HP 8110A 150Mhz pulse generator PSU problem

[zboczq]

hi,
I recently acquired HP 8110A 150Mhz pulse generator. The integrated circuit responsible for PWM is damaged.
Unfortunately, there are no circuit and list of elements in the Service manual for HP 8110A .
Does anyone have an idea what this could be for an element?
Picture in the attachment.

[Chris56000]

Hi!

There is a component–level package with schematics for the 8110a, hp part no. 08110–91031 only trouble is nobody ever bought it except calibration houses and so forth and they won't part with anything on any terms, and Keysight would deny all knowledge of it's exsistence if you asked them no doubt!

That IC looks like it could be a UC384x series most likely, with the output on pin 6 which will go to the gate of the chopper MOSFET via a resistor of 100 ohms commonly, with a zener of typically 15V 500mW between gate/source of the MOSFET.

Clean all the blast and splat–marks and post good clear pictures of both sides of the PCB and then we can take a better guess at it!

Chris Williams

[zboczq]

Thanks for the ansfer. It looks like the ground is on 4th pin of the PWM driver.
5th is the output and 6 is not connected.
This PWM drives two BUZ 332.  I can not spot any zener diode and as you said there should be low ohm resistor on the output (5).  Not sure if this will be UC384x

[duak]

I went to Digikey.ca and searched for PMIC controllers in PDIP-8 packages: https://www.digikey.ca/products/en/integrated-circuits-ics/pmic-voltage-regulators-dc-dc-switching-controllers/715

Could it be https://www.onsemi.com/pub/Collateral/KA7553A-D.PDF  Gnd on 4 and output on 5?  I didn't look any further though.

I think this unit was designed in the early 90s in Germany and may have used Euro semiconductors like Siemens, Philips and SGS.  I would try searching for older parts from those companies.   I hope the part is not obsolete.

Good Luck,

[Chris56000]

Hi!

I doubt it would be an KA7553 – that's an Asian device and HP tended to limit themselves to Western designed/sourced pwm/controller devices, apart from that, Pin 6 on the KA7553 ts the Vcc pin and that certainly won't work if the PCB has no connection to it!

There's a pretty good chance that your 8 pin driver IC will be an Internional Rectifier IR2101 – you mentioned two BUZ332s, almost certainly you'll find the drain (middle leg) of one will go direct to the +H.T. line from the mains bridge rec., then the gate (left-hand lead) of the 'top' BUZ332 will lead back to pin 7 of the i.c., whilst the source (right-hand lead) of the 'top' BUZ332 goes to a series cap of about 2.2 uF  to 4.7 uF, then the first primary pin of the main power transformer, then the second pin of the primary will lead back to the drain (middle lead) of the 'bottom' BUZ332, with the gate (left-hand lead) of the bottom BUZ332 going to pin 5 of the driver IC, with the source (right–hand lead) of the 'bottom' BUZ332 back to –H.T. from the mains bridge rectifier.

Pin 4 will go to mains –H.T., whilst there'll be an 18V zener between pins 4 and 6 and 6 and 8 of fhe i.c. to provide the low–side and high–side driver–stage supplies.

If you find these connections match up as I've described them (use a DMM 'continuity beep' range to check), then an IR2101 is the correct device to use, replace this, along with both MOSFETs and the zener diodes connected between pins 4 & 6 and pins 6 & 8 of the i.c. – if the diodes are too badly damaged to read, I think 18V 1.3W should be ok – they will both be the same voltage.

Make sure the series capacitor in series with the power transformer primary isn't low in value (if you need to replace it, get an MKP pulse withstanding type!) or o/c., resolder all the transformer and inductor joints associated with all the magnetics on the PCB, replace the mains H.T. bus capacitors (there may be two), and finally check all the secondary side rectifiers for leakage – they'll either be large axial single diodes or dual diodes of the TO-220 type – on dual diodes, the cathode is the common centre leg in most cases!

The BUZ332 is not one of the most efficent MOSFETs, you should be able to find a pair with a good Vds breakdown rating equal or better than the originals, a higher Id and therefore a lower Rds(on), and a total Qg (Gate Charge rating) lower than the originals – I.R. and SGS–Thomson have both brought out excellent modern devices ideal for high–power >75W to >200W smpsu use!

Good luck, and please post back if the above hasn't identified your device, and I'll have another go!

Chris Williams

I would be able to write & draw (after a fashion!) a replacement C.L.I.P. from one of these units if I had one but the absolutely eye-watering prices U.S. sellers are asking for 'em means I can't afford one for a long time yet!

[zboczq]

My mistake. It is 3 layers PCB and there is a connection on pin 6.
But patch from pin 6 is thin whereas patch of pin 5 thick so I assume if it would be IR210 they should be symmetrical

There is a zener diode of 20V but it is connected to element which looks like transistor to-52 case package but has only two legs.

Midle legs of transistors are indeed together (both) connected to H.T+ but trough coil of the transformer.
Pin 1 - connected trough  resistor to optocoupler.

Was thinking maybe NCP1217 but pin 7 is connected to capacitor whereas in datascheet is NC.

[Chris56000]

Hi!

Thanks for clarifying – your note confirms the circuit is a flyback–converter with the BUZ332 MOSFETs connected in parallel!

Since this piece of gear appears to have been designed and built in Germany, please see if the Siemens/Infienon TDA4605 matches up with the connections you've got – this was a very commonly used flyback PWM controller in Continental gear!

You'll need to carry on tracing what components are connected to IC401 pins 1 to 4 tho!

Chris Williams

[Chris56000]

Hi!

If the original device was a TDA4605, pin 2 (primary current sim) and pin 3 (collector volts simulation), will both be returned back to the +H.T. line from the bus–capacitors by a high–value resistor on each pin, pin 2 having a resistor of typically 270–330k and a capacitor of about 4700pF (typically) down to –H.T., and pin 3 a resistor of typically about 820k up to +H.T. and one of much lower value to –H.T.

The usual cause of catastrophic failure of this type of circuit is the high–value simulation feed resistors from the +H.T. line going very high in value or completely open–circuit.

I would check if your board has resistors like this on pins 2 & 3 of IC401, if it does this further confirms this device was a TDA4605!

I would strongly advise replacing the opto–coupler with a new one as the LED in these can go low–emission, and in any case, I wouldn't trust it after you've had a blow–out!

The TDA4605 was manufactured in four versions, TDA4605 and TDA4605–1, TDA4605–2 & TDA4605–3 and unfortunately it's years since I last did TVs and had reference to maker's manuals & service–notes!!!

However, if my memory serves me correctly, I think the TDA4605 & TDA4605–1 were intended for bipolar drive and the TDA4605–2 and TDA4605–3 for MOSFET drive, so I would suggest you get a –2 or a –3 for replacement, unless there's enough remaining of the top of the damaged device to see what it might have been!

Chris Williams

PS!

I've just had a look at your picture in your first post and I can just make out "–2" in the top right–hand corner of the damaged device, which seems to confirm it's a TDA4605–2! Please don't forget to check, and replace if necessary, the resistors on pins 2 & 3 and the opto before you fit a new '4605–2 and MOSFETs to your board!

PPS!

The two–legged item RT403 in a metal can you found connected on pin 6 would most likely be a p.t.c. thermistor whose purpose is to reduce the current flowing from the +H.T line to a very small value once the PSU has started and the main primary running supply from the power transformer is available – thsrs's a type no. on it but it's a bit smudgy, but as ling as you get a low–to–mediun value resistance value when you measure it cold, it will be fine!

[zboczq]

Thanks, it sounds very sensible and fills me with optimism.
The only thing which confuses me is that pin 2 is only connected trough capacitor to the ground - no pull up resistors. Maybe responsible for soft start not primary current simulation just guessing.

OK, my mistake, there is a trace of second track to resistor somewhere from pin 2 - just evaporate a little

Will let know when receive parts

[zboczq]

Hi again, I have replaced most of the broken elements (diodes, LED, transistors and transoptors).
There are resistors to set proper voltages on pin 3 as in application note of TDA 4605-3.
On pin 2 there is capacitor but I'm not able to trace which resistor is responsible for this pin. The track inside PCB burn out :/
Do you think I can replace it with simple resistor connected to H.T+ and pin 2? or it's more sophisticated?

[Chris56000]

Hi!

If you are unable to trace the original tracking and components, you can use the suggested values given in the datasheet for the TDA4605–2 – I would refer to the data for the "–2" version as that what your damaged device appeared to be in the first picture you posted!

Have you double–checked with a continuity–beep range of your meter to make sure these resistors on pins 2 & 3 of IC401 aren't simply some way off?

I would look for any resistors with an "orange" third (multiplier) band, as an orange band is ≥ 100k in four–band (±1%) resistors and see if any you find trace back to IC401!

Chris Williams

[CodingMarco]

Hi,

if anyone stumbles across this thread in the future:
The original CLIP has finally been discovered, even with schematics as vector graphics!
please see here: https://groups.io/g/ManualExchange/topic/wanted_hewlett_packard_8110a/85369752
It's also available on KO4BB: http://www.ko4bb.com/getsimple/index.php?id=download&file=HP_Agilent_Keysight/HP_8110A_Pulse_Pattern_Generator/HP_8110A_Pulse_Pattern_Generator_CLIP_08110-9131.pdf

Regards,
Marco

[picburner]

Sorry if I reopen this old topic but my request is inherent to HP 8110A.
Does anyone happen to have the program and firmware to update this instrument?
I have two, one with firmware v.02.02.00 and the other with v.01.05.00.
I would like to at least update the latest one without having to desolder 12 Flash 28F010 of both instruments!