03-29-2014, 04:53 PM
John - It is a Heathkit IT-18. The seller sent it to me in a brown manila envelope with no padding!
Incredibly, it seemed to have survived OK. The only problem is that the meter needle sticks sometimes in the middle of its range. So does the needle on the meter of my Heathkit TT-1A tube tester. But anyway...I replaced the "D" battery with a fresh one and it was off to the races; it has worked ever since (with the exception being the needle that occasionally sticks). Oh, I also found the manual online, downloaded it, and calibrated the tester using the procedure given in the manual (which was a fairly simple process).
So, boys and girls, I promised photos of the rebuilt predriver and preamplifier boards.
The rebuilt predriver:
[Image: http://www.philcoradio.com/images/phorum...0003-1.jpg]
Only two capacitors were changed here - the two 1 uF tantalums were replaced with 1 uF electrolytics. All four transistors are new replacements.
Now, the rebuilt preamplifier:
[Image: http://www.philcoradio.com/images/phorum...0004-1.jpg]
New electrolytics and new 0.33 uF film caps. Four of its six transistors were replaced as well.
Here's a quick look at the underside of the 700-T, with mostly new capacitors (I had not started on the control amplifier board yet):
[Image: http://www.philcoradio.com/images/phorum...0001-1.jpg]
Now, a look over in the upper right corner. New rectifier diodes and new fuseholders. One fuseholder was broken; I replaced all three so they would look alike. They were cheap, from Mouser.
[Image: http://www.philcoradio.com/images/phorum...0002-1.jpg]
Yup, I bumped one side of the AC line with the soldering iron and will have to sleeve that bare spot.
I'm working on the control amplifier now. Its ten 1 uF radial electrolytics are stubborn and do not want to come out of the board. I'm ending up with some damaged pads as a result.
More to come...
Incredibly, it seemed to have survived OK. The only problem is that the meter needle sticks sometimes in the middle of its range. So does the needle on the meter of my Heathkit TT-1A tube tester. But anyway...I replaced the "D" battery with a fresh one and it was off to the races; it has worked ever since (with the exception being the needle that occasionally sticks). Oh, I also found the manual online, downloaded it, and calibrated the tester using the procedure given in the manual (which was a fairly simple process).
So, boys and girls, I promised photos of the rebuilt predriver and preamplifier boards.
The rebuilt predriver:
[Image: http://www.philcoradio.com/images/phorum...0003-1.jpg]
Only two capacitors were changed here - the two 1 uF tantalums were replaced with 1 uF electrolytics. All four transistors are new replacements.
Now, the rebuilt preamplifier:
[Image: http://www.philcoradio.com/images/phorum...0004-1.jpg]
New electrolytics and new 0.33 uF film caps. Four of its six transistors were replaced as well.
Here's a quick look at the underside of the 700-T, with mostly new capacitors (I had not started on the control amplifier board yet):
[Image: http://www.philcoradio.com/images/phorum...0001-1.jpg]
Now, a look over in the upper right corner. New rectifier diodes and new fuseholders. One fuseholder was broken; I replaced all three so they would look alike. They were cheap, from Mouser.
[Image: http://www.philcoradio.com/images/phorum...0002-1.jpg]
Yup, I bumped one side of the AC line with the soldering iron and will have to sleeve that bare spot.
I'm working on the control amplifier now. Its ten 1 uF radial electrolytics are stubborn and do not want to come out of the board. I'm ending up with some damaged pads as a result.
More to come...
--
Ron Ramirez
Ferdinand IN