I've recently acquired a batch of service data for the Mitsubishi TV range covering mid 70s to early 80s, perhaps this will bring back some memories for those of you who serviced these back in the day. Sods-law, in the batch was the manual for the CT-2017BMs I recently had on the bench, all I had at the time was the R&TS circuit, in the end it wasn't required due to the ultra reliability.
Personally, I rather like the 1977 CT181B & CT205B, would quite like to find one of those, mostly it's the 80s ones that surface.
Personally, I rather like the 1977 CT181B & CT205B, would quite like to find one of those,
That could be the "G" or the "K" chassis.
The G chassis had two towers holding plug-in modules. The connectors became intermittent after a few years.
And the 110 degree small-neck delta CRT always had marginal convergence and purity.
The K chassis (in-line CRT) was much more reliable. Don't think I ever had to fix one.
The Q chassis that followed was around for a lot longer, but I can't recall ever having to fix one of those either.
Later sets in that list are Q chassis, the sets with 110 degree CRT are G chassis.
Our version of the CB-100B was commonly used by ENG crews as it had a battery pack.
AWA-Redifusion must have sold thousands of them, with AV In-Out conversions.
Back in the 80s we used to sell hundreds of AV In-Out conversion kits to AWA-Rediffusion because our design required less modification of the TV (Q chassis) and so was easier to fit.
In my time in TV Trade (30 years) never came across a Mitsubishi TV, let alone colour TV, for repair. Must have been extremely reliable.
The first Mitsubishi ctv sets i came across were the CT200B in late 1972, early 1973. These sets produced brilliant pics and left the UK sets for dead. Only fault i ever knew was the pbu sometimes needed replacement.
A salesman I used to work with always pronounced it "Mitsibushi" which used to do my head in!
Mitsubishi - "three diamonds".
I worked for them during this period. They were very reliable, so much so that the dealers had little experience with repairs. There were some funny dealer enquiries on the phone. The VCRs unfortunately were not as good quality.
Interestingly, mitsu 三 is (3 for objects without a specific counter) but bishi 菱 doesn't actually mean diamond but rhombus (in other words the shape). The diamond gemstone is kongouseki 金剛石.
Yes, very reliable, especially the Q series chassis from the 80s.
That was my experience in Australia.
But then the Oz Pye T34 chassis (designed and made here) used similar design concepts and was just as reliable.
I only ever encountered one Mitsubishi and that was when I was doing private work away from Philips. It's only problem was a faulty standby transformer. It was ten years old and the back had never been off. I obtained a replacement transformer which I think just plugged in, switched on and away it went giving a superb picture that didn't need any adjustments. It weighed a ton though! Built like a battleship. I took it back to the customer who was delighted that the set was working again. One of the simplest repairs I ever did.
We used to service the monster 4:3 33” Mitsubishi used in a chain of bookmakers. No chassis as such, the PCBs were mounted on the huge metal magnetic degauss shield, very reliable sets I recall.
Earlier VCRs were very good but the thick black moly grease went sticky and was a nightmare to get off your skin. Their later mid mount machines were unfortunately very mechanically fragile, a lot of plastic items were pressed into the chassis and when they broke like the rails for the cassette tray, repairs were not possible. Tthe infrared LEDs used for various sensors along with the electrolytics used in the PSU were unreliable.
The mitsubishi TVs I remember form the 80s had a blue faceplate.
My Grandad had one my Uncle picked up second hand for him, with teletext & a holder for the remote on the back.
It was still working fine when my Grandad died in 1999.
The blue faceplate tint was to correct for a cheaper, more efficient "red" phosphor that was actually orange. You might have seen it used in RCA delta CRTs.
AWA touted it as a sales feature. It certainly differentiated their TVs from others.
A salesman I used to work with always pronounced it "Mitsibushi" which used to do my head in!
Yes well in Australia what I think he was referring to is called a "map of Tassie" (state of Tasmania)
The first Mitsubishi ctv sets i came across were the CT200B in late 1972, early 1973. These sets produced brilliant pics and left the UK sets for dead. Only fault i ever knew was the pbu sometimes needed replacement.
Yes these were the first officially in the UK. They had super bright displays, let down slightly, and maybe because, they didn't use EBU phosphors. This led to the red being slightly orange. These also used a non-PAL decoder (as did the next slimline models). The decoder deserves a whole article of its own. It was designed to avoid the PAL patent and thus allow imports without having to ask or pay Telfunken. Of course this meant the sets couldn't compensate for chroma phase error and thus needed a hue control.
Of note is that Mitsubishi never made 110 degree tubes, all their slim tubes were 100 degrees. This was a sweet-spot for power, less deflection power needed and the neck could be made shorter. Tubes with 110 degree deflection were the Mullard tubes fitted in the Livingstone factory on much later sets. These also used European deflection components.
A salesman I used to work with always pronounced it "Mitsibushi" which used to do my head in!
It was recognised early on that pronunciation would be a problem. I remember an advertising campaign on London Transport busses that read: "say MIT-SOO-BEE-SHE and bring a little colour into your life".
The blue faceplate tint was to correct for a cheaper, more efficient "red" phosphor that was actually orange. You might have seen it used in RCA delta CRTs.
AWA touted it as a sales feature. It certainly differentiated their TVs from others.
The blue glass tubes were a gimmick with the name "Blue Diamond". Yes it was made to differentiate from other makes at time when CRT manufacturers were tinting the glass to improve contrast ratio.
Personally, I rather like the 1977 CT181B & CT205B, would quite like to find one of those, mostly it's the 80s ones that surface.
I believe the 181 and 205 were the pinnacle of reliability. My late mother had one for more than 25 years before swapping out for a larger model. The tube was showing its age by that time. I'm afraid that was before I treasured old sets...
Built like a battleship.
The 'made in Japan' models for Europe and UK used a mains transformer. This was a convenient way of using the same low voltage (120V) deflection components that were used in US and Japanese models. Unfortunately that made them very heavy. A bonus was that the chassis was isolated from the mains. This was picked up by the companies that supplied semi-pro monitors. They would add audio composite video interfaces and sell them on. I well remember an engineer called Joe Wilcox would do this in his shop-fronted workshop in Waterlooville. He and Roderic Snell became partners to found the broadcast technology company Snell and Wilcox. I wished I had accepted his job offer...
Not sure what made me think of this. Those early models employed the most economical deflection regulation to counteract 'blooming' at high EHT current. It was 2 resistors! One was a 200Megohm between the final anode and ground. The other was in series with the power line to the H and V deflection circuits. I think it was several hundred ohms. Its operation was simplicity itself. As EHT current demand increased, so the voltage drop across the resistor increase, so the voltage to the H and to the V deflection circuits reduced. Thus the picture size remained constant. The 200Megohm improved the dynamic picture size regulation by giving a steady demand. This could never be as good as the active regulation that was appearing in TVs at this time but it was economical and never went wrong.
Hi John, all you former TV engineers never cease to amaze me with your total recall of circuits from 50+ years ago, yet if asked what you had for lunch last week......only to be met with the thousand yard stare 😶
Great recall 👍
total recall of circuits from 50+ years ago, yet if asked what you had for lunch last week......only to be met with the thousand yard stare 😶
How true! If you care to scan the CT200B schematic I'll point out the other resistor. Actually if you do upload it, I'll write an article on how the decoder actually worked.
If you care to scan the CT200B schematic I'll point out the other resistor. Actually if you do upload it, I'll write an article on how the decoder actually worked.
Scanned, clicking on the image below will load the full resolution circuit. If on a PC, click on it, then click again to zoom to actual pixels. On a tablet or phone, pinch to manipulate. Look forward to reading your explanation of their decoder functionality.
