⟐ Commented March 29, 2026 at 21:09 MST

i bought a used device, but they didn't give me a card with a QR-code, and i can't connect to the charger to configure it, i have a pin and a puk

Symptoms:

Amplifier consumes approximately 630 mA quiescent current with no load connected.

All driver transistors in the output stage (for all 4 channels) are running hot.

All output transistors, diodes, ICs, and capacitors have already been checked and/or replaced.

Tests Performed:

1. Verified power supply rails are stable and within specification.

2. Checked biasing resistors and emitter resistors for drift or incorrect values.

3. Inspected PCB for possible leakage paths, solder bridges, or damaged traces.

4. Replaced electrolytic capacitors in both power supply and audio sections.

5. Output stage power transistors tested OK (no shorts or leakage).

Issue:

Despite the above, high idle current and overheating of the driver stage persists.

Request:

Looking for guidance on:

Possible causes of excessive idle current in the driver stage.

Recommended next steps for isolating whether the problem is related to bias circuit, thermal tracking, or feedback loop instability.

Please help me

⟐ Edited March 20, 2026 at 19:38 MST

⟐ Commented March 07, 2026 at 17:15 MST

⟐ Edited February 20, 2026 at 1:44 MST

⟐ Answered February 15, 2026 at 18:24 MST

⟐ Answered February 15, 2026 at 18:17 MST

⟐ Answered February 14, 2026 at 16:08 MST

How can I reset it back to the original firmware or reset it?

⟐ Answered February 14, 2026 at 16:08 MST

a couple of notes - starting with - it’s a Pioneer AVIC F700BT.

1. My stereo needs, badly, the firmware update. The Bluetooth stopped working with my phone 3 iPhones ago, for both calls and music (obviously).
2. Bigger problem: Yes, it started with the Bluetooth not connecting to my phone. Okay, so, I discovered that it needed an update - but I’d been just too busy or just too lazy to do it. But then it started doing the power up, try to load map (and failing), thing - but - I *can* get to the CD screen, choose a track, and it‘ll play for 2.13 minutes or something, then power itself off… rinse and repeat. Endless cycling.
3. a. It *really* feels like this is happening because of the map’s failure to load, somehow. The message saying that the system is powering up again / map is loading (I think?) covers up most of the message beneath & the button you would usually press to accept the map / pledge to not drive like a jerk / whatever isn’t visible/press able at all. (I can’t remember what that “underneath” message says, as I haven’t seen it in so long, but it’s along those lines).
4. b. During the repeated cycling, I *can* touch the CD button, get to the CD player screen, and “enjoy” a good 2.13 or so minutes of a CD before it just turns itself off and then immediately attempts to boot up again. I put “enjoy” in quotes, because… are you kidding?!! It’s bleeping maddening.
5. So - that said, I really don’t think it’s an electrical problem, as it’s far too consistent with the constant / predictable rebooting and problem loading the map and so forth. Also, it happens whenever my key in the ignition is turned enough to power everything up (without starting the car). Does not change if I’m driving, stationary, or whether the engine is on or off.
   

So - this is my problem now, in addition to all the above: I was just now going to try to do the software update, *but* the first step is to check the version of software you have - but I can’t even get to the menu to check, with all the rebooting & the messaging, and the buttons covered with the messaging. (And no, you can’t press the hidden buttons. Tried. Tried to get at the edges, maybe, middles, tops, bottoms, pressing everywhere, etc. Doesn’t work.)

Please Help! Thank you =)

⟐ Answered February 14, 2026 at 16:00 MST

⟐ Answered February 14, 2026 at 15:42 MST

⟐ Answered February 14, 2026 at 15:35 MST

⟐ Answered February 14, 2026 at 15:30 MST

⟐ Answered February 14, 2026 at 15:24 MST

Everything works except the backup camera display is black. When I put it in reverse the H/U switches to backup camera mode and it says "image may be reversed" and shows the parking assist lines. I move the gear selector either way and the H/U goes back to regular mode.

I know the camera works when i put it in reverse because I have a separate video monitor it displays on. It turns on when I select reverse and off when I select another gear.

-head unit works

-camera works

-reverse triggers a backup screen

-screen is black with warning message

-backup lines show

-hooked into brown port "r/c in"

⟐ Answer edited February 10, 2026 at 4:41 MST

⟐ Commented February 02, 2026 at 20:58 MST

⟐ Commented January 15, 2026 at 10:06 MST

I have this car stereo. I added Bluetooth and audio output through an external amplifier (I take it after the preamp, bypassing the standard TDA2005). It all works. But I noticed that the cassette feed motor is causing interference in the speakers during operation. I specifically checked it without a cassette tape, without the Bluetooth module (I removed it from the unit). There is a distinct noise in the speaker when the feed motor rotates. If I slow it down with my finger on the shaft, the noise changes accordingly. How can I overcome this interference? I replaced the electrolytic capacitors related to the power supply to the cassette part. What has changed: if previously, when playing a cassette and turning the volume to near maximum, throttling began, and after a second the cassette would be ejected (there is an electromagnetic latch that ejects the cassette when the power is interrupted or the radio is turned off), now at full volume the sound does not interrupt, and the cassette does not spit out. The motor interference hasn't gone away. I also noticed that if I remove the cassette deck from its designated slot, the interference gets louder, suggesting it might be connected to the negative line. I disassembled the motor and found nothing amiss. The brushes are still in good condition, and the fins are unworn. The rotor isn't catching anywhere. The only thing I noticed was a small buildup of carbon on the eccentric speed controller end switches. I cleaned everything and reassembled it - no change. A 103 capacitor is soldered to the motor terminals, which is actually designed to dampen contact bounce in the network, if I'm not mistaken. I didn't have a 103 capacitor in stock, so I tried connecting a 104 capacitor in parallel to it just to test it. No result. I ran three wires from the pickup head through a ferrite ring, making one turn of each wire - no effect. What else can I try?

⟐ Commented December 29, 2025 at 3:20 MST

⟐ Marked as duplicate December 15, 2025 at 23:52 MST

⟐ Answered November 20, 2025 at 15:42 MST