Hi Folks. Just an update of how things are going with the TV's I've been repairing of late. Two H.M.V.'s and three Kriesler 59-01's.

As usual, when working on the early sets, (the ones with delta tubes), the condition of the tube governs the how well the end result will be.

I like to get the sets going even if the tube only tests fair. This will produce a working chassis/set of modules that can be used in fault finding. Sourcing parts is becoming more of a problem. Sets like the Kriesler have knobs that are easy to break, or just plain missing. Buying a television just to get a set of knobs is now a reality.

The saga of the Kriesler with the rotary U.H.F tuner.
This set was a replacement for another Kriesler that had a bad tube. As usual, there were decades of time for faults to develop, caps to dry out, dry joints to form, pots to become noisy,
( carbon tracks, and the now common, the connection to the wiper arm).
This set as previously related in other reports, had a close encounter with lightning.

Now hat the set has returned to its home, the tally was, Power supply rebuild. Two switching transistors in the band switching. Seized tuner. U.H.F. mixer diode short circuit. Replacement diode sourced from over seas. Over-voltage thyristor damaged. One horizontal output transistor shorted. One line output transformer. Some of the damage was caused by a NEW part failing! A new, 0.11mfd 2kV cap reduced in value by about ½ from memory. Although the cap only had a peak voltage of 1kV, and it failed causing carnage. What to do? I made an array of four caps, series parallel and now there is only 500Volts across it. I tested it for a week before I could sleep well. Imagine. A 2kV cap failing at 1kV.

Apart from components drifting, the only fault left is that the U.H.F tuner is a bit snowy. Can't get the correct transistor. Still looking for a suitable tuner for testing purposes. Thank you to the member who sent me a couple of tuners. Not only am I finding seized shafts, but now I the tuner rotating vanes are also seized.

Next project. Now that I have the work bench back, I now have a Blaupunkt sitting on it. This set has the A67-150X tube in it. They died like flies and were what really killed off the AWA 4KA televisions. This set followed me home from my Christmas stay in Melbourne. From what is written above, things look grim, but upon removing the back cover I found it had a rebuilt tube! Never seen one of those in a Blaupunkt before.

Tested it. More than 1mA on one gun, and the other two are 0.9mA and 0.95mA Excellent. But first I must reform the main electro. It is bigger than a hand grenade, and would go off with as much force. Little electro's are scary enough when they go off.

This will do for now. I will keep you all informed .

Wayne.

Hi Wayne!

You have a KC Blaupunkt!

That HORRIBLE power supply kludge to meed Oz standards!
The original design had a half-wave rectifier, hence the big cap.
They had to convert it to a bridge, but then arrange for start-up to occur in half-wave to limit the inrush current, because no change was permitted to the main chassis. That's what that little PCB is on the side.

It frequently fails, with some drama.

How to fix:

Replace all the diodes, the SCR, the fuses.
Works OK on the isolation transformer.
Plug it in direct to mains, switch on gingerly and expect a big BANG and a destroyed bridge board!
The SCR can false-trigger and switch the full bridge in on start-up. Inrush current charging that 1000μF electro is HUGE!

I never tried this, but I reckon a better solution would be to replace the 1000μF with 330μF, wire the bridge as full-time (bypass the SCR) and add a 2.2 ohms 10 watt resistor in series with the mains. Preferably bracket this resistor onto the heatsink.

I used to repair those Blaupunkt's back in the day. That half wave full wave cct was the main source of problems.
Every time one came in I'd pull out the standard kit of destroyed parts as well as replacing the channel adjustment trim pots which all went crusty.
They made a nice picture once all their (many) ills were addressed.
Used to work on HMV C211's also.
Must have been a glutten for punishment.

Could I see a picture of a KC Blaupunkt? I think this might have been the first set I attempted to fix; I gave up after a small explosion somewhere inside.

Hi Sue.
Your e-mail address is hidden. If you e-mail me,, I will get your e-mail address and will send back some photos of the set and chassis.

Regards

Wayne.

Those KCs had the most intriguing 7 segment channel indicator lamp display I've ever seen.

Using filament lamps, all connected in series and supplied from 145 volts via a current source transistor.

Transistors shorted out the unlit segments and a diode array supplied the logic. All discrete.

The Bosch engineers loved their diodes! Check out how many there are in that set!

Interim Report.

My work on the Blaupunkt has stalled at the moment. I have the power supply working and E.H.T. but only a little vertical deflection.

My poor close up-eyesight does not help with voltage measurements. With the help of one of our members, I have a vertical module on the way. Hopefully, this will get the set going. I have tried so many things to get it going. Sprinkling Holly Water and having the set blessed by my minister is being considered.

The set draws more current than my my 600W isolation transformer finds comfortable, and it pops the internal fuse after a while. Although my C.R.O. is not earthed, many items on my work bench are.

Regarding the circuity of European sets, we were of the belief that European designers thought that one ought not use one transistor to do a job, when the job could be done just as well with ten.

Re the current draw, suggest you get rid of the half-wave circuit, fit a bridge and change the 1000μF to about 220μF or 330uF.

I worked for a time at Omnitronics who were the agents for Blaupunkt. No ordinary isolation transformer can power that set with the half-wave rectifier running.

The successor model to the KC was a vast improvement. It used the Toshiba in-line-gun CRT but the Blaupunkt ones had a finer slot pitch than we saw in the Ranks and Pyes of the time. I had to translate the service manual for it - actually mainly re-write a non-technical translation from the German that made little sense!

Hi all. It is time for another update regarding the Blaupunkt television with the delta tube. A bit of a long repair this one.

Some of the complications are as follows.
First, I am on Long Service Leave, and therefore not driving past the door of W.E.S. Components, five times a week.
Second, I am having enormous trouble sourcing suitable replacement parts. Perhaps I am unlucky but capacitors are breaking down without their voltage being exceeded. I have had a 2kV polypropylene cap decrease in capacitance although there was less than 1000 volts across it. That one took out a horizontal transistor and a line output transformer.

Eight polypropylene caps from Element 14 cost just over $60.00 These are being used in pairs to replace the 11nF caps across horizontal output transistors in Philips and Kriesler TV's.

Fake/counterfeit parts are becoming a real problem. I first encountered the problem in about 2002, when a certain, “travelling salesman,” would call into our repair shop with a van load of common parts. Video belt kits, video heads, electrolytic caps, fuses, and certain power semiconductors etc. We started to have a spate of call backs. Traced back to low quality power transistors/STK regulators.

Next roadblock. I have found it necessary in all cases, from this time on, to replace any cap with the brand name Rifa, AEE, or Wima on it. I am getting tired of having mains filter caps erupting into smoke and flames, some minutes to an hour after being tested and put back into service after decades of not being powered. All three of the Wima branded caps in the Blaupunkt failed after testing O.K. The mains filter shorted, taking out two fuses, one of the two G2 filters blew up, and the other G2 filter shorted, these took out two G2 rectifier diodes and incinerated a 68k resistor damaging the board.
No more Mr Nice Guy. Any component with form will be replaced regardless of it claiming innocence.

Finally for now, The Blaupunkt is producing a picture, but trying to keep the set running long enough to fix and adjust is delaying things. I am off to Jaycar shortly to buy some diodes. UF4007's I hope to get the G2 line back.

Will update again soon.

Wayne.

capacitors are breaking down without their voltage being exceeded

Where did you buy those? Are they 'brand name' caps?

Hi G.T.C.

The caps in the Krieslers came from W.E.S.
There is no brand name on them that I can see.
They are smaller than the original caps fitted to the set, but are decades newer.

The re-gunned picture tube looks to be not the best. I can not get the purity good. Perhaps the gun to tube alignment was not the greatest. When trying to centre the red to the centre of the screen, the raster is off the screen at the bottom right.


The temperature locally is about 2 to 3 degrees at sunrise each morning.
If you are feeling cold, I will let you stand next to the heat sink that holds the vertical transistors.Too hot to touch for more than 7 or 8 seconds. The 2N3055 transistors I've fitted have very different gains. Maybe that has something to do with the heat, and the not too good linearity.

The UF4007 diode seems to work alright, and is producing 811 volts, steady over time.

My next miracle will be to find replacements for the damaged wire wound pots.



All the best everyone.

Wayne.

Degauss thoroughly first.

The trick when doing purity on those CRTs is, don't pull the yoke right back. Just far enough to have purity errors around the edges of the screen. Then even these up.

Start with the purity magnets neutralised, i.e. so you can rotate them all together without affecting anything. Then only move away from this as far as is necessary to make the correction. Also, do a rough static converge first.

Warm up the shadowmask with a full white raster. Don't attempt purity if the tube has been displaying a bight object that takes up less than half the screen.

If the tube was an RCA you'll never get it right. Just do the best you can. It was never possible to get perfect white raster purity on those RCA tubes, not to mention the reds that are blazing orange!

Try replacing the bias diode (between the two OP transistor bases) with an ordinary 1N4004 1 amp diode. The vertical OPs in the KC always ran hot.

Re counterfeit parts from WES, some years ago when I worked for ABC TV many years back I was repairing a Sony BVM professional picture monitor which had a shorted line output transistor.
I cant remember details but it was a 2SC xxx type which I didn't have on hand so I ordered some replacements from WES.
They duly arrived and were fitted and appeared to work fine for a while then failed with a short from collector to emitter.
Much fruitless fault finding went on with no result so I bit the bullet and fitted another output transistor and fired up.
All good except the transistor was getting extremely hot after a short amount of time.
It then transpired that central maintenance had stocks of the transistor supplied direct from Sony spare parts.
I then fitted one of those and and had no further issues.
It ran cool to the touch and remained so for many hours.
I contacted WES via email to let them know that they most likely had counterfeit transistors but didn't even get so much as a reply to my email.
A lesson learned.

Hi Folks.
It has been a while since I last updated everyone on the, fun and games, I've had during the resurrection of my 1975 Blaupunkt C.T.V. The sudden and unexpected passing of my father, and all that follows had to, and still does take priority over my love of old electronics.

I now have the set running without bursting into flames or clouds of smoke, long enough to see just how much needs to be done. Listed, are some of the things that require attention. Vertical linearity. Vertical stage running very hot. Something not quite right with the tuning, or perhaps the colour decoder is out of alignment. Wire wound pots are spotted and cause things to burn in the convergence section if set to a point after an open circuit.

The re-gunned picture tube can now be examined more closely now that the set continues to run. First, probably because of the wire-wound pots in the convergence stage, and a possible misalignment of the gun assembly to the picture tube, I can not set the centre of the picture to the physical centre of the screen. This might also explain the difficulty in getting good purity.
There is also a number of missing phosphor dots on the face of the tube. Was this caused by taking a poor tube that had been stored face down, and re-gunned much later.

Must go now. I shall send some photos tomorrow.

Wayne.

Running hot is one of their traits.
Not a real good project IMO.
JJ