Date   

Re: Tektronix 532 LV rail shorted

Rajesh VS
 

Have you checked all the electrolytic caps to confirm none are leaking ?
also I guess you meant R110, which is the limiting resistor to the
plug-in. If that is burned, either the plug-in is shorted for -150V or C110
is bad.
After powering off , you can measure resistance to ground from each section
of the power supply output to confirm none are short. Each rail should be
~1k-5k Ohms.

-150V is the reference rail for all LV outputs, so if -150 is dead/bad,
none of the other will come up properly

If you want to isolate the transformer, as John said, you can remove all
5V4G tubes (note their positions to later put them back where they came
from ) and try.
You can measure AC output from the transformer to check for correct
voltages. Remember all heater and +100V rail is still active.
If you want to disconnect +100V section , remove connection to Terminal 14
of the transformer.

I would suggest then start with just -150V and see if its coming up
properly, and then move up one rail at a time, to +100(reconnect
Terminal#14) , +225, +350 by reinstalling the 5V4G tubes.

Also, check the wattage of the "dim" bulb, as these scopes suck a lot of
power.
HTH
rajesh

On Mon, Jan 6, 2020 at 4:11 PM John Williams <books4you@telus.net> wrote:

It has been a while since I had to fix a 503-series power supply. But when
C640 blows it shorts and blows the 10 ohm fuse resistor. If there are solid
state rectifiers one or more of them could also be blown. If there is a
tube rectifier you can pull the tube and see if it will power up. There is
also an electrolytic on the top by the hv supply which filters the -150. It
could also be somewhere else that is shorting the -150. There is a lot of
interconnection.



--
/Rajesh


Re: Tektronix 532 LV rail shorted

george gonzalez <grg2gonzalez@...>
 

Those kinds of shorts are hard to find.

If you have an AC current clamp you could try measuring the current in the secondary wires when your light-blob is in the primary. That will help narrow down the shorted circuit.

Without an AC clamp, but with a big variac or big light bulbs, turn the current up to a couple of amps or with a 250 watt bulb, leave it there for five minutes, then unplug the power supply, and very carefully sniff around or feel for hot diodes.

Or as a last resort start unsoldering secondary wires, one at a time, until the short goes away and the primary lamp gets real dim.

Tiresome, but the only way I know of.

The good news is if a capacitor blew, it’s probably not a shorted transformer.


Re: Tektronix 532 LV rail shorted

randolphbeebe@...
 

Thanks for the reply John... I will keep looking. I have been working on this on and off for a long time and cannot seem to trace the problem. Pulling the -150V rectifier tubes is a good idea. Worth a try


Re: Hakko FR-301 alternatives?

EricJ
 

I use a DS1 also. I too like it a lot. I have a tiny little compressor I use for it that I made from an old A/C compressor, it's about as quiet as an air conditioner or fridge running.

--Eric

On Jan 7, 2020 8:36 AM, Paul Amaranth <paul@auroragrp.com> wrote:




I use Metcal equipment and have the DS1 desoldering gun.  Some people
don't like the venturi vacuum generator, but it never bothered me.
The handpiece is small, light and easily positioned.  It's great
for, say, removing NVRAMs.

Once I got a Metcal I never looked at another iron.  None of my other
gear has been touched since.

Pricey, but they're all over the used market and you can get something
for reasonable money.  Probably not a good fit for you if you like your
current stations.

Paul


On Tue, Jan 07, 2020 at 04:49:05AM -0800, Jean-Paul wrote:
Hello all, this old EE has used solder wick and various spring loaded
solder suckers, all are slow, and damage delicate PCBs. Due to
maintenance, cost and bench space, I never got a rework station like the
Pace.   Now am restoring a number of  TEK 2465/7B and 7000 plugins, so 
easily unsoldering components and ICs without board damage is a must.

Seems the Hakko FR-301 is highly regarded and gun style, needs no
separate power supply/vacuum. (USA 120V model) But rather costly $250-350.


I have several other Hakko 926 (ancient analog control)  irons quality
and longevity is super.
I ask the Forums feedback on the Hakko, as well as lower cost
alternatives.

Most of my work is thru hole, not SMD, perhaps  3-10 jobs in a year.

MANY THANKS

Jon





!DSPAM:5e147e4b293962061714628!
--
Paul Amaranth, GCIH             | Manchester MI, USA
Aurora Group of Michigan, LLC   |   Security, Systems & Software
paul@AuroraGrp.Com              |   Unix & Windows






Re: 454 screen brightness issues?

EB4APL
 

Hi,

You are right, the 454 has not DC restores. Sorry for the misleading indications, I don't have a 454 and I had not checked the schematics.

El 06/01/2020 a las 23:15, Albert Otten escribió:
Hi Jack,
Where should I be looking for those DC restorers, in the -1920v?
The 454 has no DC restorers. The HV transformer has separate windings for the grid and the cathode circuit. The rectified voltage for the grid can be reduced somewhat by the grid bias pot R1447 (in the divider chain with R1442-R1446) and is stacked on the voltage supplied by the Z-axis amplifier.
When you follow Mike's suggestion and use a pdf of the manual, you will note that the waveform at TP1349 is almost invisible. The blue picture in the paper manual is also very faint. The voltage switches between the 2 written values 17.7 V and 6.75 V.

Albert


Re: Hakko FR-301 alternatives?

Paul Amaranth
 

Hi Jon

I got lucky and ran across a lot of MX-500P supplies for cheap, so I
have them distributed around. The auto shutoff is also a great feature
(especially for me ! :-)

Yes, they do require an air supply which may be a big downside for
some. I use a cheap ($39 HF special) oilless compressor stuck in an
enclosure to keep the noise down. It is useful to have air around the
bench anyway.

I keep thinking I'll get around to putting a tank on one of the Gast
oilless compressors I have laying around, but it hasn't annoyed me
enough to do that (yet).

Paul

On Tue, Jan 07, 2020 at 06:48:16AM -0800, Jean-Paul wrote:
Paul, I was the designer in 1991 of the Metcal SP-200 with a 500 kHz resonant mode power supply, I have several protos and comple units, and collection of the tips, stands. Agree that Metcal is the best! But I never explored their desoldering WS, thought they require an air compressor supply?

My other solder stations are ancient Hakko so I am a fan of both, just never got the urge to pay 100s $ for a tool seldom used...till now!

Many thanks
Jon





!DSPAM:5e149a49296971339315998!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix & Windows


Re: Logic families

Lawrance A. Schneider
 

Thank you very much!!

larry


Re: 'Solder Rot'

EricJ
 

Hi,

Actually I think the problem is likely even MORE prevalent when hand soldering. The intermetallic layer growth not only occurs due to aging but also happens when a joint is heated longer and/or hotter than it ought to be, which I am sure happens with some guys soldering at home. Those joints will be starting with a handicap right off the get-go. If the problem takes 10 or more years to manifest I suppose most won't worry about it.

I don't know if you have heard about Metcal's new soldering station with the LEDs that tell you when to remove the iron from the joint; it actually monitors the amount of heat applied to a joint and for how long to try to optimize that intermetallic layer thickness.

--Eric

On Jan 7, 2020 3:37 AM, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:




On Mon, Jan  6, 2020 at 08:19 PM, EricJ wrote:


National Physical Laboratory's "Good Practice Guide #136.
Hi Tam, Hi Eric .et al.:
Just a caveat... this N.P.L. article is referring to mostly low volume
automated soldering (using expensive soldering machines, such as laser
soldering)… for instruments (and their associated components) meant to
operate at high temperatures (that is instruments operating at 180 to 300
centigrade.)… according to the article's introduction, at least.
How much traction the information presented there bears upon the stuff we
deal with in this forum... well, would we still be in Kansas?
Despite the above restriction... there are some really cool pictures.
Best regards and wishes.
Roy
P.S. Eric thanks for sharing this great link, and this
information...always appreciated. Best regards.






Re: Hakko FR-301 alternatives?

Jean-Paul
 

Paul, I was the designer in 1991 of the Metcal SP-200 with a 500 kHz resonant mode power supply, I have several protos and comple units, and collection of the tips, stands. Agree that Metcal is the best! But I never explored their desoldering WS, thought they require an air compressor supply?

My other solder stations are ancient Hakko so I am a fan of both, just never got the urge to pay 100s $ for a tool seldom used...till now!

Many thanks
Jon


Re: Hakko FR-301 alternatives?

Paul Amaranth
 

I use Metcal equipment and have the DS1 desoldering gun. Some people
don't like the venturi vacuum generator, but it never bothered me.
The handpiece is small, light and easily positioned. It's great
for, say, removing NVRAMs.

Once I got a Metcal I never looked at another iron. None of my other
gear has been touched since.

Pricey, but they're all over the used market and you can get something
for reasonable money. Probably not a good fit for you if you like your
current stations.

Paul

On Tue, Jan 07, 2020 at 04:49:05AM -0800, Jean-Paul wrote:
Hello all, this old EE has used solder wick and various spring loaded solder suckers, all are slow, and damage delicate PCBs. Due to maintenance, cost and bench space, I never got a rework station like the Pace. Now am restoring a number of TEK 2465/7B and 7000 plugins, so easily unsoldering components and ICs without board damage is a must.

Seems the Hakko FR-301 is highly regarded and gun style, needs no separate power supply/vacuum. (USA 120V model) But rather costly $250-350.

I have several other Hakko 926 (ancient analog control) irons quality and longevity is super.
I ask the Forums feedback on the Hakko, as well as lower cost alternatives.

Most of my work is thru hole, not SMD, perhaps 3-10 jobs in a year.

MANY THANKS

Jon





!DSPAM:5e147e4b293962061714628!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix & Windows


Re: Hakko FR-301 alternatives?

Harold Foster
 

I've had a Hakko 808 for about 8 years or so and it ranks as one of the best investments I've made in electronic tools - ties with my soldering iron, also Hakko. The FR-301 improves on a few things from the 808 and I would imagine it would be every bit as good and durable. I realize that I sound like a fanboy but it's an opinion that I have come to through a *lot* of use and abuse and the Hakko's just keep delivering.

In short they are expensive but, IMHO, very much worth it.

Hal


Re: 'Solder Rot'

Jean-Paul
 

Besides this problem you have "tin disease" in very cold climates and "tin whiskers" for very close spaced solder connections and at higher voltages.

Jon


Re: tek 7xx4 series brightness dimming after power on

Jean-Paul
 

Hello Alberto: Wonderful to have these vintage scopes, in perfect operation and on the bench!

Just checked, my 7904 (NOT A) has no variation in intensity after turn on, and the 7104 microchannel intensifier has a ferocious beam intensity timeout/limiter, I believe the 7104 time out is inversely proportioned to beam current. The more modern 2467/B also have the timeout but in a more advanced implimentation.

Chuck and Dennis, any comments?

Jon


Hakko FR-301 alternatives?

Jean-Paul
 

Hello all, this old EE has used solder wick and various spring loaded solder suckers, all are slow, and damage delicate PCBs. Due to maintenance, cost and bench space, I never got a rework station like the Pace. Now am restoring a number of TEK 2465/7B and 7000 plugins, so easily unsoldering components and ICs without board damage is a must.

Seems the Hakko FR-301 is highly regarded and gun style, needs no separate power supply/vacuum. (USA 120V model) But rather costly $250-350.

I have several other Hakko 926 (ancient analog control) irons quality and longevity is super.
I ask the Forums feedback on the Hakko, as well as lower cost alternatives.

Most of my work is thru hole, not SMD, perhaps 3-10 jobs in a year.

MANY THANKS

Jon


Re: 454 screen brightness issues?

Albert Otten
 

Hi Jack,

The grid appears to be at
-150 to -190 volts depending on the brightness setting, and the grid bias
trimmer does essentially nothing, moving the grid bias by around 8 volts
only (not sure if this is a fault or just the design).
So far this finding has has been overlooked I think. I suppose for this you attached a DMM between grid and cathode leads. Even measured with a 10M meter there will be some reduction in voltage, so in reality the grid voltage would be still more negative. The tube T4540 is missing from tek_crt_data.pdf but the cut-off voltage of similar tubes is above -100 V. For instance -80 V for the 453 tube T4530. Your trace should be complete dark, unless there is a broken connection to the grid somewhere. (Are you sure about the sign of the voltage difference?)

Update:
Upon resistance testing the cathode and grid, it seems to want to conduct
one way (in negative resistance, according to my meter), and not conduct at
all the other...
So perhaps the grid is not broken after all? Although this was with the
whole socket connected, so for all I know I could just be reading a diode
in the circuit, although the -10Mohm resistance would be odd for that.
I'm not sure what you mean with negative resistance. Are there still some capacitor voltages present that disturb your resistance measurement? Or does you meter pick up rectified "hum" or so? You can't check for a broken connection to the grid this way; you might discover a short between grid and cathode.

Albert


Re: 'Solder Rot'

Roy Thistle
 

On Mon, Jan 6, 2020 at 08:19 PM, EricJ wrote:


National Physical Laboratory's "Good Practice Guide #136.
Hi Tam, Hi Eric .et al.:
Just a caveat... this N.P.L. article is referring to mostly low volume automated soldering (using expensive soldering machines, such as laser soldering)… for instruments (and their associated components) meant to operate at high temperatures (that is instruments operating at 180 to 300 centigrade.)… according to the article's introduction, at least.
How much traction the information presented there bears upon the stuff we deal with in this forum... well, would we still be in Kansas?
Despite the above restriction... there are some really cool pictures.
Best regards and wishes.
Roy
P.S. Eric thanks for sharing this great link, and this information...always appreciated. Best regards.


Re: Sony/Tek 318 Logic Analyser - parts needed

Gala Dragos
 

My email address is

gala underline dragos at yahoo dot com

I've sent some of you emails, hopefully I will get a reply. This groups.io this is not as convenient as the old mail list.


Re: Tektronix 570 Vacuum Tube Curve Tracer on eBay

Greg Muir
 

The legacy USAF SAGE system AN/FSQ-7 computers each (2 computers per SAGE center operating alternately for reduced possibility of failure) used approximately 50,000 vacuum tubes each. The techs replaced on the average of 300 tubes per week. As these systems continued to be used into the 1980’s the supply of US made tubes dwindled so the military had to resort to purchasing them from Russian manufacturers. Quite an irony given that the SAGE system was developed to protect us from the Russians during the cold war.

During the development of the FSQ-7 predecessor computer – the “Whirlwind” at MIT Lincoln Labs it was calculated that a computer containing 5000 vacuum tubes could be expected to fail around every 1/2 hour. They came up with a simple testing technique to determine in advance if a tube was going to fail by lowering tube electrode voltages to see where the failure point would occur. Using this method on the FSQ-7 standby computer during maintenance allowed the operation of the overall system to only experience total downtime for unscheduled maintenance for only 3 to 4 hours per year. Downtime from other factors (air conditioning, power outages or other situations) resulted to up to 24 hours a year. For mission reliability each SAGE center did not use local utility power. Instead AC power was derived from 5 - 650 kW 480 VAC 12-cylinder generators running 24/7/365 and consuming 1,800,000 gallons of diesel oil per year (thanks to our taxes). Even this form of power was not totally reliable. At one center failure of the generation system in 1979 forced the replacement of 400 vacuum tubes.

Greg


Re: 'Solder Rot'

EricJ
 

Hi Tam,

It is National Physical Laboratory's "Good Practice Guide #136."

--Eric

On Jan 6, 2020 10:04 AM, Tam Hanna <tamhan@tamoggemon.com> wrote:




Hello Eric,
May I ask for you to provide me a link or reference to the paper?

Tam
---
With best regards
Tam HANNA (emailing on a BlackBerry PRIV)

Enjoy electronics? Join 14k other followers by visiting the Crazy
Electronics Lab at https://www.instagram.com/tam.hanna/






Re: 454 screen brightness issues?

 

Jack:

In my previous email, I unsuccessfully tried to transcribe the procedure
for CRT grid bias adjustment described on page 6-11 of the manual.  Grid
bias adjustment control R1447 does not directly affect the voltage at
TP1349. Refer to the manual (page 6-11) for the exact process; my
apologies for my error.  I suggest the following:

1.  Setup the scope's controls as described on page 6-8 and 6-9
"Preliminary Procedure".
2.  Try to adjust the INTENSITY control  to get +12V at TP1349, as per
page 6-11 "Adjust CRT Grid Bias."  If this cannot be done, there might
be a Z-axis problem. If you can get +12 volts, then go to step 3 below:
3.  Adjust CRT Grid Bias potentiometer R1447 per paragraph 6.d on page 6-11.
4.  Let us know what the results are. Although at this point I might be
at a loss as to further ideas.

It's also possible that there might be an issue with the grid bias
resistors/potentiometer (R1442 thru R1449) as others have suggested.  If
you have access to a ohmmeter (such as a VTVM) that can detect
variations of about 1.8 megohms in a total resistance of about 52
megohms, then you can check this by measuring the resistance (with power
down) from the CRT pin 3 to TP1349 while varying grid bias potentiometer
R1447 from fully CCW to fully CW.  You might get one measured value with
the ohm meter's leads in one position, and another with the meter leads
"reversed"; if so then go with the higher set of measurements, as the
lower set of measurements would be due to forward bias of D1440.

Mike D N4MWP

On 1/6/20 7:37 PM, Jack Ohme wrote:
Mike,

I have a copy of the manual in PDF and on paper. The intensity dial
correctly changes the voltage (although the screen brightness shows no
change), but the grid biasing potentiometer does not change the voltage at
TP1349, which stays at around 6.8v. I'm not sure whats happening here, if
this is the grid biasing pot that is broken or something nearby on the Z
axis board, but I will inspect the schematics. Let me know if you think of
anything to look for.

-Jack

On Mon, Jan 6, 2020 at 2:15 PM Albert Otten <aodiversen@concepts.nl> wrote:

Hi Jack,
Where should I be looking for those DC restorers, in the -1920v?
The 454 has no DC restorers. The HV transformer has separate windings for
the grid and the cathode circuit. The rectified voltage for the grid can be
reduced somewhat by the grid bias pot R1447 (in the divider chain with
R1442-R1446) and is stacked on the voltage supplied by the Z-axis
amplifier.
When you follow Mike's suggestion and use a pdf of the manual, you will
note that the waveform at TP1349 is almost invisible. The blue picture in
the paper manual is also very faint. The voltage switches between the 2
written values 17.7 V and 6.75 V.

Albert



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