Date   

Re: FG-501 Output Impedance

emissionlabs
 

I have only the manual copy from tekwiki, that circuit uses 2x 100 Ohms to get exactly 50 ohms.

In my FG-501 is one carbon resistor, which measures 50 Ohms. It looks original, it's an old one, and soldering is untouched. Series nr is B127482. Part dates are from 1976.

But it won't help much to replace it by 2x 100 Ohms in parallel.

I have glued the two pages together with photoshop, here is a high resolution copy:
http://blooble.de/FG501/Output-Circuit.png

The output circuit is like an op amp they write in the manual. I probably end up testing all parts one by one.


Re: Type M Cracked Channel Position Pots

 

Harvey,

These controls have steel shafts, so I doubt that there are any dangerous voltages involved.

I also had an idea that I could simply epoxy half of a shaft coupler on top of the cracked plastic cap, since there is plenty of space in this portion of the Type M plug-in.

— Jeff Dutky


Re: Type M Cracked Channel Position Pots

 

Dave,

Yes, adesilva’s solution came right up once I had the right search terms. I’m considering my options for what I can manufacture. The rings that adesilva made were quite beefy; I’m wondering if a metal band, or even some wire, would do as good a job.

— Jeff Dutky


Re: Type M Cracked Channel Position Pots

Harvey White
 

Be careful on which controls you use this.  Some of those control bodies are at elevated voltages.  Likely, though, TEK replaced the pot shaft with a non-conductive fiber one.

Harvey

On 8/15/2021 2:47 PM, Dave Wise wrote:
“adesilva” came close to what I think is the best fix: a metal ring that slips over – or replaces – the plastic cross, drill and tap a hole through it, and run in a new long setscrew. Not my invention, I just like it. I’ll try it when one of my pots becomes difficult.

From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jeff Dutky via groups.io
Sent: Sunday, August 15, 2021 10:35 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Type M Cracked Channel Position Pots

Dave,

You are right, my mistake: it's the variable gain pots. I will try the search that you suggest ("tek-made pots")

Thanks

-- Jeff Dutky







Re: Type M Cracked Channel Position Pots

Dave Wise
 

“adesilva” came close to what I think is the best fix: a metal ring that slips over – or replaces – the plastic cross, drill and tap a hole through it, and run in a new long setscrew. Not my invention, I just like it. I’ll try it when one of my pots becomes difficult.

From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jeff Dutky via groups.io
Sent: Sunday, August 15, 2021 10:35 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Type M Cracked Channel Position Pots

Dave,

You are right, my mistake: it's the variable gain pots. I will try the search that you suggest ("tek-made pots")

Thanks

-- Jeff Dutky


Re: Tektronix 5110 oscilloscope

Mattis Lind
 

Hello Magnus,

I just bought a Tek 5111 scope without any plugins and I am very interested in purchasing two vertical plugins if you happen to still have some spares. 5A19 would be really nice. But any vertical plugin would be useful.

/Mattis


Re: Type M Cracked Channel Position Pots

 

Dave,

You are right, my mistake: it's the variable gain pots. I will try the search that you suggest ("tek-made pots")

Thanks

-- Jeff Dutky


Re: Type M Cracked Channel Position Pots

Ananda
 

After usg epoxy, can you put a sleeve on the outside with a hole for the screw? You can get some thin gage tubing for this.


Re: Tektronix 5110 oscilloscope

magnustoelle
 

Good Day Heinz,
Congratulations to your latest acquisition! The 5000 series oscilloscopes are still underrated. They can be very nice, reliable tools for Audio and instrumentation work.
I have collected dozens of plugins and would be happy to sell these at moderate price levels. Let me send you a private email, so we can get in touch. I am located near München in lovely Bavaria.
Cheers,
Magnus





Am Sonntag, August 15, 2021, 16:35 schrieb Heinz Breuer <hbreuer@...>:

Hello,
out of an estate I got a rackmount 5110 oscilloscope. I know that the former owner bought a lot of stuff surplused by the US army in Germany. Mains voltage was still set to 125V. It seems that the scope has never been used and spent its duty as a depot dog. It came with three 5B10 horizontal plugins. Maybe somebody filled the empty slots?
All seems to be working.

I need some vertical plugins and wouldn’t mind getting a 5B12 dual timebase. I can trade with 5B10 and cash or buy outright. Is there anybody in Germany who has appropriate plugins?

While I have about several series 7000 and several old older series 500 scopes this is my first unit out of the 5000 series.

Von meinem iPhone gesendet


Re: Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail

Jean-Paul
 

Hallo again Egge:

1/ I have several CTT at least two are working OK. Last Winter, I exchanged the boards and the ROM between defective CTT OPT boards, and then the ROM on the CTT boards were exchanged.
Finally, I exchanged the A5 control boards and as per Chuck Harris suggestion, the Trigger Hybrid.
Unfortunately none of these swaps between working /defective scopes made any changes in the dead CTT tests!

2/ RE your notes on jumpers, I just found that J6000 on both of the CTT 2465B, and the schema.
It closes the 131 MHz PLL clock loop. on PLL and Power dist schema #26. On both2465B indeed J6000 is properly inserted.

I await any further suggestions as I am a bit puzzled

Many thanks again,

Jon


Re: Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail

Egge Siert
 

Hi Jean-Paul,

Pdf page 327 of the 070-6864-02 (Late) 24X5B and 2467B Options Service Manual (upper right of Electric Diagram, LOC 1L). You can see the Jumper on the CTT/WR Board Section on the lower right corner of the Heatsinked IC (the Photo of the CTT-Board I sent you April this year).

Greetings,

Egge Siert


Re: Type M Cracked Channel Position Pots

Dave Wise
 

What shaft couplings, Jeff? Did you mean “gain pots” instead of “position pots”? If so, it’s been cussed and discussed for years, with at least a couple of inventive solutions in the archive. I’d try “tek-made pot” for a search string.

Regards,
Dave Wise

From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jeff Dutky via groups.io
Sent: Saturday, August 14, 2021 10:12 PM
To: TekScopes@groups.io
Subject: [TekScopes] Type M Cracked Channel Position Pots

I acquired a Type M plug-in (because I am obsessed with having a 4 channel plug-in for every scope I own that can have one) and it turns out that the shaft couplings for the channel position pots have mostly cracked from age so that the shafts and their knobs turn freely without turning the pot. This is similar to the failure of other shaft couplings in newer instruments, especially where the shaft coupling has been made of plastic, but this coupling is directly part of the pot itself.

I'm going to try removing one of the affected pots and see if I can epoxy the coupling back together. There's plenty of space around the coupling for epoxy, but I'm still worried that the epoxy won't hold when the set screw is tightened. Has anyone else fixed this failure on a Type M plug-in?

-- Jeff Dutky


Tektronix 5110 oscilloscope

Heinz Breuer
 

Hello,
out of an estate I got a rackmount 5110 oscilloscope. I know that the former owner bought a lot of stuff surplused by the US army in Germany. Mains voltage was still set to 125V. It seems that the scope has never been used and spent its duty as a depot dog. It came with three 5B10 horizontal plugins. Maybe somebody filled the empty slots?
All seems to be working.

I need some vertical plugins and wouldn’t mind getting a 5B12 dual timebase. I can trade with 5B10 and cash or buy outright. Is there anybody in Germany who has appropriate plugins?

While I have about several series 7000 and several old older series 500 scopes this is my first unit out of the 5000 series.

Von meinem iPhone gesendet


Re: FG-501 Output Impedance

Albert Otten
 

So there is 23 ohms for the drive circuit, but I wonder if that is normal.
That's not normal of course. The idea is that the output impedance is almost completely determined by the series resistor. In my manuals there are 2 resistors in parallel for this, R2033/R2131, 100R/2W each. Is that 47R resistor a replacement? Does the impedance depend on frequency (who knows because of inductance of the 47R resistor)?
First of all you might check the 3.9R resistors R2026 and R2228.
Albert


Re: Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail

Jean-Paul
 

Dear Eggie! WOW thanks for the tip: been since February that Chuck had give a long comment.

Bought it because of the CTT and WR options, epay seller said scope was 100% OK except for bad PSU , of course this was false and it arrived PSU disassembled and other boards needing rework, NVRAM, eg A5. .

I had no idea RE CTT jumpers.

This options board has only CTT/WR and not TV, etc so, 1/2 the CTT board is unpopulated.

Can you please send a link or page # and which manual (2465B OPTIONS?) for manual sections with U6130/U6131/W6131 config and jumper settings?

I really hope that your tip is the answer, been suffering with this for 2 years!


All the Best,

DANKE!

Jon


Re: FG-501 Output Impedance

Jean-Paul
 

Bonjour, I dont have FG 501 handy my 502, 503, 504 are all accurately near 50 Ohms. Otherwise the cables and loads will not be matched.

So the FG501 Zo should be very near 50 Ohms and 73 is odd.

Zo of the output amp must be near zero, so the Zo impedance is that of the resistor.

Carbon comp Rs tend to drift upwards over time especially if overloaded for a long time.

Just check the 47 ohm with an accurate DVM and replace with 2W 47 or 51 Ohm as needed.

Bon Chance

Jon


FG-501 Output Impedance

emissionlabs
 

I have an FG-501 which seems to work well, apart from the output impedance perhaps(?) being too high. It says 50 Ohms on the front panel. I measure 73 Ohms, by loading it with a potmeter until I have half of the amplitude. Then measure the potmeter value, and I find 73 ohms. The series resistor on the PCB is a big carbon resistor of 47 Ohms 5%, which measures 50 Ohms. So there is 23 ohms for the drive circuit, but I wonder if that is normal.


Re: Continued: 2465B CTT/HPIB/WR TEST 05 fail 42, all CTT fail

Egge Siert
 

Hi Jean Paul,

I assume Jumper J/P6000 Placement/Removal on the CTT Board is in accordance with the hardware (U6130/U6131/W6131)?

Greetings,

Egge Siert


Type M Cracked Channel Position Pots

 

I acquired a Type M plug-in (because I am obsessed with having a 4 channel plug-in for every scope I own that can have one) and it turns out that the shaft couplings for the channel position pots have mostly cracked from age so that the shafts and their knobs turn freely without turning the pot. This is similar to the failure of other shaft couplings in newer instruments, especially where the shaft coupling has been made of plastic, but this coupling is directly part of the pot itself.

I'm going to try removing one of the affected pots and see if I can epoxy the coupling back together. There's plenty of space around the coupling for epoxy, but I'm still worried that the epoxy won't hold when the set screw is tightened. Has anyone else fixed this failure on a Type M plug-in?

-- Jeff Dutky


Re: 475 with Vertical Amp problems?

Ed Breya
 

Looks like you've already checked the terminators OK.

Ed

8981 - 9000 of 193950