Meaco DD8l dehumidifier repair

[nicknorman]

Feeling a bit pleased with myself (not an uncommon event, you say). We leave a dehumidifier on in the boat over winter (windows shut, vents taped, dehumidifier drain pipe into the sink). It is supposed to have a "humidistat" and once the relative humidiy falls below the 50% target, the thing shuts off. Then every 30 mins the fan starts up and it sniffs the air, the main bit only coming back on if the humidity has risen otherwise the fan stops again. Or that is how it should be.

Recently I've noticed that the fan is always running. Before, when you switched it off, the fan would run for 5 mins or so (to cool it down) and the stop. But recently it never stopped until you unplugged it, and started up again as soon as you plugged it back in again. And sometimes the fault light was on.

So opened its box and had a look at the control pcb. 3 mains wires going to the fan for different speeds, controlled by little transistor things that turn out to be logic level triacs (things you use for switching ac power directly from a microcontroller). Actually I didn't know you could connect them directly to a microcontroller, so there was a learning point. The one for the fan low speed was "always on", aka "knackered".
Anyway, new device obtained. It should cost about 5p but of course from RS you have to buy 50 - which is still only £2.50
New triac soldered in, now it all works perfectly, fans stops when it should. Result.
So if anyone has a Meaco DD8L that is misbehaving, and you need a logic level triac to solder in, I have 49 to spare! They are MAC97A8.

Edited April 27, 2023 by nicknorman

[MtB]

4 hours ago, nicknorman said:

So if anyone has a Meaco DD8L that is misbehaving, and you need a logic level triac to solder in, I have 49 to spare! They are MAC97A8.

 

If only I had a a Meaco DD8L that is misbehaving, I'd deffly buy a triac off you for the 5p you paid for it (plus P&P obviously) and help you recoup your losses.  

 

Trouble is though, I haven't...

 

Have to say though, I am constantly impressed by your electronical abilities. 

 

 

Not that I'd ever tell you, obviously. 

 

 

 

 

 

Edited April 27, 2023 by MtB
Fiddle with it...

[nicknorman]

11 minutes ago, MtB said:

 

If only I had a a Meaco DD8L that is misbehaving, I'd deffly buy a triac off you for the 5p you paid for it (plus P&P obviously) and help you recoup your losses.  

 

Trouble is though, I haven't...

 

Have to say though, I am constantly impressed by your electronical abilities. 

 

 

Not that I'd ever tell you, obviously. 

 

 Not that clever really. The pcb had 3 wires connected by spade connections that went to the fan motor. Elsewhere a live and neutral coming on to the board (even labelled, to make it easy). It didn’t take much cleverness to see that the fan circuit was live to fan to little black transistor thing to neutral. Fan always running, therefore little transistor thing probably duff, always on. Disconnect resistor feeding 3rd pin of thing. Still running. Transistor thing definitely duff.
Read writing on it, look it up on Google. It’s a triac (my electronic knowledge extends to knowing what a triac is). Order from RS. Remove duff one, solder new one in. All done.

So not that clever really.

[Quattrodave]

5 hours ago, nicknorman said:

It should cost about 5p but of course from RS you have to buy 50

 

Using RS, blimey you must be feeling rich 😁

[nicknorman]

47 minutes ago, Quattrodave said:

 

Using RS, blimey you must be feeling rich 😁

RS is a bit like Midland Chandlers. Big profit margin, but very convenient. But then again, where would you have bought a MAC97A8 from that would have been cheaper?

 

Adding some detail, the USP of RS used to be no minimum order and free delivery. They dumped that earlier this year, now it’s £30 minimum order, or else there’s a £3 delivery charge. Fortunately I had other stuff to order. Still, where are you going to get a 1 off MAC97A8 cheaper?

[jonathanA]

16 hours ago, nicknorman said:

fortunately I had other stuff to order. Still, where are you going to get a 1 off MAC97A8 cheaper?

24p at CPC but you could just order 1. 

 

CPC are rapidly going down IMO, so RS may be the only option before long....  

[nicknorman]

40 minutes ago, jonathanA said:

24p at CPC but you could just order 1. 

 

CPC are rapidly going down IMO, so RS may be the only option before long....  

 

You could order one, but they don't have any stock!

[Peanut]

For broken Meaco dehumidifiers, there id a long thread here, ten pages:-

 

£0.43 Fix for Meaco DD8L Dehumidifier

 

https://forums.ybw.com/threads/£0-43-fix-for-meaco-dd8l-dehumidifier.443173/

 

 

[Jess--]

Best price I could find was £1.22 including postage from China* (although that was for 20 triacs)

 

My current big ticket fixed items for cheap parts are a £4500 laser cutter that needed a £0.12 schmitt trigger chip (smd of course) and a £8000 (estimated value) car that needed a small coil of wire, a magnet and a FET (AKA a crank position sensor) £23.17 cost.

 

* knowing the Chinese supplier it's 50:50 as to whether the item is actually in China or a UK warehouse.