Assistance with car radio issue (replacing cassette with bluetooth), low volume - Page 1
Forum section: electronics / beginners

author: v4mofo
author_rank: Newbie
timestamp: April 26, 2022, 02:48:06 pm
content: Thanks to those who've come to read, hopefully this is simple for those with experience but it's beyond my limited knowledge.I have a 1980's Toyota that I'm trying to keep original in appearance (hence modifying the OEM radio/cassette) and have installed a bluetooth module (powered by a B1205s 1w power isolator after a normal buck converter gave me lots of ground loop noise). The problem is that when I tried using the audio lines from the tape head, it sounded Terrible. So I found the L/R channels on the main board and those give me clear audio, but at a volume that can only be heard with the vehicle off and max volume on both the head unit and the phone.Anyone see a clear way to resolve either of those 2 issues with the current setup?Thanks for any help!Sorry, having issues with photos

author: floobydust
author_rank: Super Contributor
timestamp: April 26, 2022, 03:41:22 pm
content: The BT module can also have an issue with it's output, if that circuit is missing coupling capacitors, which then make it upset almost everything connected to it. What model # or chip # or pic of it to confirm that and rule it out. I usually just add a set of AUX-in RCA jacks to the tape deck.You don't want to tie in at the tape head, the signal there is very low level and it would just be overloaded by the BT module's output.You want to tie in after the tape head pre-amp, would need the part number written on IC201 to fully figure out the small PC board you have, it's likely the tape head preamp.Normally, feeding audio in, in place of the tape head preamp's output should be a reasonable signal level.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: April 26, 2022, 11:56:05 pm
content: Radio model would be nice CQ-??Picture of rear of unit DIN plug?Jeff

author: NotYourGirl
author_rank: Newbie
timestamp: July 04, 2022, 10:05:02 am
content: Why dont you try something like bluetooth FM transmitter, i think its way easier and the purpose is the same, you just plug it in your car. I got this one (https://www.mytrendyphone.dk/shop/bluetooth-fm-transmitter-dual-port-billader-bc70-272029p.html) its very slick and design is kinda vintage so i thin it will pair well with your car. I have been using it for some time and its great.

author: kripton2035
author_rank: Super Contributor
timestamp: July 04, 2022, 10:30:39 am
content: FM audio sound is awful. and if you travel long enough, you have to change the FM frequency too often.

author: chinoy
author_rank: Regular Contributor
timestamp: July 04, 2022, 10:59:04 am
content: Posting info about your bluetooh module would help.You get two kinds of blue tooth modules. All for a dollar or two thanks to China.I picked up 2 modules for something similar. One with an inbuilt amp and one without an inbuilt amp.Be careful some of the blue tooth modules with amps. Say you can not combine the grounds i.e. they need separate grounds.I also had the same problem which is the volume was too low. I solved it by inputting the signal to the 13 Pin jack behind the kenwood.I had to use a 10K resistor between 2 pins to make the deck think it was connected to a CD Changer. I then input the single ground with left right and it worked fine.Id was thinking of getting two LM386 boards 1$ each. And use them an pre-amps.Looking at your wiring its no wonder its noisy.Look at the wires that run off your tape deck head. They are shielded. You should use similar cable.I too had a noise problem till I changed the wires I was using to 3 core shielded. Grounding the shield at both ends to ground and the nose went away.Does your deck have an Aux in ?. If yes you can use it. If no you have to add an amp to your blue tooth module. And you have to fix your wires used.Another option would be to get a BT board they cost 3-4$ and they have a pre-amp and a bass / treble control.