low sound output on drum machine(DPM-48)

Algorithm · Post by **Algorithm** » Sun Mar 23, 2014 12:54 am

I am curious to know what might cause the symptom of low sound output.
Anybody else seen something fail that may cause this?
At first I thought opamp but this is not crackling or hissing, just softer sounding.

Post by **Stab Frenzy** » Sun Mar 23, 2014 1:07 am

You're really going to have to be more specific about what unit you're talking about if you want any helpful answers.

Algorithm · Post by **Algorithm** » Sun Mar 23, 2014 1:16 am

Its a drum machine with no information available virtually, no schematic publicly available unless someone got it from the patent office.

Its eeprom based, has a respective output for each sound.
Im using the mix output.
The respective output is the same story though.

Z · Post by Z » Sun Mar 23, 2014 1:38 am

Do you have a photo of this unit? Make and model? There's a chance someone here knows what it is.

Post by **Stab Frenzy** » Sun Mar 23, 2014 6:48 am

Algorithm wrote:Its a drum machine with no information available virtually, no schematic publicly available unless someone got it from the patent office.

Its eeprom based, has a respective output for each sound.
Im using the mix output.
The respective output is the same story though.

If rather than being cryptic you tell us what the name of it is, then we'll know what you're talking about.

Algorithm · Post by **Algorithm** » Mon Mar 24, 2014 4:39 pm

The name of the machine is basically irrelevant information.(considering there is no schematic or info anywhere) Thanks anyway everyone, Ill add the non-pertanent info when I fix it.

I was hoping for a more broadened horizon of answer in general, I wasnt trying to ask about 1 particular machine, really.

Z · Post by Z » Mon Mar 24, 2014 4:59 pm

So why the secrecy?

Algorithm · Post by **Algorithm** » Mon Mar 24, 2014 5:57 pm

Pertaining to the lack of service notes / info. I felt like mentioning the particular one I am working on would limit the answers from experienced cats. Shining the light on this with no schematic references seemed less fruitful. Compared to asking about any past experience dealt with, on anything.

Its a sakata dpm-48.
If someone has the schematics secretly? Feel free to share them, if its no bother?
I am not a reseller either... I am genuinely and greedily fixing everything I fix for myself.

Post by **rhino** » Mon Mar 24, 2014 6:25 pm

Here's the users manual:
http://www.cyborgstudio.com/drummachine ... manual.pdf

This machine was sold by Hammond organ co. You may try there.

If ALL audio outs are working but low, I'd suspect problems in your cabling, mixer, amp, etc.
2) check the power supply rail that supplies the output drivers...could be low due to a problem in the PS.
3) long shot: a shorted transistor or ic in the mix section may be dragging down the audio level in all channels.

Algorithm · Post by **Algorithm** » Mon Mar 24, 2014 6:57 pm

Thank you Rhino.
Sorry for questions in such a fashion, but sometimes we have to go with what our higher self tells us.

I was informed that the hi-hat was completely out. When I got it, It was, the bass was soft.
I had it hooked up to an old ibm computer speaker. Then I turned it back on to compare samples with the machine, the hi-hat was audible this time, but just barely. the bass came in a bit thicker. (made me think a cap was dry and got reheated?)

then my pops played with it the next day, seeing if it would warm up, he hit the bass and it killed the ibm speaker.
(laughs)

Does this narrow it down or give any clues?

Oh! Also, this is a japanese machine, 100v, Im in the US.
I would change the tap, but the transformer is not labeled. Just 1 bonus wire coming out of it, and a blank board, with 5 or 6 pins to choose from. (I guessed that combining the 2 wires would do 240? and blue alone is 100, green alone is 120? ) (laughs)

I inspected everything closely inside, a few old parts seemingly from the 60's in there. Also, a row of 4 diodes for a bridge rectifier it appeared.

Ill take some pictures and upload them in a bit. There is some interesting stuff in here.

All the chips are mitsubishi.

(BTW this Juggbox has a hammond sticker on the bottom, and a metal hammond stamp)
( I have the last revision of this I think? the electronic drums kit)

Post by **rhino** » Mon Mar 24, 2014 8:15 pm

Actually the net says it's from 1983.
Try unplugging and re-plugging the internal connectors if there are any, also pull and re install any chips in sockets.
Be concerned with any board-to-board connector pins.

Algorithm · Post by **Algorithm** » Mon Mar 24, 2014 10:02 pm

Took all the socketed 1's off and cleaned the edges. Put it back together to test it, nothing coming through on the bottom board of mix outputs. On the board with the individual jacks for each sound? the first 2 toms worked perfect, but then the bass was super soft, hihats were soft also.
Then I noticed that every other sound could come through softly on the hihat jack, like it was a mix output.

At first I got sound out of the mix jacks, I suppose when that speaker popped, something happened with that board too.
The PSU is built into the mix output board.

Hopefully someone still has a service manual at hammond.

njosnari · Post by **njosnari** » Wed May 31, 2023 10:23 am

Did you ever fix your problem? I have a Sakata DPM-48 with the exact problem you described here.

low sound output on drum machine(DPM-48)

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