DCC tape recorded with the DCC900 can be played back on the DCC170, but sometimes it cannot be played on the DCC900.
If the package position of the tape is shifted during playback on the DCC900, sound may or may not be produced.
The DCC170 holds the tape package firmly with a metal frame, so I think it plays normally.
With the DCC900, the tape package is set by sliding it to the back on the plastic tray, but I think the package is loosely held.
Do you know how to precisely adjust the tape package position with the DCC900?
The DCC900 is seen in sets with and without felt seals on plastic trays. Does this adjust the vertical position of the tape package?
I’m not sure what you mean with “tape package”. Do you mean the cassette?
The position of the cassette in the recorder is not very critical. It’s held more firmly in the portable recorders to avoid rattling while you’re walking around. In the stationary recorders it’s just held in the tray loosely so that it can be easily removed and inserted.
If you’re having trouble playing a tape on a DCC 900 (or any recorder really), the problem is probably that the pad that pushes the tape against the heads, is dirty and sticky. That causes the tape to not be transported smoothly enough, and the electronics can’t keep up with the speed variations so you won’t hear anything. You can use a sharp blade to try and scrape the sticky dirt off the pad in the cassette, but that’s a temporary solution. It’s better to replace the pad; you can buy replacement pads from the DCC Museum.
Note: cassettes that are recorded with a sticky pad may never be playable, because the rapid speed variations that happened while you recorded the tape are encoded on the tape.
Yes, it means the cassette.
I also thought the pad was bad at first, but the recording speed is normal and the DCC170 can play back without any speed disturbance. The DCC170 can play a commercially available DCC tape with other music recorded without any problems, but the DCC900 will play poorly.
It’s possible that your 170 happens to play the tape smoothly by coincidence. Maybe the pressure on the pad is just a fraction lower than on the other recorder. Maybe the DCC900 has a dirty head and doesn’t read one of the tracks, whereas the 170 reads all the tracks. It’s impossible to say without having a closer look.
You can’t tell from the music if a DCC tape speed is as good as it can be. Whenever the recorder can move the tape at the correct speed (and make corrections continuously once the speed is nominally correct), the music will play at perfect pitch, controlled by a crystal. It’s still possible that the tape speed varies and that the electronics are compensating for the speed variations and you won’t hear that.
That would indicate that there’s something wrong with the DCC900, not with the tape. Does the DCC900 have the original capacitors on the read-write board or did you get them replaced?
If you record a sine wave with a known frequency and check the reproduced audio output with an oscilloscope, can you tell if the tape speed is changing?
All DCC900 original capacitors have been replaced.
No. When playing a DCC, the bits from the tape are decoded from PASC to PCM and sent to the DAC with crystal-based accuracy. What comes out of the speakers (or the digital output for that matter) has probably less jitter (the digital form of wow and flutter) than you can measure with a frequency meter or oscilloscope.
The motor that drives the capstan is controlled by the bit stream coming in from the tape. The chipset reads the bits into a memory buffer and slows down the capstan motor when it gets too full and slows it down when it gets too empty. This is called a servo system. If there is a lot of variation in the speed with which the bits are recorded on the tape, the servo system gets confused because it must assume that the bits were recorded with basically no variation in speed. When the bit stream goes too slow, it must assume that the tape is running too slow and speeds up the capstan motor; when the bit stream goes too fast it slows down the capstan motor. If there is a large amount of variation in the speed of the recorded bits, speeding up and slowing down the capstan motor won’t fix the problem. If the tape gets caught on the pressure pad hundreds of times per second, it confuses the servo system because no matter what it does, it can’t slow the bit stream down or speed it up fast enough. That’s when you get a buffer underrun or overrun and the chips just give up and play silence.
I don’t know what’s wrong with your DCC900. With replaced capacitors, replaced belts and a clean head, the DCC900 usually works fine unless you have a cassette with a sticky pad. If it plays prerecorded tapes fine but has trouble with self-recorded tapes from the same machine (and you tried with multiple tapes and you’re sure the tapes are in good shape), there may be something else wrong in the electronics or you may have a bad head. If it plays its own tapes fine but not tapes recorded by other recorders, the problem may be in the other recorder.
Today i’ve had a simulair issue with a DCC900, playback was silent or interrupted.
My believe was the cassette might have a problem so a took a brandnew old stock cassette and peeled off the foil. Made a recording and play back was as interrupted as before.
However when i then (slightly) adjusted the head the playback turned out fine and without interruption.
I think this is weird, but apparently is the recording less critical for the head position than the playback, for the recording is good.
So maybe the TS has the same issue, DCC900 records fine, plays well in the DCC170, but fails in de same DCC900.
I have several (10+) DCC decks here, and a long time ago I started to fill in a matrix: record with one and playback on the others.
Soon my brain hurt and I abandoned the idea. The results were not very positive, I recall. All my decks are fully serviced.
Some decks just don’t record well.
Some decks playback a tape correctly, other decks don’t play that tape well. But they wíll playback other tapes. It’s a mess sometimes. That’s why I abandoned the idea.
I have several portables and they are all serviced and I had various troubles when changing tapes between dcc 170 and 951. Beside the lack of backtension I nailed it down with mirror casettes on th 951 there is a general problem with philips casettes on the portables which seem to be sticky and hard winding and give no recording or massive dropout. Most of them but not only these casettes are with the white felt pad but even replacing the pad with dr. dcc,s did not help. Very good results I had with japanese casettes and the portables so pls try these with same procedure and report.