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jerrykco
03-28-2008, 11:02 AM
I have had this welder several years and it has until now, always worked great. When I tried to use it this spring I was all of a sudden not able to get any welding current. HF still works. I took it to General Air in Denver and they looked it over and charged me $90 to tell me it was the Transister Heat Sink Assembly. They said the assembly was no longer available and that they did not repair them. I have some basic skills and was able to replace the transistors (the 4 2N3055's and the 2N6055) on the Heat Sink Assembly but that did not help. (see sheet 2 of 202573 and look at Q1-Q2-Q3-Q4-Q5)

I am looking for anyone who has more technical info like a schematic with voltages etc or if there is a Hobart Technician out there some where that may remember this machine.

I hate the idea of turning this into a boat anchor.

Jerry
email me if you have a hint jerryk @ jbsaddlery . com

zapster
03-28-2008, 03:51 PM
I have the same machine and all that goes wrong is the polarity switch fries itself..
I've replaced the innards twice so far..

I had DC..No AC..

But whatever..

The schematic for the machine is under the top cover..
If you don't have them I'll take pics of mine for ya..

...zap!

jerrykco
03-28-2008, 06:50 PM
Thanks Zap. I will take a look at that this weekend and let you know.

jerrykco
03-30-2008, 05:26 PM
Hi Zap,
I took a look inside both the left AC/DC+/DC- and the right AMP level big rotating switched and they both look in excellent shape.
Can you be more specific about what I should look for and what goes wrong? I do have the schematic under the top cover. Let me know where to look and what I might find.

KSellon
03-31-2008, 09:45 AM
I have several manuals for this machine, but need to get your SPEC# to narrow it down to the correct one.

ksellon@billswelderrepair.com

zapster
03-31-2008, 05:25 PM
Hi Zap,
I took a look inside both the left AC/DC+/DC- and the right AMP level big rotating switched and they both look in excellent shape.
Can you be more specific about what I should look for and what goes wrong? I do have the schematic under the top cover. Let me know where to look and what I might find.


This is what I've acomplished twice now..
http://weldingweb.com/showthread.php?t=14868&highlight=Problem

I keep an eye on the ground cable now.
When the clamp gets hot time to get a better bite for the ground..
So far so good..
Read thru the thread to where Tozzi mentions a place in Plympton, Mass.
This guy can fix anything when it comes to welders..:drinkup:



...zap!

jerrykco
04-01-2008, 12:48 PM
Hi ZAP,
The pictures definitly helped explain your problem and what you were seeing on your machine. Thanks for that.

Mine definitly does not have that problem. The contacts in my machine are all pristine.

I read the Hobart Forum and found that others have had similar problems to me and it seems related to either the heatsink (and the transistors and resisters on it) or the rectifiers on the main output.....

jerrykco
04-01-2008, 12:50 PM
KSellon,
I will also send you an email. Here is the info:
Spec Number 6088-1
Model TR-250HF
Serial # 84WS07252

Thanks

jerrykco
04-05-2008, 10:51 PM
Hi everyone, I got to the bottom of the issue with the Hobart TR-250HF. The problem was in the contactor. It was highly corroded. Beauty of it is that it is repairable. It can be taken completely apart and fixed. Running like a champ now!
Jerry

zapster
04-06-2008, 02:44 PM
I'm happy it's up and running..:drinkup::drinkup:

The contactor..
The one where the wires from the plug/panel go to?

Something to keep in mind now..

Thanks..:D

...zap!

jerrykco
04-07-2008, 01:10 PM
Hi Zap,
Yes. Exactly. The Contactor has the solenoid attached to the contactor. The solinoid is actuated either by the foot pedal when in remote or the local switch.
Jerry

fablife
05-03-2008, 10:25 AM
hey guys,
it must be something in the air...my Hobart RT 250 HF has a similar problem. it welds, but I have no current control. remote or panel has no fine current control. Can anyone point me in the right direction?
I'm searching for the wiring schems too. I've looked for burnt/blown spots on the boards and the electronics but have not seen anything obvious. any help would greatly be appreciated, JD

zapster
05-03-2008, 10:32 AM
Welds but no current control..

Hmmmmmmmmmmmmmmmm...
Could be the "Local/Remote" switch..

Could be a wire or something off inside the footpedal..
4 3/8" bolts on the bottom and off it comes..

Make sure everything is working smoothly..
There are a few extra moving parts inside due to the design..

By the way welcome to the boards..

...zap!

fablife
05-03-2008, 11:07 AM
WOW...now that's a quick response!!
tried unplugging the foot control = same
the remote panel relay is operating when switch is toggled
I remember there was an issue when they hooked up the remote pedal..a looonng time ago, (yes, it's one of the Frankenstien pedals) but has worked great since.
just from what I've read...it could be
one of the circuit board electronics
the weld current rheostat itself
the control transformer
a connection ..??
thanks zap, it's a great site! I've been watching and surfing it for a while, just never joined. JD

zapster
05-03-2008, 11:33 AM
Whatever you find out..
Make sure you let us know..

If I think of anything else I'll let you know..:cool:

...zap!

TozziWelding
05-08-2008, 01:42 AM
Call Bob at Tractor and Welding Repair in plympton MA, 508-585-6377.