New member

[wllm]

Here are some pics of the units i have. The ones in the car light up and everything seems to work except no sound. I have a spare set so i have had a look inside. I can only see one fault so far with the dsp unit. scorch mark on the underside of the lid was telltale sign.

You definitely a few burnt traces. If the short is repaired and you run a few wires where the traces have burnt it might be salvageable if there is no further damage.

[vanzep]

Thanks wllm - i checked the 7.5 volt box and it was not good news....




so the spare dsp unit is not fixable but there may be some components that could be salvaged/reused.

Next week I will have a look at the dsp unit that is in the car and see how that looks.

[wllm]

Thanks wllm - i checked the 7.5 volt box and it was not good news....

so the spare dsp unit is not fixable but there may be some components that could be salvaged/reused.

Next week I will have a look at the dsp unit that is in the car and see how that looks.

Wow, the capacitors had quite a party overthere... Hopefully the one in your car is in better shape...

The one in your car displays "DSP - 6" And a LED, this could be promising! my DSP without 7.5v module only reads "DSP - " but I wouldn't wait too long or power up the radio to minimize the potential damage.

Okay the 7.5v module looks to be the cause of the burnt traces and by the looks of it you best get rid of that quickly. Clean the area where the module was with vinegar and then with some isopropyl just to make sure there is no further corrosion to the board and store it away safely, as you said perhaps some parts can be reused later.

Depending on the outcome of the repair of my 7.5v box I may try to design a replacement circuit if I'm able to :'). if I understand this module correctly it's a small psu to generate +7.5 and -7.5 volts and a common ground.

And you may want to check the belt of the cassette player, mine was liquified and all over the place. May be a good time to put a new belt in there

[vanzep]

here are pics of the two units that i had in the car.
the radio is very dirty inside - will need to clean it up - do you have a part number or know where to get the belt for the cassette player
the dsp unit looks very good so far
hmmmm

[wllm]

here are pics of the two units that i had in the car.
the radio is very dirty inside - will need to clean it up - do you have a part number or know where to get the belt for the cassette player
the dsp unit looks very good so far
hmmmm

I was hoping your belt didn't liquify just yet. You could take the belt out and go to a store which specializes in repair of old audio gear, they usually know where to get good belts if you show the the current one. Alternative is I will order a belt set on aliexpress and find out the hard way which size it is. I'm also interested to know how the belt sits in the unit. Worst case scenario would be testing a few possible options.

Looks pretty clean indeed but do take a close look to the 7.5v module, it needs to be checked for leakage otherwise it might end up like the others

[vanzep]

thanks.
i can tell by the smell that a cap is leaking. I will take the board out later on - i am just hoping that this board will just require a new capacitor
will post up some pics once i have the 7.5v board out

[wllm]

thanks.
i can tell by the smell that a cap is leaking. I will take the board out later on - i am just hoping that this board will just require a new capacitor
will post up some pics once i have the 7.5v board out

When you get it open and the caps have leaked clean it with a toothbrush and vinegar then clean royal in isopropyl after that remove the caps to make sure it doesn't corrode further if you corrosion on the chip or close to it use a toothpick to clean in between the legs of the chip

In my case C13 (a SMD capacitor) was completely corroded away, may have to remove another capacitor to measure the capacitance and order a new one. I will first try without and see if I can revive this module.

[vanzep]

Thanks for the help
I have taken the 7.5 board out something is leaking but only a little - could be capacitor (M)106 35v 39 SFX - this is the one that had orange liquid on the body - also chip TL1451A 12B has corrosion on legs and on back of board.

[wllm]

Thanks for the help
I have taken the 7.5 board out something is leaking but only a little - could be capacitor (M)106 35v 39 SFX - this is the one that had orange liquid on the body - also chip TL1451A 12B has corrosion on legs and on back of board.

This one looks like it hasn't gone meltdown yet I think all four of the larger caps are leaky or prone to leaking atleast Do check traces near C4, L2 and C6, L4. These may need to be repaired or atleast scraped clean and add new uv curable soldermask to protect the circuit . Also get a "fiberglass pen" and some good flux, these are useful tools for cleaning and removing the caps. Corroded solder can be hard to remove and it's easy to lift a pad!

This is interesting: I thought I had a damaged C13 but I don't see any C13 on your board too but your board looks better. Good to know!

Can you confirm this for me please?
Q1 has markings N Y
Q4 has markings M Y

The following caps where on my 7.5v module you can confirm this is the same for your board? If so, I would remove all of them and clean the board with vinegar and isopropyl. Source the same ratings and all low esr 105 celsius and only go for A brands (eg Rubycon, Nichicon, Panasonic etc).
C1 35v 39uf
C2 35v 39uf
C3 10v 100uf
C4 10v 33uf
C5 10v 100uf
C6 10v 33uf
C7 50v 0.47uf

As for the cassette belts, it turns out there are three... One main drive belt and two small belts that control the head and capstan/pinchrollers. I'm going to try these:
2x 15.2x1.0mm Too big.
2x 10.8x1.2mm
1x 70x1.2mm

[vanzep]

C1 35v 39uf
C2 35v 39uf
C3 10v 100uf
C4 10v 33uf
C5 10v 100uf
C6 10v 33uf
C7 50v 0.47uf

Yes i have checked and all are the same (but I could not see what the voltage was on C4 so i have assumed you are right). If any doubt then let me know.
I will have to find the capacitors. (note 3 out of the 7 are on ebay uk)
Just wondering if i should leave the metal enclosed bigger board alone and assume its all ok.