Author
| What is wrong with R2 on the NMS 1205 Music Module?
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floppiefrans
msx friend
Posts: 1 |  Posted: November 21 2004, 17:58 |
Why are 3 of the 4 music modules I have defect on the R2 (33 ohm)?
R2 is black or burned through…
Can I do anything to prevent this in the future?
I am working with the NMS 8255…
TNX
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Repair-Bas
msx addict
Posts: 380 | Posted: November 21 2004, 18:04 |
never seen this problem
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flyguille
msx master
Posts: 1182 | Posted: November 21 2004, 18:12 |
first , what function has R2?
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HansO
msx addict
Posts: 375 | Posted: November 21 2004, 18:28 |
R2 is in the filter of the -12 V power supply circuit diagram.
As far as I can see ( www.hansotten.com - MSX Hardware Info - Philips Music Module Service manual) it is used only in the analog part of the module. Very little power will be drawn in normal circumstances from -12V.
Something wrong with the -12V powersupply in your machine? If too high the capacitors behind R2 to ground will blow up and may shortcircuit if it exceeds the max voltage allowed for the capacitor and the short will fry R2 next. |
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sander
online
msx addict
Posts: 335 | Posted: November 21 2004, 22:18 |
I've seen this before. It happened to that user when he accedently inserted the Music Module while the MSX computer was running.
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HansO
msx addict
Posts: 375 | Posted: November 21 2004, 22:52 |
Indeed, inserting a cartridge in a running MSX can cause awfull damage.
In MSX 1 machines very often the VDP died. I once revived a died MSX 2 with also a dead clock with a 7 MHz upgrade.
MSX computers are very sturdy machines, but carts are the weak point.
One should attach a label to every MSX:
SWITCH OFF POWER BEFORE INSERTING A CARTRIDGE.
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Sonic_aka_T
msx guru
Posts: 2261 | Posted: November 21 2004, 23:51 |
Is it just my idea, or did some models actually come with such a label?
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snout
msx legend
Posts: 4991 | Posted: November 21 2004, 23:59 |
Afaik my 8245 had such a clear warning in the manual. Not sure. Either way, the cartridge slots are indeed the weakest point in the otherwise nearly indestructible MSX computers 
And OK, I admit it.. I did quite some accidental and non-accidental (SCC) cartridge insertion&removal whilst my 8245 was powered |
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[D-Tail]
msx guru
Posts: 2990 | Posted: November 22 2004, 00:04 |
Other MSX computers lock the cartridge from being removed after it's inserted, or prevent them from being inserted while the machine's up and running, IIRC...
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wolf_
msx legend
Posts: 4629 | Posted: November 22 2004, 00:05 |
I think I inserted nemesis2 in my 8245 at least 50x .. without issues .. and cart.port 2 was a tricky one  |
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sander
online
msx addict
Posts: 335 | Posted: November 22 2004, 00:12 |
Well, I blew up a SFG-05 once, because I inserted the 50 to 60 din converter the wrong way. (Stupid thing was, that there was no notice on that thing how to insert it). To bad. Also to bad: there aren't any trackers that make use of the SFG-01/05 modules. Still room for explorations in MSX hardware here!
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