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Satellite Workshop 15
A nice lady brought me her Grundig GRD150 receiver for repair. Apparently, the audio had never been very good but, since her son had connected it to the stereo Hi-Fi stack, there was very noticeable sibilance.
Grundig have issued a number of upgrades and one of them covers this very problem. It took some time to locate the surface mount components around the ASIC chip so I made the time to make a layout picture which will be useful for future reference. There is not a great deal of work involved but it does make life easier if you have the necessary surface mount components and diagram to hand before you start.
The customer was delighted with the result and rang me the following day to tell me. It made a pleasant change from the usual grumbles.
In the same week, the postman delivered a GRD200 for repair. This was showing no decoder messages. Naturally I dived into the decoder board and it was only after I'd replaced every "PTV" chip that I realised I hadn't actually checked the signal going in and out of the decoder board!
My oscilloscope soon showed that the signal was not actually being routed through the decoder at all. The fault was caused by the ASIC chip beneath the board. This is a horrible 128 leg "gullwing" surface mount IC which is a pain to remove without the proper (expensive) equipment.
A replacement IC was ordered from the only Grundig stockist but they kept no stock and had to get it from Germany (although I had to find this out for myself). Meanwhile, the customer was going doolally and telephoning me every other day.
When the IC finally arrived it was packaged in an ordinary polythene bag with no antistatic protection whatsoever. My opinion of this is unprintable! Luckily, the receiver performed faultlessly once I'd soldered the new IC in place -- but whose fault will it be if that IC goes wrong in a few week's time?
Lest you get the impression that Grundig receivers are unreliable, let me assure you that the failure rate is less than half a percent. This figure is confirmed by other dealers and compares favourably with the ten percent rate of other makes.
Apparently you don't have to shout at foreigners to be understood!
This fact was driven home to me when a Scandinavian neighbour came to my workshop to seek advice about his MSS1000. This was no ordinary receiver. It was the D2Mac version and I knew that the customer had his dish aimed firmly at one degree west of south.
"What seems to be the problem?" I shouted, twice.
He explained in perfect English that the unit was self-censoring. Whenever the naughty programmes began, the picture would be blotted out by a checkerboard pattern, apart from a one inch border. The customer explained that the only way he could watch the programme was to select the menu. That way he missed only the action in the centre of the picture.
I told him to leave the unit with me and I would test it that night. Of course I had to force myself to stay awake and it took some time before I traced the problem to the fact that, if you select Norwegian subtitles, the naughty programmes are automatically blanked out. If you select any other subtitle language the pictures remain clear. I've seen this with other D2Mac decoders so it was no surprise. It probably explains why Norwegians speak such good English--they learn it from the subtitles.
Since the customer had left me his official smart card, I decided that I had better keep the receiver for at least a week's soak test ...... just to be sure that the fault was cured, you understand.
The postman looked quite pleased as he dropped an enormous box on my counter. "Been doin' weight lift'n'," he grinned and he flexed his muscles on the way out. In fact the parcel was light as a feather and contained only a FilmNet decoder in a sea of polystyrene foam chips. I remember telling the customer to pack it well and he'd made an excellent job. These units were originally shipped by some distributors in a cardboard box with no packing whatsoever and I've seen several whose main board had snapped in two.
The reported fault was "speckly pictures" and, when I hooked up my trusty SS9200 test receiver, the pictures were very blotchy indeed. After replacing the usual socketed ICs without success, I traced the fault to the VCU2133. In addition, the picture was reluctant to "lock" and would scroll leftwards for half a minute before stabilising. This was easily fixed by entering the service mode, punching in "1 5 0" and using the handset to alter the VCO setting until picture movement stopped. The Philips handsets are not cheap but mine has paid for itself several times over. The English language User Manual from SatCure was quite useful, too, as my Norwegian is a little rusty! This booklet includes all the service mode codes.
Just as I was driving away from the supermarket, I was awoken by a call on my mobile telephone. A local electronics design company had a gentleman in reception who wanted his Pace receiver mending. Could I come immediately? As luck would have it, I was less than three minutes away and the customer was quite impressed when I told him that his receiver would be ready for collection that afternoon.
He thought that intermittent audio was caused by his Scart lead which was "only a metre long." It had been stretched tight and the Scart socket was badly marked and distorted.
Back at the workshop I discovered that the real culprit was the MSP3400 audio processor. This has a zillion legs spaced close together and is time consuming to remove. If you use solder braid, be careful to avoid touching the adjacent surface mount components; I've seen one attempted repair where the dealer had unwittingly drained the solder away from these.
Once the audio processor had been replaced, I fitted a double Scart socket from a scrap MSS1000 and tested the unit. No problems so I reassembled it and gave the owner a call. Needless to say, he was delighted by my speedy service and (he thought) very reasonable charge.
I mentioned my first impression of this model in a previous article. Now that I'm seeing more faulty ones I feel that my comments were wholly justified. Last month I received a couple to repair from a dealer. Unfortunately, his installer had removed the faulty units from the customers' houses without labelling each receiver with the fault symptoms. The first lasted for twelve hours on test with no sign of a fault. If there was something wrong, it wasn't obvious. The dealer will incur a nominal charge for my time.
The second unit failed after half an hour. The actual symptom was a crackling noise which grew steadily worse until it drowned the audio. Freezer spray quickly traced the cause to one of three TDA6130-5X4 surface mount chips on the combined tuner/video/audio module.
Unfortunately, the IC is not available as a separate spare part from Amstrad and other distributors gave me various stories which ranged from "it's been withdrawn, I think it's obsolete" to "we can get it from Germany but you have to order 300 pieces." Since Amstrad stopped supplying direct to dealers, there is no such thing as a cheap Amstrad part. The actual tuner module for the SRD700 has been superseded by part number 242842 which costs around 40 from approved distributors. (Note that this is not the same as the SR950 tuner assembly).
I took the plunge and ordered the entire tuner module. When it arrived I was horrified by the length of time it took to fit. In addition, the Service Manual gives alignment instructions which include the use of a frequency counter! When finally I got the receiver back together, the audio was even worse; the new tuner had the same fault! To cut my losses and avoid wasting more time, I removed a good IC from the new tuner and replaced the faulty IC on the original tuner (so I didn't have to carry out the realignment). Once this was refitted the receiver finally worked properly.
Of course the dealer would not pay me the cost of the tuner plus four hours' labour. I didn't even charge for the ten telephone calls, three faxes and four e-mail messages it took to find that the IC was effectively unobtainable!