Date   

Re: explosion mystery on my 7104

Roy Thistle
 

On Fri, Jun 18, 2021 at 11:39 AM, - wrote:


that's not true. About 15 years ago I obtained 13 E and F series HP
1000 computers and 8 extra power supplies from a large US military
contractor.
Yup. If the equipment was stored where the humidity was high... which is not proper storage... then the cracked Rifa capacitors... or any case damaged X/Y cap could absorb moisture... and could short.
The thing to do before you power on equipment is to make sure its thoroughly dry... and that means enough time in a dry environment.
That includes Apple stuff... and stuff from the dump.

--
Roy Thistle


Re: explosion mystery on my 7104

n4buq
 

I'm in 125V land and a RIFA released smoke in my 2445 but it didn't have the violent eruption described by others. I was kind of disappointed... :)

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Tom Lee" <tomlee@ee.stanford.edu>
To: TekScopes@groups.io
Sent: Friday, June 18, 2021 1:54:30 PM
Subject: Re: [TekScopes] explosion mystery on my 7104

A quick google turns up many posts attesting to the RIFA problem. The mains
voltage matters little. Many members of this list who live in 120V lands
have experienced the multimedia spectacular that is the exploding RIFA cap.

Tom

Sent from my iThing, so please forgive brevity and typos

On Jun 18, 2021, at 11:38, - <rrrr6789@gmail.com> wrote:

Roy, that's not true. About 15 years ago I obtained 13 E and F series HP
1000 computers and 8 extra power supplies from a large US military
contractor. I powered them up and the RIFA caps blew up in about 70% of
them within minutes or up to about 2 days after I powered them up. All of
these units had been under a maintenance contract with HP up until the time
that they were removed from service and placed in inside dry storage and
everything was 100% functional when it was placed in storage. I don't know
if the problem is due to the brand of RIFA cap, or the particular model or
just a particular batch or related to being stored unused for a period of
time, but exploding RIFA caps are a KNOWN issue. I've had RIFA caps explode
in other HP equipment as well but never in the numbers that they did in
those HP computers. In fact I have owned hundreds of HP 9000 and 98xx
series computers (EVERY generation) and I've never had a RIFA cap explode
in any of them.

On Fri, Jun 18, 2021 at 2:10 PM Roy Thistle <roy.thistle@mail.utoronto.ca>
wrote:

On Fri, Jun 18, 2021 at 09:22 AM, redarlington wrote:


It's exceptionally
common that those Rifa line filter caps blow here in the States with our
120v lines.
I dunno... if it was "exceptionally common" I would have seen it... or
heard about it here... in the colonies... as we have have a nominal 120 V
system here too... and I've got those X or Y Rifa caps, in Apple II
smps...
as well as in HP... and I think Tek too.
It makes a lot of sense to say they are more common to fail in places
where the nominal voltage is 230 volts or 240 volts... as many of them
were
clearly rated for 250V.
AFAIC a lot of it is pure flummery meant to flummox "capacitor replacement
kiddies" ... who ape YouTube profiteers.
Not saying it can't happen... if the cracked RIFAs get wet enough... they
could cascade short... but I agree with other posters... it's only common
on YouTube.
--
Roy Thistle













Re: Tek 2230, almost fixed but with a problem out of my competences

Albert Otten
 

I mean to -8.6 V somewhere, say were PCB traces to pin 1 and a -8.6 V trace are very close. Could for instance be the -8.6 V trace to pin 12 or one side of R791.
Albert


Re: Tektronix 603A Storage Monitor Questions

toby@...
 

On 2021-06-18 4:35 p.m., henryfinley wrote:
I have this storage monitor here a buddy gave me. But I can find nothing about it on the internet. And I mean nothing. He gave it to me along with a Tek 465B scope, which I have already gotten working. But I think the storage monitor may be even older than that. No paperwork or information can be found on the internet. Can anybody lead me in the right direction? Thank you.

I own & have worked on a couple of these. Manuals are on Tekwiki and
should include service info. If not, contact me, as I have paper
manuals. https://w140.com/tekwiki/wiki/603

--T







Re: Tek 2230, almost fixed but with a problem out of my competences

Pitpat
 

Yes pin 1 is at -8.6v for all the sweep settings!

On Fri, Jun 18, 2021 at 08:57 PM, Albert Otten wrote:

Is there any chance that pin 1 wiring is shorted to -8.6VL? (Check with DMM?)
I think the curtain is falling for U781 now.
Do you mean the -8.6v power rail or the pin 3 Vdd input (that btw is not shorted to pin 1) ?


Re: Tek 2230, almost fixed but with a problem out of my competences

Albert Otten
 

Question: could just one of the comparator outputs gone bad? If im not wrong
inside U781 there should be 4 separate comparator so it seems logical to me
that only one could fail without affecting the others, right?
Why not? Could even be a broken wire (or bond) from pin 6 or 7 to the internal chip.
Pin 1 was also -8.6 V in all faster time/div positions isn't it? In those positions pin 6 voltage is about -8 V (HOR REF).
In theory it could be that -8.6 V is negative enough to switch the comparator output to open drain state, while -5.9 V (at .5s) or more positive is insufficient for that.

Is there any chance that pin 1 wiring is shorted to -8.6VL? (Check with DMM?)
I think the curtain is falling for U781 now.

Albert


Re: explosion mystery on my 7104

Tom Lee
 

A quick google turns up many posts attesting to the RIFA problem. The mains voltage matters little. Many members of this list who live in 120V lands have experienced the multimedia spectacular that is the exploding RIFA cap.

Tom

Sent from my iThing, so please forgive brevity and typos

On Jun 18, 2021, at 11:38, - <rrrr6789@gmail.com> wrote:

Roy, that's not true. About 15 years ago I obtained 13 E and F series HP
1000 computers and 8 extra power supplies from a large US military
contractor. I powered them up and the RIFA caps blew up in about 70% of
them within minutes or up to about 2 days after I powered them up. All of
these units had been under a maintenance contract with HP up until the time
that they were removed from service and placed in inside dry storage and
everything was 100% functional when it was placed in storage. I don't know
if the problem is due to the brand of RIFA cap, or the particular model or
just a particular batch or related to being stored unused for a period of
time, but exploding RIFA caps are a KNOWN issue. I've had RIFA caps explode
in other HP equipment as well but never in the numbers that they did in
those HP computers. In fact I have owned hundreds of HP 9000 and 98xx
series computers (EVERY generation) and I've never had a RIFA cap explode
in any of them.

On Fri, Jun 18, 2021 at 2:10 PM Roy Thistle <roy.thistle@mail.utoronto.ca>
wrote:

On Fri, Jun 18, 2021 at 09:22 AM, redarlington wrote:


It's exceptionally
common that those Rifa line filter caps blow here in the States with our
120v lines.
I dunno... if it was "exceptionally common" I would have seen it... or
heard about it here... in the colonies... as we have have a nominal 120 V
system here too... and I've got those X or Y Rifa caps, in Apple II smps...
as well as in HP... and I think Tek too.
It makes a lot of sense to say they are more common to fail in places
where the nominal voltage is 230 volts or 240 volts... as many of them were
clearly rated for 250V.
AFAIC a lot of it is pure flummery meant to flummox "capacitor replacement
kiddies" ... who ape YouTube profiteers.
Not saying it can't happen... if the cracked RIFAs get wet enough... they
could cascade short... but I agree with other posters... it's only common
on YouTube.
--
Roy Thistle









Re: explosion mystery on my 7104

-
 

Roy, that's not true. About 15 years ago I obtained 13 E and F series HP
1000 computers and 8 extra power supplies from a large US military
contractor. I powered them up and the RIFA caps blew up in about 70% of
them within minutes or up to about 2 days after I powered them up. All of
these units had been under a maintenance contract with HP up until the time
that they were removed from service and placed in inside dry storage and
everything was 100% functional when it was placed in storage. I don't know
if the problem is due to the brand of RIFA cap, or the particular model or
just a particular batch or related to being stored unused for a period of
time, but exploding RIFA caps are a KNOWN issue. I've had RIFA caps explode
in other HP equipment as well but never in the numbers that they did in
those HP computers. In fact I have owned hundreds of HP 9000 and 98xx
series computers (EVERY generation) and I've never had a RIFA cap explode
in any of them.

On Fri, Jun 18, 2021 at 2:10 PM Roy Thistle <roy.thistle@mail.utoronto.ca>
wrote:

On Fri, Jun 18, 2021 at 09:22 AM, redarlington wrote:


It's exceptionally
common that those Rifa line filter caps blow here in the States with our
120v lines.
I dunno... if it was "exceptionally common" I would have seen it... or
heard about it here... in the colonies... as we have have a nominal 120 V
system here too... and I've got those X or Y Rifa caps, in Apple II smps...
as well as in HP... and I think Tek too.
It makes a lot of sense to say they are more common to fail in places
where the nominal voltage is 230 volts or 240 volts... as many of them were
clearly rated for 250V.
AFAIC a lot of it is pure flummery meant to flummox "capacitor replacement
kiddies" ... who ape YouTube profiteers.
Not saying it can't happen... if the cracked RIFAs get wet enough... they
could cascade short... but I agree with other posters... it's only common
on YouTube.
--
Roy Thistle






Re: Tek 2230, almost fixed but with a problem out of my competences

Pitpat
 

Hi, yes ARES 2 is still a bit too low EXT ARES2= 3.2v, 0.5s ARES2=4.5v, 0.2s ARES2=3.2v, 0.1 ARES2=3.2v
So yes it might be that something is wrong with output pin 1.
Question: could just one of the comparator outputs gone bad? If im not wrong inside U781 there should be 4 separate comparator so it seems logical to me that only one could fail without affecting the others, right?


Re: explosion mystery on my 7104

Roy Thistle
 

On Fri, Jun 18, 2021 at 09:22 AM, redarlington wrote:


It's exceptionally
common that those Rifa line filter caps blow here in the States with our
120v lines.
I dunno... if it was "exceptionally common" I would have seen it... or heard about it here... in the colonies... as we have have a nominal 120 V system here too... and I've got those X or Y Rifa caps, in Apple II smps... as well as in HP... and I think Tek too.
It makes a lot of sense to say they are more common to fail in places where the nominal voltage is 230 volts or 240 volts... as many of them were clearly rated for 250V.
AFAIC a lot of it is pure flummery meant to flummox "capacitor replacement kiddies" ... who ape YouTube profiteers.
Not saying it can't happen... if the cracked RIFAs get wet enough... they could cascade short... but I agree with other posters... it's only common on YouTube.
--
Roy Thistle


Hypcon connectors

cmjones01
 

My 7104 is now working well, thanks to advice from this group. Even
the plugins are mostly OK: the 7B15 wouldn't trigger because no +5V
was getting to the trigger board due to a corroded connector. I've
given one 7A29 the epoxy treatment and it works well though needs the
low-frequency gain setting up. The other 7A29 has more serious
attenuator trouble and will have to wait.

Almost all the faults I've experienced have been due to the Hypcon
connectors not making proper contact. I guess that after 40 years
those elastomers are perhaps not as springy as they once were. What
I've found is that removing them and cleaning everything up and
carefully refitting doesn't usually help - I've done it three or four
times in some cases.

It seems that the elastomer part seems to acquire a shape which stops
some pins making contact. My strategy for getting the scope working
well has been to swap around the elastomers between different devices,
finding a combination for each one where all the pins that matter make
contact. To get both horizontal slots working properly I had to borrow
an elastomer from the poorly 7A29 to fit the horizontal channel
switch. The device I borrowed it from only uses four pins, so I'm
hoping that the less-than-perfect elastomer will still allow the 7A29
to work properly.

Apart from misbehaving Hypcons (and the expected scratchy pots and
switches) the only thing I've actually had to adjust was a bit of the
Z-axis calibration in order to get the range of the intensity
controls, especially the readout, right. There are indications from
labels I've found inside that this mainframe may have been sitting
unused since 1994, so it's done pretty well!

Chris


Re: FS: Tek 7K-series Plug-ins, TM503A & 11301A with 2 plug-ins

Eric
 

I might be interested in the 11000 plugins.

On Fri, Jun 18, 2021, 12:00 PM Liam Perkins <hifi@telus.net> wrote:

I need of a new home I have:

2 - 7B80s in good, clean, working condition @ $US35.00ea,
1 - 7B15 in good, clean, working condition @ $US75.00,
1 - TM503A, no handle or cover, otherwise perfect $US100.00,
1 - 11310A with 1 - 11A33 4-channel plug-in & 1 - 11A33
Diff Comparator. $US450 packed up to be UPS-proof.

All prices are w/o shipping and goods ship from Calgary, AB, Canada

Best regards,
Liam






Re: Tek 2230, almost fixed but with a problem out of my competences

Albert Otten
 

Tested again U781, at 0.1s A mode pin1= -8.57v , pin6= 0.6v pin7= -0.27v so it should be ok... I guess
Yes, pin 6 is correct and pin 1 is as should be then.
_ 0.2s pin6 = -3.5v pin7= -0.27v pin1= -8.6v
_ 0.5s pin6= -5.9v pin7= -0.27v pin1= -8.6v
_ EXT pin6= -3.5v pin7= -0.27 pin1= -8.6v
The pin 6 voltages again are correct.
But ... in these three cases pin 1 should be open drain, resulting in the same voltage as ARES2. ARES2 normally is between about zero and +5 V. You might check that the ARES2 voltages certainly are not -8.6 V. Previously you found that ARES2 was somewhat too low, being pulled down by -8.6 V at pin 1, resulting in the next faster time/div display (like .2s displays as .1s).
Albert


Re: explosion mystery on my 7104

redarlington
 

In the Apple II community, we call this RIFA Madness. It's exceptionally
common that those Rifa line filter caps blow here in the States with our
120v lines. We either replace before powering up old equipment, cut em
out, or deal with a cleanup if we ignore them.

-Bob N3XKB

On Thu, Jun 17, 2021 at 10:56 PM Jean-Paul <jonpaul@ix.netcom.com> wrote:

Cracked plastic encapsulant.

Much worse problem on 240 V mains, have yet to see the Rifa X/Y line
filter cap issue on a 120V mains

Jon






FS: Tek 7K-series Plug-ins, TM503A & 11301A with 2 plug-ins

Liam Perkins
 

I need of a new home I have:

2 - 7B80s in good, clean, working condition @ $US35.00ea,
1 - 7B15 in good, clean, working condition @ $US75.00,
1 - TM503A, no handle or cover, otherwise perfect $US100.00,
1 - 11310A with 1 - 11A33 4-channel plug-in & 1 - 11A33
Diff Comparator. $US450 packed up to be UPS-proof.

All prices are w/o shipping and goods ship from Calgary, AB, Canada

Best regards,
Liam


Re: Tektronix 603A Storage Monitor Questions

 

On Fri, Jun 18, 2021 at 05:35 PM, henryfinley wrote:


Can anybody lead me in the right direction?
https://w140.com/tekwiki/wiki/603

Raymond


Re: PG506 repair question.

Michael W. Lynch
 

On Fri, Jun 18, 2021 at 10:37 AM, SCMenasian wrote:


I agree. eBay has proven to be a great resource for me. One has to be very
careful. I avoid everything Chinese or listings which appear to be Chinese. I
have found a number of trustworthy suppliers. They often deal in surplus
manufacturer's inventory. Examine the photos carefully. If they don't show the
actual item(s), be careful. eBay has good buyer protection policies. If you
don't get the item pictured, you can generally get your money back unless the
listing states that the pictured item is one of many and is meant to be
representaive. For example, I recently bought a lot of NOS Motorola MJE2955s
in unopened Motorola sealed packaging for my TM500 series mainframes at a very
reasonable price. Generally, buying in quantity helps with pricing since
shipping one or two can oftern cost as much as the parts. (and not worrying
about running out of inventory for future repairs).
I agree. If one is careful, E-Bay is a treasure trove of "unobtanium". Just be wary of anything Chinese in origin, lots of counterfeit parts from China.

--
Michael Lynch
Dardanelle, AR


Re: Tektronix 603A Storage Monitor Questions

Michael W. Lynch
 

On Fri, Jun 18, 2021 at 10:35 AM, henryfinley wrote:


I have this storage monitor here a buddy gave me. But I can find nothing about
it on the internet. And I mean nothing. He gave it to me along with a Tek 465B
scope, which I have already gotten working. But I think the storage monitor
may be even older than that. No paperwork or information can be found on the
internet. Can anybody lead me in the right direction? Thank you.
There is information at TEKWiki. https://w140.com/tekwiki/wiki/Main_Page Search from there.
--
Michael Lynch
Dardanelle, AR


Re: PG506 repair question.

SCMenasian
 

I agree. eBay has proven to be a great resource for me. One has to be very careful. I avoid everything Chinese or listings which appear to be Chinese. I have found a number of trustworthy suppliers. They often deal in surplus manufacturer's inventory. Examine the photos carefully. If they don't show the actual item(s), be careful. eBay has good buyer protection policies. If you don't get the item pictured, you can generally get your money back unless the listing states that the pictured item is one of many and is meant to be representaive. For example, I recently bought a lot of NOS Motorola MJE2955s in unopened Motorola sealed packaging for my TM500 series mainframes at a very reasonable price. Generally, buying in quantity helps with pricing since shipping one or two can oftern cost as much as the parts. (and not worrying about running out of inventory for future repairs).


Tektronix 603A Storage Monitor Questions

 

I have this storage monitor here a buddy gave me. But I can find nothing about it on the internet. And I mean nothing. He gave it to me along with a Tek 465B scope, which I have already gotten working. But I think the storage monitor may be even older than that. No paperwork or information can be found on the internet. Can anybody lead me in the right direction? Thank you.

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