Admiral 17T1: Never Give Up, Never Surrender

[jr_tech]

The horizontal sweep circuit is very cleaver.... I am going to re-read this several times to try to understand how it works, maybe the cause of the apparently distorted horizontal waveform is excessive ringing.

http://www.earlytelevision.org/pdf/admiral_tv.pdf

jr

[Notimetolooz]

Originally Posted by jr_tech

, maybe the cause of the apparently distorted horizontal waveform is excessive ringing.


jr

I was thinking along the same lines. Those could be 100pf instead of 1000pf.
Also ceramic caps can change their capacitance as the voltage changes a great deal (as in a sweep circuit).

[Winky Dink]

Indeed they are ceramics. I've looked through my stuff and the only alternative I have to meet the capacitance and voltage rating is yellow film 630V caps wired in series. But first I have to post some information for reference. Thanks

[Winky Dink]

While rethinking what I've done with this set I need to deal with one issue at a time. First issue is the wiring of R41, replacement of C37 and C39, and the destruction of the H-size pot. Everything I've said is based on assumption and memory (or misassumption and forgetfulness) from 10 years ago.

I'm going to post here several 17T1 and 19A1 schematics. I'll follow that up with photos showing what I really know about these components. Patience, please...I have to write everything offline first because of my slowness I can't even write a quick response without being logged off.

This is overlay of the Rider 19A1 schematic (Red) and the Telaides 12T1 (Black):

Adm 17T12 5000 by H Boyars, on Flickr

Telaides 17T1:

Adm 17T12 5005 by H Boyars, on Flickr

Rider 19A1:

Adm 17T12 5010 by H Boyars, on Flickr

Sams 19A1:

Adm 17T12 5001 by H Boyars, on Flickr

Figure 59 19A1 (I don't know what publication this is from):

Adm 17T12 5016 by H Boyars, on Flickr

Hand-drafted 19A1 (I don't know the source of this one, either):

Adm 17T12 5014 by H Boyars, on Flickr

R41 C37 C39 H-size pot in three different schematics:

Adm 17T12 5018 by H Boyars, on Flickr

Original R41 (It definitely connects to V12 pin 2):

Adm 17T12 5017 by H Boyars, on Flickr

[Winky Dink]

A few more historic photos for illustration.

Original C37 & C39 in situ.

Adm 17T12 9003 by H Boyars, on Flickr

Actual first replacement caps:

Adm 17T12 9002 by H Boyars, on Flickr

Damaged horizontal size pot:

Adm 17T12 9004 by H Boyars, on Flickr

Regarding my scenario of destruction of the H-size pot after replacing C37 C39 with 630 volt film caps. The problem with the image on the CRT may have preceded that blunder, and instead of one or both of the 630V caps failing, I could have miswired them

[Winky Dink]

RE: Are C37 and C38 .001 mfd or .01 mfd? They are both 102K 2KV, and the Sams and Rider parts lists specify .001 and 1000 volts. I thought I had posted this before, but I can't find it.

[jr_tech]

Have you done voltage checks around horizontal, vertical and sync tubes? It would be interesting to compare to the values posted in the Telaides info.

Is there confusion caused by v12 being labeled as v13 in the Sams info and/or missing power supply connections lost in the fold of the Sams page?

jr

[Notimetolooz]

Winky Dink, please chose a schematic and stick with it. You can't mix and match sections from different schematics.
Also you are just confusing every one shifting back and forth, the part names (like R41) are different between schematics.

If you don't have the correct parts needed you will have to get them.

[Winky Dink]

I have stayed with same Telaides schematic. I know about different part numbers. If I refer to a part number from the schematic I'm using and then refer to the same part on a different schem, I will have made the number translation.

I've stayed with the Telaides schematic until I got to R41, whose original (factory) placement did not agree with the schematic. The set worked when I got it, so I chose to stick with the original R41 wiring. That's what all the photos and schems are for--to illustrate the conflict and show what I've done. I use a lot of illustration because I may not be able to communicate things is electronic language.

Thanks. I'm reviewing more photos to find when the problem started.

[Winky Dink]

Response to jr tech: I have some voltage data from 2018, and I'll run that again and compare them before addressing any issues. There is no confusion with Sams numbering. I learned that on the first project I worked on. In this case I started with Telaides and Rider which are identical, and if I look at something in Sams, I'll translate the parts numbering first--especially the tubes.

[Notimetolooz]

OK, I see now that the ceramic discs C37 and C38 in your pictures are 0.001 uf. It is a bit hard to read the value, I thought that they might be marked 100 (on some earlier ceramic discs (or even mica) that might mean 100 pf) not 102. Unless ceramic caps won't work there they should be OK.

So you haven't made it clear how you think R41 was connected if it didn't match the Telaides.
What schematic would show that.

I assume that you have already replaced the horizontal size pot R46.

[Winky Dink]

R41 is directly connected from the sweep of the horizontal size pot to pin of V12. As show in this photo, it is the original factory connection. Yes, I did replace the pot.

Adm 17T12 5017 by H Boyars, on Flickr

Also, since the question arose about some voltage data, here's a full run done last night. It's basically the same as it was in 2020 and 2018.

Adm 17T12 8910 by H Boyars, on Flickr

Thanks once again.
Winky

[bandersen]

R41 actually has nothing to do with the operation of the horizontal size control or horizontal circuit. That side of the pot is going to B+. They're just using it as a handy connection point for R41 which is part of the sync amp.

You can't use ceramic caps for C37 or C38 unless they are C0G/NP0 type. Plastic film would actually be more stable than your average ceramic cap.

[jr_tech]

Weak video might cause poor sync... the very low voltage at the plate of v9 will likely cause weak video. Fixing that might help. Check the resistance of L9, R35, L10 and R36 and replace as necessary.

jr

[Winky Dink]

jr tech: L9 and L10 coils have exactly the specified resistance, R36 is exactly right, and I can't measure R35 because it's a resistor-through-coil. I could disconnect the coil to check the resistor, but I think it's more significant that the voltage before the L10 resistance is only 65 volts. L10 is also a resistor-through-coil, but it doesn't look that way on the schematic.

Notimetolooz: To make the wiring of R41 agree with the Telaide 17T1 schematic: From V11 pin 2 there is a 1 Meg resistor R39 which connects to a tie strip. That would be the connection point for R41.