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Changing the board won't help unless the raw supply filter cap for that supply happens to be on it. You likely just need to find and replace the cap and it should be good to go. I believe the cap is chassis mounted, or on the motherboard, or on a separate assembly along with some others.

?

Ed

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Anyone know of a source or cross reference for a 1853-0063 transistor used in the 410C? ?I’ve already have a query into Walter at Sphere.

Thanks in advance,

Manuel

I'm having trouble unsubscribing.??? Twice I've sent an unsubscribe request in, and twice I've confirmed it, but still getting posts.??? Any ideas?

Bob - AE6RV

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?

In general, it is not a problem. The thing with static electricity
and vacuum cleaners is, though.

What happens is the dust inevitably has a charge, and when it gets
dragged through the hose, it deposits its charge in the vacuum
cleaner bin. As time goes on, that charge builds up, and discharges
to the motor, and if there is lots of dust, <>!

I was cleaning up sawdust from my basement floor one day, and
there was quite a lot. I was doing the area around my bandsaw,
and <>! The largest bolt of static I have ever seen,
jumped between my elbow and the bandsaw's bed. It seemed to be
5 or so inches long. Plastic hoses are the pits.

I had a coworker once that wanted to clean up his TRS-80, and
asked about using a vacuum. I told him don't. He didn't listen,
and the next day came telling of how the TRS-80 was showing a
complete memory failure. Imagine.

Air passing through the hose potentially could deposit charge too,
but usually doesn't because the blow gun is metal, and you are holding
it, returning the charge back to ground. It would be quite different
if your compressor was passing quantities of dust... but most have
air filters.

-Chuck Harris

Dave Daniel kc0wjn@... [hp_agilent_equipment] wrote:
> I looked around for something similar a while back. I was thinking of the vacuums
> used to clean out toner from printers (we used to have these when I worked for STK
> Printer Ops). They had small nozzles and were very effective at cleaning up toner. I
> wasn't able to find anything remotely affordable.
>
> I've always wondered about using compressed air on static-sensitive electronics. It
> seems to me to be a bad idea, ESD-wise, but I have no real experience.
>
> DaveD
>
> On 10/20/2017 9:31 PM, David Smith w6te@... [hp_agilent_equipment] wrote:
>>
>> Greetings,
>>
>> I was working on an HP 438A Power Meter yesterday which was absolutely filthy
>> inside. This thing must have been run 24/7 in a filthy environment over the years.
>> I had to replace the fan, as usual, so I went ahead and pulled the power supply
>> unit out to clean the dust and crap out of it. But, really, there was a layer of
>> thick dust all over the unit.
>>
>> This got me to thinking… I need a better way of vacuuming and cleaning equipment
>> that comes in that I won’t be fearful of damaging the cmos devices. Mind you I have
>> a grounded ESD pad across my bench that equipment sits on when it is being worked
>> on and I always use a grounded wrist band on my wrist. I investigated some handheld
>> vacuum cleaners and discovered a few models that are electrostatically safe. The
>> cost was a bit of a shocker as they sold for around $375 USD!!! (They must be very
>> proud of their equipment.) What are the recommendations of the group for a hand
>> held vacuum cleaner that would be safe to use around sensitive electronic
>> equipment? I don’t mind spending $100 or so on something but $375 is a bit out of
>> the question.
>>
>> Best regards,
>>
>> Dave W6TE
>>
>> Sent from Mail for Windows 10

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?

The 3M model 497 is an example of the kind of vacuum you want for this work. They can be had used on eBay for < $100.

-Pete

On Oct 20, 2017, at 20:31, David Smith w6te@... [hp_agilent_equipment] <hp_agilent_equipment@...> wrote:

Greetings,

?

I was working on an HP 438A Power Meter yesterday which was absolutely filthy inside. This thing must have been run 24/7 in a filthy environment over the years. I had to replace the fan, as usual, so I went ahead and pulled the power supply unit out to clean the dust and crap out of it. But, really, there was a layer of thick dust all over the unit.

?

This got me to thinking… I need a better way of vacuuming and cleaning equipment that comes in that I won’t be fearful of damaging the cmos devices. Mind you I have a grounded ESD pad across my bench that equipment sits on when it is being worked on and I always use a grounded wrist band on my wrist. I investigated some handheld vacuum cleaners and discovered a few models that are electrostatically safe. The cost was a bit of a shocker as they sold for around $375 USD!!! (They must be very proud of their equipment.) What are the recommendations of the group for a hand held vacuum cleaner that would be safe to use around sensitive electronic equipment? I don’t mind spending $100 or so on something but $375 is a bit out of the question.

?

Best regards,

?

Dave W6TE ?

?

Sent from??for Windows 10

?

Has anyone got an A4 board (DFA) for the Hp3562a? I am looking for a parts machine in the UK too.?

Thanks Simon

Hi everyone, the last time I asked a question I got some very good advice, so lets see if we have same luck this time.

I have the 1740A that I'm trying to restore, its in really good condition inside and out generally and certainly does not belong as landfill etc.

Last time I had distorted waveforms and your advice pointed me in the right direction and we resolved that issue and so while attempting to calibrate the scope a bit, the trace disappeared completely, did this a couple of times and never recovered. Pressing beam find confirmed that there was no HT.

Removed the HV cover and checked the supply rails coming in and all is correct but the oscillator is not running and I've confirmed this by using another scope and holding the probe in close proximity to the transformer and there is high frequency bleed at all. There is a 50Hz one if I turn the sensitivity all the way up, normally there is a high strength signal of around 30 to 40Khz but not on this one at present.

The voltages I'm getting on Q1, Q2 and Q3 are:

Q2?

Base? ? ? ? ?+16.8v

Emitter? ? ?+15v

Collector? ? 0v

Q1

Base? ? ? ? ?0v

Emitter? ? ?0v

Collector? ? +7.27v

Q3

Base? ? ? ? ?+7.27v

Emitter? ? ?0v

Collector? ? +22v

I should say as well that this particular board has the modifications to the Q1 and Q2 configuration which I have a photo of but not too sure how I can attach it in a fashion that you can see it, any ideas on how I submit the photo and on how I can resolve the oscillator issue?

All assistance is greatly appreciated.

Graham??

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