DCC 900/1st Gen Read/Write PCB Calibration

Recorders, Players, etc.
1

Hi
I am now the proud owner of 2 DCC 900s. The first sort of worked for while. I did many reworks to fix cap damage but it stopped working. So I did the logical thing an bought another!

I have many hours into #2 but as of this eve all four corners appear to work - Digital Play, Digital Rec, Analog Play and Analog Rec (to DCC). So much damage from leaky caps on both SM boards, hope it keeps going. I’ll go back to #1 soon.

In the process of trying to understand the circuit and fix the RW board I moved the Analog Feedback twiddly pots. I didn’t touch the Bias ones. So my question is, has anyone got a procedure to calibrate the RW PCB? Nothing in the Service Manual except replace the whole transport in case of issues.

What I did was (a) photograph the positions first but then had a better? idea (b) - I used an analog Dolby level tape and set the feedback pots to provide the correct Dolby level at the motherboard test points. Of course this presumes the motherboard was perfectly calibrated to start with, something I could not confirm for sure.

Any better ideas/approaches?

Jon

2

Hi and Welcome to the forum.

This might help. It is the same for all first gen. DCC Players
Ralf

3

Excellent!
Looks like the ACC playback set up is not super critical as long as the Dolby level is set right. Digging around, looks like the Panasonic level tape used is 315Hz @ 0dBVU (160nW/m DIN) for future reference. I’ll take the deck back to the bench and go through it one more time the “right” way this time.

I used to work for Philips in the UK and I remember looking at these decks in the Company Store along with the 900 series system.

Many thanks for the info and for capturing all the info on this interesting system.

Jon

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