JVC RX-6042 5 secs then shuts off

[S2udio]

Re: JVC RX-6042 5 secs then shuts off

The schematic is here.

http://www.eserviceinfo.com/download.php?fileid=34224

Ovewrite PT 0 with PT 1 ...its an update

AT least 3-5 ? logic switches to get this beast powered up ?
Disconnect the psu and simulate the power up sequence ....check and monitor the PSU first
With a 60w bulb for load on the Power tx output.
Or use a variac
Depends on OPs experience with the iron ?
Then move on.

[scampo77]

Re: JVC RX-6042 5 secs then shuts off

I can't find these parts anywhere can someone possibly help me with replacement parts that are easier to find?

[999999999]

Re: JVC RX-6042 5 secs then shuts off

I can't find these parts anywhere can someone possibly help me with replacement parts that are easier to find?

2SD637 is available on ebay with worldwide shipping from some sellers.

The QAD0012-202 can be replaced with another 2kOhm thermistor of the same form factor and current capacity (physical size). There might be a few options on http://www.digikey.ca searching for thermistor then using the filters to narrow the search.

[duane_steel]

Re: JVC RX-6042 5 secs then shuts off

Hi,

I apologize if this is a Hijack, I certainly don't intend it to be! I happen to be working on the exact same receiver and came across all this great information and it's been a great help to me.

I hope its ok to ask a couple questions (not related to the OP's questions) but on the same gear since you've all become familiar with it!

1. The receiver I'm working on has burn marks and other obvious signs of overheating around the main voltage regulator transistors for the +12v and +5v (Q1435, Q1405, Q1434, Q1404, Q1401, etc)

Is it reasonable to just replace these parts or is it likely that there's a problem somewhere else that led to so much overheating on these parts?

2. I'm new to amplifier design and wondered if anyone could explain the purpose of the pri_+B, pri_-B, inputs to each of the 5 amps. I assume B+/B- are the positive negative input but what are those separate inputs?

Thanks! and again sorry if this should be in a new post.

[scampo77]

Re: JVC RX-6042 5 secs then shuts off

im not sure if anyone is still following this but i finally figured out where all the parts came from, thermostor that weird transistor etc.. i put amp #4 all back together and the thing hand gernaded again. SIGH!!!!

the transistor was like 12$

i am really ready to throw this thing in the garbage.

[ben7]

Re: JVC RX-6042 5 secs then shuts off

im not sure if anyone is still following this but i finally figured out where all the parts came from, thermostor that weird transistor etc.. i put amp #4 all back together and the thing hand gernaded again. SIGH!!!!

the transistor was like 12$

i am really ready to throw this thing in the garbage.

Give it one last shot. Check all the resistors, transistors, and diodes.

[scampo77]

Re: JVC RX-6042 5 secs then shuts off

it is another shorted darlington pair. i hate to do it but this will be the 3rd pair i will be replacing. i even tried the lightbulb thing and it cooked anyway. i cant throw any more money into this thing.

it is still has an option for "casstte tape" so i guess its lived long enough. ill go spend the 99$ to replace it.

thanks to everyone that helped me in this thread

[ben7]

Re: JVC RX-6042 5 secs then shuts off

it is another shorted darlington pair. i hate to do it but this will be the 3rd pair i will be replacing. i even tried the lightbulb thing and it cooked anyway. i cant throw any more money into this thing.

it is still has an option for "casstte tape" so i guess its lived long enough. ill go spend the 99$ to replace it.

thanks to everyone that helped me in this thread

Hmm, did you touch the trimpot at all?! That sets the bias, if you set it wrong then it can blow the output transistors.

[abrsvc]

Re: JVC RX-6042 5 secs then shuts off

Try turnong the unit on without the output transistors installed at all. Measure each pad to ground and post those voltages here. If the outputs have blown right away, you are probably missing a voltage or have a shorted driver transistor. The voltages present without the outputs installed should provide a clue. If that appears OK, then install the outputs without the center pin connected. This should present the correct voltages WITHOUT any current draw and thus won't blow the outputs.

Post your progress here.

Dan

[scampo77]

Re: JVC RX-6042 5 secs then shuts off

my last post was just to thank everyone for their help. in order for me to try another stab at this thing i need to spend another $40-50 in parts and wait another few weeks for everything to arrive. i dont want to throw good money after bad (if i havent already). this thing is super old and although i hate to see it go and i love the challenge, i just cant in all good sense put anymore time or effort into it.

thanks again for the response and thanks to everyone here, i CAN take from this project a lot of knowlede and even that new nifty light bulb trick. so its not a loss at all

thank you again to everyone.

[Agent24]

Re: JVC RX-6042 5 secs then shuts off

You might be able to regain some money if you sell it to someone who is willing to keep trying