Potterton Puma 80e problem

[KD64]

Hi all, have a problem with my Potterton Puma 80e.

The red led mains indicator on the front user panel does not illuminate thus the boiler does not start.

Have checked the 3amp fused spur supply and is OK. Followed the wiring through to the mod board all OK. Also checked the internal T2A fuse on the modulation board and is OK. Have checked the rear of the modulation board for dry solder joints and have reflowed a couple that may have caused a problem but I would suggest unlikely as they were not that bad. The fault finding section of the manual suggests replacing the mod board completely.

Is this correct ? Has anyone had a similar problem and the fault turned out to be something else ? Don't really want to spend £150+ on a new board only to find it does not solve the problem.

Thanks in anticipation. KD

 

[Baxmax]

IT May be the transformer....

+++++++++++++++++++++++++++++++++++++++++

Foot note transformer p.n 929681 outputs 24v yellow wires/ 20v br and or wires....

 

[KD64]

Thx for fast reply Baxmax. What makes you suggest the transformer ?

Does the rest of the board run at 24v ?

Cheers
KD

 

[Agile]

It must be very difficult to find that kind of fault if you dont have ( or know how to use ) a simple voltmeter to follow the supply through the boiler.

There could always be a neutral continuity fault!

Electricity can kill!!!

Tony

 

[geoff@cetltd]

WHat about the 2A fuse on the mod pcb ?

 

[ChrisR]

I remember having a transformer down on an early puma contact. The fault finding guide didn't mention it, it DID take me to "replace PCB". I had a meter though!

 

[geoff@cetltd]

IIRC pl6 on the pcb pins 1 and 2 are 24vAC, pins 4 and 6 are neutral and live resp. from the transformer

 

[KD64]

The input to the transformer is reading 240vAC as required but the output to IC1 on the mod board is reading 70v, not the required 25v.
Do you think this will this have damaged the board?

Incidently the output from the transformer to the fan relay is reading 240v and not the required 90v as indicated in the circuit diagram.

 

[geoff@cetltd]

The input to the transformer is reading 240vAC as required but the output to IC1 on the mod board is reading 70v, not the required 25v.

I think you are not measuring the voltages correctly

Do you think this will this have damaged the board?

What is the voltagew across pins (IIRC) 1 and 2 - yellow wires?

Incidently the output from the transformer to the fan relay is reading 240v and not the required 90v as indicated in the circuit diagram.

You are not interested in the 90 volts, it's only relevant for running the slow fan in the perm. pilot version

 

[KD64]

No voltage at all across pins 1 and 2 (yellow). Is that the tranformer shot?

 

[geoff@cetltd]

Check in your manual that I told you the right pins to measure, but if you have mains going into the transformer and no 24v coming out, it sounds like it's shot to me

Make sure you're measuring on an AC range

 

[KD64]

Yeah I just double checked the manual and measured again (on AC range) and i'm definately measuring across pins 1 and 2 on PL6 (both yellow wires from the transformer output). No reading!

Thanks for the confirmation raden.

 

[geoff@cetltd]

You can double check by checking for an open circuit across one of the windings

Also worth checking that you don't have a broken wire in the connector where it plugs into the pcbthey can break and you don't notice because the insulation is also crimped

 

[Baxmax]

Transformer.......

 

[Soggy_weetabix]

Hell man, what about starting at the basics!

Re-solder the neutral connection on the top l/h corner of the PCB once removed.

David