They've used 10k thermistors in most of their older amps so that's what I'd expect to find there. You could contact Rockford tomorrow to get the exact value.
does it matter what kind i use? i see radial types and etc?
i am looking @ this one on mouser.
B57861S103F40 EPCOS Thermistors - NTC
and will i need to readjust the output puts afterwards?
i am looking @ this one on mouser.
B57861S103F40 EPCOS Thermistors - NTC
and will i need to readjust the output puts afterwards?
The package style doesn't matter as long as it will fit in the alloted space between the outputs.
This has nothing to do with the outputs.
When you get the bias transistor in the amp you'll need to readjust the bias and do some testing to confirm that the bias is not drifting significantly at various temperatures.
This has nothing to do with the outputs.
When you get the bias transistor in the amp you'll need to readjust the bias and do some testing to confirm that the bias is not drifting significantly at various temperatures.
okay got parts. soldering in now. on the transistor that replacing jumper, should it go marking side out(flat side), or marking side towards mehsa?
http://www.fairchildsemi.com/ds/KS/KSC945.pdf
heres data sheet, labeling leg one(emitter) as far left leg with flatside out
heres data sheet, labeling leg one(emitter) as far left leg with flatside out
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You should have ordered the KSC945C which has a different pin configuration. With your meter set to diode check and the red probe on the third leg, do you read ~0.6v to the other two legs?
OK. Place it with the flat side facing away from the insulator. Place a fair bit of heatsink compound between the transistor and the insulator. The fiberglass piece needs to hold the transistor against the insulator but the primary duty of the screw in that location is to hold the MEHSA insulator tightly against the heatsink. If it can't do both, tighten the screw and let the tension in the leads of the transistor hold it against the insulator.
Hello, i found this thread through google 🙂 i have the same amplifier with a burned power supply, does anyone know the real name of the shotky diodes used in this power ? in the schematic they have named them ss-1403 and ss-1378,and i have big problems finding replacement.
alright, everything is put back together, and i am ready to test amp and adjust the output pots. do i need to power up with 15 amp fuse? and how do i adjust the pots? also i can set back to oem adjustment on pots as they were marks from factory.
xbyte:
Those aren't Schottky diodes. They're standard, ultra-fast recovery diodes. The originals were likely MUR1620CT and MUR1620CTR. Grandam88 may be able to confirm.
grandam88:
This part is going to be critical. Set the pots fully counter-clockwise and confirm that all of the 0.1 ohm source resistors have 0.000v across them when you initially power it up.
Power it up through the 15 amp fuse (bypassed for a couple of seconds if necessary to prevent blowing the fuse on startup).
Connect the voltmeter across one of the source resistors in the good channel and VERY slowly turn the bias pot for that channel clockwise while very closely watching the meter. Set the voltage to 0.001-0.002v. Watch the voltage for 10 seconds to confirm that it remains at that voltage.
Do the same for the repaired channel (you'll move the meter to one of the source resistors in the repaired channel). Again, watch the voltage carefully to confirm that it remains constant.
You'll have to check the voltage on the resistors with NO signal. Even a small signal will cause the readings to be skewed.
Drive the amp to a moderate volume and let the amp warm up a few degrees. Re-check the bias on both channels. I'm assuming that you have this on subs and have the crossover set to low pass. If so, set it to full range. This will make the amp warm up more quickly. Continue to check the voltage across the source resistors every few minutes until the amp gets hot enough so that it's difficult to hold your hands on the heatsink (on the audio side). If the voltage starts to increase significantly on either channel stop testing and let us know.
Those aren't Schottky diodes. They're standard, ultra-fast recovery diodes. The originals were likely MUR1620CT and MUR1620CTR. Grandam88 may be able to confirm.
grandam88:
This part is going to be critical. Set the pots fully counter-clockwise and confirm that all of the 0.1 ohm source resistors have 0.000v across them when you initially power it up.
Power it up through the 15 amp fuse (bypassed for a couple of seconds if necessary to prevent blowing the fuse on startup).
Connect the voltmeter across one of the source resistors in the good channel and VERY slowly turn the bias pot for that channel clockwise while very closely watching the meter. Set the voltage to 0.001-0.002v. Watch the voltage for 10 seconds to confirm that it remains at that voltage.
Do the same for the repaired channel (you'll move the meter to one of the source resistors in the repaired channel). Again, watch the voltage carefully to confirm that it remains constant.
You'll have to check the voltage on the resistors with NO signal. Even a small signal will cause the readings to be skewed.
Drive the amp to a moderate volume and let the amp warm up a few degrees. Re-check the bias on both channels. I'm assuming that you have this on subs and have the crossover set to low pass. If so, set it to full range. This will make the amp warm up more quickly. Continue to check the voltage across the source resistors every few minutes until the amp gets hot enough so that it's difficult to hold your hands on the heatsink (on the audio side). If the voltage starts to increase significantly on either channel stop testing and let us know.
yes perry is correct on the part numbers. i have extras, but unless you live close to houston tx it would be pointless as their price on mouser is pretty cheap (1-2$ a piece.)
and i will do the testing now and let you know what happens in the next hour. thanks
and i will do the testing now and let you know what happens in the next hour. thanks
alright i think i messed up.
i was testing the resistors with amp powered up while driving a signal, was testing a resistor and accidentally touched a probe to the resistor leg nearest heat sink to the first leg(or far right).
now amp powers directly into protect mode.
what did i short out?
i was testing the resistors with amp powered up while driving a signal, was testing a resistor and accidentally touched a probe to the resistor leg nearest heat sink to the first leg(or far right).
now amp powers directly into protect mode.
what did i short out?
Probably an output but it could be a driver. It's also possible that you damaged the protection circuit. You'll have to start testing everything in that area, resistors included.
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