Blowing the head of DCC 730 and DCC951

Yesterday it was the 3rd time I blew a head of a 3rd gen DCC player. And now I’m afraid of doing anything else on a player other than replacing pinch rollers and cleaning the head.

I really don’t know why this happens. Normally I replace the caps when needed and apart from that everything remains roughly the same. I have a lot of experience in electronic repairs (and I am certified).

The player can play DCC cassettes for many hours (I test them on my desk while I am working), and without hick-up, or any other distortion.

But then it happens: after making 1 (yes only one) recording, the player will never play a tape again (i.e. no sound). I switched boards and cables from other, perfect players, and it seems like he head is gone. There’s no sound whatsoever. And after playing the recording on another DCC player, there’s also no sound.

Has anyone seen this happening? I’m stunned this happens so often. Can someone explain what happens? Is it a broken read/write board, or chip?
I do not dare to try the probably defective read/write board in another player, risking I blow that head too, while making a recording.

Thanks for sharing your experience :wink:

Oh my word! What a tragedy!
Did you replace the heads on the recorders? When playing back all is fine, as soon as you record the head blows…

As far as I know every head has it’s own specific recording current. It is written on a sticker on its leads. For playback it doesn’t matter. If your read write board is giving too much current to the new head I figure that might me the cause… but ai in no way an expert… maybe @drdcc or @Jac can give you the correct reason why…

After refurbishing, each player played perfectly for a long time, 100% and without any errors. I rarely record music on DCC tapes myself.

After breaking down after recording, I set the mechanics and electronics aside and replaced it with another block. The new mechanic and read/write/digital boards still play and record perfectly.
So there seems nothing wrong with the power supply and/or main boards.

I did not replace the heads of the possibly faulty read/write board, for I was afraid of damaging the replacement head too. I once placed the ‘blown’ head in a working machine and it didn’t play. So I suspect the read/write board for 99% being faulty. Measuring and comparing with other read/write boards didn’t show any differences.

This happened to me for the 3rd time now. I was just wondering if it’s only me…

I never measured the head, because they are so sensitive to static electricity.
So if the head ‘blows’ this way, should I be able to measure that?

We have done only a few of them. Never had that problem. I agree however that it cannot be a coincidence.

@Jac and @drdcc
Before I say something silly… the only possibility of blowing a recording head is if the recording current is exeding the limit of that particular head… is that right? Apart from static energy that would be the thing right?

So after recapping a third gen dcc player would it be possible that the factory determined and regulated current may have changed? If that is the case that might have something to do with this problem.

Since 3rd gen recapping is not common (yet) it might be worth looking in this problem, to prevent damage in the future?

Hope this helps!

Dear Henrie,
I found this in my old manuals. Mabe your heads suffer from a construction fault which has been fixed later. "Qoute
SYMPTOM: DCC head defect, no recording, several isolation shorts on DCC head.
CURE: Isolation shorts are caused by ESD. To protect against ESD replace (or bridge) C2999 on Read/Write panel by a 4k7 resistor (4822 051 20472). It is advised to introduce this in all sets with which will be offered for repair, and the modification has not yet been implemented yet. Implementation date: In R/W boards from production week 9540 onwards. Unquote”

Mabe there are a lot of hypersensitive units out without the protection.

Bye Michael

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