Hi,
i have a Parasound Hca-806a which one channel has current protection problem,
It had 2 blown transistors , checked the other pair of transistors too, and 6 caps which was bad, I replaced them and replaced several other components with out luck.
I checked the speaker relay took it out and gave it 12 volts and it work greit,
any ideas, or someone sitting on a scematic ??
thanks in advance.
Niklas.
i have a Parasound Hca-806a which one channel has current protection problem,
It had 2 blown transistors , checked the other pair of transistors too, and 6 caps which was bad, I replaced them and replaced several other components with out luck.
I checked the speaker relay took it out and gave it 12 volts and it work greit,
any ideas, or someone sitting on a scematic ??
thanks in advance.
Niklas.
Get a schematic/service manual. if you can not get one then you are in for some fun.
If one channel works, then it is a simple matter of make one match the other, easier said than done, but you can use your ohmmeter and do nodal comparisons, which should lead to the area where there is an difference. You can remove the o/p devices to make it easy and check them separately out of circuit, bit the 2 ckts should have the same comps installed to do a comparison.
You can use you ohmmeter to test resistors, semiconductor junctions.
If one channel works, then it is a simple matter of make one match the other, easier said than done, but you can use your ohmmeter and do nodal comparisons, which should lead to the area where there is an difference. You can remove the o/p devices to make it easy and check them separately out of circuit, bit the 2 ckts should have the same comps installed to do a comparison.
You can use you ohmmeter to test resistors, semiconductor junctions.
I been measuring for a day or so, but it seems to be nothing really wrong after a replaced the output transistors, all seems to measure pretty normal, have the same measurement over the transistors on all channels, I actually have 5 working channels. same built... but still it wont activate because of error on protection. but im sure i will figure it out soon. would like too know wich component measure the current draw for the protection. the o/p is just a dc servo right on this model ?
I do not know anything about your unit, speaking generally
they usually sense the voltage drop across one or more of the emitter resistors. so trace from there. Something got damaged with the last blow up.
if you can identify a speaker protection IC look it up to get more info.
they usually sense the voltage drop across one or more of the emitter resistors. so trace from there. Something got damaged with the last blow up.
if you can identify a speaker protection IC look it up to get more info.
I been trying to study the schematic on a hca-1500,
its look similar to mine.
It seems to have the same input and o/p but just less output transistors.
so I will try to use this,
and as you see in orange and red marks,
that the sense emitter resistor of the over current protection.
if im not mistaken.
its look similar to mine.
It seems to have the same input and o/p but just less output transistors.
so I will try to use this,
and as you see in orange and red marks,
that the sense emitter resistor of the over current protection.
if im not mistaken.
Attachments
found the problem With q005 was defekt, after replacement it Works good and no over current problem 🙂