Alignments are in the tuner section? I know modding fm tuners is/was popular. I almost forgot these tv's needed tuners!
I did on a Sony KV-2501 Profeel monitor back in the early / mid '80s. I retrofitted a 3 line comb filter from a Sony Broadcast VA-1V Betacam deck adapter. I also modified the sync stripper to exact 50% sync level to get rid of horizontal jitters. That monitor also had a designed in defect where they put the terminator resistor at the back panel rather than at the end of the cable where it connected to the PCB. It showed up as mild ringing. There was a problem in the vertical linearity due to capacitor tolerances. Replacing a fixed resistor with a pot cleaned that up. When I got it it was set up for 9300 Kelvin (too blue) and set it back to 6500. The tuner (separate chassis) that was part of it also had component tolerance problems in the EQ network in the video demodulator causing group delays. I also modified the multiplex output level (added an opamp) to work with a Sanyo (Fisher) stereo decoder. When the CRT wore out the second time it found it's way to the curb for a large trash pickup.
That separate tuner was pretty sophisticated for consumer use. It had a Surface Acoustical Wave (SAW) filter for the visual IF and had split IF and intercarrier for the aural demodulating. In true Sony tradition, the VHF Hi RF amp MOSFET failed for no apparent reason. I replaced just the MOSFET, not the whole RF module.
Digital TV fixed all of those problems. YEA!
Good riddance to analog TV.
G²
Last edited:
The FM radio frequency band was between former analog TV channels 6 and 7 in the USA.
These analog TV tuners were big and clunky, with a huge complicated multiple contact rotary switch
for channels 2-13. Originally the UHF section (for extending channels up to 83) was a separate,
continuous tuner, like an analog radio. It was a big deal when they were able to integrate the UHF
into the VHF tuner module, because the small time UHF TV stations were often ignored by the users
not wanting to fiddle with the separate UHF tuning knob. The UHF tuner had poor performance anyway.
NEW Zenith 175-1814R Tuner Module *FREE SHIPPING* | eBay
Last edited:
Jacking in for a computer
I modified a portable TV to convert it into a monitor for my first computer (an Ohio Scientific Superboard II).
I built the computer into an old cash register tray, and used it to predict the growth rate of the New Zealand National Library as a new graduate in the Architecture Department at the Ministry of Works and Development.
I imported it from the US in about 1979, and programmed it in BASIC and Forth.
I modified a portable TV to convert it into a monitor for my first computer (an Ohio Scientific Superboard II).
I built the computer into an old cash register tray, and used it to predict the growth rate of the New Zealand National Library as a new graduate in the Architecture Department at the Ministry of Works and Development.
I imported it from the US in about 1979, and programmed it in BASIC and Forth.
Junk TV sets were common in the early 1960's. I drug home every dead TV I found as a kid with the hope that I could fix it. Usually I blew up some more parts leading to the eventual cannibalization of the TV for its tubes, transformers and other parts. I had amassed a rather large collection of stuff that I used to make things, mostly guitar amps.
Somewhere around age 12 I got lucky and managed to create a working TV set out of two or three junk sets. How many 12 years old kids in about 1964 had their own TV? Certainly not anyone I knew.
At age 14 I went to a technical high school which had a 3 year electronics program. There we learned how to fix TV sets. There were plenty of dead TV's to learn on, mostly junk from the 1950's that had been donated to the school system. A student could claim a TV, radio or other donated item, and if he fixed it and successfully wrote a report detailing how and why, he would get a grade, AND get the item to take home.
After claiming and fixing a Baldwin organ and several Stromberg Carlson PA amps (converted to guitar amps), I helped unload a fresh truck load of junk, and there it was.....a COLOR TV. It was a large Emerson branded console which was actually made by RCA. Color TV's sets were rather rare and expensive in 1968, so I claimed it. My enthusiasm died when I figured out that the CRT was dead. It almost got gutted for its huge power transformer when the school got me a job in a TV repair shop and I made a deal for a used but live CRT.....It would take a few months of work at $1 to pay for it, but it happened.
It took me most my 11th grade year, but I rebuilt that TV, one stage at a time. From the tuner to the CRT and speaker we measured every resistor, tested every tube, swapped out every suspicious looking capacitor, ran sweep alignments on the IF stages, tuned every coil in the set, and even rewired the 6CB5 socket to run a 6146 to save the $5 for a new tube. The horizontal efficiency was about the same as what the SAMS showed for a 6CB5.
Near the end of my junior year (age 16) I got the CRT and brought it to school. We mounted it, and with minimal futzing around the TV worked. This was the biggest and most successful project of my young life, and my parents were rather surprised when I came home from school with a large console TV. Thew asked why I wanted such a big TV, and I replied ....just wait till you see the picture it gets. It was the first color TV in our entire neighborhood, and it did get quite a bit of attention. There were about 40 people in my bedroom the night color TV images were first transmitted from the moon.
That TV worked flawlessly until I gave it away when I left home in 1973. I spent some time experimenting with an early video recording system known as Cartrivision after the company folded and the systems appeared on the surplus market cheap. The cheap surplus systems were intended to be built into a TV set that was designed around the Cartrivision system. I got a system and successfully wired it into a RCA XL-100 solid state TV set. The only camera we had at the time was black and white, but it would record color TV from off the air TV. The system used large cartridges that only held 1 hour of video which was less than stellar in quality.
My attention shifted to computers and music synthesizers in the 70's, and I never went back to TV work.
Somewhere around age 12 I got lucky and managed to create a working TV set out of two or three junk sets. How many 12 years old kids in about 1964 had their own TV? Certainly not anyone I knew.
At age 14 I went to a technical high school which had a 3 year electronics program. There we learned how to fix TV sets. There were plenty of dead TV's to learn on, mostly junk from the 1950's that had been donated to the school system. A student could claim a TV, radio or other donated item, and if he fixed it and successfully wrote a report detailing how and why, he would get a grade, AND get the item to take home.
After claiming and fixing a Baldwin organ and several Stromberg Carlson PA amps (converted to guitar amps), I helped unload a fresh truck load of junk, and there it was.....a COLOR TV. It was a large Emerson branded console which was actually made by RCA. Color TV's sets were rather rare and expensive in 1968, so I claimed it. My enthusiasm died when I figured out that the CRT was dead. It almost got gutted for its huge power transformer when the school got me a job in a TV repair shop and I made a deal for a used but live CRT.....It would take a few months of work at $1 to pay for it, but it happened.
It took me most my 11th grade year, but I rebuilt that TV, one stage at a time. From the tuner to the CRT and speaker we measured every resistor, tested every tube, swapped out every suspicious looking capacitor, ran sweep alignments on the IF stages, tuned every coil in the set, and even rewired the 6CB5 socket to run a 6146 to save the $5 for a new tube. The horizontal efficiency was about the same as what the SAMS showed for a 6CB5.
Near the end of my junior year (age 16) I got the CRT and brought it to school. We mounted it, and with minimal futzing around the TV worked. This was the biggest and most successful project of my young life, and my parents were rather surprised when I came home from school with a large console TV. Thew asked why I wanted such a big TV, and I replied ....just wait till you see the picture it gets. It was the first color TV in our entire neighborhood, and it did get quite a bit of attention. There were about 40 people in my bedroom the night color TV images were first transmitted from the moon.
That TV worked flawlessly until I gave it away when I left home in 1973. I spent some time experimenting with an early video recording system known as Cartrivision after the company folded and the systems appeared on the surplus market cheap. The cheap surplus systems were intended to be built into a TV set that was designed around the Cartrivision system. I got a system and successfully wired it into a RCA XL-100 solid state TV set. The only camera we had at the time was black and white, but it would record color TV from off the air TV. The system used large cartridges that only held 1 hour of video which was less than stellar in quality.
My attention shifted to computers and music synthesizers in the 70's, and I never went back to TV work.
There was a fellow student in my classes at high school who liked to use o-scopes for TV's. Yup, TV images in green. Pretty small too.
I was only ever attracted to used TVs for the parts and amassed a collection of my own. That's were all my parts came from before high school, and the bulk of them during high school. I did rebuild paging amplifiers and other audio things, messed with digital electronics and all the other more common pursuits back then. A TV only looked like a pile of dust and parts to me. Won't touch them these days.
-Chris
I was only ever attracted to used TVs for the parts and amassed a collection of my own. That's were all my parts came from before high school, and the bulk of them during high school. I did rebuild paging amplifiers and other audio things, messed with digital electronics and all the other more common pursuits back then. A TV only looked like a pile of dust and parts to me. Won't touch them these days.
-Chris
> Originally the UHF section (for extending channels up to 83) was a separate,
continuous tuner
Ours was a separate box.
The TV had places for two knobs, VHF and UHF. But there was no UHF in the area so Dad got the VHF-only job, with a blank filler in the other hole. He said we could install a UHF tuner in that hole, someday. When someday came, he got a Gavin external UHF converter. Hot-chassis, damp floor, I learned about shock. Later I met one of the people who assembled those converters, zero knowledge of electronics, just rote iron-work.
As said, external video inputs were a common hack, for tape and computer display, though on hot-chassis sets this was risky. The book is Lancaster's "TV Typewriter Cookbook". The hot ticket was a series of Sony which could be run on battery, and for line had a genuine transformer 12V supply.
I came into a set of three HUGE Trinitrons, very tired. They already had ext inputs. I coded a 5150 PC with a self-invented markup grammar to display upcoming events in fonts and colors, for a concert hall lobby. Ran for years unattended. Each week I opened an editor and typed the new events. All on half a 360K flop.
continuous tuner
Ours was a separate box.
The TV had places for two knobs, VHF and UHF. But there was no UHF in the area so Dad got the VHF-only job, with a blank filler in the other hole. He said we could install a UHF tuner in that hole, someday. When someday came, he got a Gavin external UHF converter. Hot-chassis, damp floor, I learned about shock. Later I met one of the people who assembled those converters, zero knowledge of electronics, just rote iron-work.
As said, external video inputs were a common hack, for tape and computer display, though on hot-chassis sets this was risky. The book is Lancaster's "TV Typewriter Cookbook". The hot ticket was a series of Sony which could be run on battery, and for line had a genuine transformer 12V supply.
I came into a set of three HUGE Trinitrons, very tired. They already had ext inputs. I coded a 5150 PC with a self-invented markup grammar to display upcoming events in fonts and colors, for a concert hall lobby. Ran for years unattended. Each week I opened an editor and typed the new events. All on half a 360K flop.
I modified a generic CGA composite monitor's H freq to accept an MDA signal in order to get better resolution running DOS OrCAD during my teenage years. Took my grandfathers non-working 12" B/W TV apart, removed all parts off the board, tested them with my $2 mailorder VOM, replaced bad parts, put TV back together and got it working.
20 years later I was fixing obsolete industrial displays and reverse-engineering most of them, schematic was non-existent on 99.9% of the units. Typical work was adopting other types of available CRTs, FBTs, HOT to work with the old units. I also designed LCD replacement for CRT (and EL) monitors that were not compatible with available parts. In the process I ended up with piles of VAS transistors off the CRT driver boards. Used but otherwise original working parts for building amps.
On one of my vacations to my old home overseas, I found the Sony 21" TV that I bought from the duty-free many years earlier as gift for my mom was languishing outside the house. It was sentenced to be dumped after being diagnosed by a Sony repair depot as having a bad CRT. I didn't believe it all, so I checked the CRT 6.3V heater supply and found it to be low. The culprit was the series fusible series resistor, replaced it with a same value wirewound resistor plus slightly higher rating and Trinitron was back in service.
20 years later I was fixing obsolete industrial displays and reverse-engineering most of them, schematic was non-existent on 99.9% of the units. Typical work was adopting other types of available CRTs, FBTs, HOT to work with the old units. I also designed LCD replacement for CRT (and EL) monitors that were not compatible with available parts. In the process I ended up with piles of VAS transistors off the CRT driver boards. Used but otherwise original working parts for building amps.
On one of my vacations to my old home overseas, I found the Sony 21" TV that I bought from the duty-free many years earlier as gift for my mom was languishing outside the house. It was sentenced to be dumped after being diagnosed by a Sony repair depot as having a bad CRT. I didn't believe it all, so I checked the CRT 6.3V heater supply and found it to be low. The culprit was the series fusible series resistor, replaced it with a same value wirewound resistor plus slightly higher rating and Trinitron was back in service.
As a kid I modified a Emerson color TV set, a hybrid unit with some IC and transistors but still with 40KG6A and 42EC4A tubes. I added a RGB input and a insulation transformer, to use it as a computer monitor. I still remember the tedious convergency adjustements that had to be repeated every now and then with 16+ controls on a side panel.
Before that, I "fixed" b&W tube TVs that had been scrapped, by randomly exchanging tubes and turning the internal controls. A friend father was a TV repairman so the supply was plentyful. Everyone was discarding the old tube gears at that time, some of them were still mostly working. I built a PCL86 amplifier with scrapped parts and it mostly worked, but suffered from motorboating every now and then, probably bad solder joints. Since I had no training, that amp was built by tracing back a TV schematic from the speaker back to the volume control knob.
Before that, I "fixed" b&W tube TVs that had been scrapped, by randomly exchanging tubes and turning the internal controls. A friend father was a TV repairman so the supply was plentyful. Everyone was discarding the old tube gears at that time, some of them were still mostly working. I built a PCL86 amplifier with scrapped parts and it mostly worked, but suffered from motorboating every now and then, probably bad solder joints. Since I had no training, that amp was built by tracing back a TV schematic from the speaker back to the volume control knob.
You could hack old TVs, but in the 1960s and 70s Heathkit sold a color TV kit. it was a pretty good TV in fact. You built it like any Heathkit, though the IF strip came pre-built and aligned.
A friend of mine - a kid I used to "electronics" with - built himself a TV set.He made it from scratch in a huge plywood cab. Instead of a click tuner, his tuner was a continuous analog thing, like a table radio. I guess it really was a glorified table radio, come to think of it. So sure enough, right above channel 6 was the whole FM band, then other gaps in the channel series.
A friend of mine - a kid I used to "electronics" with - built himself a TV set.He made it from scratch in a huge plywood cab. Instead of a click tuner, his tuner was a continuous analog thing, like a table radio. I guess it really was a glorified table radio, come to think of it. So sure enough, right above channel 6 was the whole FM band, then other gaps in the channel series.
The popular Sony CPD - 1302 Multiscan computer monitor had some TO220 resistors on the video driver board that would fry causing the loss of one color. After having the same issues with genuine Sony replacement parts, I too jury rigged some big fat resistors into the monitor fixing the problem forever.
I might have built a video stabilizer thingy that simply created a sync signal in a PIC chip and switched it into the video signal with a mosfet switch.
An argument with some members of the Motorola ham club led me to design and build a amateur TV transmitter (ATV) for the 432 MHz ham band that used one of Motorola's RF power amp bricks. The "experts" in the ham club said that it couldn't be done since the modules were not linear, but a technique called "sync stretching" (basically pre-distortion) can overcome that. Several such transmitters were built.
Let's just say that it's possible to use the same technique with a power amp brick from an 800 MHz two way radio to build a similar transmitter so that your neighbors could watch the blacked out NFL game that you picked up on your DIY satellite dish made with PVC pipe and aluminum window screen using an old TV set that went to channel 82.
back around 1970 I opened up my parents basement 1960's 21 inchblack and white all tube tv and hot wired the volume control and put a RCA jack on the back. I then ran a cable to a 20 watt guitar amp and fed a pair of Altec VOTTs . I started watching an old war movie with the volume and bass turned up a bit, maybe a lot. It was my first home theater experience. My parents weren't too happy.
a few years later I bought a Philips 26" colour tv and I made a dot generator so I could align the tv. The tv needed colour alignment every 6 months or less.
a few years later I bought a Philips 26" colour tv and I made a dot generator so I could align the tv. The tv needed colour alignment every 6 months or less.
Back in the mid-1950's, my dad's friend, a local farmer, acquired a TV/radio set from an auction - with the tv section not working. In those days, you had to have a licence for both. It was checked by an engineer from the Post Office who fixed an official notice stating "TV not working-Licence as Radio only ".
After a week or so of fiddling round, the TV was working in glorious greenish/grey. It was a round tube with a mask to give a pseudo square face.
Andy
After a week or so of fiddling round, the TV was working in glorious greenish/grey. It was a round tube with a mask to give a pseudo square face.
Andy
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.