[sdiy] Debugging problem with 4-track

Corey K coreyker at gmail.com
Sat May 26 12:22:35 CEST 2018


I have the original power supply which has 12V printed on it. The input
voltage range is also printed on the machine itself (it says 11-15V). It
also takes 10 AA batteries, which is 15V.

On Sat, May 26, 2018, 04:25 Chromatest J. Pantsmaker <
chromatest at chromatest.net> wrote:

> Stupid question... How do you know that it's supposed to take 12v? Maybe
> 7.5 is correct.
> On May 25, 2018 6:14 PM, "Corey K" <coreyker at gmail.com> wrote:
>
>> Yes, indeed I used a cassette with the "tabs in". I was even able to
>> monitor, record, and playback with the 4-track using the 7.5V supply. I
>> just don't understand why the 12V supply doesn't work (neither the original
>> 12V Fostex supply nor my adjustable one works).
>>
>> On Fri, May 25, 2018 at 10:06 PM, Jay Schwichtenberg <
>> jschwich53 at comcast.net> wrote:
>>
>>> Did you put a cassette in it?
>>>
>>>
>>>
>>> Might be it needs a cassette with the plastic write protect tab not
>>> broken out.
>>>
>>>
>>>
>>> Good luck.
>>>
>>> Jay S
>>>
>>>
>>>
>>> *From:* Synth-diy [mailto:synth-diy-bounces at synth-diy.org] *On Behalf
>>> Of *Corey K
>>> *Sent:* Friday, May 25, 2018 3:53 PM
>>> *To:* *SYNTH DIY
>>> *Subject:* [sdiy] Debugging problem with 4-track
>>>
>>>
>>>
>>> I was hoping someone here might have some suggestions for me.
>>>
>>>
>>>
>>> I recently purchased a Fostex x18 4-track cassette recorder.
>>> Cosmetically it is in mint condition, and it came with the original box and
>>> power supply. When I plug in the power supply the green power LED
>>> illuminates. The play, fast forward, and rewind controls seem to work. So
>>> far so good, however, when I push the record button, the record LED does
>>> not illuminate. I connected a few different sources to the machine and
>>> raised up the input gain, but the level meters do not light up, and I can't
>>> hear anything from the headphones output...
>>>
>>>
>>> I noticed something strange which might point to the problem: if I
>>> unplug the power supply (while the record button is depressed) the record
>>> LED and level meters light up momentarily. I wondered if there was a
>>> problem with my power supply, so I tried using an adjustable one. The
>>> machine is supposed to use a DC supply in the range 11-15V. When I set my
>>> adjustabe supply to 7.5v the machine actually seems to work correctly! But
>>> when I set the adjustable power supply to 12V (which is the same voltage as
>>> the original supply), the machine exhibits the same bad behavior I describe
>>> above.
>>>
>>> What might be happening here? I'd love to hear any hypotheses. Seems
>>> like a problem with the power distribution system, but what would be the
>>> first things to check? (I have a multimeter and scope). Is this a case that
>>> might require recapping? What would be the best way to investigate this?
>>> Any ideas would be much appreciated.
>>>
>>> Thanks,
>>> Corey
>>>
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>>> Synth-diy at synth-diy.org
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>>>
>>>
>>
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