RE: IBM 1620
> -Original Message- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of ben > Sent: 31 August 2015 01:43 > To: cctalk@classiccmp.org > Subject: Re: IBM 1620 > > On 8/30/2015 6:32 PM, Tothwolf wrote: > > > On page 5, they describe 0.0031" 40 AWG magnet wire being reduced to > > 0.002" after soldering with 60/40 tin-lead solder. That 0.0011" > > reduction is basically 1/3 of the diameter of the wire. This explains > > the failures of the enamel wires in CHM's IBM 1620. > > > > Copper erosion from tin is something I'd never really given a lot of > > thought to, but it will certainly be something I keep in mind from now on. > > > But is that the case? Would not heat induced failure be the real case here as I > suspect that a amp or two of current is flowing that now very thin thread of > wire? Digging though the doc's and a little calculation clear this up. > Ben. > > I seem to remember that 1620 core runs warm, and you have to wait for it to get warm before the machine comes on-line ... see last paragraph http://www.angelfire.com/oh3/ebjoew/IBM_1620_Core_Memory.html Dave Wade
RE: Advice about repairing an IBM 5151
> Hi Tony, > > I have checked the horizontal signal from the MDA using an > oscilloscope. It is pin 8 like you mentioned. I get a regular 18KHz or > so signal out of that. Pin 9 gives the vertical signal at roughly > 50Hz. OK. Your PC and MDA card seem to be OK. Now trace through the horizontail circuit in the 5151. IIRC there is a driver transistor, the collector load of which is a transformer which couples to the base of the horizontal output transistor (sorry, I am doing this from memory, I don't have the techref in front of me). Do you get the 18kHz on the collector of the driver transistor? Are both transistors good? -tony
RE: APL\360
There are two other working vintage APL implementations. There is one for the IBM1130 which can be downloaded from here:- http://ibm1130.org/sim/downloads and the other APL/360 on MTS so again Hercules is needed. http://archive.michigan-terminal-system.org/discussions/programming-language s-available-under-mts is probably a good starting place Dave Wade > -Original Message- > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of > paul_kon...@dell.com > Sent: 30 August 2015 23:54 > To: cctalk@classiccmp.org > Subject: APL\360 > > Probably old news to some, but I just ran into this 3 year old article. Gotta > dust off your Hercules: http://www.computerhistory.org/atchm/the-apl- > programming-language-source-code/ > > And also http://wotho.ethz.ch/mvt4apl-2.00/ > > paul
Re: IBM 1620
> [...] then in 1996 I built a laser photoplotter that cranks out > 1000x1000 DPI images on red-sensitive film at 0.6 inches/minute. I'd be very interested in anything you care to share about its design and building /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTMLmo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
Re: Sales of unearthed Atari games total more than $100,000
As a kid that grew up with the Atari 2600 as my first system, I played ET a fair bit. I know it gets all the hate, but yea, when I first saw Donkey Kong on the 2600 I literally had a tear or two roll down, it was that bad. Christmas morning and the excitement and yea, maybe this one is defective I thought. Maybe it's stuck in black and white. Yes. I know Coleco was pimping their own system (Which was my 2nd console system) and I realize that people went back and remade Donkey Kong on the 2600 so it wasn't quite as bad. On the flip side, there are some games on the 2600 that are just so good with the limited hardware. Frogs and Flies, a very very good game. Of course Pitfall II is the one that pushes it to the limits, but I never had that one. ET was not the best but not that worst. I'll never forget when I finally got picked up by the spaceship or whatever. I was really young so really didn't know what I was doing. -- Ethan O'Toole
Re: Sales of unearthed Atari games total more than $100,000
> On Aug 31, 2015, at 10:40 AM, et...@757.org wrote: > > > As a kid that grew up with the Atari 2600 as my first system, I played ET a > fair bit. I know it gets all the hate, but yea, when I first saw Donkey Kong > on the 2600 I literally had a tear or two roll down, it was that bad. > Christmas morning and the excitement and yea, maybe this one is defective I > thought. Maybe it's stuck in black and white. Yes. I know Coleco was pimping > their own system (Which was my 2nd console system) and I realize that people > went back and remade Donkey Kong on the 2600 so it wasn't quite as bad. > I had the same sad experience when they released Pac Man for the 2600. IIRC, the Pac Man did not even change orientation when he moved in different directions! And the ghosts lost their individuality. I think I had moved on to ColecoVision by the time Donkey Kong was released on the 2600 and I felt so sorry for my friend who was still stuck on the 2600 when I saw it for the first time. Donkey Kong on Coleco was killer.
Re: IBM 1620
On 08/31/2015 02:59 AM, Dave G4UGM wrote: I seem to remember that 1620 core runs warm, and you have to wait for it to get warm before the machine comes on-line ... see last paragraph http://www.angelfire.com/oh3/ebjoew/IBM_1620_Core_Memory.html Yes, many IBM machines used heaters to stabilize the core temperature. The 360/40 and 360/50 had heaters for the local store (register stack). Not sure about the 360/30 where local and main store were all in the same unit. Not sure if the higher machines also heated the main store. Jon
Re: IBM 1620
On 08/30/2015 02:00 PM, Jon Elson wrote: I hacked a fiber optic light pen onto a Calcomp plotter and made some artwork directly onto film, and then in 1996 I built a laser photoplotter that cranks out 1000x1000 DPI images on red-sensitive film at 0.6 inches/minute. It can do up to 20 x 24" films, but I've never gone over about one foot square. The trick is, it has to be VERY accurate to line up with existing PC boards. I mostly use it to make solder paste stencils, now, but originally made it for PC board master artwork. That's pretty impressive, Jon. I do remember the headaches with registration of early multi-layer PCBs. Lots of rejects. --Chuck
photoplotter
On 08/31/2015 07:51 AM, Mouse wrote: [...] then in 1996 I built a laser photoplotter that cranks out 1000x1000 DPI images on red-sensitive film at 0.6 inches/minute. I'd be very interested in anything you care to share about its design and building Here's my web page on it: http://pico-systems.com/photoplot.html I built this in 1996, as soon as red laser diodes became available. (I'd been trying to make it work with LEDs before, but the optics got difficult.) I just converted it over recently to run off a Beagle Bone computer. Jon
Re: Sales of unearthed Atari games total more than $100,000
On August 31, 2015 at 10:17:25 AM, Peter Cetinski (p...@pski.net) wrote: I had the same sad experience when they released Pac Man for the 2600. I do remember feeling disappointment when I got Pac Man. It was a hot game. My mother picked it up as a surprise. We got it home and… what? I enjoyed E.T. at the time. It wasn't until I got on the Internet years later that I read it was the worst video game ever and had caused the collapse of a billion dollar industry. Cheers, m
Re: Sales of unearthed Atari games total more than $100,000
On Mon, Aug 31, 2015 at 10:09 AM, Mike Whalen wrote: > On August 31, 2015 at 10:17:25 AM, Peter Cetinski (p...@pski.net) wrote: > > I had the same sad experience when they released Pac Man for the 2600. > I do remember feeling disappointment when I got Pac Man. It was a hot > game. My mother picked it up as a surprise. We got it home and… what? > > I enjoyed E.T. at the time. It wasn't until I got on the Internet years > later that I read it was the worst video game ever and had caused the > collapse of a billion dollar industry. > I don't think E.T. caused the collapse of the industry. Pac Man was the worst game ever on the 2600. At least the worst that I ever played. ET had primitive graphics, but was playable (though frustrating if you hit one of the pit loops which, despite doom-sayer videos on the net, you can get out of with a little patience). Pac Man, in contrast, was so bad as to be almost unplayable. The translation from the arcade experience was horrible. Especially since the Activision carts at the time were so much better Atari hit a classic problem of failing to transition from a wide-open market to a saturated market and massively over-spent thinking the growth would last forever. When it hit the inevitable knee in the curve, they weren't prepare and had so many huge bets on the table they hadn't hedged that they imploded from bad management, not some silly game that disappointed. Warner
Re: MEM11 Status Update
On 8/30/2015 1:08 AM, Guy Sotomayor wrote: The MEM11 is a multi-function memory board for Unibus based PDP-11 computers. It contains: * 128KW memory * Emulates console ROM & boot ROMs * 2 SLUs (DL11s) * KW11K * KW11P * KW11L * KW11W * RF11 (emulating up to 8 RS11 disks) * KE11 Guy, Fascinating and great work (not that I understand more than a bare minimum). Is this board something that will work with the PDP-11/05? The 11/05 has a built-in console SLU which I'm not sure whether can be disabled or not. Thank you- -John
Re: MEM11 Status Update
On 8/31/15 10:05 AM, j...@cimmeri.com wrote: On 8/30/2015 1:08 AM, Guy Sotomayor wrote: The MEM11 is a multi-function memory board for Unibus based PDP-11 computers. It contains: * 128KW memory * Emulates console ROM & boot ROMs * 2 SLUs (DL11s) * KW11K * KW11P * KW11L * KW11W * RF11 (emulating up to 8 RS11 disks) * KE11 Guy, Fascinating and great work (not that I understand more than a bare minimum). Is this board something that will work with the PDP-11/05? The 11/05 has a built-in console SLU which I'm not sure whether can be disabled or not. It should work (famous last words!) in any Unibus based PDP-11. Any of the devices can be configured enabled/disabled and as to what the based address is (this includes the memory...if you want to use the memory to "fill in" the remainder, it can do that too). There is space for 32 boot ROM images, of which you can select any 4 to appear in the Unibus address space. So, that was a long answer to if (for example) on the 11/05 you want to retain the built in console SLU, you can do that and either have 2 additional SLUs, (or 1 or none). TTFN - Guy
Re: Sales of unearthed Atari games total more than $100,000
Funny you should mention Pitfall! Because it wasn't really until the 3rd party 'blockbusters' from outfits like Activision appeared, that the gaming public came to realize just how seriously lazy and unimaginative Atari's in-house development team was. On Sun, Aug 30, 2015 at 8:09 PM, Tothwolf wrote: > On Sun, 30 Aug 2015, drlegendre . wrote: > >> On Sun, Aug 30, 2015 at 1:41 PM, Ali wrote: >> >> How might a collector discern a "landfill" E.T. cart from any other E.T. cat that some snarky guy buried in the clay of his back forty? >>> >>> Not that I am expert or anything but my understanding is that the ET >>> cart is extremely rare to begin with. In fact the landfill collection is >>> the largest supply of the cart to be injected into the market. >>> >> >> A quick search of eBay would correct your 'understanding'. There are >> dozens of copies for sale, many with boxes and manuals. They start at about >> $5.00. >> >> The game is very common, and generally considered worthless. It's a joke, >> possibly the "worst video game ever made" - up there with Superman 64 for >> N64. >> > > When I used to buy Atari stuff at resale shops to build my own collection > (back in the early to mid 1990s when people were practically giving away > 2600 stuff), ET seemed to be pretty common. It wasn't nearly as common as > Pac-Man or Pitfall! or a pack-in game like Combat, but I saw them > frequently. I gave/traded away quite a few copies of ET but kept at least > one. >
Re: Sales of unearthed Atari games total more than $100,000
Low, uninformed blow. By the time Pitfall comes out, the Atari 2600 has been extant for five full years, and David Crane On Mon, Aug 31, 2015 at 1:41 PM, drlegendre . wrote: > Funny you should mention Pitfall! Because it wasn't really until the 3rd > party 'blockbusters' from outfits like Activision appeared, that the gaming > public came to realize just how seriously lazy and unimaginative Atari's > in-house development team was. > > On Sun, Aug 30, 2015 at 8:09 PM, Tothwolf wrote: > > > On Sun, 30 Aug 2015, drlegendre . wrote: > > > >> On Sun, Aug 30, 2015 at 1:41 PM, Ali wrote: > >> > >> How might a collector discern a "landfill" E.T. cart from any other E.T. > cat that some snarky guy buried in the clay of his back forty? > > >>> > >>> Not that I am expert or anything but my understanding is that the ET > >>> cart is extremely rare to begin with. In fact the landfill collection > is > >>> the largest supply of the cart to be injected into the market. > >>> > >> > >> A quick search of eBay would correct your 'understanding'. There are > >> dozens of copies for sale, many with boxes and manuals. They start at > about > >> $5.00. > >> > >> The game is very common, and generally considered worthless. It's a > joke, > >> possibly the "worst video game ever made" - up there with Superman 64 > for > >> N64. > >> > > > > When I used to buy Atari stuff at resale shops to build my own collection > > (back in the early to mid 1990s when people were practically giving away > > 2600 stuff), ET seemed to be pretty common. It wasn't nearly as common as > > Pac-Man or Pitfall! or a pack-in game like Combat, but I saw them > > frequently. I gave/traded away quite a few copies of ET but kept at least > > one. > > >
Re: Sales of unearthed Atari games total more than $100,000
Worst game - Journey Escape or whatever it was called. On Mon, Aug 31, 2015 at 1:41 PM, drlegendre . wrote: > Funny you should mention Pitfall! Because it wasn't really until the 3rd > party 'blockbusters' from outfits like Activision appeared, that the gaming > public came to realize just how seriously lazy and unimaginative Atari's > in-house development team was. > > On Sun, Aug 30, 2015 at 8:09 PM, Tothwolf wrote: > > > On Sun, 30 Aug 2015, drlegendre . wrote: > > > >> On Sun, Aug 30, 2015 at 1:41 PM, Ali wrote: > >> > >> How might a collector discern a "landfill" E.T. cart from any other E.T. > cat that some snarky guy buried in the clay of his back forty? > > >>> > >>> Not that I am expert or anything but my understanding is that the ET > >>> cart is extremely rare to begin with. In fact the landfill collection > is > >>> the largest supply of the cart to be injected into the market. > >>> > >> > >> A quick search of eBay would correct your 'understanding'. There are > >> dozens of copies for sale, many with boxes and manuals. They start at > about > >> $5.00. > >> > >> The game is very common, and generally considered worthless. It's a > joke, > >> possibly the "worst video game ever made" - up there with Superman 64 > for > >> N64. > >> > > > > When I used to buy Atari stuff at resale shops to build my own collection > > (back in the early to mid 1990s when people were practically giving away > > 2600 stuff), ET seemed to be pretty common. It wasn't nearly as common as > > Pac-Man or Pitfall! or a pack-in game like Combat, but I saw them > > frequently. I gave/traded away quite a few copies of ET but kept at least > > one. > > > -- Bill vintagecomputer.net
Re: Worst Video Game Ever was Re: Sales of unearthed Atari games total more than $100,000
"3.5 million of the 4 million produced were sent back to the company as unsold inventory or customer returns. Despite sales figures, the quantity of unsold merchandise, coupled with the expensive movie license and the large amount of returns, made E.T. a major financial failure for Atari" Thats not good for Atari, but that doesn't make it the worst game ever. I agree with those who say Pac Man... I mean it looked nothing like the Arcade and it sounded like they sampled a rubber band. Not a good game at all. But it was the Atari 2600, at that day and age I don't think there was an expectation that the game on the home system would look like the arcade? It was from the era of tennis tv games and such? It had a mouth, and a pass thru, and ghosts and dots. Colecovision and others started to change expectations. I guess it wasn't too long after ColecoVision that Atari 8 bit computers and that brought with it pretty good ports of Arcade titles -- I was probably late to the 8bit atari (800XL here) I guess the people with the 400/800 were first to have arcade-ish gameplay. The 8bit computers still isn't as same as playing the real arcade PCB though. Just closer. That day I got the NES. I think I hit reset 100 times over and over just to hear the intro music from the Gyromite cart. It had clear drumbeats! And multiple part music. It was so good. The reset button felt nice and quality even. -- Ethan O'Toole
Re: Worst Video Game Ever was Re: Sales of unearthed Atari games total more than $100,000
On 8/31/2015 12:56 PM, et...@757.org wrote: "3.5 million of the 4 million produced were sent back to the company as unsold inventory or customer returns. Despite sales figures, the quantity of unsold merchandise, coupled with the expensive movie license and the large amount of returns, made E.T. a major financial failure for Atari" Thats not good for Atari, but that doesn't make it the worst game ever. I agree with those who say Pac Man... I mean it looked nothing like the Arcade and it sounded like they sampled a rubber band. Not a good game at all. But it was the Atari 2600, at that day and age I don't think there was an expectation that the game on the home system would look like the arcade? It was from the era of tennis tv games and such? It had a mouth, and a pass thru, and ghosts and dots. Colecovision and others started to change expectations. I guess it wasn't too long after ColecoVision that Atari 8 bit computers and that brought with it pretty good ports of Arcade titles -- I was probably late to the 8bit atari (800XL here) I guess the people with the 400/800 were first to have arcade-ish gameplay. The 8bit computers still isn't as same as playing the real arcade PCB though. Just closer. That day I got the NES. I think I hit reset 100 times over and over just to hear the intro music from the Gyromite cart. It had clear drumbeats! And multiple part music. It was so good. The reset button felt nice and quality even. -- Ethan O'Toole You're right re the expectations of that time. It's very difficult to put oneself back in that naive mindset, to remember how things *first* struck us. That said, however, I'm still quite happy playing with my Bally Arcade... ;-) - J.
Re: De-yellowing results
On 08/30/2015 05:55 PM, Tothwolf wrote: Wrong type of UV. You are mostly getting long wave UVA outdoors, so blacklight lamps would seem to be the correct (and MUCH safer) choice. When I looked at 24" T8 bi-pin blacklight lamps, they were going for about USD $10 per lamp. UVC germicidal lamps would also require an enclosure to protect the user from exposure to short wave UV. This isn't as necessary with long wave UVA (unless someone was going to be around it for long periods of time on a regular basis). Some digging for anectodal evidence (there's very little methodical technical stuff) on the process indicates that the ordinary aquarium-style UVA lamps work extremely slowly; the germicidal UVC lamps work very quickly, but overexposure to UVC is counter-productive in that it furthers the breakdown of the flame retardant bromine-containing stuff that caused the yellowing. So perhaps UVB is the best compromise, assuming that Planck was onto something... Note that much of the material on the web does not concern computer equipment. The most disturbing reports were from the people to de-yellowed gloss-finish items reporting that said items come out less than glossy, particularly when percarbonate (Oxiclean) was added to the mix. Reports were varied and interesting. UV was cited repeatedly as a suspect when it came to causing yellowing in the first place This flies in the face of my experience in that I've had gear that's spent almost all of its life in a closed storage cabinet that yellowed anyway. Regardless of all of this, it seems that yellowing does recur, which is what one would expect from what amounts to a surface treatment. No, I don't plan on using this process... --Chuck
Re: Worst Video Game Ever was Re: Sales of unearthed Atari games total more than $100, 000
It was thus said that the Great j...@cimmeri.com once stated: > > That said, however, I'm still quite > happy playing with my Bally Arcade... ;-) I remember that system! My uncle had one. What I remember most about it is the controller, a combination joystick and paddle in one. It was quite a nice controller. -spc
Re: Worst Video Game Ever was Re: Sales of unearthed Atari games total more than $100, 000
I remember that system! My uncle had one. What I remember most about it is the controller, a combination joystick and paddle in one. It was quite a nice controller. -spc I think a friend is looking to buy a set of controllers for a Bally Astrocade if anyone has a set they're interested in selling. He is located in Chesapeake VA but shipping is not a big deal. I was just poking around inside a few arcade games yesterday including Battlezone, Tron, Tempest and a few others. -- Ethan O'Toole
Re: IBM 1620
On 08/30/2015 05:09 PM, Chuck Guzis wrote: On 08/30/2015 02:00 PM, Jon Elson wrote: I hacked a fiber optic light pen onto a Calcomp plotter and made some artwork directly onto film, and then in 1996 I built a laser photoplotter that cranks out 1000x1000 DPI images on red-sensitive film at 0.6 inches/minute. It can do up to 20 x 24" films, but I've never gone over about one foot square. The trick is, it has to be VERY accurate to line up with existing PC boards. I mostly use it to make solder paste stencils, now, but originally made it for PC board master artwork. That's pretty impressive, Jon. I do remember the headaches with registration of early multi-layer PCBs. Lots of rejects. YIKES! Multilayer! I do have a system for registering 2-layer boards, back when I used to make those myself. You need a piece of Plexiglas about the same thickness as the PC board material. You need a scrap of PC board material to use as a spacer between the front and rear artwork films. You put this on a light table, and glue the strip of PC board material to the edge of the film, place the Plexiglas on the film and place the other film on top of the Plexiglas. Glue the top film with rubber cement and use a magnifier to adjust alignment until it is as close as you can get it, then put a weight on the glued joint and leave it for a couple hours. When the glue is dry, you can slip a photoresist-covered board between the two films and expose in a vacuum frame. The two sides will come out well-aligned. Jon
Re: photoplotter
I have a "hot tub" scanner which could be adapted to plotting which is IIRC 4 x 4' It would be free for the taking to an interested party in LA CA area. It has the mechanism to move a mirror which was used to scan with a very nice scan camera, so has all the logistics of holding paper while you move around under it. It is an Ektagraphic, again IIRC which was made by Kodak. Was one of those, "You can have the pile for $200 less if you take the scanner" thanks Jim On 8/31/2015 8:41 AM, Jon Elson wrote: On 08/31/2015 07:51 AM, Mouse wrote: [...] then in 1996 I built a laser photoplotter that cranks out 1000x1000 DPI images on red-sensitive film at 0.6 inches/minute. I'd be very interested in anything you care to share about its design and building Here's my web page on it: http://pico-systems.com/photoplot.html I built this in 1996, as soon as red laser diodes became available. (I'd been trying to make it work with LEDs before, but the optics got difficult.) I just converted it over recently to run off a Beagle Bone computer. Jon
Re: De-yellowing results
On 8/31/2015 1:43 PM, Chuck Guzis wrote: > > Reports were varied and interesting. UV was cited repeatedly as a > suspect when it came to causing yellowing in the first place This flies > in the face of my experience in that I've had gear that's spent almost > all of its life in a closed storage cabinet that yellowed anyway. > > Regardless of all of this, it seems that yellowing does recur, which is > what one would expect from what amounts to a surface treatment. > > No, I don't plan on using this process... > > --Chuck > My VT100 is most yellow on the side facing the window, which for years had ordinary glass. It is less yellow front and back, and almost no yellow on the side away from the window. Same with its keyboard. So, in at least some cases, it does seem to be related to how much light that falls on the surface. JRU
Re: De-yellowing results
On 08/31/2015 09:10 PM, Jay Jaeger wrote: My VT100 is most yellow on the side facing the window, which for years had ordinary glass. It is less yellow front and back, and almost no yellow on the side away from the window. Same with its keyboard. So, in at least some cases, it does seem to be related to how much light that falls on the surface. Yup. I pulled a ITT clone of a AT&T 2500 series desk set phone from the storage cabinet. You know, the usual made-to-last 50 years iconic phone. It was a light brownish-beige after I picked it up cheap back in the 1980s. It has never been used, much less seen the light of day. Today, the beige has developed an ugly yellow cast--and it's uniform over the entire phone. The material, as I seem to recall, is ABS (Cycolac). Oddly, the WE-made same-color phones that I have and are out in the open (and the same color) don't show this discoloration. --Chuck
Somewhat OT: Freighting Items
I know this is a topic that comes up quite often and I have archived a number of threads. However, I am still not finding what I need. The back story is that I need to have a desk shipped across the country to me. The desk measures 28" long, 27" wide, 35" tall and is ~125 pounds unpacked. While it is possible to disassemble the desk I rather not. I've gotten quotes form a number of outfits as follows: 1. UPS: $1200 to pack/crate the desk and ship it. 2. Craters and Freighters: $895 to wrap in PE Foam, Styrofoam, bubble wrap, and box shipped door to door (i.e. not real freight). 3. Freightquote: $475 if I palletize it/pack it myself (have to clarify if this is door to door or do I have to drop off and pickup). Anybody else have other suggestions/recommendations? From what I understand this desk is not that heavy (in the freighting scheme of things) and would easily fit on one pallet and maybe even a half pallet. But I've never shipped something via freight so maybe these are all accurate prices. Any help/guidance is very much appreciated. Thanks. -Ali
Re: Advice about repairing an IBM 5151
Hi, I traced the 18Khz signal all the way from the moment it enters the logic board until the video board (attached to the neck of the CRT). The signal is there (it has different shapes but it is 18KHz). The output of both transistors is 18KHz and so is the output of the transformer. I traced it across resistors and capacitors as well. The voltage (Vpp) does change as expected but the signal is present. Pin 6 and 7 have the 18KHz signal too on the CRT connector. However they only measure 7 and 10V respectively. Regards, Vlad. On 31 August 2015 at 02:26, tony duell wrote: > >> Hi Tony, >> >> I have checked the horizontal signal from the MDA using an >> oscilloscope. It is pin 8 like you mentioned. I get a regular 18KHz or >> so signal out of that. Pin 9 gives the vertical signal at roughly >> 50Hz. > > OK. Your PC and MDA card seem to be OK. > > Now trace through the horizontail circuit in the 5151. IIRC there > is a driver transistor, the collector load of which is a transformer > which couples to the base of the horizontal output transistor > (sorry, I am doing this from memory, I don't have the techref > in front of me). Do you get the 18kHz on the collector of > the driver transistor? > > Are both transistors good? > > -tony
RE: Advice about repairing an IBM 5151
> Hi, > > I traced the 18Khz signal all the way from the moment it enters the > logic board until the video board (attached to the neck of the CRT). > The signal is there (it has different shapes but it is 18KHz). The No, that is a different 18kHz signal. That is the video, which will have a significant component at the horizontal frequency. It starts from pins 6 (intensity) and 7 (video) of the DE9 connector You need to trace on from pin 8 to transistors on the main board, right up to the flyback transformer. -tony
Re: TK50/TK70 Info
Am 28.08.15 um 06:39 schrieb Mark J. Blair: > I have very limited experience with this family of drives so far, but what > little I have is not good. Pictures: > > https://twitter.com/nf6x/status/617511461452013568 > > https://twitter.com/nf6x/status/617519989721923584 I had the exact same problem a few years ago. Tape sticks to head... I wanted to use 9 track instead of TK50, but those tapes where unreliable too. I finally gave up on tapes, any tape technology, as the media has deteriorated into uselessness. -- tschüß, Jochen
