Troubleshooting question

Unknown

printed circuit board has a damaged printed circuit on the back of the board. The customer has no heat, it will take a day or two to get the new board. The printed circuit is not repairable.

WHAT WOULD YOU DO?

I will let you have some fun with this and then give you the answer. It will be interesting to see what the answers are.

Keep in mind this is a warm air system with delay for fan on and delay for fan off, all controlled from with in the board by setting dip switches.

Keep trying I will give little hints along the way.

Nice try Chris but not what I am looking for.

Paul you missed it to but nice try. Drop back 10 yards and punt. The game is not over however so try again with a new game plan.

Some more information: this is a Honeywell ST9101A EFT used with a standing pilot 24 volt system. The break is on the printed circuit board between the "R" terminal and the the #4 terminal on the nine terminal mated plug on the board which then exits the mated plug and goes to the high limit.

Paul Rohrs

It's 4th and long, punting team comes in...........

But wait, it's the old end around play!.....

I am not well versed in fan timer circuitry, but you must have bypassed the timer and hard-wired the fan on a non-intermittent cycle so that it is always on, and let the hot-water coil zone valve open and close as prescribed?

You have to tell me....should I have just gone ahead and punted?

Okay coach, I'll go sit on the bench.

Where is my electronic fan timer playbook when I needed it.

PR

J.C.A.

Timmy,

Hard to say without a wiring diagram.
See...you taught me well !

I may try a 110/24 V switching relay, depending on the type of furnace, and have the fan come on with the burner till the new board arrived .

Without a schematic..I'm just takin a stab at it . Chris

rob

PC Board

I have in the past observed the burnt spot on the solder trail. I have re-soldered to burnt spot and returned the board to temporary service until I picked up the replacement. I believe it was a HW found on a Rheem/Ducane 90% WA and a Rheem Criterion. Would it be possible to run the fan in the ON mode? Constant circulation for temporary repair. What does the board do with a R to G call?

Tom M.

Guess from an oil fired wethead

Wire tstat to burner control T and T, turn on continuous low speed fan switch, connect to higher speed wire if desired. Fan switch bypasses damaged printed circuit and temp sensors still kill power to burner control for high limit protection.

Eric

strap a clicks-on (high temp auto reset) to the flue pipe?

Fan runs when flue is hot and keeps running after untill flue is cold fan off?

Eric

not high limit

backwards,Not a high limit (normally closed) Need normally open. close on rise and fall.

Unknown

Eric the flue

temperature gets so hot the fan would run forever. It would also probably damage the normqlly open close on a temperature rise Klixon Disc.

This system also has a combustion air blower that is powered off the board so it has to also get powered on a call for heat.

Nice try though.

Unknown

R to G

would be for an air conditioning coil if so equipped. This is a heating only furnace. We are using "R" to "W" for the heating connection from the thermostat.

The soldering is a good idea but often can cause other problems with the board. Nice try but there is an easier way.

gman

?

therm switch on auto

Unknown

The problem is that

this particular board also controls the Combustion Air Blower. That has to come on when the system calls for heat and then pull in the suction pressure switch. This break in the printed circuit part of the board is preventing that from happening along with the other operations this board controls.

Nice Try Tom M.

Unknown

gman - How do you

get the Combustion Air Blower to come on and how do you get the gas valve to operate?

Unknown

Private e-mail

from a real wethead Answer SELL THEM A BOILER!!!

Sorry wrong answer, nice try though.

A felt a nice scorched air problem would be good for a change.

Glenn Harrison

I'm pretty sure I know, but..

I'll hold off for a little. However, if anyone wants to see what Timmie is talking about, go to

http://hbctechlit.honeywell.com/techlit/PDF/69-0000s/69-0686.pdf

to see the wiring diagram for this board (you have to have Adobe Acrobat Reader).

Glenn Harrison, Residential Service Techician

Althoff Industries, Crystal Lake, Illinois

Althoff Industies Link

Unknown

The wiring diagram

should be a big help for those that want to look it up.

Thanks Glenn for holding off let us see what folks come up with. It will be interesting to see if we agree.

I will post my solution to this problem late tomaorrow.

Don_4

Timer Board

I have to admit I had to check out the schematic to fully get what connections you were refering to. I believe the simple remedy would be to install a jumper between the high limit and "r" terminal. (low voltage stat wire would be adequate)

Howard

I concur. Jumper R to limit

to bypass the burned spot. Thanks Glenn for the drawing. Working as an airhead, I've found that the usual failure for fan boards is near the relay contacts. The midnight fix is to hotwire the heat speed (and tape up the unused speeds). For this particular problem, I think Don nailed it.

Howard Hansen Service Technician Extraordinaire

Dan Law

Fan By pass

Remove all fan speed leads from the board, (leave neutral connected) and
reconnect only the appropriate speed lead to the incoming power connection.
Tape off unused leads. Run the fan continuously until new board arrives.

Unknown

Congratulations Don you got it

also Howard who agreed with Don. A jumper from "R" to high limit left in place until a board can be obtained.

Chris had the idea in the begininng that you need a diagram.
Thanks Glenn for putting folks on to the Honeywell site for the diagram.

With the diagram you can figure out which part of the board is damaged by tracking voltage from one terminal to the other.

It is perfectly okay to jump out a broken circuit until a part can be obtained. As long as no safeties are jumped out it will work. The key to jumping from the "R" terminal
to the high limit is it is quick and effective and does not change the operating charcteristics of the system.

Good job to all of you who entered in. I hope this helps with your troubleshooting. This technicque can be used on just about any printed circuit type control and will allow you to give your customer heat or cooling until a part can be obtained.

To many who troubleshoot the printed circuit boards they are sometimes intimidating. This type of little trick can help to make you a little more comfortable.

As time permits during the off season from heating I will do a few more of these.

We teach all of this type of thing at our center and try to make your job easier.

Glenn Harrison

That was my answer too.

Either a Jumper between the "R" terminal and pin # 4 on the Molex plug, or up to the main Limit (easy for me to say now, right ).

And your all welcome for the wiring diagram (made it easy, didn't it). By the way, if you guys didn't know, you can get info like that for any Honeywell part by going to

http://hbctechlit.honeywell.com/

click on "accept" on the first page, and then enter the part number or a part description and all available info will come up, just like the diagram I linked.

Glenn Harrison, Residential Service Techician

Althoff Industries, Crystal Lake, Illinois

Althoff Industies Link

Unknown

Congratulations Glenn

I figured you knew the answer good of you to give others a chance to learn.

I was on a job today helping a technician out. We had some fun using my laptop into customers cable hookup for internet. We diagnosed the job and used wiring diagrams from Honeywell right off the internet, then downloaded some info for the homeowner on some Honeywell products they asked us a question about. Technology what a world.

Glenn Harrison

Thanks, Timmie

What you described is exactly what I see myself and eventually everyone doing, Laptop connected to the web getting info right on the spot in front of the unit, or maybe even tech support instant messaging. Your right, technology, what a world.