He's talking about a 5385A...not exactly "vintage"; certainly not to the level that you're talking about here.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

Many thanks to those who helped in this thread. The advice and encouragement (and proffered manual) yielded sanitary unit and a workaday solution for those who have smashed their gate pots to smithereens.

Before I proceed with my resolution, I need to ask about the protocol of placing items in the files section. I have a decent manual passed along by another member and I'd like to place it in the appropriate directory along with a more formal documentation of this resolution. The Manual is a .PDF file about 15MB in size and the write-up is about 600KB. If there is no taboo on uploading these, I shall do so.

Herein hangs the tale. Firstly, the litany of problems:

?? The gate pot – a 500K Ohm unit with a switch built in to accommodate a “HOLD” function was destroyed.

?? The A channel Sensitivity pot knob was unremovable. Some genius had jack-hammered one of the two grub screws in place with one of a different size and threading. No amount of coercion could extricate it thus it fell to Dremel sawing and was destroyed. That left me with two decent knobs and a gate pot with none. (The three knobs on the unit are identical. A spare parts Tek 7700 series plugin knob served as a replacement.)

?? Similarly, the input assembly – where the two input BNCs reside – was secured by four Philips head screws one of which was fused in place. (It is always that way, isn’t it?)

This last point was remedied by something I saw on a YouTube video. The Kroil had not arrived yet but bathing in 3-in-1 oil did nothing to budge the screw. Some guy said to take an ordinary rubber band about 4-6 mm wide and push that into the stripped Philips head with the screwdriver and, pressing down with as much weight as is possible, attempt to turn the screw. I was very skeptical of this but, to my amazement, it worked! (Similar success later experienced with another item in my shop!)

Anyway, a member of the group offered a remarkably sanitary copy of a .PDF manual with pictures and schematics which I gratefully received so I was off and running!

The first step was to examine the spot where the gate pot resided and to figure out how the gating function worked. Below is a shot of the A1 board after the pot was removed. It was very easy to wick out and clean the holes and what was left was a mostly intact gate pot case from which I extracted the necessary dimensions for a replacement. The original was, as stated above, a 500K ohm Bourne potentiometer that six leads to be accommodated by the six holes shown below. The three in the front were for the delay and the three in the rear were for the “HOLD” switch. Also below is a schematic excerpt of the gate pot with the hold circuit. Note that the circuit is simplicity in itself. The gate pot’s wiper runs to pin 6 of U2 and controls the voltage. The “HOLD” pins grounds pin 7 of U2.? (See the picture below of the connections after the original pot has been removed.)

In Searching for a replacement, I located a Bourne 3310 pot on eBay from a nearby seller. (Image of the pot's dimensions below.) Mounting the pot is not a flush fit; you’ll have to do a little lead bending to get the pot seated correctly. I accomplished this by mounting the pot in it’s panel hole, bending the leads backwards at a 45° angle and carefully fitting the panel in place. Then the leads can be pushed into the three front holes and – eventually – soldered in place. If you are a tad squeamish about whether the pot functions correctly or not, just push the leads such that they make contact with the board, fire the unit up, and rotate the shaft. Fully CCW will cause the gate LED to pulse quickly and fully CW will cause a pulse of about 10-15 seconds. ?

I added a simple switch to implement the "HOLD" function wired as shown below. Caution should be taken to use a very small switch and wired as shown so as to allow the front panel to be removed later if necessary. It's crude, but I could not resist positioning the switch such that the handle would point towards the "HOLD" panel label when on.? ?

Good luck and good hunting!
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."

I've done that too. It can be a lot of work and messy but it is nice once it's finished. I didn't opt to do that for my 7603 as I've not had good luck desoldering the cans when they're intact (too much heat sinking) and I opted to cut them at the pins, desolder, and use adapters. Someone had already lifted some pads so I didn't want to contribute to that if I could avoid it.

Thanks,
Barry - N4BUQ

Don't know it would work with PCB mount caps, but when I restored a bunch of 1940s-1960s Cossor and Telequipment 'scopes, I found that as modern caps were so much smaller for a given capacitance/voltage than the originals it was easy to split the can (round the circumference, above the 'crimp') and replace the guts with a new cap. Then put a bit of clear heatshrink tube over the whole can to hold the two halves together.
I also pulled the insides out of the the Selenium EHT rectifiers and hid new diodes inside the paxolin tubes.? Looks pretty authentic but without the risk of smoke and smells!

Look in the files section here under “Gerber files” I uploaded all of my gerbers for our various snap-in to pin adapters. Two of them are measured copies of HP’s adapter plates

steve

Those little adapter PCBs are an interesting spin on it. I'll dig further into that
when I get back on Sunday - maybe they have some that fit these HP Spragues.

If you're replacing a can cap, the ones in the link below work nicely. I just recapped one of my Tek 7603's rectifier/filter boards with them.

For the "square" style, he now has two different configurations; one where the + pin is directly in line with the negative terminals and one where that pin is 0.050" closer to the center of the can's old pins which happened to fit the hole pattern in those boards better. I used Harwin H2105-01 PCB pins to connect the adapter disks to the board as I wasn't too fond of the pins that are provided. It turned out quite nice.



Good luck,
Barry - N4BUQ

On 11/24/23 09:39, jslcanuck wrote:

Hayseed Hamfest manufactures a wide variety of can caps. They did some direct
replacement caps for an HP volt meter I restored.

Interesting - what a peculiar specialty. Looks like they mainly do twist-lock tabs with
solder terminals, and a few with pigtails. No PCB pins.

Yeah they're primarily aimed at vintage stuff.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

Hayseed Hamfest manufactures a wide variety of can caps. They did some direct
replacement caps for an HP volt meter I restored.?

Interesting - what a peculiar specialty. Looks like they mainly do twist-lock tabs with
solder terminals, and a few with pigtails. No PCB pins.

Jonathan

On 11/24/23 07:50, Reginald Beardsley via groups.io wrote:

Not filtering at all. Composing reply. It's a significant project.

Ok, just wanted to be certain. No rush.

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA

Dave,

Not filtering at all. Composing reply. It's a significant project.

Have Fun!
Reg

Sadly there does not seem to be a manual of any kind relating to any of the different versions of the 1336 display - other than the spec sheet from various HP catalogues. Or at least my excavations on the internet have not revealed anything.

And it is not in the Artek manual portfolio either.

Internally they have a very different design to the later 1340A displays that I am more familiar with.

BW

Tony

Thanks Tom - I saw the spec sheet and was intrigued by the high definition of these (albeit quite small) displays.? I was aware that they had some significance for the movie mentioned :-)

BW

Tony

开云体育

Hi Tony,

If you assume that the 1336A and 1336S are similar, then maybe the schematics for the latter can be used as a rough guide, at the very least. A quick look at the connectors supports your initial guess that "R" stands for return.

If you haven't downloaded the 1336S's manual, take a look at it and see if it's at all helpful.

-- Cheers
Tom

-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070

Hi Dave,

No schematics, no pictures, nothing - this XY model (1336A) seems to be a bit of a ghost.

I have not traced the +/-15V circuit yet (or indeed any of the others!)? - that's a job for the weekend coming. I had assumed that the chassis was the ground for the 15V circuits.

Would the 250/21V rails need specific returns if they were (for some reason) AC supplies?

Tony?

The question today happens to apply to my 5385A counter, but I suspect it's a FAQ
(as in: RTFF). Nothing hard about getting a 2200uF 25V radial to replace these HP
0180-3276 parts, but it'd be nice - mechanically speaking - if I could find this kind of
three-terminal version. Can anyone suggest any leads, or do I just have to suck it up
and get the closest-fit two-terminal part I can find?