开云体育

Hi

NO NO NO Standard 1W resistors only have a working voltage of 350V and some of rare ones of 500V, use resistors from the Vishay VR range or equivalent. R4434 must be suspected.

G Edmonds On Thursday 6 March 2025 at 16:34:03 GMT, Mark Vincent via groups.io <orangeglowaudio@...> wrote:

James,

The focus problem may be due to resistors in and around the focus circuit. They should be raised to 1W types due to the voltage drop across them. These resistors are from B+ to the collectors and from C to B of a few transistors on the h-v board. The part numbers are from Mouser. The 150,000 ohm: 71-CCF60-150K-E3, 180,000 ohm: 279-H4P180KFDA, 332,000 ohm: 71-CCF60-332K-E3, 442,000 ohm: 71-CMF60442K00FEWF (12 week delay) or (2) 660-MF1/2CC2213F (in series), 430,000 ohm: 279-H4P430KFZA, 100meg: 708-HVA12FA100M or (measure in mm the hole spacing of the original carbon then select the on that will drop in which will be larger in wattage than original). If yours has the two 39meg 1/4w carbons on the bottom board, use two 594-MBE04140C2005FC1 in series. These will be R710 and R910.

When you finish recapping the unit, use high temp, low ESR and long life types. Make sure to get the polarity and look to see if yours has the incorrect voltage and values of two condensers in the supply. Replace them as you find them. There are resistors in the supply that should be increased in wattage. The two 4,7mfd tantalums likely will test bad. I used 50V film types to replace them. M. Yachad has a kit for these to recap and some resistors that should be replaced.

Mark

James,

The focus problem may be due to resistors in and around the focus circuit. They should be raised to 1W types due to the voltage drop across them. These resistors are from B+ to the collectors and from C to B of a few transistors on the h-v board. The part numbers are from Mouser. The 150,000 ohm: 71-CCF60-150K-E3, 180,000 ohm: 279-H4P180KFDA, 332,000 ohm: 71-CCF60-332K-E3, 442,000 ohm: 71-CMF60442K00FEWF (12 week delay) or (2) 660-MF1/2CC2213F (in series), 430,000 ohm: 279-H4P430KFZA, 100meg: 708-HVA12FA100M or (measure in mm the hole spacing of the original carbon then select the on that will drop in which will be larger in wattage than original). If yours has the two 39meg 1/4w carbons on the bottom board, use two 594-MBE04140C2005FC1 in series. These will be R710 and R910.

When you finish recapping the unit, use high temp, low ESR and long life types. Make sure to get the polarity and look to see if yours has the incorrect voltage and values of two condensers in the supply. Replace them as you find them. There are resistors in the supply that should be increased in wattage. The two 4,7mfd tantalums likely will test bad. I used 50V film types to replace them. M. Yachad has a kit for these to recap and some resistors that should be replaced.

Mark

On Mon, Feb 5, 2024 at 07:48 AM, Ozan wrote:

FM18W08

I have also with success replaced DS1230 Dallas chips in HP scopes with FM18W08 and a SOIC to 28DIP board from CPC Farnel + IC socket = 5$/GBP and works well.

Last night I swapped the entire supply over and the problem remains. Surely the chances of two PSU's having identical and 'uncommon' faults, rules out that possibility.

Considering that we have both vertical and horizontal deflection, Sweep, and intensity control, then it seems to me that I need to deep dive into the focus section.

2430A I had last week had no display, a 2.7Uf tant cap was loading a reg circuit (top PCB rear left)

--
Jeffeelcr

Due to a mistake on a drawing Tektronix had 012-0482-00/01 cables made with RG-58/U cable.
They have now corrected the error and have the correct RG223/U cable and have 012-0482-01 made with the correct cable.
--
Jeffeelcr

On Wed, Feb 26, 2025 at 12:43 PM, Barry Breaux wrote:

I changed DC502 to SC503.

Hello,

I posted a picture in photo of a waveform being drawn by an SC503. I asked if
anyone wanted to guess the cause. I know the answer, but take a guess if you
want. I will post the component failure a little later.

/g/TekScopes/album?id=300884

Barry

Makes sense. They added the optocoupler later, it looks like.

It doesn't look like the 492 used the line trigger for power-good reset, at
least at first glance, so it sounds like the disconnected capacitor may have
been failing to suppress some noise that kept the controller from booting
properly.

-- john, KE5FX

Hi all,
I'm having an issue today with 'View/Reply online' (I'm not able to find the window to enter a message) and that's the reason for using 'Reply to group'.If Edward's 'Please explain more' request refers to my previous message 'Not clear about the role of DC502 here...' then Barry's first sentence of this topic should be re-read
RegardsT

The PSU hasn't been fully recapped although it the ESR was checked

Hi Menahem.

Before, it wouldn't turn on. The two 0.068?F's had exploded.

James.

And before the RIFA's were replaced, what was its condition?

Menahem

Please explain more.

On Tue, Mar 4, 2025 at 04:37 PM, Dave Brown wrote:

The museum is open to the public with no admission charge. We participate in
external STEM events for free. The museum relies 100% on volunteers,
donations, and eBay sales for its operation. These sales help keep the museum
open.

Hi Dave,
If you feel that this discussion is harmful to the Museum's revenue stream, then I will certainly "cease and desist". I'm just a hobbyist, and I don't want my interests and curiosities to harm a small business. The museum I work at ( ) struggles with funds of course also. We do charge admission, and have several paid staff in addition to a number of volunteers like me; but we also have over 50 acres of property and 8 or 9 buildings to maintain (one of which is on the CO Historic Register). We host multiple school group tours every week, host STEaM camps, etc. We think we are one of the very best museums of its kind anywhere.

Pete

Nothing shorted nor open on the A9 board

Thank you Craig. The museum is open to the public with no admission charge. We participate in external STEM events for free. The museum relies 100% on volunteers, donations, and eBay sales for its operation. These sales help keep the museum open. If you haven't noticed lately, a lot of museums have folded.

On Tue, Mar 4, 2025 at 03:23 PM, Brian Cockburn wrote:

Open sourcing would be nice, but I would guess that the museum see this as a
(small) revenue generator. Although, an open source set of instructions could
include a request for a donation.

My understanding is that the fellow that wrote the code for the VintageTEK design passed away (per a note from Tom Fang). And I inferred (but could be wrong!) that the source code is lost/missing, so making changes would require a re-write.
Please correct me if these things are not true.

Meanwhile, I want to re-iterate that I won't be selling anything, and I have no interest in "reverse-engineering" someone else's design. If my project (basically just FW/SW) seems useful to someone, I will share it. If a non-profit (such as VintageTEK) feels that sharing my code is a bad thing for them, then we can talk about that... I volunteer at a local Museum every week, so I fully understand the issues.

Pete

Open sourcing would be nice, but I would guess that the museum see this as a (small) revenue generator. Although, an open source set of instructions could include a request for a donation.

As to volume, 25 at a time seems about right to me. Go for 250 and you'll be left with a lot of stock I'd reckon. Demand has been pent up, but is limited.

On Tue, Mar 4, 2025 at 3:09?PM saipan59 (Pete) via groups.io <saipan1959=
gmail.com@groups.io> wrote:

Correct, AFAIK. The distinction (I think) would be: To draw a line, you
have an X-Y START point, and also an X-Y END point. You could have analog
circuitry that causes the X and Y voltages to move linearly from the start
point to the end point, thus drawing a perfect line.

The 2430 and its ilk have a relatively simple vector generator circuit for
X and Y that recreates absolutely beautiful traces on the CRT. The slope is
generated by subtracting the current and the desired X/Y, which is then
sampled at the appropriate time. I guess to generate arbitrary vectors
you'd want to be able to set a starting point ... or just control the Z
axis as well?

No clear about the role of DC502 here...
T