Suprima: changing PCB

[therealmark]

I have a Suprima 50 which (etc etc)

After reading other users' posts (for which many thanks) I decided to buy
the replacement kit P/N 5111603.
I believe that this kit is badly designed and the fitting instructions are defective.

Earthing. You are told to connect the earth wire from the spark gap to
the earth screw on the control chassis. But this screw is tucked away
inside the chassis and you cannot reach it without first removing the control chassis from the boiler.

Instructions do not mention the need for earth bonding on the gas & water pipes.
Also nothing about keeping wires away from hot metal.

Both the gas valve and the fan have earth terminals; instructions say
"unused". But if these earth wires were needed on the original design, they are surely still needed.

Instructions say that the side cover must be earthed. If this is so, then
the main cover must also be earthed; no provision is made for this.
I filed off the paint under the fixing screw heads.

Gas valve. The wires to this valve end in a so called "molex plug"
(actually a socket). Originally this had 5 terminals: 2 & 4 connected together and 3 = earth. In the new
socket these 3 terminals are all missing. Again, if these were
needed on the original
design, they are surely still needed. The new socket was very loose,
it will fall off if not secured.

Fuse. The top of the control chassis bends over the fuse. The only way
to get at the fuse is to remove the control box from the chassis. Instructions say "3A". Fuse actually
fitted was 4A. Please could anybody tell me the correct rating?

Side panel. When at last I came to refix this, I found that Pot have
moved the socket for the fixing screw about 15mm to one side. Also they have changed the thread.
The old screw is useless and they neither provide a new screw nor tell you what thread it needs to be. ?? 2M ??

Finally: "turn the boiler temperature control to the required
setting". This control is not graduated, how is anybody supposed to know what the required setting is?

IMHO: Label all the sockets on the PCB & their matching plugs.
Unplug all the wires from the PCB & install them into the boiler.
Refit fan & air pressure sensor etc.
Connect all earth wires to a new earth point in an accessible
place (X) on the main chassis.
Put another wire (W) on the earth point of the control chassis.

Insert the control chassis, connect W and X.

The idea is to get all the wires in place before you install the PCB,
so you do not have to install both at once. Also you can then replace
the PCB without having to take the whole boiler to pieces.

 

[John506]

I decided to buy
the replacement kit P/N 5111603.
I believe that this kit is badly designed and the fitting instructions are defective.

Why buy it then?

I'm sorry I can't help you with your problem, I'm not an electrician, you will probably have more luck over in the electrics forum

 

[kevplumb]

jeez its a pcb with a harness

first one i did took me 15 mins

mind it was in a stable and the hoss was frisky

 

[gasacs]

You would be better off taking your complaints up with the board manufacturer rather than an internet forum.

 

[petit_pablo]

Cant comment on what the instructions say ive never read them. These boards are so easy to change, no idea what your on about with earthing to main chassis, the earth is on the PCB assembly. Its easier to fit the wires to the board then wire the components up. The new molex plugs are different because the boards different so no it dosnt need exactly the same connections as the old.

Jeez

 

[Softus]

You lot are very narrow-minded - I think therealmark's observations will be very useful to other novices undertaking the PCB replacement.

 

[nickso]

You lot are very narrow-minded - I think therealmark's observations will be very useful to other novices undertaking the PCB replacement.

not being a novice i find it hard to understand the difficulties and think he is making the proverbial mountain.

After reading other users' posts (for which many thanks) I decided to buy
the replacement kit P/N 5111603.
I believe that this kit is badly designed and the fitting instructions are defective.

lets see shall we.

Earthing. You are told to connect the earth wire from the spark gap to
the earth screw on the control chassis. But this screw is tucked away
inside the chassis and you cannot reach it without first removing the control chassis from the boiler.

if you are removing the old pcb chassis you have ample opportunity to connect this earth to the new chassis, it is in fact the very first thing i do in my little suprima sequence after removing the old setup.

Instructions do not mention the need for earth bonding on the gas & water pipes.
Also nothing about keeping wires away from hot metal.

irrelevant.

Both the gas valve and the fan have earth terminals; instructions say
"unused". But if these earth wires were needed on the original design, they are surely still needed.

irrelevant

Instructions say that the side cover must be earthed. If this is so, then
the main cover must also be earthed; no provision is made for this.
I filed off the paint under the fixing screw heads.

irrelevant

Gas valve. The wires to this valve end in a so called "molex plug"
(actually a socket). Originally this had 5 terminals: 2 & 4 connected together and 3 = earth. In the new
socket these 3 terminals are all missing. Again, if these were
needed on the original
design, they are surely still needed. The new socket was very loose,
it will fall off if not secured.

the old one was also very loose, it didnt "fall off". i have never been to one that has "fallen off".

Fuse. The top of the control chassis bends over the fuse. The only way
to get at the fuse is to remove the control box from the chassis. Instructions say "3A". Fuse actually
fitted was 4A. Please could anybody tell me the correct rating?

irrelevant. whatever the fuse rating it is sufficient in almost all cases as i have never had to replace one yet. if you do replace a blown one let me know so i can fall off my seat in shock.

Side panel. When at last I came to refix this, I found that Pot have
moved the socket for the fixing screw about 15mm to one side. Also they have changed the thread.
The old screw is useless and they neither provide a new screw nor tell you what thread it needs to be. ?? 2M ??

the newest version case has a hole for the seemingly defunct 15mm offset screw. older verions dont have this provision. i suggest you follow common practice and remove the pcb fixing screw and then refit the case and secure using the pcb screw. the top mounted "earth fixing" is both unnesscessary and in some cases impossible.

Finally: "turn the boiler temperature control to the required
setting". This control is not graduated, how is anybody supposed to know what the required setting is?

most boiler stats are "not graduated", i would suggest you change the setting dependant on your personal preferences.

IMHO: Label all the sockets on the PCB & their matching plugs.
Unplug all the wires from the PCB & install them into the boiler.
Refit fan & air pressure sensor etc.
Connect all earth wires to a new earth point in an accessible
place (X) on the main chassis.
Put another wire (W) on the earth point of the control chassis.

or alternatively follow the perfectly acceptable manufacturer instructions which do in fact tell you how to do the job properly without any issues.

The idea is to get all the wires in place before you install the PCB,
so you do not have to install both at once. Also you can then replace
the PCB without having to take the whole boiler to pieces.

no, the idea is to install the pcb as it comes out of the box and then route the wiring as instructed in the supplied booklet. i read the manual once then proceded to do several hundred of these pcb swaps without a single hitch. perhaps you want to step off that high horse and read those intstructions again.

the only thing i do differently from those instructions is to cut the cable ties for the aps and thermistor/OH stat wiring as i find it easier to route/connect them without those ties.

 

[Softus]

I'm sorry I can't help you with your problem...

Cant comment on what the instructions say ive never read them.

not being a novice i find it hard to understand the difficulties...

And yet, you all found something unhelpful to say.

 

[nickso]

and it was amazingly lucid after 7 guinness, a double white russian and a double rum.

 

[gas4you]

and it was amazingly lucid after 7 guinness, a double white russian and a double rum.

A normal day at work then nick

 

[ollski]

Apart from the fact that I did do one this week which was very loose on the gas valve connections and the fact that you don't get replacement clips for the the ones which snap as soon as you touch them I have found replacement very simple. First one took about 90 mins following the book to the letter but now abpout 15 mins.
The only thing with the instructions is that they guide you to remove the fan for absolutely no reason!.

 

[mickyg]

fact of the matter is you have to enter the combustion chamber as part of the replacement, which should only be done by a competent person. Competent persons have no problem fitting this pcb kit. figure.

 

[Softus]

Competent persons have no problem fitting this pcb kit. figure.

And yet those same "competent" people seem to having trouble understanding where the novice is coming from.

Competence isn't just about doing something that's familiar, safely. It's also about being able to think about what you're doing and about taking an engineering approach.

 

[mickyg]

It's also about being able to think about what you're doing and about taking an engineering approach.

exactly, so as he couldnn't do that..........not competent.
thanks for your agreement.

 

[Softus]

he couldnn't do that.

The evidence is to the contrary, so you and I don't agree.