Resurrecting a Mitsubishi Diatone DP-EC1

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bra10n
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Resurrecting a Mitsubishi Diatone DP-EC1

Post by bra10n » 17 Jan 2020 20:01

I recently bought the above in a non working state. Nice looking TT, not one I knew of... a Mitsubishi unit in Australia I figure is not that common?

This particular table being fully auto employs the prism/sensor -> light mechanism to set record size. As some of you will know, the platter mat is vital for this to function correctly. Strike 1, no mat came with the table.

A quick power up inspired a little confidence though. The arm seemed to respond to various manipulations and all seemed well enough given the early trials. I did notice the motor turned on the first and say, second power ups but then the motor failed to turn after that. It seemed to spin freely without any binding or unusual noises but turned slowly. Perhaps, 1 back my way... all even going into removing the base.

Removing the base of the TT and I was struck by the condition and layout. I'll post some pics later and let them tell the story but for now just keep in mind this is a 44 year old TT.

Ok, so now we are inside and the first thing I notice is a power capacitor well away from its board and physically oversized. Two 300mm wires are run from the board to the cap wedged in the other side of the table so, someone has been in here, and *likely* chasing the same issues I am. Fair assumption? I notice 6-8 caps that look like they've been replaced over the years and now wonder if they don't need redoing? Anyway, only 19 caps in this thing so I'll replace all of them as a starting point.

Also, I'll need to ask a few questions re the transformer wiring in this thing.

That's it for now... I'll get some pics up later.

cheers,

D

bra10n
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by bra10n » 17 Jan 2020 21:10

Pics
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scrapjack+
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by scrapjack+ » 18 Jan 2020 07:05

Wow, they really crammed the circuits in there, and twin worm gears.

As I understand, if a circuit is blowing capacitors, then there is another problem causing it to do so. If you don't fix that first it'll just keep blowing capacitors.

I don't know much about your prism system, but is it possible that you might be able to print a high-res scan to fool it, or was there special reflective or uv/ir ink?

bra10n
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by bra10n » 18 Jan 2020 19:04

@scrappy

Don't get me wrong, I'm not a tech so I'm only guessing what might be wrong with this. I'll just do what I can and see where I end up starting with a re-cap and replace the prism globes x 3.

Can I ask the knowledgeable what they make of the following transformer wiring;
IMG_20200118_074918.jpg
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Now there are two groups of wires (red,blue,brown) gathered in two plastic sleeves in the pic. The red (27v) and blue (8v) I am ok with, but the brown?
The brown connects to both sides of the transformer? Anyone enlighten me here...

Japi Roelofs
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by Japi Roelofs » 18 Jan 2020 19:09

I see there are no belts between the motors and the worm gears. Did you remove them?

bra10n
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by bra10n » 18 Jan 2020 19:16

Japi Roelofs wrote:
18 Jan 2020 19:09
I see there are no belts between the motors and the worm gears. Did you remove them?
Hi Japi,

I removed the belts and have ordered new replacements.

cheers

Coffee Phil
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by Coffee Phil » 20 Jan 2020 05:45

Hi Bra10n,

Congratulations on the nice looking acquisition. Looks like you have a project.

Keep us up on the progress.

Phil
bra10n wrote:
17 Jan 2020 20:01
I recently bought the above in a non working state. Nice looking TT, not one I knew of... a Mitsubishi unit in Australia I figure is not that common?

This particular table being fully auto employs the prism/sensor -> light mechanism to set record size. As some of you will know, the platter mat is vital for this to function correctly. Strike 1, no mat came with the table.

A quick power up inspired a little confidence though. The arm seemed to respond to various manipulations and all seemed well enough given the early trials. I did notice the motor turned on the first and say, second power ups but then the motor failed to turn after that. It seemed to spin freely without any binding or unusual noises but turned slowly. Perhaps, 1 back my way... all even going into removing the base.

Removing the base of the TT and I was struck by the condition and layout. I'll post some pics later and let them tell the story but for now just keep in mind this is a 44 year old TT.

Ok, so now we are inside and the first thing I notice is a power capacitor well away from its board and physically oversized. Two 300mm wires are run from the board to the cap wedged in the other side of the table so, someone has been in here, and *likely* chasing the same issues I am. Fair assumption? I notice 6-8 caps that look like they've been replaced over the years and now wonder if they don't need redoing? Anyway, only 19 caps in this thing so I'll replace all of them as a starting point.

Also, I'll need to ask a few questions re the transformer wiring in this thing.

That's it for now... I'll get some pics up later.

cheers,

D

bra10n
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by bra10n » 20 Jan 2020 09:25

Well no biscuit after recapping... there doesn't seem to be any change whatsoever. What chance this transformer is the culprit?
Coffee Phil wrote:Hi Bra10n,

Congratulations on the nice looking acquisition. Looks like you have a project.

Keep us up on the progress.

Phil
Hello Coffee Phil,

I was hoping on less of a project tbh and more of a few hours whipping this back into shape. Not to be it seems.

cheers,

Dennis

bra10n
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by bra10n » 20 Jan 2020 22:17

Ok measured transformer and 18v tap is almost open. 27v measured 20.3v and 8v measured 7.95v. So I will need some help with this. What am I looking for in a replacement transformer and are there any other options? Keep in mind I don't want this to become a costly pit :shock:

I just need to establish what this needs and what that will cost before I likely just dive in anyway :lol:

cheers

D

Monkey_Relish
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by Monkey_Relish » 21 Jan 2020 08:06

Do you have a schematic ?

Mr Relish

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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by Monkey_Relish » 21 Jan 2020 08:33

According to notes on the schematic, you should have 35.6V DC at +ve C311, 19.6V DCat +ve C313 and 8.2V DC at C325.
I can’t see the voltages on the taps on the LHS of your pic, assuming 30v and 0v, but the wiring looks wrong.
Brown should be between 18v and it’s corresponding 0v. Unless both secondary 0v taps on the left and right are internally wired.

Mr Relish
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Monkey_Relish
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by Monkey_Relish » 21 Jan 2020 08:37

And red should be between the 30v and 0v on the lhs secondaries.

Mr Relish

bra10n
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by bra10n » 21 Jan 2020 09:00

Thanks for posting Monkey.

As per the transformer.
The blue = 8v, red = 27v and brown = 18v with 0v tap on the primary and 18v tap on the secondary side. This I haven't seen before but it checks out on the schematic. I have continuity between each pair of taps and nowhere else which seems correct.

Coffee Phil
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by Coffee Phil » 21 Jan 2020 17:59

High Dennis,

If the 30 volt winding is open it is bad. Disconnect the secondary leads and measure the open circuit AC voltage from each winding. Expect the unloaded voltage to be a bit high. If the windings other than the thirty volt winding seem OK and the transformer does not get hot, you can abandon the thirty volt winding and use a single secondary transformer to replace it.

Phil
bra10n wrote:
20 Jan 2020 09:25
Well no biscuit after recapping... there doesn't seem to be any change whatsoever. What chance this transformer is the culprit?
Coffee Phil wrote:Hi Bra10n,

Congratulations on the nice looking acquisition. Looks like you have a project.

Keep us up on the progress.

Phil
Hello Coffee Phil,

I was hoping on less of a project tbh and more of a few hours whipping this back into shape. Not to be it seems.

cheers,

Dennis

bra10n
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Re: Resurrecting a Mitsubishi Diatone DP-EC1

Post by bra10n » 21 Jan 2020 18:52

Coffee Phil wrote:
21 Jan 2020 17:59
High Dennis,

If the 30 volt winding is open it is bad. Disconnect the secondary leads and measure the open circuit AC voltage from each winding. Expect the unloaded voltage to be a bit high. If the windings other than the thirty volt winding seem OK and the transformer does not get hot, you can abandon the thirty volt winding and use a single secondary transformer to replace it.

Phil
Hi Coffee Phil,

Thanks for keeping an eye on this :wink:

I'll post up the unloaded secondary voltages a little latter. Re a second transformer it seems the way to go ATM given I am yet to see this TT spin. I just need to establish what needs doing to this to get it up and running. If it is declared a keeper then I have no issue spending some with the aim of returning it to regular spinning duties.

The only other concern is the state of these transistors (Q303-Q305). Pulling back the plastic insulation and the legs are all gunked up. Now this could just be a breakdown of the plastic insulation over the years. An *equivalent* replacement is NTE152 AFAIK but not sure given their use there? (fine motor speed control?) Pics up of these also just in case.

Many thanks to all,

D

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