Re: Tek 7854 intermittent issues
There are a lot of test points on the various digital cards. Even without
extenders, you can pull the card, clip on a probe, and then reinstall for
test.
For example, the +5VD bus is on TP1200 pin 11 of the A27 CPU board.
Even without dedicated test points, you can clip on to component leads or
even tack on a small wire temporarily.
Dave Casey
toggle quoted message
Show quoted text
On Sun, Sep 6, 2020 at 12:30 AM Nick Corvid <awsomedrack@...> wrote: I imagine that you can't get proper readings with the boards out? Shame
that they made it so hard to service without many extra pieces of
equipment/accessories.
Could you send me a link to those files? Would no doubt prove useful for
future repairs.
Guess as soon as I'm able I'll dig through my manual and try and find some
good test spots for the 5 and 12 volt that I can reach.
|
Re: Tek 7854 intermittent issues
I imagine that you can't get proper readings with the boards out? Shame that they made it so hard to service without many extra pieces of equipment/accessories.
Could you send me a link to those files? Would no doubt prove useful for future repairs.
Guess as soon as I'm able I'll dig through my manual and try and find some good test spots for the 5 and 12 volt that I can reach.
|
Re: Tek 4654M; No Trace, No +5V, No +95V; Help
455 and 465M use the same parts U550 152-0635-00. See section 12-3 of the Semiconductor Catalog for applicable specifications. This will tell you what you need to know to build the appropriate multiplier.
--
Michael Lynch
Dardanelle, AR
|
Re: Tek 4654M; No Trace, No +5V, No +95V; Help
My 455M had a failed HV multiplier. It was blowing the fuse same as your 465M. It has a 1.5 times multiplier as part of U550 this is confirmed in the Tektronix Yellow covered X Ref catalog. I built a separate multiplier section to replace only the failed part of the module. Wired this to the Transformer output previously used by U550. The rest of the U550 module Circuitry remained in place and working as before the failure. I 3D printed a small enclosure for the multiplier, assembled the components, tested, verified performance, potted and then mounted it as shown in the photos here: /g/TekScopes/album?id=253227Unit now works as originally designed. Good luck with your repair. -- Michael Lynch Dardanelle, AR
|
Re: Tek 4654M; No Trace, No +5V, No +95V; Help
Using the diode test method I found what I believed to be a bad Q552 transistor. At the same time F558 was blowing. I have replaced Q552. But F558 does indeed blow every time the power on switch is pulled. The low voltage readings, except the 95V, are good at this point. 32V reads 32V. -5V reads -5V. +5V reads +5V. 95V reads 7.5V. I have checked every component in the 95V circuitry. All were good or have been replaced. Could I be looking at a bad T550 transformer or a bad HV module (U550)? From the schematic I have it would appear HV module pins 3, 5, and 11 feed T550 pins 8, 9, and 10 respectively. What would be the expected voltages on T550 pins 8, 9, and 10? Harrison N1FAM
|
Re: Tek 4041 GPIB Controller
Monty: That 840 Error Message means the drive belt came off the rollers
and the tape is not moving. The tapes are not attached on either end as I
am sure you are well aware. There are a series of holes punched into the
magnetic tape, and if the LED optical system does not detect the holes,
then it gives the 840 error message. There is nothing wrong with your
lamp/sensor circuit. Please don't mess with the sensors or you will have
real problems to cope with.
I still would like to buy 1 more 4041 tape with all of the files on it.
Please let me know if you have the time to produce it. Thanx.
Gary
toggle quoted message
Show quoted text
On Sat, Sep 5, 2020 at 8:02 AM Monty McGraw <mmcgraw74@...> wrote: I just received my EBAY purchase of another 4041 - this time with the DDU
disk drive unit attached.
The auction indicated they were working at the time they were taken out of
service - I'm not so sure of that, but both 4041 and DDU powered up during
my test last night.
However, even though the 4041 powered up, showed v2.1 firmware and 512KB
of memory, the LED display showed a prompt, so I suspected it did not load
any AUTOLD file from the DDU.
There are SCSI DIP switches on the 4041 rear panel for SCSI Option 03, one
of which changes the default storage from internal tape drive to DDU hard
disk - and that switch was set to DDU hard disk.
Looking at the front of the DDU, I could see the hard drive LED blinking
three times, repeatedly. The DDU service manual indicated in the Shugart
hard drive section that this meant the spindle failed to come up to speed :(
I turned off both units and changed that switch to tape, powered up the
4041 by itself with one of my tapes, but got an error on the LED display
indicating 840 Lamp/Servo failure.
The tape did not move, so it appears I need to troubleshoot the tape Lamp
circuit.
In the meantime, I pulled off the right side cover and did my front panel
board mod to allow my USB to TTL serial adapter to be used with the front
panel keyboard connector.
- Power off the 4041.
- Remove the 4041 two rear plastic "corners" securing the right panel and
slide off the right panel.
- I dipped my desolder braid in flux, place the braid on the pad and apply
your hot soldering iron to the braid and resistor lead to suck the solder
completely from the pad. Be sure to cut off the braid and apply fresh flux
before desoldering the pad for each resistor.
- Unsolder and lift the 'left' side of the two resistors closest to the
unused J86 connector as shown in my resistor mod photo: [4041 Resistor Mod](
/g/TekScopes/photo/247590/4?p=Created,,,20,2,0,0)
- Solder a 1K ohm resistor into the hole (I first cut the resistor lead
down to .25 inch).
- Then solder the tomb-stoned 1K ohm resistor to the lower resistor and
clip off any extra leads per my photo
- Replace the right side panel to ensure proper 4041 cooling.
- Connect your TTL Serial interface ground to the top left keyboard
connector female contact.
- Connect your TTL Serial interface TX to the lower left keyboard
connector male pin.
- Configure your TTL Serial interface for 4800N2 speed, parity, stop bits.
- Power on the 4041 and you should be able to type on your PC using the
TTL Serial interface - and see your typed characters on the front panel LED
I only use this TTL Serial interface to bootstrap to the rear panel COMM0
interface (if you have the Programmer ROMs installed in the ROM tray behind
the front panel grill):
1. Type "SET DRIVER "COMM0(BAU=9600,FLA=BID,EDIT=STORAGE):"
2. Type "SET CONSOLE "COMM0(ECHO=YES):"
I find the EDIT=STORAGE parameter is easier to use when correcting PC
typing errors, as the console will echo back each character you are
deleting.
After the 4041 keyboard mod, I used my PC to type the command to format a
DDU 5 1/4" floppy, and to run the DDU service manual program to do write
and read performance tests on the floppy.
I got 1117 Bytes per second, which meets the 1000 bytes per second listed
in the floppy spec.
So my DDU SCSI controller and floppy drive are working and I've ordered a
Seagate 40MB ST-506 drive to replace the failed Shugart drive.
I also noticed my new 4041 has a newer CPU board which includes the memory
on the CPU board and also only has four EPROMs!
The 4041 service manual indicates 4041 serial numbers B070100 and above
have this CPU board.
The service manual also indicates two of the EPROMs contain 128KB of
system ROMs - 28KB more than the earlier CPU boards. I believe the
additional 28KB is the UTL2 ROM only available for these CPU boards.
The service manual indicates the Option 10 for this CPU board is the two
additional 27256 EPROMs, which contain the R01 Graphics, R02 Plotting, R03
Signal Processing, R04 Utility1 option ROMs, which leaves room in the ROM
drawer for developer ROMs to be installed.
I ran the ASK$("ROMPACKS") command and got the list of all those option
ROMs and the UTL2.
I will capture the two Option EPROM images and post them on my 4041 github
repository sometime this weekend.
--
Gary Robert Bosworth
grbosworth@...
Tel: 310-317-2247
|
Re: Tek 4041 GPIB Controller
I have captured the four CPU board EPROMs and two SCSI Option 03 board EPROMs and posted them on my github repository:
- System ROMs were two 27512
- Option 10 ROMs were two 27256
- SCSI Option 03 board had two 27128 EPROMs
|
Re: Tek 4041 GPIB Controller
|
Re: DEC PDP11/05 on a 202D cart - did one survive?
Is this the one that had an onion skin thermal printer and when you printed the screen, a horizontal line when from top to bottom like it was scanning the inside of the CRT? At Aerotech labs in the early 70's, one was used to create Ultrasonic transducer certifications. The Scope Main Frame had a spectrum analyzer module in it. The output on the Green Screen was set up, I think, to look like a complete cert. There was options to have text and calculations on that screen and the screen shot of the spectrum analyzer. On Sun, Aug 30, 2020 at 11:17 AM Holger L¨¹bben < tekscopesinput@...> wrote: Hi!
I've added an old picture of a Tektronix DPO/DEC PDP 11/05 combination on
a 202D cart to the photo section:
/g/TekScopes/photo/252847/0
Has one of these machines survived?
I'm looking for some detailed pictures of this combination.
Holger
|
Re: Tek 4041 GPIB Controller
I just received my EBAY purchase of another 4041 - this time with the DDU disk drive unit attached.
The auction indicated they were working at the time they were taken out of service - I'm not so sure of that, but both 4041 and DDU powered up during my test last night.
However, even though the 4041 powered up, showed v2.1 firmware and 512KB of memory, the LED display showed a prompt, so I suspected it did not load any AUTOLD file from the DDU.
There are SCSI DIP switches on the 4041 rear panel for SCSI Option 03, one of which changes the default storage from internal tape drive to DDU hard disk - and that switch was set to DDU hard disk.
Looking at the front of the DDU, I could see the hard drive LED blinking three times, repeatedly. The DDU service manual indicated in the Shugart hard drive section that this meant the spindle failed to come up to speed :(
I turned off both units and changed that switch to tape, powered up the 4041 by itself with one of my tapes, but got an error on the LED display indicating 840 Lamp/Servo failure.
The tape did not move, so it appears I need to troubleshoot the tape Lamp circuit.
In the meantime, I pulled off the right side cover and did my front panel board mod to allow my USB to TTL serial adapter to be used with the front panel keyboard connector.
- Power off the 4041.
- Remove the 4041 two rear plastic "corners" securing the right panel and slide off the right panel.
- I dipped my desolder braid in flux, place the braid on the pad and apply your hot soldering iron to the braid and resistor lead to suck the solder completely from the pad. Be sure to cut off the braid and apply fresh flux before desoldering the pad for each resistor.
- Unsolder and lift the 'left' side of the two resistors closest to the unused J86 connector as shown in my resistor mod photo: 4041 Resistor Mod
- Solder a 1K ohm resistor into the hole (I first cut the resistor lead down to .25 inch).
- Then solder the tomb-stoned 1K ohm resistor to the lower resistor and clip off any extra leads per my photo
- Replace the right side panel to ensure proper 4041 cooling.
- Connect your TTL Serial interface ground to the top left keyboard connector female contact.
- Connect your TTL Serial interface TX to the lower left keyboard connector male pin.
- Configure your TTL Serial interface for 4800N2 speed, parity, stop bits.
- Power on the 4041 and you should be able to type on your PC using the TTL Serial interface - and see your typed characters on the front panel LED
I only use this TTL Serial interface to bootstrap to the rear panel COMM0 interface (if you have the Programmer ROMs installed in the ROM tray behind the front panel grill):
1. Type "SET DRIVER "COMM0(BAU=9600,FLA=BID,EDIT=STORAGE):"
2. Type "SET CONSOLE "COMM0(ECHO=YES):"
I find the EDIT=STORAGE parameter is easier to use when correcting PC typing errors, as the console will echo back each character you are deleting.
After the 4041 keyboard mod, I used my PC to type the command to format a DDU 5 1/4" floppy, and to run the DDU service manual program to do write and read performance tests on the floppy.
I got 1117 Bytes per second, which meets the 1000 bytes per second listed in the floppy spec.
So my DDU SCSI controller and floppy drive are working and I've ordered a Seagate 40MB ST-506 drive to replace the failed Shugart drive.
I also noticed my new 4041 has a newer CPU board which includes the memory on the CPU board and also only has four EPROMs!
The 4041 service manual indicates 4041 serial numbers B070100 and above have this CPU board.
The service manual also indicates two of the EPROMs contain 128KB of system ROMs - 28KB more than the earlier CPU boards. I believe the additional 28KB is the UTL2 ROM only available for these CPU boards.
The service manual indicates the Option 10 for this CPU board is the two additional 27256 EPROMs, which contain the R01 Graphics, R02 Plotting, R03 Signal Processing, R04 Utility1 option ROMs, which leaves room in the ROM drawer for developer ROMs to be installed.
I ran the ASK$("ROMPACKS") command and got the list of all those option ROMs and the UTL2.
I will capture the two Option EPROM images and post them on my 4041 github repository sometime this weekend.
|
Re: 1S1 sampling unit; (also 7B53AN & 7A18 plugins)
|
Re: Tek 7854 intermittent issues
The digital board supply is only accessible if you remove all the logic boards - it hides away at the front of the 'scope to the left (as viewed from the front) of the logic boards.
You can't get at that board while the scope is running, so you have look at the schematics and board layouts to find places to check the -12V and +/-5V that it supplies to the logic boards.
Refer to pp 2-124 and 2-125 for a description of that supply and Schematic <38> for the A7 Auxiliary regulator board.
You really need extenders to work on this beast - Gerber files available - sorry I have NO SPARE edge connectors.
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Nick Corvid Sent: 05 September 2020 06:36 To: [email protected]Subject: Re: [TekScopes] Tek 7854 intermittent issues Alright I've checked all the power supply test points I knew the location of (A12,A22,A17) Except I didn't get that digital supply David mentioned, which I'm not sure where the test points are, how to reach them, or what the specs are for that. Of the stuff I checked though everything came out relatively normal from what I could measure with my less than great instruments, well all but one thing, TP126 for the +108 volts that read 108.5 volts which is barely in spec but had some funky ripple pictured here on my auxiliary scope: /g/TekScopes/photo/252782/0?p=Created,,,20,2,0,0 . That was the only thing I saw that was out of the ordinary so far.
|
Re: DEC PDP11/05 on a 202D cart - did one survive?
HI!
The P7001 digitizer is relatively rare, thats true. But I'm wondering more about the always missing minicomputers. I think 90% of the overall functionality of the DPO system sits in the computer - but nobody seems to have one...
Holger
|
Re: DEC PDP11/05 on a 202D cart - did one survive?
Egge,
You're correct, of course; I wonder why so few of them are left?? I have the only one I've ever seen locally (core memory).
-Dave
toggle quoted message
Show quoted text
On Saturday, September 5, 2020, 12:29:45 AM PDT, Egge Siert <eggeja2@...> wrote:
Hi Dave,
You mean x010101 (the first of the production). I also have P7001 Manuals referring to B07xxxx and B09xxxx SN's.
Greetings,
Egge Siert
|
Re: DEC PDP11/05 on a 202D cart - did one survive?
Hi Dave,
You mean x010101 (the first of the production). I also have P7001 Manuals referring to B07xxxx and B09xxxx SN's.
Greetings,
Egge Siert
|
Re: Tek 7854 intermittent issues
Alright, thanks for the info Dave. I checked everything in table 4-4 as well as any other areas that had a marked voltage test point that I could see (definitely could have missed some) on A22 (The LV regulator) But I only checked the 108 on A12 as everything else proved (at least for the time I had available to test things today) too difficult to do. I also couldn't figure out how I could leave it attached to the rest of the scope while removing the shield that separates A12 from the outside as to get any access to the front of the power supply I had to pull it out too far for the shortest cables to reach.
|
Re: Tek 7854 intermittent issues
That 108 is the pre-regulator voltage. I don't think that ripple is of
great concern. There's not a lot of bulk capacitance on the 108 because it
is the feedback to the inverter controller (A12U75), so it's going to have
some ripple.
Did you check all the supplies coming off the A12 board, or just the
voltages listed in table 4-4?
You need to check all of the supplies for level and ripple.
The digital supply mentioned is generated by the auxiliary regulator,
assembly A7, schematic sheet <38>.
This is where the +5VD (D = digital), -5VD, and +12VD are generated; these
are the voltages that run the processor/digital half of the scope and thus
the most likely to cause your specific problems.
There are test points on A7, but you should also check the supplies from
the A12 and A22 boards, as they are the inputs to the auxiliary regulator,
which can only clean up a dirty input so much. Except for the -5VD rail,
most of the filtering for the digital supplies happens beforehand in the
analog supplies along with all the caps for localized filtering at the ICs.
Dave Casey
toggle quoted message
Show quoted text
On Sat, Sep 5, 2020 at 12:36 AM Nick Corvid <awsomedrack@...> wrote: Alright I've checked all the power supply test points I knew the location
of (A12,A22,A17) Except I didn't get that digital supply David mentioned,
which I'm not sure where the test points are, how to reach them, or what
the specs are for that.
Of the stuff I checked though everything came out relatively normal from
what I could measure with my less than great instruments, well all but one
thing, TP126 for the +108 volts that read 108.5 volts which is barely in
spec but had some funky ripple pictured here on my auxiliary scope:
/g/TekScopes/photo/252782/0?p=Created,,,20,2,0,0 . That
was the only thing I saw that was out of the ordinary so far.
|
Re: Tek 7854 intermittent issues
Alright I've checked all the power supply test points I knew the location of (A12,A22,A17) Except I didn't get that digital supply David mentioned, which I'm not sure where the test points are, how to reach them, or what the specs are for that. Of the stuff I checked though everything came out relatively normal from what I could measure with my less than great instruments, well all but one thing, TP126 for the +108 volts that read 108.5 volts which is barely in spec but had some funky ripple pictured here on my auxiliary scope: /g/TekScopes/photo/252782/0?p=Created,,,20,2,0,0 . That was the only thing I saw that was out of the ordinary so far.
|
Re: DEC PDP11/05 on a 202D cart - did one survive?
But don't the Tek part numbers sequences typically start at x100001?? To me, that means 772 were sold before the update, and I doubt they sold many P7001s after 1980; they were getting fairly old at that point.?
-Dave
toggle quoted message
Show quoted text
On Friday, September 4, 2020, 01:12:30 PM PDT, Egge Siert <eggeja2@...> wrote:
Hi Tim,
I have a P7001 Manual with dated MCI (06-17-80) for SN B100773 and above. Thus it seems thousands are sold.
Greetings,
Egge Siert
|
Re: 7854 front panel locking up
Martin -
I'm no 7854 expert, but I've been poking around in a few lately, and the manual has been my bedtime reading material, so I know just enough to be dangerous. That being said, a few thoughts:
From experience, the CPU can look like it's running, but be running through garbage, a problem I'm still trying to troubleshoot on a comatose 7854.
Do the button lights change when you press them?
Does it start working again after powering down & powering back up, or does it need time to cool down?
Being able to send a debounced _RESET is a handy trouble-shooting tool. I think I just brought TP1200-1 to ground.
The mode select buttons are read to the data bus through buffer U61 whenever the _FPR signal is active. This is triggered by the CPU's DBIN line OR'd with some address decoding logic.
Ya got a hard-copy of the manual? I can't imagine trying to troubleshoot these without one (or two!). There's a few folks on here that /really/ know their way around the 7854 - hopefully you can tease out enough details to pique their interest!
cheers,
Paul
|
Michael W. Lynch
Gary Robert Bosworth
David C. Partridge