730/951 Deck swap?

Hi, I have been using my DCC 730 for a few weeks now and it has performed faultlessly. I made a recording today but no audio on playback. I tried an existing tape but that did not play either. This has been used regularly and left in standby when not in use. Analogue tapes however do play ok. I would like to try to narrow down the problem by substituting one of the decks from a 751. Is the 751 deck interchangeable with the one in the 730? I’m hoping that if I can do this that the problem still exists, as I’m sure it would be easier to locate a fault on the main board than on the delicate digital boards. Any suggestions as I would like to keep the 730 as part of my main setup.

Thanks as always.

The problem would most likely be in the so-called DDU (the mechanism with circuit boards), but you can swap them to test.

The whole block can be removed by removing Just 2 screws.
The 730 and 951 mechs can be swapped without any problem.

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Hi, thanks for the help. I have swapped the drive decks over and as suggested, it confirmed that the issue is with the 730’s DDU. As the 730 was powered up but left in standby and was working fine a couple of days ago something has failed while in this state. Any ideas what a good starting point would be for diagnosis? I would like to get the 730 running again so I’ll put some time to it, just need guidance!

Thanks @Max and @drdcc

Have you tried putting it in service mode to see if all the heads are getting a signal? Maybe if you use it so intensively, you just got the head dirty.

=== Jac

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Hi @Jac, test mode shows 20 on all heads so that’s not good. The deck has had a thorough clean and new belts but as I said before It was working perfectly with no signs of trouble. Is there anything that can be done? I’ve already lost two 951’s with the same issue, I can’t really afford to loose another one.


That is almost too much of a coincidence. These decks do not like ESD that much.
Did you recap all 3 before the problems occurred?


@drdcc Interesting statement. I was under the impression (perhaps wrongly) that 3rd gen machines did not suffer from the cap issue. I too thought this was far too much of a coincidence. I do take care when handling components and always wear a wrist strap. So the obvious question is do I need to recap 3rd gen decks? If so I am prepared to try this on one of the 951’s. Would it just be the r/w board? Thanks for pointing this out, at least there may be hope!

Normally, the caps on the 3rd gen are better and all the machines at the DCC Museum have not been recapped. We do however have to look at your situation differently. We have handled 40-50 3rd gen in the last year and not lost 3 to these problems. Very strange. We do not want to assume anything but do not want your house to be a 3rd Gen Rocket Launcher either.

I would recap one and see if it helps. Only the R/W Board on the top/back.

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Thanks for the advice @drdcc. I count 11 caps so that’s not too bad. I’m guessing a hot air gun is the preffered method of removal? DCC is my adopted format so I will put time into improving my soldering skills before I tackle the 951 board!

Thanks again and I’ll keep you posted.

For me personally, hot air is the only way. There are other methods, but it depends on your preference.


Update. I have just replaced the caps on the 951 that did not record. It still doesn’t but at least it still plays so I suppose my replacement job (not the neatest in the world!) has worked. I do seem to have issues with 3rd gen machines as a whole though.

Current state of play as follows:

2 x DCC 900 awaiting cap replacement (just trying to build myself up to it)

1 x DCC 951 - Playback only

1 x DCC 951 - No issues

1 x DCC 730 - Playback only

2 x DCC 730 - No Rec or Playback

1 x DCC 730 - No Issues

1 x DCC 380 - Analogue recording only

2 x DCC 600 - No Issues

I must admit the DCC 600’s are the superastars. They cope with whatever is thrown at them and are much more robust at playback. The 3rd gen machines are very twitchy sometimes and seem to prefer nos tapes (and they love the ‘Clean Head message’). I am quite happy though to have a playback only machine in my main setup as i usually create my tapes in another room with a 600. I would be interested in your thoughts as to the ‘robustness’ of individual decks.


For me the 600 are the superstars as well. They are my go to machines. All 951’s I have ever had here have problems. It is not a series I would want anymore.
Surprisingly I have one 730 (that is supposed to be identical sort of) that is working flawlessly, Except for the known gear noise problem. But I will deal with that when it does break.
But, with the number of machines that Ralf deals with, his statistical data is of course much more valuable.
This is just my personal experience.


And here I stand with 5x 951’s and 1x 730… all with their own “will”.
Just switched to a good looking 600 that’s in need of a lot of attention… I just can’t wait!

Best of luck with the 600 @Henrie. I’m sure it will turn in to a fine machine! My aim is to get at least one 100% reliable 730 and 951 but may have to sell the rest on as spares and take a hit with them. Still got the 900’s to recap when I feel confident enough. I am looking around for another 600 though…

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Just looking at the 730 ‘play only deck’. In self test mode, should SW101 and SW102 respond to this test? SW103, 4 and 5 are operating ok. I was wondering if this was part of the ‘no record’ issue?

@Richard_Symes - if you are still thinking of parting out a 730 or a 951, I am after a tape drive pcb! :wink: Its part of process of elimination.

@saturn5 If you can bear with me for a couple of days I may have one. Watch this space!

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@Richard_Symes, that would be brilliant, I would be so grateful if I could get my deck going again. I’m in Staffs UK. :+1:

@saturn5 Yep, got one. Send me your address and i’ll pop it in the post to you.