Bluetooth problems JVC RC-880

[amoorey]

Hi,

We’ve had some success with the RC-880 (I’ll post updates on the original threads soon) but have a question about Bluetooth mods.

The RC-880 does not have a dedicated line in, only a 3.5mm headphone jack. When we use the jack to connect to a small Bluetooth device, no sound comes through to the box. We’ve tried all manner of switch combinations. We’re missing something. Does the tape mech have to be engaged? Do you have to tap it somewhere like Fonzie?

Side note: We’ve lost radio play on the box when unplugging the headphone jack cord. It was working then intermittent and now is gone. The contacts were really oxidized but cleaning up shiny has not brought it back. It will play the radio through the headphone jack to an older portable speaker with a 3.5mm jack but it’s very quiet. Would love any ideas before we fire up the soldering iron and remove the 3.5mm box to look inside.



We’re already investigating hard wiring an adapter to an input, perhaps even preamp but want to make sure there isn’t any easier solution right in front of us. I guess the powered tape Bluetooth widgets are an option as well but that’s a lot of stress on the deck to have the play button engaged so much no?

We do want to preserve all other inputs: tape, and all radio bands.

Any suggestions or knowledge would be much appreciated. We’ve watched tons of videos but most mods seem to sacrifice the tape deck.

Thanks!

 

[Superduper]

Are you saying you tried adding a bluetooth receiver by plugging it into the headphone jack as an alternate input signal source?

It seems you already know this, but that headphone jack is for headphones. It OUTPUTS an audio signal, it is NOT intended as an INPUT. Yeah, it doesn't work that way.

As for the headphone jack issue -- the jack on that particular boombox was very fragile to begin with, made out of plastic that is probably already excessively brittle, it has 2 internal switches that switches out the speakers and routes it to the headphones instead. I'm pretty sure that the internal switches are either broken, or the metal switch springs have lost their tension. You can try to disassemble it and see if there's anything you can do to fix it, but I'm not optimistic. Furthermore, there's probably no new replacements available either. If broken, my only recommendation to you is to permanently bridge the contacts to restore function to the speakers. In the process, you should modify the circuit to take the headphones out of circuit. This involves simply removing the 2 capacitors that powers that headphone. The system is only intended to power either the speakers or the headphones, not both. If you bridge the contacts for the switch, the speakers will always be ON and plugging in the headphones will result in both the headphones and speakers to be powered on. This may or may not be problematic, I suggest you simply avoid that scenario altogether.

 

[blu_fuz]

Yeah, if you used the headphone jack to send audio signal back into the radio, you might have damaged something. I looked on google and the headphone jack you used is for AUDIO OUT only, not for inputting any signal. You do have a LEFT and RIGHT external microphone jack that you can send signal into the radio using a dual 3.5mm mic input adapter but depending on how that system is setup, you might need the cassette in play or even record mode to get the mic signal to come through the speakers and the quality of the signal might not be that good.....

 

[amoorey]

Thanks guys. Dang, I could have sworn I saw multiple references and sources about using the headphone jack and that it was two way. I always thought in the back of my mind that logic would dictate it was output only. Lesson 1 - follow logic before all else. Lesson 2 - check here first to avoid costly mistakes.

I’ll get back with an update after we decide best steps.

 

[Tinman]

There can't be many of the vintage boxes that don't have some kind of line in.
This is the first one I've seen.
Hell, even my cheap JcPenney box from when I was a kid had them.

 

[amoorey]

There can't be many of the vintage boxes that don't have some kind of line in.
This is the first one I've seen.
Hell, even my cheap JcPenney box from when I was a kid had them.

Yep, and that was the first thing on my list when I was looking for a box. Somehow how I missed it or missed the specs.

 

[amoorey]

Are you saying you tried adding a bluetooth receiver by plugging it into the headphone jack as an alternate input signal source?

It seems you already know this, but that headphone jack is for headphones. It OUTPUTS an audio signal, it is NOT intended as an INPUT. Yeah, it doesn't work that way.

As for the headphone jack issue -- the jack on that particular boombox was very fragile to begin with, made out of plastic that is probably already excessively brittle, it has 2 internal switches that switches out the speakers and routes it to the headphones instead. I'm pretty sure that the internal switches are either broken, or the metal switch springs have lost their tension. You can try to disassemble it and see if there's anything you can do to fix it, but I'm not optimistic. Furthermore, there's probably no new replacements available either. If broken, my only recommendation to you is to permanently bridge the contacts to restore function to the speakers. In the process, you should modify the circuit to take the headphones out of circuit. This involves simply removing the 2 capacitors that powers that headphone. The system is only intended to power either the speakers or the headphones, not both. If you bridge the contacts for the switch, the speakers will always be ON and plugging in the headphones will result in both the headphones and speakers to be powered on. This may or may not be problematic, I suggest you simply avoid that scenario altogether.

As always, thank you Superduper. How long have you been working on boomboxes?

 

[Tinman]

Yep, and that was the first thing on my list when I was looking for a box. Somehow how I missed it or missed the specs.

I did something similar once.
I had sold an Aiwa tpr-950H and after regretting it for a while, I wanted to get another one.
I ended up buying one on ebay from a guy in England.
Unfortunately I didn't realize until afterwards it was a 950K.
He didn't have the connectors side shown in any of his pics so I asked him what kind it had.
He told me it had DIN connections and if I wanted to cancel it I could but I ended up keeping it.
After receiving it, I did my usual routine of belts and cleaning but also added some RCA connectors.
That how I learned to know exactly what I'm buying beforehand.
I assume you won't make that mistake again, lol.

 

[amoorey]

I did something similar once.
I had sold an Aiwa tpr-950H and after regretting it for a while, I wanted to get another one.
I ended up buying one on ebay from a guy in England.
Unfortunately I didn't realize until afterwards it was a 950K.
He didn't have the connectors side shown in any of his pics so I asked him what kind it had.
He told me it had DIN connections and if I wanted to cancel it I could but I ended up keeping it.
After receiving it, I did my usual routine of belts and cleaning but also added some RCA connectors.
That how I learned to know exactly what I'm buying beforehand.
I assume you won't make that mistake again, lol.

Thanks, I really appreciate the story. I have learned so much from this experience. Glad it was a $125 box vs a $1,000 one.

 

[amoorey]

Good news! We popped the cover off the headphone assembly and after some liberal spraying with contact cleaner it’s working again. The little white piece moves side to side when plugging and unplugging the headphone connector in. The piece was moving to the side during plug in but then not moving back to Center without a nudge. Sometimes it’s still getting hung up when removing the connector but if you insert the connector back in halfway and then remove - bingo, speakers come back. The tension is very strong with the spring connectors inside. The cover popped back on no problem.

The switch inside the power cable connector on the box is also still finicky, even after cleaning. Something for another day.