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The thing to remember is in general “like dissolves like” with solvents, where like refers to non-polar dissolves non-polar gunk, and polar dissolves polar gunk. IPA is non-polar, acetone is polar, and most grease is polar. Acetone here is probably too aggressive. Try deoxit products for potentiometers.

On Tue, Mar 5, 2019 at 08:12 PM, <wilson2115@...> wrote:

I have some 91% Isopropyl Rubbing Alcohol sitting around and I have a Tek 577
with dirty horizontal and vertical display controls, I have used this to clean
residue on circuit boards and grime off surfaces and it works quite well so I
was wondering if it could be used to clean the dirty potentiometers on the 577
curve tracer. 91% seems the best the best I can find. I also have a can CRC
Lectra Clean. What are your thoughts, recommendations? Thanks

Hi Colin,

Replacing the connector sounds like the right thing to do - not sure I agree that using a NOS part is risky, there's a quadzillion backplane connectors out there that have /not/ cracked with age after all, but I order from Digikey regularly and could order up a new one if you want.

I'm more than happy to lend a hand. How practical that is for you I'm not sure -'London' covers a big area!

If you are north(ish) of London then I'm just outside Cambridge and should have enough stuff around to do that and fix any issues that may arise, I've re-capped a couple of my TM500 series chassis and while a little 'awkward' in parts there's nothing too tricky about taking them apart.

Either shipping it to me or a visit - with free, quite passable coffee - would work fine. Oh, no cost (other than return postage) of course!

Adrian

On 3/21/2019 3:22 PM, Colin Herbert via Groups.Io wrote:

a) Unsolder the entire faulty connector and replace it with the new one - this looks like a formidable task, since there are a total of 56 pins to unsolder and re-solder and access isn't straightforward but it would be the most ideal option, I think. Unfortunately I don't have a de-soldering tool, only a solder-sucker and some poor de-soldering braid (I suppose I could buy a de-soldering tool).

I have some 91% Isopropyl Rubbing Alcohol sitting around and I have a Tek 577
with dirty horizontal and vertical display controls, I have used this to clean
residue on circuit boards and grime off surfaces and it works quite well so I
was wondering if it could be used to clean the dirty potentiometers on the 577
curve tracer. 91% seems the best the best I can find. I also have a can CRC
Lectra Clean. What are your thoughts, recommendations? Thanks

Center pin of Q741 was unsoldered. When I recapped the board I must have
desoldered the wrong pin and forgotten to resolder it. Great.

On Thu, Mar 21, 2019 at 01:47 PM, Siggi wrote:

On Thu, Mar 21, 2019 at 12:26 PM <thespin@...> wrote:

Okay one more question before I dig in. How is the trace A brightness
intensified when you first pull the SEC/DIV knob? I assume somehow

through

U650. How does it know when to kick the trace brightness up a little

over

the region which will later be focused in on? I assume there's some
comparators somewhere.

Per the service manual, page 3a-18:

"To produce the intensified zone on the A Sweep trace for A intensified

by

B Sweep displays, an additional current is added to the crt drive signal

by

the Z-Axis Amplified during the concurrence of the /SGAZ and /SGBZ (sweep
gate A and B z-axis) signals."

If you think about it for a spell, it makes sense for this to be a

function

of the sweep gate signals, because of the complexity that goes into the
timing of the sweeps. If you've ever played with a triggered intensified
B-sweep, you'll know how it jumps around with the B-trigger position.
On these scopes you can view the A and B sweeps simultaneously, with the

B

sweep intensified on the A sweep, and then again with a separate trace

for

the B sweep. This takes two total sweeps, one for each trace, with
alternate sweep generators coupled to the horizontal amplifier.
I've never tried to verify this, but I expect you'll see both the A and B
gate signals change on every sweep when the B-sweep is engaged, whether

the

A or B or both are on display at the time.

Good luck,
Siggi

In the case of switches that are not immediately behind the front panel on your 7CT1N, remove the side panel and introduce the CRC 5-56 to the switch shaft proper while the unit is standing with the front panel up. This is not a difficult procedure.

Four 5/7CT1N's have gone through here and were made operational with this method of cleaning/lubing the switches.

Rolynn

a) Unsolder the entire faulty connector and replace it with the new one - this looks like a formidable task, since there are a total of 56 pins to unsolder and re-solder and access isn't straightforward but it would be the most ideal option, I think. Unfortunately I don't have a de-soldering tool, only a solder-sucker and some poor de-soldering braid (I suppose I could buy a de-soldering tool).

Good to know. Right now I need to locate a .01uF cap with 5kv or better voltage rating. All that I have in stock only go up to 1kv. I am at the Radio Museum tomorrow. Will see what we have there.

Ripley

The words are mine but this iPad does what it will with them.

On Mar 21, 2019, at 6:13 PM, Reed Dickinson <reed714@...> wrote:

Hi Ripley:

If your scope does not fire up when you have the .01uF cap between the transformer and the NTE539 tripler then the tripler may be blown as your last note implied you tried the tripler without the cap. The cap was present inside the original tripler but you could not see it as the original tripler was potted in Hysol. Try the .01uF cap, the tripler just possibly might still be good.

Reed

On 3/21/2019 4:37 AM, SuddenLink wrote:
Hello Reed,

Ahhh. A .01uF capacitor is the secret. The NTE539 sure doesn’t work with a direct connection to the HV transformer’s secondary. I will give it a try and report back.

Ripley

The words are mine but this iPad does what it will with them.

On Mar 21, 2019, at 12:50 AM, Reed Dickinson <reed714@...> wrote:

Hi Ripley:

You are correct, do not connect to the focus lead, a blob of silicon seal should work. You need to splice the cable going from the tripler to the socket. Slide a piece of shrink wrap tubing over a piece of thick wall plastic tubing over the wires to be spliced, make sure that you have a good lapping solder joint. After the joint cools look closely and be sure there are no sharp pieces of wire showing then generously coat the entire joint with silicon sealer and slide the large piece of tubing over the joint then slide the shrink tubing over the plastic tubing and heat the shrink tubing to seal it. If it is loose use two small tie wraps. Mount the mew tripler where the old tripler was by drilling two holes and install screws. Next connect the transformer output to the IN terminal using a .01uF, 5KV or 10KV cap. The cap must be used to make it work. Connect up and fire it up. Good luck!


Reed

On 3/17/2019 5:28 PM, SuddenLink wrote:
Hi Reed,

I received the NTE539 a few days ago and pulled out the existing HV trippler these evening. It is going to be a tight fit but it looks I can squeeze the new trippler in it’s place. The question is, what do I do with the Focus tab on the NTE539. I am thinking that it gets clipped off and covered with a glob of silicon seal.

I am going to hold off until I hear back from you.

Thank you.

Ripley

Sent from Mail for Windows 10

From: Reed Dickinson
Sent: Tuesday, March 5, 2019 3:11 PM
To: [email protected]
Subject: Re: [TekScopes] 475 with no Display and no HV

Hi:
See answers in red below.

On Thu, Mar 21, 2019 at 12:26 PM <thespin@...> wrote:

Okay one more question before I dig in. How is the trace A brightness
intensified when you first pull the SEC/DIV knob? I assume somehow through
U650. How does it know when to kick the trace brightness up a little over
the region which will later be focused in on? I assume there's some
comparators somewhere.

Per the service manual, page 3a-18:

"To produce the intensified zone on the A Sweep trace for A intensified by
B Sweep displays, an additional current is added to the crt drive signal by
the Z-Axis Amplified during the concurrence of the /SGAZ and /SGBZ (sweep
gate A and B z-axis) signals."

If you think about it for a spell, it makes sense for this to be a function
of the sweep gate signals, because of the complexity that goes into the
timing of the sweeps. If you've ever played with a triggered intensified
B-sweep, you'll know how it jumps around with the B-trigger position.
On these scopes you can view the A and B sweeps simultaneously, with the B
sweep intensified on the A sweep, and then again with a separate trace for
the B sweep. This takes two total sweeps, one for each trace, with
alternate sweep generators coupled to the horizontal amplifier.
I've never tried to verify this, but I expect you'll see both the A and B
gate signals change on every sweep when the B-sweep is engaged, whether the
A or B or both are on display at the time.

Good luck,
Siggi

On Mar 21, 2019, at 6:13 PM, Reed Dickinson <reed714@...> wrote:

Hi Ripley:

If your scope does not fire up when you have the .01uF cap between the transformer and the NTE539 tripler then the tripler may be blown as your last note implied you tried the tripler without the cap. The cap was present inside the original tripler but you could not see it as the original tripler was potted in Hysol. Try the .01uF cap, the tripler just possibly might still be good.

Reed

On 3/21/2019 4:37 AM, SuddenLink wrote:
Hello Reed,

Ahhh. A .01uF capacitor is the secret. The NTE539 sure doesn’t work with a direct connection to the HV transformer’s secondary. I will give it a try and report back.

Ripley

The words are mine but this iPad does what it will with them.

On Mar 21, 2019, at 12:50 AM, Reed Dickinson <reed714@...> wrote:

Hi Ripley:

You are correct, do not connect to the focus lead, a blob of silicon seal should work. You need to splice the cable going from the tripler to the socket. Slide a piece of shrink wrap tubing over a piece of thick wall plastic tubing over the wires to be spliced, make sure that you have a good lapping solder joint. After the joint cools look closely and be sure there are no sharp pieces of wire showing then generously coat the entire joint with silicon sealer and slide the large piece of tubing over the joint then slide the shrink tubing over the plastic tubing and heat the shrink tubing to seal it. If it is loose use two small tie wraps. Mount the mew tripler where the old tripler was by drilling two holes and install screws. Next connect the transformer output to the IN terminal using a .01uF, 5KV or 10KV cap. The cap must be used to make it work. Connect up and fire it up. Good luck!


Reed

On 3/17/2019 5:28 PM, SuddenLink wrote:
Hi Reed,

I received the NTE539 a few days ago and pulled out the existing HV trippler these evening. It is going to be a tight fit but it looks I can squeeze the new trippler in it’s place. The question is, what do I do with the Focus tab on the NTE539. I am thinking that it gets clipped off and covered with a glob of silicon seal.

I am going to hold off until I hear back from you.

Thank you.

Ripley

Sent from Mail for Windows 10

From: Reed Dickinson
Sent: Tuesday, March 5, 2019 3:11 PM
To: [email protected]
Subject: Re: [TekScopes] 475 with no Display and no HV

Hi:
See answers in red below.

Hello Reed,

Ahhh. A .01uF capacitor is the secret. The NTE539 sure doesn’t work with a direct connection to the HV transformer’s secondary. I will give it a try and report back.

Ripley

The words are mine but this iPad does what it will with them.

On Mar 21, 2019, at 12:50 AM, Reed Dickinson <reed714@...> wrote:

Hi Ripley:

You are correct, do not connect to the focus lead, a blob of silicon seal should work. You need to splice the cable going from the tripler to the socket. Slide a piece of shrink wrap tubing over a piece of thick wall plastic tubing over the wires to be spliced, make sure that you have a good lapping solder joint. After the joint cools look closely and be sure there are no sharp pieces of wire showing then generously coat the entire joint with silicon sealer and slide the large piece of tubing over the joint then slide the shrink tubing over the plastic tubing and heat the shrink tubing to seal it. If it is loose use two small tie wraps. Mount the mew tripler where the old tripler was by drilling two holes and install screws. Next connect the transformer output to the IN terminal using a .01uF, 5KV or 10KV cap. The cap must be used to make it work. Connect up and fire it up. Good luck!


Reed

On 3/17/2019 5:28 PM, SuddenLink wrote:
Hi Reed,

I received the NTE539 a few days ago and pulled out the existing HV trippler these evening. It is going to be a tight fit but it looks I can squeeze the new trippler in it’s place. The question is, what do I do with the Focus tab on the NTE539. I am thinking that it gets clipped off and covered with a glob of silicon seal.

I am going to hold off until I hear back from you.

Thank you.

Ripley

Sent from Mail for Windows 10

From: Reed Dickinson
Sent: Tuesday, March 5, 2019 3:11 PM
To: [email protected]
Subject: Re: [TekScopes] 475 with no Display and no HV

Hi:
See answers in red below.

On Mar 21, 2019, at 13:33, tom jobe <tomjobe@...> wrote:

My suggestion would be to post a few photos of the problem connector and contact.
tom jobe...

On 3/21/2019 8:22 AM, Colin Herbert via Groups.Io wrote:
Does no-one really have any observations on this?
Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Colin Herbert via Groups.Io
Sent: 17 March 2019 13:43
To: [email protected]
Subject: [TekScopes] TM504 backplane repair

I have a TM504 where contact B22 on the high-power compartment connector has got mangled. It can be seen that it is sitting badly and maybe shorting to A22. I know that this connector isn't used very frequently, but I was hoping to use my PS503A in that compartment to take advantage of the 1A output. I have obtained a brand-new connector (#131-1078-00) and was hoping to be able to use it to effect a repair. I think I have a number of options:

a) Unsolder the entire faulty connector and replace it with the new one - this looks like a formidable task, since there are a total of 56 pins to unsolder and re-solder and access isn't straightforward but it would be the most ideal option, I think. Unfortunately I don't have a de-soldering tool, only a solder-sucker and some poor de-soldering braid (I suppose I could buy a de-soldering tool).

b) Somehow remove the faulty contact and replace it with a good one from the new connector. This would be fine, but it doesn't look easy because of the way the contacts are secured in the new connector, they are not easy to remove as they are retained by way of a punched indentation which has resulted in a raised "dot" on the other side. I have tried crushing this down, but it isn't easy. If the mangled contact in the existing connector is retained in the same manner, I can't see how removal can be managed.

c) Just remove the mangled contact by "brute force and ignorance" and forget about its function for the PS503A (it is -V output) . This wouldn't be ideal but would probably be functional, even though it would irritate me as being imperfect.

d) disconnect the electrical connection to the faulty contact on the TM504. I don't like this idea at all.

e) disconnect the electrical contact on the PS503A. I like this option even less than (d).

Does anyone have any experience of doing such a repair or any other/better ideas?

TIA, Colin.