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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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"The Box" monitor speaker ...
Got an MA-120 powered monitor speaker from "The Box" (what a ****-street
name for a company ...) in for repair. The output I.C is blown to pieces, but even before this happened, looks like it had had the legend ground off it. Anyone happen to know what it is ? TIA Arfa |
#2
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"The Box" monitor speaker ...
"Arfa Daily" wrote in message news Got an MA-120 powered monitor speaker from "The Box" (what a ****-street name for a company ...) in for repair. The output I.C is blown to pieces, but even before this happened, looks like it had had the legend ground off it. Anyone happen to know what it is ? TIA Arfa What package is it, and is there a separate amp for the tweeter, or does it use a passive crossover? Gareth. |
#3
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"The Box" monitor speaker ...
"Gareth Magennis" wrote in message ... "Arfa Daily" wrote in message news Got an MA-120 powered monitor speaker from "The Box" (what a ****-street name for a company ...) in for repair. The output I.C is blown to pieces, but even before this happened, looks like it had had the legend ground off it. Anyone happen to know what it is ? TIA Arfa What package is it, and is there a separate amp for the tweeter, or does it use a passive crossover? http://uk.farnell.com/on-semiconduct...sip/dp/2400415 Gareth. |
#4
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"The Box" monitor speaker ...
On 23/10/2014 18:23, Arfa Daily wrote:
Got an MA-120 powered monitor speaker from "The Box" (what a ****-street name for a company ...) in for repair. The output I.C is blown to pieces, but even before this happened, looks like it had had the legend ground off it. Anyone happen to know what it is ? TIA Arfa Assuming no info out there. For such situations I determine which are the power rails and output and ground, "eductaed" guess the inputs , compensation, feedback etc. Put a sleeved splay-pinned TDA7293 in there and power up at half rail voltages and see what happens |
#5
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"The Box" monitor speaker ...
"N_Cook" wrote in message ... On 23/10/2014 18:23, Arfa Daily wrote: Got an MA-120 powered monitor speaker from "The Box" (what a ****-street name for a company ...) in for repair. The output I.C is blown to pieces, but even before this happened, looks like it had had the legend ground off it. Anyone happen to know what it is ? TIA Arfa Assuming no info out there. For such situations I determine which are the power rails and output and ground, "eductaed" guess the inputs , compensation, feedback etc. Put a sleeved splay-pinned TDA7293 in there and power up at half rail voltages and see what happens TDA7293 is a common part in these applications, but the Manufacturers spec of The Box's 120W RMS @ 4 ohms rules this out, being as the TDA is only 100W. Unless of course there is a separate 20W amp driving the tweeter. Or they are lying. Its probably a Chinese clone of an existing device, hence my Googling and finding the STK device. The weird thing is the STK is max rated at 6 ohms. Now, how many 6 ohm speakers are out there? Why would you produce such a device and rate it with that output parameter? (Mind you, I doubt this is the IC in question here, so this is kind of OT) Gareth. |
#6
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"The Box" monitor speaker ...
"Gareth Magennis" wrote in message ... "N_Cook" wrote in message ... On 23/10/2014 18:23, Arfa Daily wrote: Got an MA-120 powered monitor speaker from "The Box" (what a ****-street name for a company ...) in for repair. The output I.C is blown to pieces, but even before this happened, looks like it had had the legend ground off it. Anyone happen to know what it is ? TIA Arfa Assuming no info out there. For such situations I determine which are the power rails and output and ground, "eductaed" guess the inputs , compensation, feedback etc. Put a sleeved splay-pinned TDA7293 in there and power up at half rail voltages and see what happens TDA7293 is a common part in these applications, but the Manufacturers spec of The Box's 120W RMS @ 4 ohms rules this out, being as the TDA is only 100W. Unless of course there is a separate 20W amp driving the tweeter. Or they are lying. Its probably a Chinese clone of an existing device, hence my Googling and finding the STK device. The weird thing is the STK is max rated at 6 ohms. Now, how many 6 ohm speakers are out there? Why would you produce such a device and rate it with that output parameter? (Mind you, I doubt this is the IC in question here, so this is kind of OT) Gareth. TDA7293 is indeed the correct package, so it might be. There is actually an electrolytic on the opposite end of the board that has also blown apart so badly that you can't see what value it originally was. The IC has burnt pins and print as it went up, and deposited a fair bit of soot around. I might get the IC out tomorrow and clean up a bit and see if it is actually going to be worth spending the time on. It is basically a piece of Chinese garbage, and probably not worth very much in the first place. It certainly isn't in very good condition, and doesn't look like it has been very well looked after, so it might be time to replace it anyway ... Arfa |
#7
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"The Box" monitor speaker ...
On 10/23/2014 1:23 PM, Arfa Daily wrote:
Got an MA-120 powered monitor speaker from "The Box" (what a ****-street name for a company ...) in for repair. The output I.C is blown to pieces, but even before this happened, looks like it had had the legend ground off it. Anyone happen to know what it is ? TIA Arfa Hi, Found this link to an owner's manual of the MKII version: http://images.thomann.de/pics/prod/1...manual_eng.pdf The last page as an address and a web address.: http://www.thomann.de/gb/index.html?...575203df1d90a2 Hope this helps, Tim Bristol Electronics |
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