Seafarer Mark III blown capacitor

[rptb1]

I'm helping to fix up an old boat which has a Seafarer Mark III depth sounder. It was probably working a few years ago, but is dead to the world now. Electrolytic capacitor C1 on the board has decayed and likely exploded (see photo). Can anyone tell me what capacity it had?

What I'd *really* like is a copy of the circuit diagram.

 

[TernVI]

The usual way to blow up an electrolytic is to reverse the supply volts.
They are rarely close tolerance parts, often used for supply rails, anything of suitable voltage might work.
It's C1 and right next to ZD1, which is odds-on a simple regulator circuit near the power supply.
The cap being absent is unlikely to stop the unit functioning, if powered from a clean supply.

 

[rptb1]

The usual way to blow up an electrolytic is to reverse the supply volts.

Indeed, though very old ones (e.g. in early 1980s micros that I have fixed) dry out and explode even with the current in the right direction. It is possible that the previous owner did something dodgy with the battery though.

They are rarely close tolerance parts, often used for supply rails, anything of suitable voltage might work.
It's C1 and right next to ZD1, which is odds-on a simple regulator circuit near the power supply.

Yes, I think that's likely. I can likely guess a reasonable capacity just from the size.

The cap being absent is unlikely to stop the unit functioning, if powered from a clean supply.

It shows no life when powered from a clean 12V supply on its labelled 12V inputs.

The photo was taken by a friend, and I haven't got my hands on it yet. We'll get it on a bench and have a close look, but not today. That's why a circuit diagram would help.

 

[Buck Turgidson]

Full set of spares on eBay for £10
Seafarer 3 Range Depth Below Transducer Electronic Laboratories Echo Sounder | eBay

I couldn't find a manual online when I had one and ended up binning it when I upgraded. I don't have room to keep old stuff.

 

[VicS]

I'm helping to fix up an old boat which has a Seafarer Mark III depth sounder. It was probably working a few years ago, but is dead to the world now. Electrolytic capacitor C1 on the board has decayed and likely exploded (see photo). Can anyone tell me what capacity it had?

What I'd *really* like is a copy of the circuit diagram.

I have the instruction book complete with circuit diagram., but it does not give any component values

If nobody helps maybe I can photocopy or photograph it later but after this morning I will be away from home for the rest of the week living it up to celebrate "stage 3"

 

[penfold]

Given the huge hole in the heat sink it's probably had a battery leak corrosive ooze everywhere; is it really worth spending time on? An advert in the wanted section might turn one up, or post a message on one of the facebook groups for old boat gear. Here's one on ebay.

 

[DownWest]

I have a Seafarer, I will look inside and see if the value is marked. Prob this PM.

 

[DownWest]

Looks like I can't help, mine is a 700 and the board is different. Only two big caps: C3 at 470uf & 16v. and C29 at 1000 uf and 10v.

 

[Cap'n Creosote]

Hope this helps.

 

[rptb1]

Hope this helps.

This will certainly help with testing and fixing. I don't suppose there was a table of component values attached?

 

[savageseadog]

The "+" mark shows it to be an electrolytic capacitor. I would suggest the value to be non critical perhaps 10-100uF

 

[JohnGC]

Some of the text on the old capacitor wrapping is still readable. Might be worth giving it a gentle wipe and examining with a magnifying glass.

 

[Cap'n Creosote]

This will certainly help with testing and fixing. I don't suppose there was a table of component values attached?

Unfortunately, there is no more information about the circuit. But I have a copy of the "Installation and operating instructions" which I could scan and post here, if it's of any use.

John

 

[Nick Barnes]

Given the huge hole in the heat sink it's probably had a battery leak corrosive ooze everywhere; is it really worth spending time on? An advert in the wanted section might turn one up, or post a message on one of the facebook groups for old boat gear. Here's one on ebay.

The unit had a PP9 battery in it, dead but clean and intact, when we first opened it. And aside from that hole, the innards are pretty clean - very little residue. So I suspect that it has been cleaned up, and functioned OK, since the leak of some previous PP9.

 

[Nick Barnes]

Some of the text on the old capacitor wrapping is still readable. Might be worth giving it a gentle wipe and examining with a magnifying glass.

We had a go at this. Capacitance sadly illegible, and the wrapping basically disintegrated to the touch.

 

[rptb1]

We bought the unit from eBay and it appears to work. The capacitor C1 is 10µF in that unit. I will try to revive the old one at some point and will update here if we get anywhere, but it may be a while. We have a lot to do to get this boat launched!

 

[andsarkit]

25V 10uF the same as the other 3 on the board. Black band is towards the outside of the case.
I still have the original mk3 from my boat and I have just powered it up and it appears to work - it must be over 50 years old. I get a reading in air bouncing off the wall which appears correct allowing for the difference in speed of sound in air and water.
If you are interested in keeping old electronics going you are welcome to it plus a spare unused transducer for the cost of a donation to your charity of choice. PM me if you want it.