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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Hi All
My old (1980's) Marantz SD230 cassette deck 'died',,,,, suddenly !. Symptoms - lights on - but no reponse to the 'play' button. A quick check of the voltages shows that 'something' appears to be pulling more current than it should, puling the main DC rail down from 19V to about 6V. Disconnecting the multi-way connector that drives connects to the drive motor and the play / record / pause switches restores the DC rail to nominal. 12V dc applied direct to the motor results in a current of about 400mA - but no rotation. Is it a fair assumption that the motor's at fault ? If so - anybody know where I could find a replacement - motor is marked MMI-6A2LK - or is it one of those things that won't be economical to source / repair ? Thanks in advance Adrian Suffolk UK ======return email munged================= take out the papers and the trash to reply |
#3
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HI Sam
Thanks for the comments. Last night, in a 'well it doesn't work at the moment so it can't get any worse' mood, I did a bit of 'open heart surgery' on the offending motor. It's in a little tin can - and by carefull levering with a small screwdriver I was able to get the 'lid' off the can - after which the motor and the control pcb could be winkled out of the can. Further dismantling separated the motor itself from the pcb - and showed that the motor was reading short-circuit. Having reached the point of no return g - I dismantled the motor, and found that there was an amount of something or other between the segments of the armature. Careful cleaning, followed by a tiny drop of contact cleaner - reassembled the whole thing - and, lo and behold, the motor spins !! Put it all back together and everything works...... I'm not sure about long-term reliability g - and it would probably be a better job long-term with a replacement motor - but I only need the deck for a quick recording project (taping hymns for our local Church) - so provided it lasts long enough for that I'm happy.... Thanks again for your help Adrian Suffolk UK On Thu, 24 Feb 2005 09:16:55 +1100, wrote: Hi Adrian, I dont know who would supply them in the UK - they're not a difficult item to obtain here and i expect the same would apply over there. Get a copy of a magazine called "Television" - it's a UK publication with plenty of parts suppliers advertisements. Cheers, Sam T On Wed, 23 Feb 2005 17:56:52 +0000, Adrian Brentnall adrianthepapersand the wrote: Hi All My old (1980's) Marantz SD230 cassette deck 'died',,,,, suddenly !. Symptoms - lights on - but no reponse to the 'play' button. A quick check of the voltages shows that 'something' appears to be pulling more current than it should, puling the main DC rail down from 19V to about 6V. Disconnecting the multi-way connector that drives connects to the drive motor and the play / record / pause switches restores the DC rail to nominal. 12V dc applied direct to the motor results in a current of about 400mA - but no rotation. Is it a fair assumption that the motor's at fault ? If so - anybody know where I could find a replacement - motor is marked MMI-6A2LK - or is it one of those things that won't be economical to source / repair ? Thanks in advance Adrian Suffolk UK ======return email munged================= take out the papers and the trash to reply ======return email munged================= take out the papers and the trash to reply |
#4
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Many of the electronic suppliers can have a universal type cassette tape
machine motor. You need to tell them the operating voltage of the motor, if the servo control is built in to the motor or not, and if the motor is CCW, or CW. If the motor is non standard, they need to have the model of the machine. You will have to transfer the pulley from the old motor to the new one. -- Jerry G. ====== "Adrian Brentnall" adrianthepapersand the wrote in message ... Hi All My old (1980's) Marantz SD230 cassette deck 'died',,,,, suddenly !. Symptoms - lights on - but no reponse to the 'play' button. A quick check of the voltages shows that 'something' appears to be pulling more current than it should, puling the main DC rail down from 19V to about 6V. Disconnecting the multi-way connector that drives connects to the drive motor and the play / record / pause switches restores the DC rail to nominal. 12V dc applied direct to the motor results in a current of about 400mA - but no rotation. Is it a fair assumption that the motor's at fault ? If so - anybody know where I could find a replacement - motor is marked MMI-6A2LK - or is it one of those things that won't be economical to source / repair ? Thanks in advance Adrian Suffolk UK ======return email munged================= take out the papers and the trash to reply |
#5
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Adrian,
Your were quite ambitious to take apart the motor and fix it, and what you did was clean out the brush dust that was shorting the segments of the commutator. Hopefully you also lubricated the bearings with a drop of good quality (synthetic) oil. While the motor may now work for years, you'll probably have to check the speed, as its likely to be off after all of that. The standard way to check speed is with a reference tape (usually 3KHz) and a frequency counter. Simply play the tape and connect the output of the deck to the counter, and adjust the pot for a reading that is the same as the frequency of the tape. I think the motor is a Panasonic (Matsu****a), and can be replaced by a Mabuchi, which is a common brand of replacement motors. They are nominally 2200 RPM, you already know its 12V, and you can see if it rotates Clockwise or Counter-clockwise (anti-clockwise). Here in the US a motor like that costs around 3-6 pounds. The new motor is likely to be quite a bit smaller overall, but should mount right up. You'll have to transfer the pulley from the old motor to the new one. Don't forget to measure the height of the pulley from the motor top before removing it. As you are doing recording, I'd suggest that the speed be checked as soon as possible, so that the recording can be played on other machines. Regards, Tim Schwartz Bristol Electronics Adrian Brentnall wrote: Hi All My old (1980's) Marantz SD230 cassette deck 'died',,,,, suddenly !. Symptoms - lights on - but no reponse to the 'play' button. A quick check of the voltages shows that 'something' appears to be pulling more current than it should, puling the main DC rail down from 19V to about 6V. Disconnecting the multi-way connector that drives connects to the drive motor and the play / record / pause switches restores the DC rail to nominal. 12V dc applied direct to the motor results in a current of about 400mA - but no rotation. Is it a fair assumption that the motor's at fault ? If so - anybody know where I could find a replacement - motor is marked MMI-6A2LK - or is it one of those things that won't be economical to source / repair ? Thanks in advance Adrian Suffolk UK ======return email munged================= take out the papers and the trash to reply |
#6
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Be careful to check if the motor is shielded, or chassis grounded.
Failure to do this caused me to blow a Technics M205 decks board when I replaced the motor with an otherwise correct replacement. JR Adrian Brentnall wrote: Hi All My old (1980's) Marantz SD230 cassette deck 'died',,,,, suddenly !. Symptoms - lights on - but no reponse to the 'play' button. A quick check of the voltages shows that 'something' appears to be pulling more current than it should, puling the main DC rail down from 19V to about 6V. Disconnecting the multi-way connector that drives connects to the drive motor and the play / record / pause switches restores the DC rail to nominal. 12V dc applied direct to the motor results in a current of about 400mA - but no rotation. Is it a fair assumption that the motor's at fault ? If so - anybody know where I could find a replacement - motor is marked MMI-6A2LK - or is it one of those things that won't be economical to source / repair ? Thanks in advance Adrian Suffolk UK ======return email munged================= take out the papers and the trash to reply -- -------------------------------------------------------------- Home Page: http://www.seanet.com/~jasonrnorth |
#7
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HI JR
Thanks for the comment It seems as if the motor is electrically isolated from chassis. Inside the nice metal screening can is a plastic-bodied motor, which connects to the regulator pcb - both terminals of which are wired but not directly connected to ground. Anyway - (at the moment) it would appear to be working (after the disassembly, clean - reassembly process described in this thread - so - fingers crossed - I shall not need to go looking for a replacement just yet... Thanks for the warning ! Adrian Suffolk UK On Thu, 24 Feb 2005 22:20:21 -0800, JR NORTH wrote: Be careful to check if the motor is shielded, or chassis grounded. Failure to do this caused me to blow a Technics M205 decks board when I replaced the motor with an otherwise correct replacement. JR Adrian Brentnall wrote: Hi All My old (1980's) Marantz SD230 cassette deck 'died',,,,, suddenly !. Symptoms - lights on - but no reponse to the 'play' button. A quick check of the voltages shows that 'something' appears to be pulling more current than it should, puling the main DC rail down from 19V to about 6V. Disconnecting the multi-way connector that drives connects to the drive motor and the play / record / pause switches restores the DC rail to nominal. 12V dc applied direct to the motor results in a current of about 400mA - but no rotation. Is it a fair assumption that the motor's at fault ? If so - anybody know where I could find a replacement - motor is marked MMI-6A2LK - or is it one of those things that won't be economical to source / repair ? Thanks in advance Adrian Suffolk UK ======return email munged================= take out the papers and the trash to reply ======return email munged================= take out the papers and the trash to reply |
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