I tried cleaning off the corrosion and that wasn't exactly a good thing..If it matches R494, then ok.
Glad I've got it right. Once I get all the parts in had I'm going to take my time re-assembling, soldering, fixing whatever tracks need it, etc..That's a gold stripe thanks. And the green does show to be a 1k, and 31 Ohm more, not a prob with that.
As for the blue resistor, that stripe looks to be gold, thus 68 Ohm range.
Also in cases here the Diode test function on some resistors have helped clear to the absolute values, as the diode test on many meters are not usually loss, meaning that the Diode test usually reads low values on Ohm to low K Ohm ranges as it depends on the tool used. Again thanks for the reading.
Thanks for the advice and insights.. I supposed I could get the resistor in series (didn't finish that task) at the spkr terminals, assemble, test, and if all seems goodIf you go with that method, may want to use a power strip with an on off switch, all tho, even if the power cord is switched off, the caps can hold enough power co cause problems if something else is affected, however there is really no way around this without testing methods that involve at least a scope of some kind and test leads all over the place. The resistor should not be to unusual to add in at the speaker, close back with a few screws, power in then test, any strange buzzing or hum, remove the power, also may want to watch the speaker on power on, if it goes one way in or out of the cone and hangs there, then something is latched on the driver control. Not likely but a possibility. If any issues result, then a prompt power removal is advised. If things work well, then the resistor can be removed. Current lock through a speaker is low, it just doesn't take much to damage them. Have some Pioneer procomps here rated at 1000W RMS that went up when an amp decided to latch on the push stage due to the ceramic resistor exploding. The fet went latch ballistic as they need removal of signal power when supposed to be off, the low current volt flow to the device had no where to go and the shut down rating of the device was not properly met.
Hi Spec,That is correct. But strictly speaking (sorry for pun) the resistor should go in the high side- if there is one (some amps have a bridge output so there is no high side).
Yes, that is correct. You can forget about the speaker now that you have protected it and tested it. Yes, we will be working on the power amplifier board mainly.
Bear in mind that mains voltages will be present on the circuit up to the primary of the toroid transformer (big & round) so please take care.
The next test is to set your meter to DC volts and measure the voltage across the speaker terminals. (it should be 0V to +-0.1V).
Hi CJ,Hi Spec,
Quick question.. I'm not sure what "go in the high side" means. No rush as I'm waiting for a delivery of white grease before I re-assemble
Excellent, thank you! Now I understand... Not being in this space so much I hadn't heard that term, or recall it.Hi CJ,
In a normal audio power amplifier, the amplifier output connects to one terminal of the loudspeaker (the high side), and the other terminal of the loudspeaker connects to 0V (also called ground, earth, or chassis). It makes no difference which side the resistor connects: it will protect the speaker equally well. But from a technical, purist, point of view it is best to connect the protection resistor in series with the high side of the speaker.