Topcat's Dream Service Bench Reborn!

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

....and last but not least, the CM2000 monitor tester.... This one still worked.



Full test of all its patterns....

Circle/crosshatch


Color Bars


Color Steps


Windows


Text


Raster


There were a couple others not shown, they didn't photograph well.

All the accessories were found.


My original full collection of Sencore pieces back from the service center days...and a soon-to-be HTPC for the benchtop...since its the same color & size of these machines, it'll fit in well.



Several of which were never taken out of service in over 20 years! The external power brick for the LC102 died about 8 years ago....so I cobbled one together from a charger from a dead Toshiba laptop until I found a real replacement....but all the rest has been solid during its useful lifetime....the storage rot on a few of the above doesn't count!


Some of this stuff I bought new (the LC102, PR570, CM2000, SC3100, and VC93)....some came from a defunked shops (VG91, TV92, CVA94, all the vintage Sencore, the bench supplies, and most of the rest).

That concludes this portion of this little experiment....next is to actually build the bench...and I haven't got that all figured out yet.

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

Honorable mention for an old Sencore scope I bought cheap on ebay....I don't know what inspired it, but I've started a weird collection of old test equipment to go along with the vintage pieces I already have (not shown)...old test equipment has a majesty & marvelous aura about it....

Anyway, Sencore PS148 scope, in mint condition with probe.... It seems to work fine....but y'all know me... I had to see what was inside... I opened it up and realized there was an empty tube socket, yet it still seemed to work. I looked through the paperwork that came with it and googled a little, apparently it was a modification which eventually became the "PS148A" version, where a heavier transformer was used and the rectifier tubes were replaced with diodes. This one has had those modifications. This one also included its original glare visor, which is also extremely rare....something that's been pitched in the trash long ago, so for it to still be there on a ~50yr old scope, not bad!!

Quick test from 110VAC.



Glowing tubes baby!!!

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

Unexpected pick-up....A cheap ebay score (open bidding for $21.00). Basically a small PC with a dead CMOS battery, so it wouldn't boot....seller didn't have a clue.....so:

...yea...a rather unusual piece...I didn't even know this existed till I stumbled upon it.


2 dead batteries....the onboard is the CMOS, not sure about the other.....but both are dead as farts. The 2 replacement batteries cost me more than I paid for the unit.


Once I set the paramteres in the BIOS, it would boot and function. The monitor on the right is the test output, the monitor on the left is just a mirror of what's on the internal display.



The output connector is a standard EVC connector....so for testing, what better than a voodoo3500 VGA dongle....


Internal HDD with DOS and its proprietary software. I will make a full image of this HDD and store it....I imagine obtaining a copy of this would be near impossible if it ever had to be reinstalled.


Getting to the nitty-gritty....the dead Varta CMOS battery leaked and damaged the PCB and one of the memory slots.


Battery removed and PCB cleaned up.




memory slot cleaned up....not that it'll ever get used....it has 1mb RAM in it and likely doesn't need more.


This sorry piece of shit.....I did order an identical replacement since it's a rechargeable 3.6v, not a standard 3v....but I'll likely relocate it to a self-contained unit off the PCB....so if this one leaks eventually, it won't further harm the PCB.


Awaiting the batteries.......so to be continued....

[ratdude747]

Re: Topcat's Dream Service Bench Reborn!

^Quantum fireball? Yeah, image that shit. And put in a different HDD that isn't as failure prone.

[TechGeek]

Re: Topcat's Dream Service Bench Reborn!

^quantum fireball? Yeah, image that shit. And put in a different hdd that isn't as failure prone.

qft

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

Yep, Quantum 'furball' isn't known for its long lifespan...the only reason it's probably still alive is because this machine probably wasn't heavily used.. It's already in the works. My attempt to cure this is a CF card with an IDE adapter. That hdd is 2.1gb. The OS (IBM DOS) and the control software consume 740KB <--yes, thats KILOBYTES....so a 64mb CF card + adapter on the way.

I might have to dig out an old copy of norton ghost.... clonezilla would not recognize the partition for some reason.....I guess fat16 is too old for it. I did dump all the files off it though, and being DOS-based, making it all work again probably wouldn't be too difficult. The machine was made ~2003 (that's what the calibration tag said), but the technology inside it is very early 90's.

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

I replaced the batteries, that fixed the obvious (checksum errors and bios settings)... I haven't tried the CF card mod yet, the adapter isn't here yet.....but I've been diddling around with custom resolutions......and with all the timings & frequencies, its a tad confusing....so its something I'm just going to have to research and tinker with.....

After repairs & reassembly....I also located the correct EVC to VGA cable.







1920x1200 test....





still some more diddling around to do....but not bad for a $21 gamble.

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

Well so much for the CM2220.... The CF card mod was a success...but a couple days after completing that, it began popping up 'video card firmware error' messages @ boot and it had no output. Eventually the errors went away, but it still has no output....even if I go back to the original drive. It still boots fine, and goes through all the motions....it just has no output... :-/ I have no clue....and as rare as it is, the odds of finding another to donate the output card is probably on par with winning the lottery.... Ohh well, lots of time wasted.....but thankfully not much money.

[TechGeek]

Re: Topcat's Dream Service Bench Reborn!

Well so much for the CM2220.... The CF card mod was a success...but a couple days after completing that, it began popping up 'video card firmware error' messages @ boot and it had no output. Eventually the errors went away, but it still has no output....even if I go back to the original drive. It still boots fine, and goes through all the motions....it just has no output... :-/ I have no clue....and as rare as it is, the odds of finding another to donate the output card is probably on par with winning the lottery.... Ohh well, lots of time wasted.....but thankfully not much money.

This may be worth a shot:
https://www.tulsa-ads.com/Sapulpa-/A...r-w-manual.JSP

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

This may be worth a shot:
https://www.tulsa-ads.com/Sapulpa-/A...r-w-manual.JSP

I saw that yesterday when I was googling solutions.....the pics are 11 years old and theres no contact information....

[TechGeek]

Re: Topcat's Dream Service Bench Reborn!

Could you try tearing it down completely and cleaning all the boards, interconnects, etc thoroughly and see if maybe that'll bring it back?

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

Could you try tearing it down completely and cleaning all the boards, interconnects, etc thoroughly and see if maybe that'll bring it back?

Already done, it was the first thing I did. no-go. Interesting thing turned up through the googling, there is a CM2250-PC, which is an ISA PC card with a windows95 based control software package..... That would be a neat one to find....I could use my own PC with it....but I'm sure the odds of finding one intact with the software would be on-par with winning the lottery.

Actually, the control board in the CM2220/CM2250 IS the ISA card fitted into their case....but without drivers/software, a conversion would be impossible....and the problem appears to be on that control board. If I remove it completely, the CM2220 still boots/loads the DOS-based software.

[stj]

Re: Topcat's Dream Service Bench Reborn!

does it have a video-rom?

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

does it have a video-rom?

It appears to, on the control board. The ROM itself wouldn't be difficult to find....the binary that's on it OTOH...

[stj]

Re: Topcat's Dream Service Bench Reborn!

the rom content is probably generic matched against the gfx chip - other than the boot strings.
it just sets up the bios to access the correct registers and such for the chip.

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

the rom content is probably generic matched against the gfx chip - other than the boot strings.
it just sets up the bios to access the correct registers and such for the chip.

I have no idea....its what drives the test output. The internal display/VGA out is another GPU all together.

[stj]

Re: Topcat's Dream Service Bench Reborn!

i was refering to the internal display - i didnt know you wreent.

post some decent pcb images.
it could be a dead ramdac - had those fail in the past.

[Topcat]

Re: Topcat's Dream Service Bench Reborn!

I got annoyed with it the other day and reassembled it and set it aside..... I'll take it apart and get some pics here pretty soon.

[stj]

Re: Topcat's Dream Service Bench Reborn!

if you have a good multimeter, see if it's generating goot H & V sync pulses.

[BigTroll]

Re: Topcat's Dream Service Bench Reborn!

I replaced the batteries, that fixed the obvious (checksum errors and bios settings)... I haven't tried the CF card mod yet, the adapter isn't here yet.....but I've been diddling around with custom resolutions......and with all the timings & frequencies, its a tad confusing....so its something I'm just going to have to research and tinker with.....

After repairs & reassembly....I also located the correct EVC to VGA cable.







1920x1200 test....





still some more diddling around to do....but not bad for a $21 gamble.

Nice! now if only topcat could do housecalls for a widescreen CRT convergence adjustment.