UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Test Gear and Workshop Equipment

Notices

Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders.

Closed Thread
 
Thread Tools
Old 4th Nov 2021, 8:12 pm   #81
M3VUV51
Banned
 
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 203
Default Re: Tek 2215. Vertical Amplifier Issues.

heres a pic of the front panel
Attached Thumbnails
Click image for larger version

Name:	Webp.net-resizeimage.jpg
Views:	61
Size:	78.3 KB
ID:	245045  
M3VUV51 is offline  
Old 4th Nov 2021, 9:00 pm   #82
M3VUV51
Banned
 
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 203
Default Re: Tek 2215. Vertical Amplifier Issues.

well i pulled q763 and it tests as a good npn with a beta of 166,not sure what to pull and test next.
M3VUV51 is offline  
Old 4th Nov 2021, 9:04 pm   #83
M3VUV51
Banned
 
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 203
Default Re: Tek 2215. Vertical Amplifier Issues.

with these small signal transistors would 2n3904 or 2n3906 be ok as a sub for testing if i find bad ones?
M3VUV51 is offline  
Old 4th Nov 2021, 9:09 pm   #84
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,228
Default Re: Tek 2215. Vertical Amplifier Issues.

A TRIG needs to be on AUTO. You don't seem to have the A SEC/DIV on X/Y mode?
PJL is offline  
Old 4th Nov 2021, 9:10 pm   #85
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,228
Default Re: Tek 2215. Vertical Amplifier Issues.

I said Q763 looked OK from your earlier test. Do the X/Y test.
PJL is offline  
Old 5th Nov 2021, 4:00 am   #86
M3VUV51
Banned
 
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 203
Default Re: Tek 2215. Vertical Amplifier Issues.

well i have removed the following transistors and tested them: q763=ok,q780=ok,q789=ok,q785= tests as a back to back diode,see pic,just wondered what i can use as a replacement?,also is it likley to have led to more damage like in an audio amp when theone transistor fails and wipes out others?
Attached Thumbnails
Click image for larger version

Name:	Webp.net-resizeimage (1).jpg
Views:	27
Size:	55.9 KB
ID:	245061  
M3VUV51 is offline  
Old 5th Nov 2021, 6:24 am   #87
M3VUV51
Banned
 
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 203
Default Re: Tek 2215. Vertical Amplifier Issues.

any idea what q785 actualy is ie what does the tek part number = in the real world,i cant find the civy part number in the manual.
M3VUV51 is offline  
Old 5th Nov 2021, 6:33 am   #88
tony brady
Pentode
 
Join Date: Mar 2014
Location: Peacehaven, East Sussex, UK.
Posts: 246
Default Re: Tek 2215. Vertical Amplifier Issues.

from page 8-9 in the may 1982 manual on tek wiki it says that Q785 is 2N5551
tony brady is offline  
Old 5th Nov 2021, 7:01 am   #89
M3VUV51
Banned
 
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 203
Default Re: Tek 2215. Vertical Amplifier Issues.

well ive been told by the folks at tech groups io that its a 2N5551,just need to find its pnp partner now,ive just ordered 20 from ebay for 1.50,just hope there not Chinese fakes!!
M3VUV51 is offline  
Old 5th Nov 2021, 7:02 am   #90
M3VUV51
Banned
 
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 203
Default Re: Tek 2215. Vertical Amplifier Issues.

is this transistor failing likley to cause the symptoms i have?
M3VUV51 is offline  
Old 5th Nov 2021, 10:43 am   #91
RogerEvans
Hexode
 
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 278
Default Re: Tek 2215. Vertical Amplifier Issues.

The PNP transistor Q789 is marked as SPS6700 in the manual, direct replacements look pricey. A suggested equivalent high voltage PNP is NTE288 and these are on eBay from a UK seller at a reasonable price.

If you compare the circuitry around Q785 and Q789 with the parts you replaced in the Y amplifier you will see that a failed Q785 would probably lead to one of the X plates being stuck at an extreme voltage. It would make good sense to check Q775 and Q779 since a failure here would lead to both plates being at a fixed voltage and the spot not moving at all in the X direction.

It seems you have two other faults as well which are not related to the X amplifier but could possibly have a common cause, ie the spot does not move in Y and there is no trigger light. It would be worth doing a thorough check on both Ch1 and Ch2 to see if there is any situation where you can get the trigger light on. This would eliminate the early parts of the Y amplifier chain from the search.

If you fail to get anywhere with the trigger light and you do have a second scope then you can apply a signal to the Ch1 input and see how far you can trace it along the Ch1 amplifier chain. You need to be aware that after the attenuator the signal is quite small amplitude and also that there are points in the amplifier chain where the signal is at a very low impedance (it is essentially a current rather than a voltage) so the circuit may be working even if you see almost no voltage signal.

Roger
RogerEvans is offline  
Old 5th Nov 2021, 10:50 am   #92
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,228
Default Re: Tek 2215. Vertical Amplifier Issues.

We don't know the symptoms. This is what we know:
- PSU voltages OK
- Vertical amplifier was faulty but may now be OK as output transistors replaced
- Solder has shorted main board causing smoke and unknown new faults
- XY mode shows 2 dots (only when beam finder pressed?). Channel 1 moves spots vertically (unsure of movement extent). Channel 2 position that should move spots horizontally has not been tested.
- The TRGD lamp is not lit BUT the scope is not set for AUTO trigger so this is expected.

You are running threads on 3 different forums, I suggest you run with one forum and post a link from the others. Let us know which one you choose.
PJL is offline  
Old 5th Nov 2021, 11:14 am   #93
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,228
Default Re: Tek 2215. Vertical Amplifier Issues.

Quote:
Originally Posted by M3VUV51 View Post
Well the measurements between the horiz def plate wires are horiz pos control fully ccw=-22.43 fully cw=27.06, I cant locate Q736 yet to measure it, there is only one horizontal pos pot that serves both channels.
Just a while back and after the solder short the horizontal amplifier was working OK so why is it being taken to bits?
PJL is offline  
Old 5th Nov 2021, 12:40 pm   #94
RogerEvans
Hexode
 
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 278
Default Re: Tek 2215. Vertical Amplifier Issues.

PJL - I think I should probably keep out of this thread, I started following the thread on TekScopes and not all the information appears on all three forums. After re-reading this thread I see that the spot does respond to Y changes so the vertical circuitry may be OK. Also the voltage measurements on the X 'wires' are not consistent with no horizontal spot movement so are the wires connected to anything?

Too many cooks ...

Regards,

Roger
RogerEvans is offline  
Old 5th Nov 2021, 1:05 pm   #95
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,228
Default Re: Tek 2215. Vertical Amplifier Issues.

Don't leave us, we need all the help we can get!

My suspicion is this reading was taken without XY mode as the horizontal position is active. In XY mode the horizontal position of the dot is set using the Channel 2 position pot.
PJL is offline  
Old 5th Nov 2021, 1:08 pm   #96
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,228
Default Re: Tek 2215. Vertical Amplifier Issues.

Quote:
Originally Posted by PJL View Post
My recommendation is we test the vertical and horizontal amplifiers first and that requires the scope to be setup in XY mode (see page 30). XY mode is selected using the A SEC/DIV control. You should be able to centre the dots using the channel 1 position (vertical) and channel 2 position (horizontal). If this works then injecting a signal (you can get 50Hz by simply holding the probe with your fingers but you may need to adjust the VOLTS/DIV) on channel 1 should result in a vertical bar, and channel 2 should show a horizontal bar. If this test passes then we have working channel and vertical and horizontal amplifiers so can move on.

The next stage would be to get the Trigger working as without a trigger you will not get a sweep. To complete any trigger test the scope must be setup correctly as on page 161. It might be worth posting a picture of the scope front panel so we can confirm it is correct. If we can confirm the trigger is definitely not working then it would be worth inspecting that area of the circuit board looking (or smelling) for 'cooked' components.

This is a complex scope with many parts so we will need to be methodical.
I suggest the transistors are replaced and we follow an organised approach to establish the fault symptoms.
PJL is offline  
Old 5th Nov 2021, 7:32 pm   #97
MotorBikeLes
Octode
 
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
Posts: 1,890
Default Re: Tek 2215. Vertical Amplifier Issues.

It seems to me if OP has three separate "help" zones, ignores your good advice, and ploughs on blithely without seeming to know what he is doing, the best thing to do is leave him to his own devices, and save yourselves pointless effort.
Les.
MotorBikeLes is offline  
Old 5th Nov 2021, 10:55 pm   #98
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 18,543
Default Re: Tek 2215. Vertical Amplifier Issues.

With three fora providing advice, confusion is a problem. It sounds like further damage has occurred and what may have started as a single fault is likely more complex.

I think we'd better stop contributing to the confusion, so let's halt it here.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now  
Closed Thread

Thread Tools



All times are GMT. The time now is 11:59 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.