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Hello, I had a similar crackling and hissing problem with my 7904 years ago. It turned out to be the voltage multiplier U1615, internal arcing. The only visible indication of something being wrong was

Thanks for the reply Jon, The nick on the HV cable is about half way along from the dog hole to the connector, visible on the third image. If I don't need to mess with the transformer I won't, it's

Merci Jean-Paul Probing the TGA signal from pin 18 of U500, the triggering waveform there is as I see it on the screen i.e. intermittent. So it looks like U500 or circuitry before it in the trigger

Thanks for your suggestion, today I received a secondhand 80e02 in good condition for an acceptable price ?

Keith bravo for your work on NV Ram, beware of Chinese knock-off and old date code parts. Use machine pin socket Full cal is needed after RAM replacement See service manual and proper test

Hello again Last two photos show Carbon and dirt accumulation on HV box , cables and Kapton film insulation Needs through cleaning with 99% isopropyl alcohol. Where is the HV cable nick, photo

Hello Keith, I also have trigger problems with my 2465B. The SRAM Dallas has already been replaced and refilled because of the old Li battery. Because the Scope also had (and still has) the error

Hi all, I had some time so dug into the PSU a bit, swapped ot the last tantalum in there, and upgraded the aluminium 'lytics as per revisions list in the manual. The big storage caps I ran up to 195V

So I desoldered the DS1225 nvram carefully and fitted a 28 pin DIL socket. Took the nvram and just to see if there was still any life in it I programmed it using a TL866ii programmer, using a .bin

Very useful. Let me have a rummage and see if I can find any of the 3 units mentioned. I agree the LM1881 ads nothing here, indeed already tried it -- Christopher Hilton-Johnson The Stone

The original posting refers to the signal as RGBHV. All five components are already separated. As much as I like the LM1881, there is no need for it (i.e. sync separator) in this application. To

Evan, Thanks. I have never seen a 7704 so I don't know if a 7704 cover would fit on a 78xx or 79xx 'scope. I imagine that the only characteristics that matter would be the outside dimensions of the

Hi Dave, The 79xx scopes have different geometry on the front panel. The display is lower down (smart), the power switch is in a slightly less obvious place, I think the controls might be taller,

I guess I should have said proto-bord or air circuit.

John Williams <books4you4@...> added the photo album LM1881 built into type L plugin ( /g/TekScopes/album?id=300050 ) : Small addition to type L for NTSC sync seperation

Here is the data sheet for the LM1881. https://www.ti.com/lit/ds/symlink/lm1881.pdf?ts=1736763609625&ref_url=https%253A%252F%252Fwww.google.com%252F I will post a photo of how I built this.

It me again..I just took with a scope on the suppose 32 volts unreg.. it show 56 volts with praticaly NO ripple... What do they mean when they indicate 32 volts unreg... Do they mean really 32

Ah sorry Victor, when I wrote that I had not noticed the SM caps on A5. They do look OK - no leakage - and measure OK in circuit as far as I can tell. But they probably should be replaced. Keith

Look at the data sheet for the LM1881. With only a little care you can use it on a bread-board.

Thanks Jon, I have a DS1225 on order from Mouser. When you say 'use EEPROM programming to load default CAL' what do you mean - is there some default binary for the NVRAM? As regards the triggering