I like to use high brightness LED's with a current limiting resistor sized to bring the brightness waaaay way down.
I have found that often with 'normal' brightness LED's, the colour doesn't shine through very well due to the colour mismatch between the green of the LED and the green of the jewel in the lamp holder.
I currently use green LED's that put out 5000mcd, then use an appropriate resistor I chose by checking the LED brightness by eye, usually it means the LED is consuming around low single-digit milliamps or so.
P.s. The SG502 manual at Tekwiki also has the manual change info re. the polarity change of the lamp.
|
Well, it looks like LED it is (see? /g/TekScopes2/photo/278771/3494775?p=Created%2C%2C%2C20%2C2%2C0%2C0, where the solder looks dull, which is some artifact of the picture).? Anyway, I think this is a very neat solution. A 3mm LED is about the size of a grain-of-rice. I had the opposite experience than Zen, I had to lower the R to 1k (I'd have gone lower, but I'd get into power resistor territory), for about 18mA through?the LED. Even so, there's not much light coming through, and it may just be the LEDs I have at hand (and maybe the "density" of the green jewel?). These were just vanilla?green 3mm LEDs I had at?hand.?
Supply to bulb reverses polarity (C5/279) Much more importantly, though, for anyone doing?this down the line, there's a Manual Change (Reference C5/279), which?is only available at the Boat Anchor Archive, which reverses?where the light bulb attaches - instead of the positive rail it goes to the negative. So a good idea is to check if your unit has this implemented.?
I initially?polarized the LED as per the main schematic, and upon it not turning on and seeing it not lit, I realized I've previously glanced at the revision?(last page on the BAMA PDF). So I had to unsolder and reverse it.?
Radu.?
Thanks Radu, Ill take a look at this one seems relatively straight forward and reversible, If need be. ? Zen ? ? ? No I have not done any of the low distortion mods to the 502¡¯s in the lab but I am now curious as to what these entail. I popped mine open tonight and found I used a 10K resister to calm the LED down and make it liveable and not eye searingly green. Do you have a link to the low distortion information? ? Zen ? ? How could I miss it: 7220 bulb, 26mA?@ 18V...? ? On Mon, Sep 26, 2022 at 6:20 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: One concern I do have with my grain of rice bulb is it wants 60mA. The entire plugin I recall reading somewhere - can't find it now - needs 70mA, so I'm a bit weary of raising the current through the pass transistors quite a bit. True, I don't know the draw of the original bulbs. Knowing the specs of the original bulbs would help quite a bit. ? On Mon, Sep 26, 2022 at 5:15 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: Zen - glad to see you here! Yes, a very cute unit. I'm looking forward to checking it closer against?my instrumentation - such as looking at its distortion through the AP S1. Also, checking the levels and all that (though this far it looks absolutely dead on). Calibrate it, if it needs it. Have you done the?"low distortion mods," I'm curious?....? The LED suggestion is a very good idea, I may go that way.? Glenn - no, the bulb looks like a legged... whatchumacallit - "grain-of-rice" bulb? I do have some Radioshack #7219s, though I may have to change the series?resistor if I use one of those. They do have 10,000hrs average life, so not a bad option.? ? Does it look like this?
Glenn On 9/26/2022 9:28 AM, Radu Bogdan Dicher wrote: Hi all, Does anyone have information on the correct power lamp for this unit? I can't find that info - all I can find in the manual is it being a "DS346." ? On Sun, Sep 25, 2022 at 10:12 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: Well, I had no symptoms yet to?file, as until tonight I didn't get a chance to even plug it in. Visually, the only?clear issue I was seeing prior to tonight was the detached C160 (one leg was simply?mechanically loose). It was not trivial to resolder it, the short leg pretty much refused to take solder. But I ultimately won. ? I got it, I will not change this cap. Equivalents today seem to require an arm and both legs (except some surplus?places I know...). After taking care of C160, this outputs beautifully a very clean sine. The switches and pots are a bit in need of TLC, but other than that I'm very happy.? Thank you all for your input! ? On Sun, Sep 25, 2022 at 9:26 PM Froggie the Gremlin <jonpaul@...> wrote: what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted rants.
Clean controls and trimmers
Should be simple to debug
Jon
? -- ----------------------------------------------------------------------- Glenn Little??????????????? ARRL Technical Specialist?? QCWA? LM 28417 Amateur Callsign:? WB4UIV??????????? wb4uiv@...??? AMSAT LM 2178 QTH:? Goose Creek, SC USA (EM92xx)? USSVI, FRA, NRA-LM??? ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license"
|
|
|
Thanks Radu, Ill take a look at this one seems relatively straight forward and reversible, If need be. ? Zen ?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]> On Behalf Of Radu Bogdan Dicher Sent: Monday, September 26, 2022 11:19 PM To: [email protected]Subject: Re: [TekScopes2] SG502 Repair ? ? No I have not done any of the low distortion mods to the 502¡¯s in the lab but I am now curious as to what these entail. I popped mine open tonight and found I used a 10K resister to calm the LED down and make it liveable and not eye searingly green. Do you have a link to the low distortion information? ? Zen ? ? How could I miss it: 7220 bulb, 26mA?@ 18V...? ? On Mon, Sep 26, 2022 at 6:20 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: One concern I do have with my grain of rice bulb is it wants 60mA. The entire plugin I recall reading somewhere - can't find it now - needs 70mA, so I'm a bit weary of raising the current through the pass transistors quite a bit. True, I don't know the draw of the original bulbs. Knowing the specs of the original bulbs would help quite a bit. ? On Mon, Sep 26, 2022 at 5:15 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: Zen - glad to see you here! Yes, a very cute unit. I'm looking forward to checking it closer against?my instrumentation - such as looking at its distortion through the AP S1. Also, checking the levels and all that (though this far it looks absolutely dead on). Calibrate it, if it needs it. Have you done the?"low distortion mods," I'm curious?....? The LED suggestion is a very good idea, I may go that way.? Glenn - no, the bulb looks like a legged... whatchumacallit - "grain-of-rice" bulb? I do have some Radioshack #7219s, though I may have to change the series?resistor if I use one of those. They do have 10,000hrs average life, so not a bad option.? ? Does it look like this?
Glenn On 9/26/2022 9:28 AM, Radu Bogdan Dicher wrote: Hi all, Does anyone have information on the correct power lamp for this unit? I can't find that info - all I can find in the manual is it being a "DS346." ? On Sun, Sep 25, 2022 at 10:12 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: Well, I had no symptoms yet to?file, as until tonight I didn't get a chance to even plug it in. Visually, the only?clear issue I was seeing prior to tonight was the detached C160 (one leg was simply?mechanically loose). It was not trivial to resolder it, the short leg pretty much refused to take solder. But I ultimately won. ? I got it, I will not change this cap. Equivalents today seem to require an arm and both legs (except some surplus?places I know...). After taking care of C160, this outputs beautifully a very clean sine. The switches and pots are a bit in need of TLC, but other than that I'm very happy.? Thank you all for your input! ? On Sun, Sep 25, 2022 at 9:26 PM Froggie the Gremlin <jonpaul@...> wrote: what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted rants.
Clean controls and trimmers
Should be simple to debug
Jon
? -- ----------------------------------------------------------------------- Glenn Little??????????????? ARRL Technical Specialist?? QCWA? LM 28417 Amateur Callsign:? WB4UIV??????????? wb4uiv@...??? AMSAT LM 2178 QTH:? Goose Creek, SC USA (EM92xx)? USSVI, FRA, NRA-LM??? ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license"
|
toggle quoted message
Show quoted text
No I have not done any of the low distortion mods to the 502¡¯s in the lab but I am now curious as to what these entail. I popped mine open tonight and found I used a 10K resister to calm the LED down and make it liveable and not eye searingly green. Do you have a link to the low distortion information? ? Zen ? ? How could I miss it: 7220 bulb, 26mA?@ 18V...? ? On Mon, Sep 26, 2022 at 6:20 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: One concern I do have with my grain of rice bulb is it wants 60mA. The entire plugin I recall reading somewhere - can't find it now - needs 70mA, so I'm a bit weary of raising the current through the pass transistors quite a bit. True, I don't know the draw of the original bulbs. Knowing the specs of the original bulbs would help quite a bit. ? On Mon, Sep 26, 2022 at 5:15 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: Zen - glad to see you here! Yes, a very cute unit. I'm looking forward to checking it closer against?my instrumentation - such as looking at its distortion through the AP S1. Also, checking the levels and all that (though this far it looks absolutely dead on). Calibrate it, if it needs it. Have you done the?"low distortion mods," I'm curious?....? The LED suggestion is a very good idea, I may go that way.? Glenn - no, the bulb looks like a legged... whatchumacallit - "grain-of-rice" bulb? I do have some Radioshack #7219s, though I may have to change the series?resistor if I use one of those. They do have 10,000hrs average life, so not a bad option.? ? Does it look like this?
Glenn On 9/26/2022 9:28 AM, Radu Bogdan Dicher wrote: Hi all, Does anyone have information on the correct power lamp for this unit? I can't find that info - all I can find in the manual is it being a "DS346." ? On Sun, Sep 25, 2022 at 10:12 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: Well, I had no symptoms yet to?file, as until tonight I didn't get a chance to even plug it in. Visually, the only?clear issue I was seeing prior to tonight was the detached C160 (one leg was simply?mechanically loose). It was not trivial to resolder it, the short leg pretty much refused to take solder. But I ultimately won. ? I got it, I will not change this cap. Equivalents today seem to require an arm and both legs (except some surplus?places I know...). After taking care of C160, this outputs beautifully a very clean sine. The switches and pots are a bit in need of TLC, but other than that I'm very happy.? Thank you all for your input! ? On Sun, Sep 25, 2022 at 9:26 PM Froggie the Gremlin <jonpaul@...> wrote: what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted rants.
Clean controls and trimmers
Should be simple to debug
Jon
-- ----------------------------------------------------------------------- Glenn Little??????????????? ARRL Technical Specialist?? QCWA? LM 28417 Amateur Callsign:? WB4UIV??????????? wb4uiv@...??? AMSAT LM 2178 QTH:? Goose Creek, SC USA (EM92xx)? USSVI, FRA, NRA-LM??? ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license"
|
No I have not done any of the low distortion mods to the 502¡¯s in the lab but I am now curious as to what these entail. I popped mine open tonight and found I used a 10K resister to calm the LED down and make it liveable and not eye searingly green. Do you have a link to the low distortion information? ? Zen ?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]> On Behalf Of Radu Bogdan Dicher Sent: Monday, September 26, 2022 9:58 PM To: [email protected]Subject: Re: [TekScopes2] SG502 Repair ? How could I miss it: 7220 bulb, 26mA?@ 18V...? ? On Mon, Sep 26, 2022 at 6:20 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: One concern I do have with my grain of rice bulb is it wants 60mA. The entire plugin I recall reading somewhere - can't find it now - needs 70mA, so I'm a bit weary of raising the current through the pass transistors quite a bit. True, I don't know the draw of the original bulbs. Knowing the specs of the original bulbs would help quite a bit. ? On Mon, Sep 26, 2022 at 5:15 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: Zen - glad to see you here! Yes, a very cute unit. I'm looking forward to checking it closer against?my instrumentation - such as looking at its distortion through the AP S1. Also, checking the levels and all that (though this far it looks absolutely dead on). Calibrate it, if it needs it. Have you done the?"low distortion mods," I'm curious?....? The LED suggestion is a very good idea, I may go that way.? Glenn - no, the bulb looks like a legged... whatchumacallit - "grain-of-rice" bulb? I do have some Radioshack #7219s, though I may have to change the series?resistor if I use one of those. They do have 10,000hrs average life, so not a bad option.? ? Does it look like this?
Glenn On 9/26/2022 9:28 AM, Radu Bogdan Dicher wrote: Hi all, Does anyone have information on the correct power lamp for this unit? I can't find that info - all I can find in the manual is it being a "DS346." ? On Sun, Sep 25, 2022 at 10:12 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: Well, I had no symptoms yet to?file, as until tonight I didn't get a chance to even plug it in. Visually, the only?clear issue I was seeing prior to tonight was the detached C160 (one leg was simply?mechanically loose). It was not trivial to resolder it, the short leg pretty much refused to take solder. But I ultimately won. ? I got it, I will not change this cap. Equivalents today seem to require an arm and both legs (except some surplus?places I know...). After taking care of C160, this outputs beautifully a very clean sine. The switches and pots are a bit in need of TLC, but other than that I'm very happy.? Thank you all for your input! ? On Sun, Sep 25, 2022 at 9:26 PM Froggie the Gremlin <jonpaul@...> wrote: what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted rants.
Clean controls and trimmers
Should be simple to debug
Jon
-- ----------------------------------------------------------------------- Glenn Little??????????????? ARRL Technical Specialist?? QCWA? LM 28417 Amateur Callsign:? WB4UIV??????????? wb4uiv@...??? AMSAT LM 2178 QTH:? Goose Creek, SC USA (EM92xx)? USSVI, FRA, NRA-LM??? ARRL TAPR "It is not the class of license that the Amateur holds but the class of the Amateur that holds the license"
|
How could I miss it:
7220 bulb, 26mA?@ 18V...? Radu.?
On Mon, Sep 26, 2022 at 6:20 PM Radu Bogdan Dicher via <vondicher= [email protected]> wrote: One concern I do have with my grain of rice bulb is it wants 60mA. The entire plugin I recall reading somewhere - can't find it now - needs 70mA, so I'm a bit weary of raising the current through the pass transistors quite a bit. True, I don't know the draw of the original bulbs. Knowing the specs of the original bulbs would help quite a bit. Radu.?
On Mon, Sep 26, 2022 at 5:15 PM Radu Bogdan Dicher via <vondicher= [email protected]> wrote: Zen - glad to see you here! Yes, a very cute unit. I'm looking forward to checking it closer against?my instrumentation - such as looking at its distortion through the AP S1. Also, checking the levels and all that (though this far it looks absolutely dead on). Calibrate it, if it needs it. Have you done the?"low distortion mods," I'm curious?....? The LED suggestion is a very good idea, I may go that way.?
Glenn - no, the bulb looks like a legged... whatchumacallit - "grain-of-rice" bulb? I do have some Radioshack #7219s, though I may have to change the series?resistor if I use one of those. They do have 10,000hrs average life, so not a bad option.? Radu.?
Does it look like this?
Glenn
On 9/26/2022 9:28 AM, Radu Bogdan
Dicher wrote:
Hi all,
Does anyone have information on the correct power lamp for
this unit? I can't find that info - all I can find in the
manual is it being a "DS346."
Thank you,
Radu.?
On Sun, Sep 25, 2022 at 10:12
PM Radu Bogdan Dicher via <vondicher= [email protected]>
wrote:
Well, I had no symptoms yet to?file, as until
tonight I didn't get a chance to even plug it in. Visually,
the only?clear issue I was seeing prior to tonight was the
detached C160 (one leg was simply?mechanically loose). It
was not trivial to resolder it, the short leg pretty much
refused to take solder. But I ultimately won.
I got it, I will not change this cap. Equivalents
today seem to require an arm and both legs (except some
surplus?places I know...).
After taking care of C160, this outputs beautifully a
very clean sine. The switches and pots are a bit in need
of TLC, but other than that I'm very happy.?
Thank you all for your input!
Radu.?
On Sun, Sep 25, 2022 at
9:26 PM Froggie the Gremlin < jonpaul@...>
wrote:
what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted
rants.
Clean controls and trimmers
Should be simple to debug
Jon
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
|
One concern I do have with my grain of rice bulb is it wants 60mA. The entire plugin I recall reading somewhere - can't find it now - needs 70mA, so I'm a bit weary of raising the current through the pass transistors quite a bit. True, I don't know the draw of the original bulbs. Knowing the specs of the original bulbs would help quite a bit. Radu.?
On Mon, Sep 26, 2022 at 5:15 PM Radu Bogdan Dicher via <vondicher= [email protected]> wrote: Zen - glad to see you here! Yes, a very cute unit. I'm looking forward to checking it closer against?my instrumentation - such as looking at its distortion through the AP S1. Also, checking the levels and all that (though this far it looks absolutely dead on). Calibrate it, if it needs it. Have you done the?"low distortion mods," I'm curious?....? The LED suggestion is a very good idea, I may go that way.?
Glenn - no, the bulb looks like a legged... whatchumacallit - "grain-of-rice" bulb? I do have some Radioshack #7219s, though I may have to change the series?resistor if I use one of those. They do have 10,000hrs average life, so not a bad option.? Radu.?
Does it look like this?
Glenn
On 9/26/2022 9:28 AM, Radu Bogdan
Dicher wrote:
Hi all,
Does anyone have information on the correct power lamp for
this unit? I can't find that info - all I can find in the
manual is it being a "DS346."
Thank you,
Radu.?
On Sun, Sep 25, 2022 at 10:12
PM Radu Bogdan Dicher via <vondicher= [email protected]>
wrote:
Well, I had no symptoms yet to?file, as until
tonight I didn't get a chance to even plug it in. Visually,
the only?clear issue I was seeing prior to tonight was the
detached C160 (one leg was simply?mechanically loose). It
was not trivial to resolder it, the short leg pretty much
refused to take solder. But I ultimately won.
I got it, I will not change this cap. Equivalents
today seem to require an arm and both legs (except some
surplus?places I know...).
After taking care of C160, this outputs beautifully a
very clean sine. The switches and pots are a bit in need
of TLC, but other than that I'm very happy.?
Thank you all for your input!
Radu.?
On Sun, Sep 25, 2022 at
9:26 PM Froggie the Gremlin < jonpaul@...>
wrote:
what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted
rants.
Clean controls and trimmers
Should be simple to debug
Jon
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
|
Zen - glad to see you here! Yes, a very cute unit. I'm looking forward to checking it closer against?my instrumentation - such as looking at its distortion through the AP S1. Also, checking the levels and all that (though this far it looks absolutely dead on). Calibrate it, if it needs it. Have you done the?"low distortion mods," I'm curious?....? The LED suggestion is a very good idea, I may go that way.?
Glenn - no, the bulb looks like a legged... whatchumacallit - "grain-of-rice" bulb? I do have some Radioshack #7219s, though I may have to change the series?resistor if I use one of those. They do have 10,000hrs average life, so not a bad option.? Radu.?
Does it look like this?
Glenn
On 9/26/2022 9:28 AM, Radu Bogdan
Dicher wrote:
Hi all,
Does anyone have information on the correct power lamp for
this unit? I can't find that info - all I can find in the
manual is it being a "DS346."
Thank you,
Radu.?
On Sun, Sep 25, 2022 at 10:12
PM Radu Bogdan Dicher via <vondicher= [email protected]>
wrote:
Well, I had no symptoms yet to?file, as until
tonight I didn't get a chance to even plug it in. Visually,
the only?clear issue I was seeing prior to tonight was the
detached C160 (one leg was simply?mechanically loose). It
was not trivial to resolder it, the short leg pretty much
refused to take solder. But I ultimately won.
I got it, I will not change this cap. Equivalents
today seem to require an arm and both legs (except some
surplus?places I know...).
After taking care of C160, this outputs beautifully a
very clean sine. The switches and pots are a bit in need
of TLC, but other than that I'm very happy.?
Thank you all for your input!
Radu.?
On Sun, Sep 25, 2022 at
9:26 PM Froggie the Gremlin < jonpaul@...>
wrote:
what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted
rants.
Clean controls and trimmers
Should be simple to debug
Jon
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
|
Does it look like this?
Glenn
On 9/26/2022 9:28 AM, Radu Bogdan
Dicher wrote:
Hi all,
Does anyone have information on the correct power lamp for
this unit? I can't find that info - all I can find in the
manual is it being a "DS346."
Thank you,
Radu.?
On Sun, Sep 25, 2022 at 10:12
PM Radu Bogdan Dicher via <vondicher= [email protected]>
wrote:
Well, I had no symptoms yet to?file, as until
tonight I didn't get a chance to even plug it in. Visually,
the only?clear issue I was seeing prior to tonight was the
detached C160 (one leg was simply?mechanically loose). It
was not trivial to resolder it, the short leg pretty much
refused to take solder. But I ultimately won.
I got it, I will not change this cap. Equivalents
today seem to require an arm and both legs (except some
surplus?places I know...).
After taking care of C160, this outputs beautifully a
very clean sine. The switches and pots are a bit in need
of TLC, but other than that I'm very happy.?
Thank you all for your input!
Radu.?
On Sun, Sep 25, 2022 at
9:26 PM Froggie the Gremlin < jonpaul@...>
wrote:
what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted
rants.
Clean controls and trimmers
Should be simple to debug
Jon
--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@... AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI, FRA, NRA-LM ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
|
I LEDed mine when it went out. If I remember correctly, I used a fairly high current limiting resister because the LED was so bright it needed to be cut back quite a bit. ? Glad to hear everything is working. The SG502 is a wonderful unit to have in the lab. ? Zen ?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]> On Behalf Of Radu Bogdan Dicher Sent: Monday, September 26, 2022 9:28 AM To: [email protected]Subject: Re: [TekScopes2] SG502 Repair ? Hi all, Does anyone have information on the correct power lamp for this unit? I can't find that info - all I can find in the manual is it being a "DS346." ? On Sun, Sep 25, 2022 at 10:12 PM Radu Bogdan Dicher via <vondicher=[email protected]> wrote: Well, I had no symptoms yet to?file, as until tonight I didn't get a chance to even plug it in. Visually, the only?clear issue I was seeing prior to tonight was the detached C160 (one leg was simply?mechanically loose). It was not trivial to resolder it, the short leg pretty much refused to take solder. But I ultimately won. ? I got it, I will not change this cap. Equivalents today seem to require an arm and both legs (except some surplus?places I know...). After taking care of C160, this outputs beautifully a very clean sine. The switches and pots are a bit in need of TLC, but other than that I'm very happy.? Thank you all for your input! ? On Sun, Sep 25, 2022 at 9:26 PM Froggie the Gremlin <jonpaul@...> wrote: what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted rants.
Clean controls and trimmers
Should be simple to debug
Jon
|
Hi all, Does anyone have information on the correct power lamp for this unit? I can't find that info - all I can find in the manual is it being a "DS346." Thank you, Radu.?
On Sun, Sep 25, 2022 at 10:12 PM Radu Bogdan Dicher via <vondicher= [email protected]> wrote: Well, I had no symptoms yet to?file, as until tonight I didn't get a chance to even plug it in. Visually, the only?clear issue I was seeing prior to tonight was the detached C160 (one leg was simply?mechanically loose). It was not trivial to resolder it, the short leg pretty much refused to take solder. But I ultimately won. I got it, I will not change this cap. Equivalents today seem to require an arm and both legs (except some surplus?places I know...).
After taking care of C160, this outputs beautifully a very clean sine. The switches and pots are a bit in need of TLC, but other than that I'm very happy.?
Thank you all for your input! Radu.?
On Sun, Sep 25, 2022 at 9:26 PM Froggie the Gremlin < jonpaul@...> wrote: what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted rants.
Clean controls and trimmers
Should be simple to debug
Jon
|
Well, I had no symptoms yet to?file, as until tonight I didn't get a chance to even plug it in. Visually, the only?clear issue I was seeing prior to tonight was the detached C160 (one leg was simply?mechanically loose). It was not trivial to resolder it, the short leg pretty much refused to take solder. But I ultimately won. I got it, I will not change this cap. Equivalents today seem to require an arm and both legs (except some surplus?places I know...).
After taking care of C160, this outputs beautifully a very clean sine. The switches and pots are a bit in need of TLC, but other than that I'm very happy.?
Thank you all for your input! Radu.?
On Sun, Sep 25, 2022 at 9:26 PM Froggie the Gremlin < jonpaul@...> wrote: what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted rants.
Clean controls and trimmers
Should be simple to debug
Jon
|
what is symptom?
never replace timing caps
suspect the usual range switches, possible PS shorted rants.
Clean controls and trimmers
Should be simple to debug
Jon
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It should also be noted that if it is a timing cap tek sold the timing caps as a set, ratio stability is importent here not absolute value. Should NOT be replaced unless proven beyond a doubt bad. Timing service was also not a high stress application so in this case ESR is not a critical spec.
On Sun, Sep 25, 2022, 1:04 PM benx618(g) < benx618@...> wrote: C160 is Sprague type 113D which listed as high stability, low leakage tantalex foil 85¡ãC tolerance +30/-15%. ?
Likely a timing circuit premium component.? I would reattach it, ?debug all other issues and attempt calibration before considering replacement.?
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Re: Unable to perform CAL08 in a Tek 2465B- now vertical position not working on the four Ch
I suppose the most likely way is the -15V supply provides all of the power to the HV transformer, and as such is full of ripple. The -15V is used all over the rest of the scope. To keep the ripple from confusing other parts, they have a big electrolytic cap right where the power comes onto the board. They are often bad. High grid bias will cause the CRT to be over bright, and will cause the traces that are supposed to be dark to be visible. It usually results in a haystack of connecting lines that are the beam traveling between sections that are supposed to be visible. The position of the display lines is supposed to be just inside of the outermost graticule line. It is adjusted by a pot on the A5 board... or on early models by a pot on the display board. You can make this adjustment without any risk to your calibration. -Chuck Harris On Sun, 25 Sep 2022 07:37:14 -0700 "Rogerio O" <rodd414@...> wrote: Dear Chuck,
Thank you very much for your support.
After spending hours trying to figure out why the scope had all sort
of "strange behaviors and displays", I decided to replace the HV
board. I have one spare since there are unobtainium components there.
After replacing the HV board the dots disappeared as well as the
"strange behaviors and displays".
Can you explain why a high grid bias interfere with the workings of
the A5 board?
I could conclude CAL08, normally, but the top message line is
positioned almost out of the CRT. What is causing that?
I noticed that I have to checked the high volatges after replacing
the boards; maybe that is causing the proble. I will search the
service manual for the djustments, in case there are some.
Regards,
Roger
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Re: Unable to perform CAL08 in a Tek 2465B- now vertical position not working on the four Ch
Hi folks,
Checking the SM I discovered that there is a procedure specific to adjust the gain and centering the message display which is CAL07.
I have two questions:
1 - SM stats that CAL07 should be do "in sequequence". with other calibration routines.
?How can I perform AND STORE the calibration constants when I execute just this procedure?
2 - I could not find in the SM (yet) the instructions reltive to high voltages required by the CRT.
Where is this information?
Thanks,
Roger
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Re: Repairing a TDS684A power supply
Also Jared, in your video you show some TDS544A schematics labeled VintageTek, but their web site doesn't show any way to get these. How did you get them?
Reinhard
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Re: Repairing a TDS684A power supply
Thanks Jared! So, where, how do I get one of your testers, or the PCB and parts list? Or at the least, what pins are the front panel on/off button so the supply can be turned on on the bench?
Reinhard
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C160 is Sprague type 113D which listed as high stability, low leakage tantalex foil 85¡ãC tolerance +30/-15%. ?
Likely a timing circuit premium component. ?I would reattach it, ?debug all other issues and attempt calibration before considering replacement.?
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Jared Cabot
Froggie the Gremlin