probably come to you with more questions regarding the wire
bonding machine.

73!
Razvan

Razvan, to get an idea of the components of the machine try looking up the patent for that bonding model.

I did the same thing for the 1470 and found these two patents:
US4202482
US4239144

I suggest you try looking them up at this site:

As for the heater, you can build it yourself with a power resistor.
In my heater I used a 50W resistor to get maximum 150 °C .
I attach some photos to give you some ideas.

Regards,
Massimo

Great job !
I would like 1 bare board,

thanks,
rick

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A goofed up character generator (ROM) or maybe a dodgy address line to the character generator would be my first guesses. Address buffer chip gone poof maybe?
I do not expect this problem to be caught by POST.

Wilko

I have a HP 8566B as the title implies. The CRT tube does not turn on and I believe I have traced (at least one) fault to A1A3 high voltage regulator board. The HV oscillator does not oscillate and it just blows the 1A fuse. The Q7 bjt's collector is connected to the high voltage transformer making up the inductor part of the oscillator. The base is also connected to the transformer in a feedback configuration.

The display worked for the first 30 minutes or so of operation after I bought it and then when I inserted low (-10dBm) power at the input the display suddenly turned off, no smoke, no smell but the fuse on A1A6 was blown.

Have you had a high voltage transformer be damaged or do you have any good idea how I can verify whether it is working or not? I can't see any induction values nor turn ratio of the transformer in the troubleshooting manual so I don't know what are normal values.

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My pleasure, Marco! Let me know if I can provide any other information!

Hi Jeremy and group,

any updates on the HP8405A probe repair ?

I've bought now a bunch of MMBFJ176 from Mouser and found a source for the 5082-2835 diode here in Europe. In browsing thru Avago Schottky diode data sheets, I found an interesting pair of common anode (HSMS-2823) and cathode (HSMS-2824) double diodes. From the data sheet their electrical characteristics look identical to the single 282Z you tested. Maybe they could make an equivalent circuit to the 4 separate diodes of the HP8405A sampler. What do you think ?
From the HSMS-282x series there is also a bridge and a ring quad (-P & -R) with identical (?!?) pin-out. But they have "wrong" orientation compared to the HP8405A sampler.
Any other suggestions ?

Regards?????? Andreas

Great!
So it's time to retire the 8350B and hire the 8340B!
Thank you for your time.
All the best Steve

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Hi Marco,