EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: EyeDontKnow on November 20, 2024, 09:49:19 pm
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This mystery chip is for "option 04" on my
Anritsu MG3631a signal. gen.
If this schematic below is all that is required, I might have a go at building this optional "audio frequency card".
The service manual only lists the IC as "UG-1".
I'm not a digital guy, but is this an ADC from the 1980's ?
It looks like its only purpose is to digitize the quartz crystal frequency......and most of the pins are unused (grounded).
Thanks for looking.
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Looks like some wires for SPI input, a lot of GND and power connections and just a single signal out (Pin 26, nr 1 on the connector)
From the schematic, it looks more like a DDS chip then an DAC, but it's a guess of course.
This mystery chip is for "option 04"
So, what does that option 4 enable on your gadget?
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This mystery chip is for "option 04"
So, what does that option 4 enable on your gadget?
With no options, this sig gen range is 100 khz up to 1040 khz.
Option 04 extends the lower range, down to 20 hz.
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If this schematic below is all that is required, I might have a go at building this optional "audio frequency card".
The service manual only lists the IC as "UG-1".
Reverse engineering this depends if the host expects much to come back via SOUT ?
You could connect a logic analyser to the serial in to see what message length and data it tries to send, and if that looks complete, or aborts due to no-reply-seen.
Oh wait, unless that SOUT is the signal out, as tagged in another place.
If there is no serial reply expected, reverse engineering has a higher chance of success.
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With no options, this sig gen range is 100 khz up to 1040 khz.
Option 04 extends the lower range, down to 20 hz.
What step size and ranges does that give ? Is it sine only ?
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Are you sure it's an IC, and not a module with stuff on it? eBay shows many pictures of parts with similar part numbers, they're widely varied modules.
DIPs went from 48 pin (rare) to 64 pin (common, ie 68000 CPU). Never seen a 50 pin DIP.
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could be an hybrid .... or some pcb ...
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Agree with Coromonadalix.
Back in the 1980s it was still common to find hybrid circuits for functional blocks for which ICs still didn’t exist, and making them out of discrete components would not give the required performance.
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I will apologize, this unit is year 2008 vintage, not 1980's.
:palm: ;)
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It may still be a hybrid. As I have mentioned, you can achieve very high performance for the simple reasons that you can incorporate components that are impossible to integrate within an IC, think film caps, and simultaneously enjoy tight thermal coupling and improved characteristics like reduced parasitics as compared to discrete components. Since the substrate is also rigid, low or no mechanical stresses are applied to the components.
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DIPs went from 48 pin (rare) to 64 pin (common, ie 68000 CPU). Never seen a 50 pin DIP.
https://en.wikipedia.org/wiki/Signetics_8X300
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Just great. Another thing to look for on ebay. Kallax shelf space reserved.
...and ordered. :palm:
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This Signetics 8X300 microprocessor is precisely a hybrid. The regulator is very likely a different semiconductor technology than the processor itself. And there is a ceramic decoupling capacitor.
[attachimg=1]
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Strange, the pinout and the photos disagree on pin count
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This guy has 50 pins.
https://www.ebay.ca/itm/392844736661 (https://www.ebay.ca/itm/392844736661)
It better, I just made some room for it. My astute observation indicates it's probably 700 mils across, or about 18mm, so wider than the 48 pin DIPs in my junk.
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If only I could find a product search engine that could limit the criteria to something like "pin count", and list all the results.
I have tried various Google search methods (using quotation marks) "50pin" "50 pin" "integrated" "ic" "chip" "processor" ... and more.
But anything that comes up, the pin callouts do not match.
Yes, there are a couple of processors but nothing matches the schematic.
I have not been able to find a photo of the option board either.
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I have not been able to find a photo of the option board either.
Can you give a photo of the unit it plugs into ?
Is this unit required to be installed to select the new frequencies ?
What happens if you wire to the connector, with GNDs as shown in the SCH in #1 ? That may be enough to signal 'installed' ?
Or, is there a factory jumper somewhere that also is needed ? (or a ROM upgrade ? )
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I found this info looks to be 100ppm, 0.1Hz LSB and 20Hz ~ 100kHz
100kHz is nothing special, but the 0.1Hz suggests it needs to be DDS based.
That means you will need a small MCU to decode the serial stream, and act as a bridge to some small DDS part.
Looks to be a 24b DDS adder clocked at 1.6777216MHz to give the 0.1Hz step size.
I will apologize, this unit is year 2008 vintage, not 1980's. :palm: ;)
If this dates from 2008, maybe they used a Analog Devices DDS, as AD were making a few DDS ~ 2006 and earlier. (AD9833 dates from ~2003)
If you can fool the unit into thinking it has a card fitted, you can see what the data stream looks like.
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MG3633A A5 board has UG-1 ceramic module.
perhaps this.
5x 74 logic
1x 28256 EPROM
1x ssop-8 unknown chips
1x plcc-68 uC. package looks simillar CHIPS P82A205.
https://www.ebay.com/itm/285674167525 (https://www.ebay.com/itm/285674167525)
[attachimg=1]
[attachimg=2]
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Like others wrote, most likely a DDS, that based on the schematic can either be controlled with a serial interface or a parallel interface. (8 bits data and 3 bits address)
I tried to find the service manual, but the link found (http://chrisgrossman.com/manuals/aniritsu/md3631A_mg3632a/Aniritsu_MG3631A-MG3632A-Service_Manual.pdf (http://chrisgrossman.com/manuals/aniritsu/md3631A_mg3632a/Aniritsu_MG3631A-MG3632A-Service_Manual.pdf)) does not load, and another is behind a paywall.
What it could tell a bit more is where the connections of the 10 pins interface lead to. It might be possible to reverse engineer the communication and put together your own module with a more modern MCU. The frequency range is low so should not be that difficult.
The question is what the STB signal does. SDAT will be the data line, SCLK the clock. Maybe it is used as a byte clock?
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MG3633A A5 board has UG-1 ceramic module.
perhaps this.
5x 74 logic
1x 28256 EPROM
1x ssop-8 unknown chips
1x plcc-68 uC. package looks similar CHIPS P82A205.
That looks to be some PC/AT motherboard chip ?
I see the ADSP2105 came in PLCC68 and dates from 1996, and loaded from external EPROM. so maybe that's what was used here ?
They likely used it elsewhere, doing a 24 bit looping add & table output would hardly break sweat.
Could it do that in 5 clock cycles ?
2105 had a max clock of 13.824 MHz, so the 8.388608MHz chosen here for 0.1Hz is in the right ballpark ?
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The pictured hybrid looks to be the right thing, even has the trimmers shown in OPs schematic. SCL, SDA, STB, is definitely some kind of SPI with the strobe (stb) indicating bytes or words.
It seems unlikely that you can build a copy given that the hybrid shown has at least one Anritsu branded part. But an SPI controlled AF synthesizer isprobably not too difficult to build if you manage to reverse engineer the SPI protocol. For this you'll need to trick the unit into thinking this option is fitted, monitor the data lines while trying to access the option and go from there.
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MG3633A A5 board has UG-1 ceramic module.
perhaps this.
I wonder if that is the exact part ? It comes from a model close in age, and is marked with the exact name ( UG-1).
But what's hiding in the eprom ?
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But what's hiding in the eprom ?
If the PLCC68 part is a relabeled ADSP2105, that would be the loader EPROM, for the DSP code that runs some DDS loop.
Less clear is what they do for a DAC ?
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If the PLCC68 part is a relabeled ADSP2105
No, I mentioned,
1x plcc-68 uC. package looks simillar CHIPS P82A205.
look at the picture of the P82A205, package shape is very similar. The pin markings and the location of the air vent holes in the molding.(and date and lot number markings)
P82A205 package is marked MB113T313.
Made in Japan and starting with "MB" are FUJITSU ICs.
search "FUJITSU PLCC-68", can find CG24512.
CG24512, package shape is very similar.
I think it is probably a FUJITSU gate array.
[attachimg=1][attachimg=2]
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MG3633A A5 board has UG-1 ceramic module.
perhaps this.
5x 74 logic
1x 28256 EPROM
1x ssop-8 unknown chips
1x plcc-68 uC. package looks simillar CHIPS P82A205.
https://www.ebay.com/itm/285674167525 (https://www.ebay.com/itm/285674167525)
(Attachment Link)
(Attachment Link)
well i do think it is your module on a different carrier ... since it's for the MG3633 ....
even buying this board and do some transplant on another carrier board, if this board is indeed the one you need, and this hybrid could be fragile to manipulate
it may not work if the eeprom / flash content is not the same
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the ebay seller dropped the price when i tagged it, sent me a close up of the pcb
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[attachimg=1]
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Does that gate array you are thinking of, have internal configuration memory or is it fuse based programmable logic?
Most FPGA's from the olden days needed external memory to hold the configuration data.
There are microprocessors in PLCC68 carriers too. Like for instance the SAB80515, or the already mentioned ADSP2105.
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There are microprocessors in PLCC68 carriers too. Like for instance the SAB80515, or the already mentioned ADSP2105.
I dug into the ADSP2105 some more and the XTAL pins do not match - different corner and adjacent on the ADi part, and no Rfb needed.
I'd expect the ADi part to need fewer external parts too.
They look to latch the EPROM with the HC174 to get 8 sync data lines, but the 2 x HC86 are a strange way to then get a DAC ?
EPROM looks to have all upper address lines connected so presume the lower ones are too on PCB rear.
The not labelled 7 pin part is ?? Too few pins for a full R2R DAC, plus a bit narrow, tho it does have some thick film resistors around it.
The OP seems to have a couple of choices :
a) Check the physical size and buy this module with fingers crossed
b) use a scope/logic analyser to see if they can fool their host into talking to a 'connected UG-1'
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It dropped on me later that the bigger chip is an EPROM (OTP in this case). Did not look to good at the marking and thought it to be RAM, but the coin dropped that it was marked 27C256 and that indicated ROM. :palm:
So it could also hold configuration data for an FPGA.
Also wondering about the bottom side of the ceramic carrier. You can see on the top side that there are also bridging traces, making it kind of a multi layer?
Looking at the EPROM one would assume that there have to be traces on the bottom too.
The external logic would probably also not be needed when programmable logic with enough gates was used.
The DAC remains the question indeed.
Edit: the unnamed IC could also be just TTL logic. One can barely make it out, but it looks like 74HC1xxx.
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guessing from the fujitsu databook on Bitsavers.org.
At first I thought it might be a uC, but none of the fujitsu uC's seem to use PLCC-68.
since Fujitsu seems to have manufactured gate arrays as well, I think it is gate arrays.
it is an ASIC, not a "Programmable" such as FPGA or CPLD.
I believe ROM is used as a kind of logic device.
The unknown upper left IC is a TOSHIBA 74 logic. The shape is exactly the IC made by TOSHIBA.
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Does that gate array you are thinking of, have internal configuration memory or is it fuse based programmable logic?
It's common for 1980s-1990s Japanese products to have mask programmed gate arrays, not FPGAs.
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Based on the extra external TTL logic I'm not so sure that it will be an ASIC or mask programmed gate array.
Take for instance the two 74HC174 ic's. They could be used to make part of the address bus for accessing the EPROM. Just like how it is done in 8051 based microcontrollers like the SAB80535.
But without pictures of the backside of the ceramic carrier it is basically impossible to be sure about any of it.
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Based on the extra external TTL logic I'm not so sure that it will be an ASIC or mask programmed gate array.
It may not have been large enough (pin or IO limited) to swallow the extra logic.
Take for instance the two 74HC174 ic's. They could be used to make part of the address bus for accessing the EPROM. Just like how it is done in 8051 based microcontrollers like the SAB80535.
They look to be connected to the EPROM BUS tho - and it is unclear if the PROM BUS even goes elsewhere ?
It may be the sine table for a DDS adder
Likely they chose 2 x HC174 over a HC374 for routing/area reasons.
A 27C256 seems somewhat large for a Sine PROM, (especially for a modest DAC) but maybe they standardized on that memory.
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the writhing on the last chip seem to be like 74hc74 i dont see clearly if it's 2 digit or 3 digit, but seems 2 ???
in the end say buying this board and do some creativity
The big Q is : would it still work in the mg3631 ??
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Based on the extra external TTL logic I'm not so sure that it will be an ASIC or mask programmed gate array.
It may not have been large enough (pin or IO limited) to swallow the extra logic.
I don't know. Feels like bad design if there was no room left for so little extra logic.
in the end say buying this board and do some creativity
The big Q is : would it still work in the mg3631 ??
For me it would be an expensive gamble for an old device and the frequency range gained. For 200 bucks you can , most likely, get a good generator with more options.