Hi,
I just replaced the power cord on the TV with one that’s very close to the original. As the case was already open, I decided to make some adjustments, as the brightness and color control had to be turned down really far to get a good picture.
In the course of this process, I decided to check the voltages in the power supply and found out that +A was a bit low (around 240V instead of 255V). I checked the resistors in that area and noticed that two of the big wire wound resistors had valves that differ from what is indicated in the schematic. R604 is 10 Ohms instead of 5.1, and R606 is 82 Ohms instead of 75. I assume someone did this in order to compensate for todays higher line voltage (230 instead of 220V). However, it does not fully explain the low A+ voltage. It does seem like power consumption is too high. Any ideas where I should start looking? Could an incorrectly adjusted HV lead to these symptoms?
Generally, the TV works extremely well, so I don’t think there are any major faults. Any help would be appreciated!
Gunther
The component variations may be a manufacturing modification, not someone playing with values. I experienced this myself only yesterday on a Thorn 9000-series chassis. A cap on an earlier version circuit was a 0.22uF only to be changed to 100uF electrolytic on a latter circuit diagram, all due to a variation in how the 24V supply rail was regulated.
The variation you have found might be such as case. The UK version is virtually identical but for the two resistors in question being 9.1R/7W and 56R/10W.
As for your 255V H.T. rail being low, is there a "set H.T." procedure that needs to be performed as part of the TV set up?
As Chris says check if there is a Set HT control and also an over voltage control or circuit.
Its possible the HT was turned down due the over voltage circuit triggering early.
Thanks a lot for your replies!
Even though I still couldn’t find any documentation that there could be varying values for the resistors in question, I think you are right! It wouldn’t make any sense for the resistors to have been replaced.
There is no procedure to set this rail, however I think I solved the issue by adjusting the HV. While I do not have a HV probe, there is a procedure for setting the HV by measuring the voltage at a pin on the lopt and setting it to 49V. This voltage was a bit high (over 50V) and the adjustment led to the rail voltage going up to slightly above 250V. I think I will leave things like this, the TV works great!
As always, this forum never disappoints.
Thanks again,
- Gunther
Nice looking set, not as common as the British & Japanese made smaller colour TVs.
Thank you! We had this type of Grundig as our only TV from the mid 70s until the end of the 80s. Worked great. Was very happy to find this one, after regretting throwing the original one out after it developed various issues.
I do think it is a very nice looking set, and I feel like Grundig was ahead of most of their competitors in Germany at the time.
You may or may not be aware that our main website contains multiple vintage brochures. Grundig is represented for both the early 70s and 80s, your set is featured on one front cover.
I have a rather splendid 26" 5011 that has been waiting its time on the bench for more years than I care to admit. 🙄
Thank Crusty, haven't seen the brochures on this website, but have browsed the Grundig Revue, as it is called in German, many times.
That's a beautiful set you have there! Looks to be in great condition too. You think it needs a lot of work?
We were a Grundig family, Grandma and one uncle had a 8200 model, other uncle had a 8022. I think most sets were bought for the football world championship in Germany in 1974. My impression is that the Grundig sets outlasted the, generally more expensive, Telefunken sets of that era by quite a bit. Also, comparing the ultrasonic remotes of the sets, the TelePilot 12 was much smaller and worked with pulsed signals than the massive Telefunken Supersonic 200 that doesn't appear to be all that reliable.
