RE: [funwithtransistors] Re: HP 3465A Repair


Aug 11, 2010

 


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#251 Aug 11, 2010

I was given a non-functional HP 3465A which I would really like

to get operational. I opened it up enough to look around, but

not break the calibration seal, and sniffed. It smells like the

power transformer has a burnt winding. I'm considering just attaching

to the output of the rectifier and applying some DC power, and

see if I can get it to power up.



Does anyone have any experience with this equipment, know where to

get info, or have suggestions? I see manuals for sale, but being

a laid off telecomm engineer, I find $$$ hard to come by.



Mac

--

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Oppose globalization and One World Governments like the UN.

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----------------------------

#252 Aug 11, 2010

Mac,I just got through fixing my HP331A Distortion Analyzer.�� Ifound the manual on the internet, free download. ��Just what is an HP3465A?�� Give me a little more diagnosis.��Power supply problems are usually easy to fix.�� Smoking transformer? Check thediodes.�� One shorts, load on transformer. ��Larry ��From:funwithtransistors@yahoogroups.com [mailto:funwithtransistors@yahoogroups.com] OnBehalf Of Mike McCarty

Sent: Wednesday, August 11, 2010 12:23 PM

To: Fun with Transistors

Subject: [funwithtransistors] HP 3465A Repair



----------------------------

#253 Aug 12, 2010

Mac.......I Googled HP 3465A........The fourth item on the page mentions the FSM Directory where for $5.00 you can download the service info you require....bob p

--- On Wed, 8/11/10, Mike McCarty Mike.McCarty@...> wrote:

From: Mike McCarty Mike.McCarty@...>Subject: [funwithtransistors] HP 3465A RepairTo: "Fun with Transistors" funwithtransistors@yahoogroups.com>Received: Wednesday, August 11, 2010, 10:22 AM

��I was given a non-functional HP 3465A which I would really liketo get operational. I opened it up enough to look around, butnot break the calibration seal, and sniffed. It smells like thepower transformer has a burnt winding. I'm considering just attachingto the output of the rectifier and applying some DC power, andsee if I can get it to power up.

Does anyone have any experience with this equipment, know where toget info, or have suggestions? I see manuals for sale, but beinga laid off telecomm engineer, I find $$$ hard to come by.

Mac-- p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}Oppose globalization and One World Governments like the UN.This message made from 100% recycled bits.You have found the bank of Larn.I speak only for myself, and I am unanimous in that!



----------------------------

#254 Aug 12, 2010

Larry Beaty wrote: > Mac,

>

> I just got through fixing my HP331A Distortion Analyzer. I found the manual

> on the internet, free download.



No such luck with the 3465A.

> Just what is an HP3465A? Give me a little more diagnosis. Power supply



It's a nice bench top DMM.

> problems are usually easy to fix. Smoking transformer? Check the diodes.

> One shorts, load on transformer.



The transformer does not smoke. The unit does not power up. All I did

was a preliminary "sniff test", and I know that smell all too well.

I haven't gotten into it yet, but I'm pretty sure the power transformer

is shot. I am pretty sure I could cobble up a replacement from a

wall wart or similar, but I'd like to know the characteristics of

the original.



Of course, I'll check the diodes. I don't see any burns or similar

on resistors or the board, so I don't think it went because of something

inside the DMM itself. If it's just the power supply, it should be

easy to fix. The fuse is not blown. Sometimes, transformers just go,

as well, and that's what I think may have happened here.



What I'd like to know is what the voltages are supposed to be.

Voltage and current rating on the power transformer would be

very nice to have.



Mac

--

p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}

Oppose globalization and One World Governments like the UN.

This message made from 100% recycled bits.

You have found the bank of Larn.

I speak only for myself, and I am unanimous in that!



----------------------------

#255 Aug 12, 2010

Mac,I disagree with you.�� Power transformers do not ���justgo���.�� Especially the transformers used in high quality testequipment.�� Please take my suggestion and check everything else ratherthan settling on the power transformer as the problem. ��More than likely, capacitors go.�� Usually unit continues towork but really badly.�� Capacitors have a limited life.�� Transformerscan run forever.�� OK forever: The transformers I used in the equipment I designedwere built for 100 year life.�� Forever for me! ��As you know, check for voltages.�� Look for an IC that hasexpired.�� Very slight chance in an piece of HP gear, a wire unsoldered orbroken.�� I did have large HP signal generators with the power transformerspulled out of the PC board.�� Some careless person had dropped the signalgenerator.�� The transformer being heavy, pulled out of the PC board. ��Best wishes, but fun to trouble shoot! ��Larry ��From: funwithtransistors@yahoogroups.com[mailto:funwithtransistors@yahoogroups.com] On Behalf Of Mike McCarty

Sent: Thursday, August 12, 2010 2:20 AM

To: funwithtransistors@yahoogroups.com

Subject: Re: [funwithtransistors] HP 3465A Repair







----------------------------

#256 Aug 12, 2010

Larry Beaty wrote: > Mac,

>



A kind soul sent me a link to the operation and service manual. It looks

like a 6V 200mA tranny would be about right.

> I disagree with you. Power transformers do not "just go". Especially the



The windings of transformers experience the electromotor effect just

like any other coil of wire, and they do eventually fail due to

stresses. Nothing lasts forever.

> transformers used in high quality test equipment. Please take my suggestion



I agree that high quality test equipment normally uses transformers

quite a cut above a "wall wart", and otherwise unexplained failure is

rare. Certainly, I don't intend just to wire something in, plug her

in, and let her go.

> and check everything else rather than settling on the power transformer as

> the problem.



Absolutely, that's good advice. I didn't mean to convey the idea that

I had settled on "the fix". I am sure the power tranny has been blown

in some fashion. There was a reason that happened. I intend to find out

what that was.

> More than likely, capacitors go. Usually unit continues to work but really

> badly. Capacitors have a limited life. Transformers can run forever. OK

> forever: The transformers I used in the equipment I designed were built for

> 100 year life. Forever for me!



I'm sure you refer to FITs or MTBFs here. What any given transformer

does is not predictable, of course.



If the transformer "went" b/c of the failure of another component, then

I intend to find out. My first step is going to be to check the

rectifier diodes and the pass transistors and reference diode, then

attempt to reform the electrolytics. If that looks good, then I intend

to apply current limited DC to the place where the PS transformer was

originally intended to provide AC, with the power supply disconnected

from the rest of the circuit. If that works, then I'll gradually apply

voltage to it, connected up, and watch the current flow. If that's ok,

then I'll try to power it up.



BTW, rectifiers normally do not "just go", either. Usually, there

is a transient event, often from the power line, which causes failure.

That doesn't mean that there aren't unexplained failures.

> As you know, check for voltages. Look for an IC that has expired. Very

> slight chance in an piece of HP gear, a wire unsoldered or broken. I did



This one has the option of using NiCd battery packs, internally, and I

found the clip to hold one disconnected and lying on the back of the

main circuit board. I don't see any marks to indicate damage, but who

knows?



The unit has obviously seen some service, so I suppose it was working

at one time. I don't think I'll see an unsoldered wire. It has a

calibration sticker on it, as well. There is another sticker saying

"INACTIVE 21MAY99" on it. It has several stencils on it. One reads

"MCC TE", another "CC404", both on the top. On the sides are stencils

reading "uP ENG." ("mu", not "u") So, at one time, I'm sure, this

was being used regularly.



It may not be reasonable to restore this unit to service, depending

upon what is wrong. It may just fire up and run after replacement

of a component or two. Who knows?

> have large HP signal generators with the power transformers pulled out of

> the PC board. Some careless person had dropped the signal generator. The

> transformer being heavy, pulled out of the PC board.



Oh, no! :-(

> Best wishes, but fun to trouble shoot!



Thanks. Of course, I have no way to calibrate it, and don't have

$200 to have it calibrated.



Mac

--

p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}

Oppose globalization and One World Governments like the UN.

This message made from 100% recycled bits.

You have found the bank of Larn.

I speak only for myself, and I am unanimous in that!



----------------------------

#257 Aug 12, 2010

How long is forever? Over the years I have had power transformers that "just went". Exactly where I know not. Probably insulation break down and shorted turns.....Of course these days we run into few pieces of equipment with power transformers but in days of old most everything but the AA5's had power transformers......Also I have had speaker field coils "leave" for no apparent reason....bob p

--- On Thu, 8/12/10, Larry Beaty lbeaty3@...> wrote:

From: Larry Beaty lbeaty3@...>Subject: RE: [funwithtransistors] HP 3465A RepairTo: funwithtransistors@yahoogroups.comReceived: Thursday, August 12, 2010, 6:29 AM

��Mac,

I disagree with you.�� Power transformers do not .just go..�� Especially the transformers used in high quality test equipment.�� Please take my suggestion and check everything else rather than settling on the power transformer as the problem.

��

More than likely, capacitors go.�� Usually unit continues to work but really badly.�� Capacitors have a limited life.�� Transformers can run forever.�� OK forever: The transformers I used in the equipment I designed were built for 100 year life.�� Forever for me!

��As you know, check for voltages.�� Look for an IC that has expired.�� Very slight chance in an piece of HP gear, a wire unsoldered or broken.�� I did have large HP signal generators with the power transformers pulled out of the PC board.�� Some careless person had dropped the signal generator.�� The transformer being heavy, pulled out of the PC board.��Best wishes, but fun to trouble shoot!��Larry��From: funwithtransistors@ yahoogroups. com [mailto:funwithtran sistors@yahoogro ups.com] On Behalf Of Mike McCartySent: Thursday, August 12, 2010 2:20 AMTo: funwithtransistors@ yahoogroups. comSubject: Re: [funwithtransistors ] HP 3465A Repair







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#258 Aug 12, 2010

Larry, ��Thisis a true story.�� Some 45 years ��ago I was working at a physiology researchlaboratory and one of the Tektronix oscilloscopes in the lab failed.�� I ransome quick checks and found that one of the windings on the power transformer appearedto be open. ����We called Tektronix and described the symptoms and whatI had found.�� A few days later an engineer arrived and I watched as he checkedseveral components and then replaced the transformer.�� After doing athorough calibration on the unit, he packed up his tools and started to leave.����I asked him for a copy of the service report and also the cost ofreplacing the transformer so I could tell my boss.�� He just looked at mefor a few seconds and then said, ���What transformer?�� Tektronix makestheir own transformers and they never fail.��� ��JerryFeldman�� ������ ��From:funwithtransistors@yahoogroups.com [mailto:funwithtransistors@yahoogroups.com] OnBehalf Of Larry Beaty

Sent: Thursday, August 12, 2010 5:30 AM

To: funwithtransistors@yahoogroups.com

Subject: RE: [funwithtransistors] HP 3465A Repair



----------------------------

#262 Aug 13, 2010

Jerry,One product I was responsible for design had a small voltagesniffing transformer.. After many failures in the field, I tore one apart.. Themanufacturer had banjo strung the winding wires from the coil to the terminals..As temperature changed the ���banjo��� strings stretched and finally broke. ��I contacted the manufacturer about the problem.. Themanufacturer had no intention of changing how his transformers were made..Contract was cancelled.. His competitor had service loops of the winding wiresat the terminal. ��Most inductor problems are at the terminals... Not all.. If themanufacturer uses really cheap wire insulation, it will fail for shortedturns.. Insulation is so cheap and excellant today, that real manufacturers usegreat insulation.. Thereby extending the life of transformers.. The main powertransformers I had built for my products had 200.C insulation on the windings..At the running temperature of these transformers, life was predicted to be over100 years. ��Your open winding of a tek transformer was probably a failure ata terminal.. Coils do not just open without a severe temperature violation..And the burn marks are easily seen. ��Larry ��From:funwithtransistors@yahoogroups.com [mailto:funwithtransistors@yahoogroups.com] OnBehalf Of Gerald Feldman

Sent: Thursday, August 12, 2010 5:02 PM

To: funwithtransistors@yahoogroups.com

Subject: RE: [funwithtransistors] HP 3465A Repair



----------------------------

#265 Aug 13, 2010

--- On Fri, 8/13/10, Larry Beaty lbeaty3@...> wrote:

> From: Larry Beaty lbeaty3@...>

> Subject: RE: [funwithtransistors] HP 3465A Repair

> To: funwithtransistors@yahoogroups.com

> Date: Friday, August 13, 2010, 10:32 AM

>

> Jerry,

>

> One product I was responsible for design had a small voltage

> sniffing transformer.. After many failures in the field, I tore one apart.. The

> manufacturer had banjo strung the winding wires from the coil to the terminals..

> As temperature changed the .banjo. strings stretched and finally broke.

>

> I contacted the manufacturer about the problem.. The

> manufacturer had no intention of changing how his transformers were made..

> Contract was cancelled.. His competitor had service loops of the winding wires

> at the terminal.

>

> Most inductor problems are at the terminals... Not all.. If the

> manufacturer uses really cheap wire insulation, it will fail for shorted

> turns.. Insulation is so cheap and excellant today, that real manufacturers use

> great insulation.. Thereby extending the life of transformers.. The main power

> transformers I had built for my products had 200.C insulation on the windings..

> At the running temperature of these transformers, life was predicted to be over

> 100 years.

>

> Your open winding of a tek transformer was probably a failure at

> a terminal.. Coils do not just open without a severe temperature violation..

> And the burn marks are easily seen.



There used to be a phenomenon where humidity would enter a transformer.

Then, a pinhole in the enamel on one of the windings would allow the moisture

to cause electrolytic corrosion of the winding. The result was a broken wire

somewhere in the middle of the winding. :-(



Transformers designed for humid locations typically were potted. to keep

any/all moisture/humidity out.



I'm told that that's a good reason to bake an unpotted transformer which has

been in a non-environmentally controlled storage location before putting it

into use.

> Larry



Dave



----------------------------

#266 Aug 13, 2010

Dave wrote:



[...]

> I'm told that that's a good reason to bake an unpotted transformer which has

> been in a non-environmentally controlled storage location before putting it

> into use.



What is the theory? Are you talking about short term storage, or

protracted? I don't understand how baking a tranny with corrosion

would reverse the corrosion.



I've seen equipment used in the tropics which had mold growing

inside it. One wonders what it finds in there to eat.



Mac

--

p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}

Oppose globalization and One World Governments like the UN.

This message made from 100% recycled bits.

You have found the bank of Larn.

I speak only for myself, and I am unanimous in that!







----------------------------

#267 Aug 13, 2010

--- On Fri, 8/13/10, Mike McCarty Mike.McCarty@...> wrote:

> From: Mike McCarty Mike.McCarty@...>

> Subject: Re: [funwithtransistors] HP 3465A Repair

> To: funwithtransistors@yahoogroups.com

> Date: Friday, August 13, 2010, 12:18 PM

> Dave wrote:

>

> [...]

>

> > I'm told that that's a good reason to bake an unpotted transformer which has

> > been in a non-environmentally controlled storage location before putting it

> > into use.

>

> What is the theory? Are you talking about short term storage, or

> protracted? I don't understand how baking a tranny with corrosion

> would reverse the corrosion.



No, it wouldn't fix the problem if the corrosion has already happened. But,

baking it will drive out any moisture which may have accumulated in the

transformer during the storage period. Driving this accumulated

humidity/moisture out prior to putting the transformer back in use will,

hopefully, prevent the electrolytic driven corrosion once the device has

voltage applied.

> I've seen equipment used in the tropics which had mold growing

> inside it. One wonders what it finds in there to eat.



Not sure I want to know!

> Mac



Dave



----------------------------

#268 Aug 13, 2010

Dave wrote: > --- On Fri, 8/13/10, Mike McCarty Mike.McCarty@...> wrote:

>

>> From: Mike McCarty Mike.McCarty@...>

>> Subject: Re: [funwithtransistors] HP 3465A Repair

>> To: funwithtransistors@yahoogroups.com

>> Date: Friday, August 13, 2010, 12:18 PM

>> Dave wrote:

>>

>> [...]

>>

>>> I'm told that that's a good reason to bake an unpotted transformer which has

>>> been in a non-environmentally controlled storage location before putting it

>>> into use.

>> What is the theory? Are you talking about short term storage, or

>> protracted? I don't understand how baking a tranny with corrosion

>> would reverse the corrosion.

>

> No, it wouldn't fix the problem if the corrosion has already happened. But,

> baking it will drive out any moisture which may have accumulated in the

> transformer during the storage period. Driving this accumulated



Ok, then we are talking about short term storage.



[...]

>> I've seen equipment used in the tropics which had mold growing

>> inside it. One wonders what it finds in there to eat.

>

> Not sure I want to know!



Anyone who has lived near the Gulf of Mexico is familiar with

the stuff that grows everywhere on everything. When we were kids,

we called it spanish moss. It hangs from telephone wires, trees,

and anywhere else it can get a purchase, and looks like greenish

grey beards. The commonly held belief is that it lives simply on air.



That is, the humidity is high enough, and the mineral content

due to sea spray is high enough, that everything the plant

needs to live can be obtained simply from the air.



www.sfrc.ufl.edu/4h/Spanish_moss/spanmoss.htm



Mac

--

p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}

Oppose globalization and One World Governments like the UN.

This message made from 100% recycled bits.

You have found the bank of Larn.

I speak only for myself, and I am unanimous in that!



----------------------------

#271 Aug 14, 2010

Politicians appear to be self perpetrating on hot air alone!....bob p

--- On Fri, 8/13/10, Mike McCarty Mike.McCarty@...> wrote:

From: Mike McCarty Mike.McCarty@...>Subject: Re: [funwithtransistors] HP 3465A RepairTo: funwithtransistors@yahoogroups.comReceived: Friday, August 13, 2010, 12:38 PM

��Dave wrote:> --- On Fri, 8/13/10, Mike McCarty Mike.McCarty@...> wrote:> >> From: Mike McCarty Mike.McCarty@...>>> Subject: Re: [funwithtransistors] HP 3465A Repair>> To: funwithtransistors@yahoogroups.com>> Date: Friday, August 13, 2010, 12:18 PM>> Dave wrote:>>>> [...]>>>>> I'm told that that's a good reason to bake anunpotted transformer which has>>> been in a non-environmentally controlled storage location before putting it >>> into use.>> What is the theory? Are you talking about short term storage, or>> protracted? I don't understand how baking a tranny with corrosion>> would reverse the corrosion.> > No, it wouldn't fix the problem if the corrosion has already happened. But,> baking it will drive out any moisture which may have accumulated in the> transformer during the storage period. Driving this accumulated

Ok, then we are talking about short term storage.

[...]

>> I've seen equipment used in the tropics which had mold growing>> inside it. One wonders what it finds in there to eat.> > Not sure I want to know!

Anyone who has lived near the Gulf of Mexico is familiar withthe stuff that grows everywhere on everything.When we were kids,we called it spanish moss. It hangs from telephone wires, trees,and anywhere else it can get a purchase, and looks like greenishgrey beards. The commonly held belief is that it lives simply on air.

That is, the humidity is high enough, and the mineral contentdue to sea spray is high enough, that everything the plantneeds to live can be obtained simply from the air.

www.sfrc.ufl.edu/4h/Spanish_moss/spanmoss.htm

Mac-- p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}Oppose globalization and One World Governments like the UN.This message made from 100% recycled bits.You have found the bank of Larn.I speak only for myself, and I am unanimous in that!







----------------------------

#272 Aug 16, 2010

--- In funwithtransistors@yahoogroups.com, "Larry Beaty" lbeaty3@...> wrote:

...

>The manufacturer had banjo strung the winding wires from the coil to the

> terminals. As temperature changed the "banjo" strings stretched and finally

> broke.



Back in the '70s had a part time job repairing Motorola VHF handie-talkies for a police/fire radio shop. In the winter when those were subjected to 40 below temperatures would get the same thing in the IF transformers, the thin (about 30 gauge or smaller) tight winding wires contracted and broke at the terminals. An extra couple millimeters of wire spliced in cured the problem.



In the '80s I had a Honda Civic whose starter failed one cold winter morning. A tight banjo-strung wire (about 14 gauge or so) had broken its solder joint, so I resoldered. Two years later the same thing happened. This time I took the trouble to splice in an extra inch of wire to form a stress relief loop. Never a problem for many years after that.



In the '90s I used what I had learned to ensure that products manufactured at my job with similar wire connections always had thermal relief loops.



----------------------------

#273 Aug 16, 2010

One of the few people who investigated and learned.�� Myadmiration goes with you!Larry ��From:funwithtransistors@yahoogroups.com [mailto:funwithtransistors@yahoogroups.com] OnBehalf Of zeeglen

Sent: Sunday, August 15, 2010 10:12 PM

To: funwithtransistors@yahoogroups.com

Subject: [funwithtransistors] Re: HP 3465A Repair



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