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itsthatidiotagain · 04-29-2017, 04:18 PM

Re: Metrix 803B Oscilloscope power supply issue

Very late reply, but @rbarreiros the short answer is yes. Your PSU issue sounds very similar. Follow through the thread and check/replace the parts I replaced first.
Once you have done this, if it is still not working, check the HT side of things.

itsthatidiotagain · 01-24-2016, 04:02 PM

Re: Recaping Victor VC921...

The Victor VC921 "True RMS" is not a bold unsubstantiated claim.

This variant is based on the HY12P65/HY12P66 the pinout of the little black blob matches this chip *exactly*. (The meter is not as I previously though, based on a Fortune Semiconductor FS9XXX)

This probably makes the "VC921 True RMS" the cheapest true RMS meter on the market (and also probably the lowest build quality

)

The HY12P65/66 is in fact a True RMS DMM chip. The board layout out is a similar arrangement...

itsthatidiotagain · 01-21-2016, 11:20 AM

Re: Recaping Victor VC921...

Sorry to wake up a long dead thread, but I thought it worth pointing out that the design of this multimeter has changed.

The new design uses a chip on board (aka little black blob), and more surface mount components. It appears to be based on a variant of the Fortune Semiconductor Corporation FS9XXX series multimeter chips, but exactly which one is difficult to tell as not all pins are broken out. There is a high probability that it is one of these guys... http://www.ic-fortune.com/eng/new_product3_3.asp ... exactly which...

itsthatidiotagain · 02-07-2015, 05:05 PM

Re: Metrix 803B Oscilloscope power supply issue

For the record, the tube in a large number of these Metrix scoopes is almost certainly..

D14-364GY / 123
CRT Heerlen BV
Made in the Netherlands

https://cdn.badcaps-static.com/pdfs/...0274745688.pdf

Furthermore, the tube in my OX 803B is most probably very similar (the principal difference being the Phosphor coulour).

itsthatidiotagain · 02-06-2015, 07:22 AM

Re: Metrix 803B Oscilloscope power supply issue

I'm trying to figure out what the purpose of Pin 8 is on the PSU board, my best guess is that this is some sort of crowbar protection, but I thought I'd find out if anybody else has any better ideas based on the previous images and the image below....

itsthatidiotagain · 02-01-2015, 03:51 PM

Re: Metrix 803B Oscilloscope power supply issue

Quick update on the pinout of the connectors.

Code:

Metrix 803B PSU

12 pin power connector

Although the board has no obvious markings, assume pin 1 is the one with the black stripe.

Note: DC ground is tied to main earth, and that for safe operation of the scope it must be earthed.
As with most scopes, all scope input BNC connectors therefore have the Ground side tied to mains earth.

DC Power connector (J1)

Pin 1) -12V Checked on multimeter

...

itsthatidiotagain · 01-28-2015, 04:05 PM

Re: Metrix 803B Oscilloscope power supply issue

Tracing back to the source would require me to dismantle the front panel, which I might end up doing, but for the time being I'm trying to avoid doing so....

itsthatidiotagain · 01-28-2015, 01:14 PM

Re: Metrix 803B Oscilloscope power supply issue

I had 5 minutes to spare today, to check the signals on J18 this is what I have so far.

The colours in the list below are just those of the bit of ribbon cable I used, so they have no particular significance.

Code:

 
J18 Pinout - Pin1 at PSU end (same as J19)

Pin- Colour - Signal
1 - Blue1  -  0V slight periodic ripple (Polled output perhaps???) 
2 - Purple1 -  0V slight periodic ripple (Polled output perhaps???) 
3 - Grey1  -  0V slight periodic ripple (Polled output perhaps???)

...

itsthatidiotagain · 01-27-2015, 04:55 PM

Re: Metrix 803B Oscilloscope power supply issue

What is the fault on your OX 836?...

itsthatidiotagain · 01-27-2015, 04:11 PM

Re: Metrix 803B Oscilloscope power supply issue

I also found a programming manual for the OX8040, OX8042, OX8062, OX8050 and OX8100, but I can't remember where I found the original link.

I've attached it in case it proves useful to someone in the future.

Also there is a slight screwup in the previous post's links, but I only spotted it after the 90 minute edit window had closed....

itsthatidiotagain · 01-27-2015, 02:08 PM

Re: Metrix 803B Oscilloscope power supply issue

I found a couple of other links to Metrix user manuals.

Another couple of copies of the OX 863 user manual.

https://cdn.badcaps-static.com/pdfs/...3f3f3e5329.pdf
www.ghvtrading.cz/download.php?fileid=1880

(both with the same md5sum, so both are the same manual)

.. and a photocopy of the 8620/8627 manual ..

http://www.ghvtrading.cz/download.php?fileid=1880

.. I also connected up a chunk of ribbon cable to J18...

itsthatidiotagain · 01-27-2015, 02:42 AM

Re: Metrix 803B Oscilloscope power supply issue

Thanks for the link to the manual, it seems to confirm what I suspect, namely that the Metrix scopes all use the same serial protocol, and pinouts.

What are the issues on your OX863? Also is there a daughter card mounted on J18. Can you share some pictures of the inside of the OX863.

A fairly complete set of teardown pictures of my OX803B are here.

https://plus.google.com/u/0/photos/1...81872199591361...

itsthatidiotagain · 01-25-2015, 03:50 PM

Re: Metrix 803B Oscilloscope power supply issue

Thanks. Where did you find that? It looks very promising, lots of similarities, but also this...

"(∗) The same SUB-D 25 pin output (at the back of the oscilloscope) is used
for the RS232 and CENTRONICS interfaces (use an RS232 or CENTRONICS lead
as required)."

... the internal connector on the 803B that I thought might be the serial option is a 14 way inline header, but that probably isn't enough pins for a combined centronics and rs232 port.
...

itsthatidiotagain · 01-25-2015, 02:01 PM

Re: Metrix 803B Oscilloscope power supply issue

That would not surprise me in the slightest. The Metrix onine sales brochure states that the tube is Philips, "All models are equipped with blue screen
filters and, thanks to their Philips tubes..." so the rest of the design being outsourced or based on a Philips design would not be a surprise.

I have also seen the same scopes with an ITT badge and the Metrix designation on them. This is a pretty incestuous industry it seems.

There would be a higher probability perhaps of finding...

itsthatidiotagain · 01-25-2015, 11:25 AM

Re: Metrix 803B Oscilloscope power supply issue

I quite agree, if I had purchased a bunch of these scopes for work, and later discovered there were no service manuals available, then that would be one less company on my preferred suppliers list.

As far as reverse engineering goes however, the layout of the scope is fairly obvious, digitlal stuff mainly on the front panel, mixed digital/analog on the main board. I haven't even whipped off the front panel, but from the look of the tracks on the back of the front digital board, there is one, perhaps...

itsthatidiotagain · 01-25-2015, 06:14 AM

Re: Metrix 803B Oscilloscope power supply issue

I had a good hunt round the internet for a service manual for any of this series of scopes, but found nothing. I even emailed the manufacturer, who didn't even bother to respond (I emailed a bunch of email addresses, so I presume it must be company policy to treat their users this way).

It was mainly as a result of the manufacurer's attitude that I decided sod them I'll fix it without their assistance, and then decided to publish my efforts here.

It looks like others have been in this boat...

itsthatidiotagain · 01-24-2015, 04:06 PM

Re: Metrix 803B Oscilloscope power supply issue

I had a quick prod around inside the 'scope this afternoon looking for anything that was obviously an RS232 port, and in the process discovered something which might actually be more useful than the serial port.

The OX 803B differs from the higher spec OX 863B in a number of important respects. One of which is that the 863B substitutes on screen cursors and a couple of TV line mode buttons for the "Component Tester" of the 803B

The difference looks to be exactly that, the 803B has a couple...

itsthatidiotagain · 01-23-2015, 09:03 AM

Re: Metrix 803B Oscilloscope power supply issue

Hmm... good point, it would rather depend on the failure mode of the MOSFET. In that case I suspect changing all of the compnents I listed probably is the minimum necessary for this fix.

You might get luck and not need to change the TDA4605, but equally it might be blown, and thus take out your replacement MOSFET, and given the fragility of the board, you probably dont want to have to rework the MOSFET twice.

On the subject of the serial port, the labview drivers give access to the following...

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