Blanpunkt Radio Getting Hot - PeachParts Mercedes-Benz Forum

turbodrabbit · #1 06-05-2011, 09:14 PM

I recently came across a Blanpunkt Las Vegas cd player and installed it in my lady's 1985 300td. I previously had the factory Becker, and when I bought the car the fuse attached to the radio was blown. I swapped out the fuse and no problem. My lady then tried to use the cig lighter to charge the gps and the fuse blew. I cleaned the contacts on the fuse box and the radio was functional, but I am unsure if she tried to charge anything.

Fast forward to the blankpunkt install, I wired everything up, splicing the Las vegas harness into the factory harness, and it works. I was about the place the radio back in the dash, and I noticed the unit was very hot.

I just added an additional ground to the Blanpunkt body, in addition to the factory spade ground. It is still getting hot.

Any ideas?

G-Benz · #2 06-06-2011, 12:30 PM

Adding additional grounding won't reduce heat, or enhance anything.

Adding grounding might, in fact, introduce noise.

If the HU (head unit) isn't blowing fuses, there are a couple of things to look for:

Suffcient gauge wire...unless you are using doorbell wire for power and ground, you should be okay in this area...the OEM gauge is sufficient.

Are you using the internal HU amp to power the speakers in the car? I know from experience that Blau HUs DO get hot, moreso if the internal amp is being used for duty.

If the HU is too hot to the touch, there may be other factors involved pointing to a defective unit to begin with...new ones are plenty cheap these days, so there's no need to risk a fire if you suspect a problem with the HU!

Amp limit on cig lighters vary from one vehicle to the next, and I've blown 15A fuses on my ML (hooking up a crock pot), but noted 30A fuses being used for cig lighters on my daughter's Mustang. Typically, cig lighters and sound systems should not share the same circuit.

tbomachines · #3 06-06-2011, 03:53 PM

Does the audio cut out at semi-high volumes (especially with bass)? Either a grounding issue or the resistance of the old speakers are outside the specs of the HU. For example, hooking up two speakers to the same speaker output will cause the HU to cook since it will have to pump out twice the current to achieve volume. I would have to double check, but I know some of the old early 80s speakers were 6ohm (2,4,8 ohm for typical newer HU output).

turbodrabbit · #4 06-07-2011, 11:11 PM

They are hooked to the original speakers (blown), the audio is starting to cut out. I will try disconnecting the speakers and see if that helps.

G-Benz · #5 06-08-2011, 10:19 AM

Good point on the ohm rating, tbomachines. Forgot about that one.

External amps are better designed to handle speakers showing weird resistance, and they have far better cooling capabilities and large heat sinks.

Head unit amps are squeezed in a compact chassis, and heat dissipation is well, buried in a cramp enclosed dash cavity...a recipe for overheating and amp failure (signal cuts out intermittently, especially at loud volumes).

Perhaps that same limitation is why the Becker systems have the head unit behave as a control interface only. The tuner and amps are located elsewhere.