If I make a recording on my dcc175, sometimes (not always) there is this weird problem that the recording is not compatible with my other recorders. It mostly plays but sometimes the time is not displayed. If I put the playback recorder (other than the dcc175) in service mode the first digit is changing to 1 often. If I put a recording from my dcc 951 in the 175 and put that in service mode it is rock solid all zeroes! And vice versa. In my opinion that rules out a azimuth problem. It originates during recording. Sometimes it is visible in service mode on the 175. This compatibility problem rules the 175 useless for recording and I think that is a shame. Could it be that the caps on my machine are on the way out?
I know that the read write boards are adjustable on stationary recorders but I never read about adjusting this on a portable. Can this be done? Perhaps a tad more power to the head may solve this?
Sure the belt is slipping somewhat but with playback of albums or other tapes made with my other recorders everything is fine…
Could be a mechanical problem: If the edge of the tape is not making good contact with the head, the AUX track and the first audio track may have trouble because they are closest to the edge. That would explain the missing time codes and the solid 1 for the first audio head in service mode. If the signal from one head is consistently missing, the recorder has just enough information to play the audio, however if there are any dropouts or misread bits in the other channels, there is not enough data to reconstruct the missing bits.
Does the problem occur on side A as well as side B? In that case, it’s not, it’s likely a mechanical problem.
You may want to inspect the RDMUX/RDCLK signals on the recorder that has trouble playing back tapes. Also don’t forget to compare against known-good tapes (e.g. prerecorded tapes). You will need an oscilloscope, the service manual and some good electronics experience.
===Jac
Thanks @Jac ! Within a few weeks I will acquire a oscilloscope, the maintenance manual I allready have… so I will find out what the problem is… perhaps it is still something stupid as head alignment… not so much east or west but north and south… keep you updated!
Sorry, next question… could it be the capacitors? It is not impossible with the 170/175 that they go wrong… allmost 30 years…
Heads in DCC recorders normally don’t need to be aligned. Azimuth accuracy is a lot less critical than with analog cassettes, and the mechanical design of the DCC head assembly makes it so that the tape pretty much always goes along the heads at the right position and at the right angle. However if a previous owner messed with the head adjustments or if there’s just too much mechanical wear in one of your recorders, it’s possible that the edge of the tape gets pushed away from the head for some reason. You should also carefully check with a magnifier or microscope that there’s no debris or dirt on the heads as well as the pins on the corners of the heads (they’re often overlooked). Adjustments should really only be made if you’re positive that the tape isn’t in the right place. It’s really much more likely that something is dirty.
It’s not impossible, but at this time it’s unlikely I would say, since the other channels are working fine according to what you say.
===Jac
Is the problem on side A and B? If it is on one side only it could be a problem with the pinch roller on that side. We have had the same problem 2x and both times it was related to the head. Both times side A would record but not always play great on other machines, because of it.
Are new pinchrollers ready available for the portables?
Working on that right now and hopefully we have some news later this year.
That would be great! I’ve seen an add on a website but they were only providing the rubber, not the entire roller… it might work but I am reluctant to price off the rubber of my existing rollers. ’ Cause if it turns out not to work, I ruined my 175… I will wait for the Museum to find a solution!