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If you don't have the Programming Development ROMs in the ROM Carrier - you cannot use the 4041 keyboard (you hear 'BELL' for every key press), nor can you use the remote COMM console ('BELL' control characters are sent in reply to every remote console key press).

I've shipped out a full copy of the System Verification Tape.

Instructions for running the System Verification Tape are in the 4041 Systems Controller Guide - all known 4041 manuals including Programming are posted on bitsavers.org:

This tape will either run automatically if inserted when you power on the 4041 or it will re-run if you press the front panel Auto Load button.

It starts with the TERMIN program asking if you want to configure the COMM port as the System Console. If you have write protection off on the tape, it will save the CONFIG.AS file if the configuration you requested is accepted by pressing "1" on the external console when prompted.

However, this file will not be used - unless you either copy it to another tape or copy it to the AUTOLD file. Follow the instructions on page 4-15 to format a blank tape and write the CONFIG file to AUTOLD, so that tape will boot to remote console mode.

If you only have one tape and want to use the System Verification tape as your boot tape, then from the remote COMM console:

Enable writing to the SysVer tape: 1 - LOAD "AUTOLD" 2 - SAVE "BACKAU" 3 - LOAD "CONFIG" 4 - SAVE "AUTOLD"

Then write protect the SysVer tape :)

Your tape would then automatically boot the 4041 to the COMM console with the configuration you selected with the TERMINAL program.

To run the System Verification programs after this - from the COMM console: LOAD "BACKAU", then RUN (although I haven't tested these instructions)

gmail

Colin,

If there are intermittent segments on the LEDs then the 74(LS)47 7 segment decoder is the likely culprit and is probably socketed (it is on my DM501).

Roger

I've had a look at that possibility, Roger. I have cleaned the attenuator cam-switch contacts on a couple of 400-series scopes, but I can't see how to clean them on the DM502. I have taken the cover off the cam-switch assembly, but I simply can't see the gold-plated (?) contact fingers and pcb contacts. It seems more like the time-base switch contacts on 400-series scopes than the attenuators on the same scopes.
Correction: I have taken another look after removing the cover and I can see the contacts underneath the cam-switch. I think I'll have a go with the IPA and paper, though whether IPA is as required as it is with attenuator contacts, I'm not sure. The pcb material looks as though it is fairly ordinary, rather than the polyphenylene oxide used in scope attenuators, which can be damaged by some solvents.
Another fault is that sometimes one or more sections of the seven-segment led displays tend to flick on or off - maybe this will improve with switch-contact cleaning?
Colin.

On Fri, Jun 5, 2020 at 10:08 AM, David C. Partridge wrote:

Looking at the datasheets these devices appear the be the same, am I missing
something, or was it just a case of the MCM68766 superseding the MCM68764?

AFAIR the two are mostly the same. The main/only difference is in the Enable lines. The 68764 has a Chip Enable(low) ('CE) line, which in the 68766 is an Output Enable(low) ('OE) line.
Data availability in the 68766 after 'OE is faster (100 ns) than in the 68764 after 'CE (450ns). OTOH, the ('CE) in the 68764, when high (i.e. Disabled), puts the chip in a low-power mode.
Raw read access time for both chips is the same (450ns) and 'CE is as fast as the delay from Address Valid to Data Valid with 'CE asserted. (Nominal max. times for the most popular versions).
If the low power capability of the 68764 is irrelevant, a 68766 will always do, the 68764 may not. I haven't checked if the 68764 will fulfill the 7854's timing requirements.

Raymond

Correction, I don't think the cam switches improve with use, if they are dirty they need cleaning with IPA and strips of paper.

Roger

Colin,

Some of the TM500 plugins had notoriously unreliable IC sockets. I would certainly remove the socketed ICs, clean pins and see if anything improves. Several people have commented that the long term solution is to replace with decent IC sockets, I expect someone will know how to identify the unreliable originals. Have you checked for ripple on the +/-12V and 5V lines? Also it is worth exercising the range switch a few dozen times! Is the DM502 a new acquisition or one that was working OK but has now failed?

Regards,

Roger

I have a DM502 which isn't working correctly. I have checked the power supply voltages at +5V, and +/- 12V and they are within spec. I have also adjusted the clock frequency to 20.48 kHz and that is fine. On initial switch-on and warming-up, the display "jumps about" rather than staying stable as one would expect, even with only a battery connected to the test-terminals and a suitable DC voltage range selected or with a resistor across the test terminals and a suitable ohms range selected. After being powered on for a while, the display just shows a constant sequence of digits, whatever the position of the range switch, only the position of the decimal point changing. I haven't got around to checking anything else, yet, but after the plug-in has been on for a while,the transformer T410 is rather hot to the touch, so much so that I can't keep a finger-tip in contact with it. Is this correct behaviour, or should I check other components (don't forget that the voltages out of the transformer are within spec.)?
TIA, Colin.

Looking at the datasheets these devices appear the be the same, am I missing
something, or was it just a case of the MCM68766 superseding the MCM68764?

Thanks
David

Hi group

Just a success story with a very minor repair and hint to others later:
Today fixed two 602's with SAME fault (no spot, no HV) - fuse F217 had
blown.

Reason for blown fuse was C216 and/or C217 electrolytics had failed short.

The Bussman fuse MDL-1 is still available from Mouser.

Hope this saves someone some time or saves a 602 unit. They are
beautiful when running.

--Toby

Showed up on the local Craigslist. I'm not the seller. I'd take it myself but I already have too many old Tek scopes.

Greetings, on pin removal tools, I have a box full of old telescopic TV and radio antennas collected over the years and another box of ones that have been taken apart and cut into various lengths over the years. Perhaps you might have one in just the right diameter to use as a pin remover.

I often use some of these short length ones as punches. If you run the pointed end of an exacto blade (duh, the other end would be the handle) or even the kitchen steak knives into the end of the tubing and scrape, or a deburring action on the edge, it will sharpen up near razor sharp, it should take less than 10 seconds. It will punch great holes in rubber, card, paper etc. Sometimes with thick rubber a bit of lube (spit is usually available) and spin in a drill chuck for better holes without the squishing from punching effect on the holes. You can easily spin and do lovely binder holes in a phone book. Sometimes a small triangular needle file can put some saw teeth on the end of the tube if need be. Ive even used them for banana jacks on occasion, a taper end of a punch or ball bearing easily with a bit of hammering will flare the end, or flare and then flatten for a nice flush end if pushed into a panel hole

The telescopic pins in old watch straps are another source for some handy tubing

You find you will want them right near your bench so you don't have to go far to utilize their handyness.

Dave

Hi,

Here's a possible pin removal tool solution:



You're most welcome!

the (F) suffix for CRTs always indicates a Flat Face. a 5UP1 has a
spherical face, but a 5UP1(F) is flat (these tubes only come from Japan, the US makers did not offer this variation). I have never seen an (S) suffix in real life, maybe someone has added that to distinguish between the flat and spherical versions of the same tube.

the 5DEP1(F) was a very popular CRT for low end scopes, it has very high brightness with low anode voltages, and good deflection sensitivity, coupled with a flat face, and you have the makings of a very nice lower frequency (10-20Mhz) scope.

we do have some if you need one (although not so cheap), see:

they also show up on ebay regularly, as they were used in many 5" low end scopes and kits.
often new tubes from un-built kits show up at a good price.

all the best,
walter

--
Walter Shawlee 2
Sphere Research Corp. 3394 Sunnyside Rd.
West Kelowna, BC, V1Z 2V4 CANADA
Phone: +1 (250-769-1834 -:-
+We're all in one boat, no matter how it looks to you. (WS2)
+All you need is love. (John Lennon)
+But, that doesn't mean other things don't come in handy. (WS2)
+Nature is trying very hard to make us succeed, but nature does not depend on us.
We are not the only experiment. (R. Buckminster Fuller)

A public thank you for all the work you have put into this, Monty.
Will contact you directly to progress things.
DaveB, NZ

The behaviour is decidedly odd, when it does POST correctly, the digital section works for a time then crashes so none of the mode controls work and the OSD disappears. Whilst researching, I found mention of the TI P25 sockets, so I checked and found mine uses them; should I bite the bullet and swap them all for a better type? What's the consensus as to which is the best alternative?

It does appear not to be the ROMs after all, they all read and verify correctly for rthe -01 revision.

Thanks Michael, Albert.

Michael, the data sheets for this tube do indicate that there are different phosphor options available for different writing speeds so I think that the speed is defined by the phosphor given that standard theory.

Albert, I believe that your observation of the suffix is true. As to why they offered both features is beyond me. As for a 5UP1 being interchangeable with the 5DEP1, I first thought that I could go ahead and pick a 5UP1 up but later found that it has a much lower deflection sensitivity. Otherwise it would be a fit.

There is one (F) tube on the auction site that I wanted to get and looks to be in good condition but the seller never responded to any of my offers nor emails. I think there might be a possibility that they may have fallen prey to the virus. Anyone else have this problem with purchasing things recently?

Greg

At the CRT page Sphere often mentions flat face for 5xxx(F) tubes. In one case, 5UP1(F), the description explicitly states "Electrostatic CRT with flat face (F)".
Albert