View Full Version : Another Motorola VK-106 restoration attempt


pdr-fml
11-24-2016, 03:55 PM
Happy Thanksgiving everybody. I am in process of trying to restore a 1948 Motorola VK-106 that i had found at estate sell. I have never done this before so I am on the learning curve soaking in information when I can. Mine is very similar to the one Banderson posted a few weeks ago so I wont include too many pics. When I got the set I did not know anything about the current condition whether or not tubes were all there or CRT any good. Well so far things have turned out pretty well and have not run into any project stopper problems so far I think. I do have a problem I would like to get an opinion on and I will detail this a few post down but first just a few pics of project and what I have done so far -see posts below.

Here is pic of set the day I got it and by the way I paid 50 and not 100 so not exactly a bargin.

pdr-fml
11-24-2016, 04:00 PM
Here are some more pics of set. All tubes were there except for HV rectifier tube and one tube was wrong type.

pdr-fml
11-24-2016, 04:23 PM
I have been busy last few weeks with this whole thing just hoping that CRT was going to come to life. My hopes were up because i found some problems that may have been reason for shelving the set that were not CRT related. Two burned up resistors and a blown fuse so I kept thinking CRT may be okay. By the way I did check crt filament and tube filaments and none were open. I restuffed two can caps and relocated two to inside chassis bottom.

pdr-fml
11-24-2016, 04:43 PM
After recap job and replacing few resistors I cranked her up saw a flame up down below in chassis. Turned out to be a tapped power resistor that had one bad section that I had bypassed with new dale screw down power resistor but was still shorting out. Ended up replacing whole thing. I do have variac and was gentle with set at first. All tubes were glowing and static from speaker (no signal attached just looking for raster) but nothing at all on tube. adjusted ion trap all over the place and nothing at all. Also appeared to have high voltage using screwdriver arc test. Pulled all tubes out and let crt filament glow for a couple hours. Still nothing. I looked at voltages at crt neck and looked at schematic for orgins of voltages and started doing a little trouble shooting and pulled 12au7 video output tube. Had put everything back to normal and powered back up and still nothing. Decided to adjust ion trap again and finally got a raster. I got a replacement tube from a source and reinstalled. I am not a 100% percent about tube being problem but am going to test one day. I was really getting discouraged but now very hopeful.

Current problem I am trying to solve is shown in pic below. I got a old tv repair book and for the white vertical strip problem I am seeing as shown the book suggest either damping tube or bad deflection yoke. What do you guys think?

Kevin Kuehn
11-24-2016, 06:58 PM
Very nice job on replacing those caps and resistors! :thmbsp: I'd agree the damper tube is generally responsible for those type defects on the left side of the picture. First thing I'd try is replacing the damper tube, possibly try a few. Adjusting the horizontal drive control could also have some effect.

decojoe67
11-24-2016, 09:41 PM
Great job. I think you got a great bargain with that set. Those Motorola's a fairly uncommon and a classic '40's console. The CRT alone would cost at least $50.
Enjoy it!

pdr-fml
11-25-2016, 10:35 AM
Very nice job on replacing those caps and resistors! :thmbsp: I'd agree the damper tube is generally responsible for those type defects on the left side of the picture. First thing I'd try is replacing the damper tube, possibly try a few. Adjusting the horizontal drive control could also have some effect.

Thanks for the advice. Well I am fresh out of damper tubes -calls for a 5v4g so I guess I will place an order might get two just in case. I will try the drive control before I do that and see what happens.

pdr-fml
11-25-2016, 10:39 AM
Great job. I think you got a great bargain with that set. Those Motorola's a fairly uncommon and a classic '40's console. The CRT alone would cost at least $50.
Enjoy it!

Thanks. I guess I lucked out on the 10bp4 not being a dud. Have not tested it but it seems bright enough. Just to add the crt appears to be a rebuild to me due to the neck having a cut line around it.

kvflyer
11-25-2016, 11:39 AM
Looking good and you are certainly on track for a complete restoration. The 5V4 could be a 5V4GA also if that is easier to find and I guess you got a HV rectifier since you have a raster.

Nice job, keep the pictures coming.

Kevin Kuehn
11-25-2016, 11:44 AM
You can use a 5V4GA in place of the G. The audio guys covet those G style for their more curvy sound. ;)

pdr-fml
12-04-2016, 06:09 PM
Very nice job on replacing those caps and resistors! :thmbsp: I'd agree the damper tube is generally responsible for those type defects on the left side of the picture. First thing I'd try is replacing the damper tube, possibly try a few. Adjusting the horizontal drive control could also have some effect.

Ok. I got rid of the white vertical lines by adjusting the horizontal drive control. When I went to adjust I found that trimmer screw was completely missing. Stole screw from another from trimmer in tuner for channel that will not be used. Unfortunately I have other problems with set and have decided that I need to test all tubes before I go any further. I know someone at work that has a tester and will try to get this done shortly.