Repair: Hantarex MTC 9000 — detailed troubleshooting¶
The MTC 9000 is the most widespread Hantarex chassis in European cabinets. This page works at component level — references, values, test points and symptoms — where the general Hantarex page covers the range and the method. The MTC 9110 is the same chassis and almost everything below applies to it.
Where this page comes from
A rewritten synthesis of the troubleshooting guide by Thierry 04 (December 2006), a document he built from information found on the web and expanded with his own experience. The original PDF is archived here: MTC 9000 — Dépannage (Thierry 04, 12/2006) (French). Every component reference below comes from that document; none is inferred.
Safety — read before opening¶
Lethal voltages, including with the set switched off
The chassis produces up to 28,000 V. On top of that there is mains voltage in the degaussing circuit and 130 V DC on the chassis.
- Work with one hand only, the other well away: that is what stops a circuit closing through your chest and your heart.
- On the bench, use an isolation transformer and a supply protected by a low-rated RCD.
- If in doubt, don't touch it.
Identifying your chassis¶
The descriptions below tell the Hantarex chassis apart by eye, oldest to newest. Worth doing before ordering a part or following a procedure: several of these look alike and do not get repaired the same way.
| Chassis | How to recognise it |
|---|---|
| MTC 90 | Split into two halves with a large empty gap between them. Four plug-in cards on the flyback side, three on the other. Very old. |
| MTC 900 | Two main boards — one is half the size of the other — plus a small vertically mounted power supply board. Sometimes an East-West correction board (pincushion) on the side opposite the supply. Brightness/contrast pots and the degauss pushbutton sit on a removable plastic bracket on long leads. Deflection yoke socket on the right-hand side. |
| MTC 900E | Two main boards of the same size. Left: power supply, video and power connections, triple contrast pot. Right: scan circuits, yoke connector, vertical IC2 (TDA 2593). |
| MTC 9000 | The chassis this page is about. 14″, 16″, 20″ and 25″ tubes. Seen from behind, a slide switch on the left. In the centre, a small vertically plugged PCB carrying the adjustment pots. A sheet-metal heatsink wraps the flyback and carries TR15 (BU508), IC1 (TDA1670A) and TR17 (BDX53A) on the left, with a large ceramic resistor on the right. |
| MTC 9110 | Same as the MTC 9000 plus a fan above the flyback and a thermal cutout that kills the supply on overheat. Added for the extra power the 25″ tubes need. |
| POLO | A mains-independent chassis: 180–264 V / 50 Hz for the Europe model, 80–130 V / 60 Hz for the USA model. Works with any tube from 10″ to 33″. From behind, recognisable by the sheet-metal cover over the switch-mode supply on the left. |
MTC 900: the two-connector trap
On the MTC 900 the video input socket is identical to the mains input. Swapping them is instant failure. Identify both before plugging anything back in.
Two versions of the MTC 900 / 900E¶
Look at IC3, mounted on a heatsink (vertical circuit), immediately behind the six adjustment pots on the main board:
| IC3 | Heatsink | Version |
|---|---|---|
| TDA 1470 — pins on both sides | U-shaped | version 1 |
| TDA 2653A — all pins on one side | L-shaped | version 2 |
The manuals only reflect this difference in the schematic, not in the cover photos.
Interchangeability and tube¶
The MTC 9000 is mechanically and electrically interchangeable with the MTC 900 and MTC 900E: same input signals, same supply voltages, same deflection connections, same mounting points. Only the tube socket (the plug on the end of the neck) differs.
No purity or convergence rings — and that is deliberate
Later MTC 9000 versions use an RCA tube, which you can spot by looking at the neck. The purity and convergence rings normally found just behind the deflection yoke were replaced by a non-adjustable ferrite sleeve, selectively magnetised by computer at the factory so the three beams line up. After adjustment, glue is injected between the yoke and the tube.
In practice: the yoke can no longer be removed — it is part of the tube — and there is nothing to adjust. That is what gives this chassis its very fine colour, and what removes any risk of it drifting out. Don't go looking for rings that aren't there.
Degaussing¶
If the screen is magnetised the colours are no longer pure — blue areas turn red, for instance. At power-on, a rapidly decaying AC voltage is applied to a large coil around the tube, which degausses it.
On the MTC 9000, degaussing is usually automatic: it acts at power-on and needs the monitor to have been left off for about a quarter of an hour to work.
To switch to manual: wire in a pushbutton and cut a strap on the PCB. To go back to automatic, re-wire the strap — the pushbutton can stay, it will simply do nothing.
Removing the HV anode cap safely¶
The tube holds a residual voltage even after weeks unplugged. The HV output has to be shorted to ground.
- Monitor off. Take a long, well-insulated screwdriver and a lead with a crocodile clip at each end.
- Clip one end to the ground braid around the tube, the other to the metal shaft of the screwdriver.
- Using one hand only, slide the tip of the screwdriver under the anode cap. The tube discharges with a healthy spark to ground.
- Hold the screwdriver there for a few seconds, then keep it in place while you unplug the cap.
- Repeat the procedure when refitting it: the tube can "recover" some charge after a while, even disconnected.
Setting the flyback "Screen" (G2)¶
Quick and reliable method:
- Disconnect the video input.
- Turn brightness to minimum.
- Look closely at the screen — a mirror helps if you can't see it — and turn the screen control clockwise until the grey raster appears.
- Back off slightly until it disappears: the screen should be black. Screen voltage is now correct.
- Reconnect the video and use the normal brightness control to get a normally bright picture.
- Then adjust focus for a perfectly sharp picture.
Troubleshooting, in order¶
Start by looking
You can spend hours on a strange fault with the cause right under your nose. Little test gear is needed — common sense, patience and observation. First check that every plug is connected in the right place, then that the black earth wire from the board on the back of the tube to the ground braid around the tube is properly in place.
The schematic is on the web in several places; the author kept a copy on his own site
(the.nerv.free.fr, offline today).
1. Dry joints¶
Check all of them, with a magnifier if needed. In particular cracked joints at the flyback mounting points, and more generally on anything under significant mechanical stress: heavy parts, parts that run hot, connectors.
Any doubtful joint should be redone. You won't regret the time.
2. Flyback transformer¶
After checking every fuse, listen at power-on: you should hear the usual "rustling paper" noise.
If you don't, check whether the large ceramic resistor on the side gets boiling hot.
Why that resistor heats — and why it is a clue
R105 (330 Ω, 30 W) sits in parallel with the voltage regulator transistor. When the short-circuit protection acts and blocks the regulator, the unregulated current goes straight to ground through R105. A 30 W resistor then dissipates close to 60 W — hence the overheating and then the burning. In normal operation it should be warm, no more.
No start-up and a boiling 330 Ω resistor: the flyback and/or the BU508 output transistor are very likely shorted.
- Unplugged from the mains, use an ohmmeter to check for continuity between pins 1, 3, 9 of the flyback and pin 5.
- Abnormal swelling or cracks in the plastic body of the flyback confirm it.
The fuse does not blow — and that misleads
Hantarex does not make its own flybacks, and the ones used on this series are poor quality. When replacing the flyback, also check R81 (4.7 Ω 9 W), which may have failed too.
A disconcerting side effect of the protection system: on any other TV or monitor this kind of fault would destroy the fuse immediately. On the MTC 9000 it trips the protection, but the fuse does not blow. An intact fuse therefore clears nothing here.
3. Check the 130 V¶
The best measuring point is the centre strap of the connector going to the deflection yoke (the conical coil on the tube): meter's red lead on the black-coloured strap, black lead on the metal chassis ground. Test point TP10 works too.
You should read 130 V DC, varying by no more than a few volts. If it is clearly off:
| # | What you see | Cause to check |
|---|---|---|
| A | You read 60 to 70 V | C34 (22 µF 160 V) or C53 (470 µF) |
| B | No 130 V | TR20, the TIPL762 (or BU508) regulator transistor mounted on the chassis under the 330 Ω resistor, open. It has to be removed to test — ⚠️ don't lose the insulator underneath |
| C | No 130 V | R110 (33 kΩ, top right). Desolder one end and measure. Replace with ½ W or more, not the original ¼ W |
| D | Voltage too high and the picture wavers | TR20 shorted. Other possibility: C53 faulty — you should read 170 to 180 V across it |
| E | 130 V present but no HV | X-ray protection tripped — see below |
E. The X-ray protection, and how to test it without removing it
A reference voltage generated by the HV circuit arrives, through a resistive divider, at pin 8 of IC2 (TDA 2595). It is compared against a precise reference: if the HV exceeds 28 kV, the voltage on pin 8 trips a circuit that stops the line oscillator and shuts the monitor down. The symptom is unmistakable — the monitor starts and stops a moment later.
To confirm: temporarily disable the protection by desoldering one end of D10, then power up. If you now get a picture, the protection was indeed acting — and the problem most likely lies in the voltage regulator circuit.
⚠️ Never leave a monitor running without its protection circuit. Check C36, C37, C40 and C41, then put D10 back.
4. Vertical amplifier¶
A white horizontal line across the middle of the screen points to IC1 (TDA 1670A). Equivalents: TDA 1670, TDA 1675.
- If it burns out, R94 (3.9 Ω) may be destroyed as well. When replacing that resistor, keep it away from the PCB — leave the legs long: it runs hot and can burn the board.
- IC1 is supplied with 26 V DC on pin 2 via D5 (1N4004) — test point TP13.
- Also check that the pot board is fully seated.
- No vertical sync: check slide switch SW4, or replace C18 (10 µF 25 V).
5. Horizontal output stage¶
TR15 (BU508A) is the hardest-working transistor in the whole monitor: it supplies all the current feeding the horizontal deflection yoke and the flyback. Shorted, you get nothing on screen.
- Test it out of circuit (desoldered) — neither open nor shorted.
- ⚠️ Don't lose the insulator between the transistor tab and the metal support.
- Horizontal hold stops working after 5 to 10 minutes: check C38 (1 µF 63 V), D5 (1N4004) and D4 (1N4148).
- Intermittent fault: check C9 (100 µF 35 V).
6. Symptom table — other components¶
| Symptom | What to check |
|---|---|
| Supply fuse blows the moment you power up | Diodes D19 to D22. Any 400 V 1.5 A diode will do (BYV96C, 1N4007) |
| Brightness varies while the 130 V is correct | R90 (270 kΩ) open |
| White retrace lines across the picture, 130 V correct | TR18 (BC639) and the parts around it |
| All-white screen | Voltage on C205: should be 190 V DC. If not, R126 (47 Ω) and D15 (BYD 33G) |
| Picture width too small and variable | C42 |
| Picture too wide | C42 (4.7 µF 50 V — NON-POLARISED) or the flyback |
| Brightness artefact at the picture edges | C57 (1000 µF 35 V) |
| Whistling | C34 (22 µF 160 V) |
| Ripple across the whole picture | C34 as well |
| R62 glowing red | Linearity coil open |
| Audible clicking at any supply voltage up to 128 V | Flyback |
| General drift of the adjustments | RV7 (220 kΩ pot) — its value drops sharply with age |
C42 is non-polarised
4.7 µF 50 V non-polarised. Fitting a polarised electrolytic out of habit is a mistake you pay for later.
Component summary¶
| Ref | Value / type | Role, observed behaviour |
|---|---|---|
| IC1 | TDA 1670A (eq. TDA 1670, TDA 1675) | Vertical amp — white horizontal line if it fails |
| IC2 | TDA 2595 | Line oscillator + X-ray protection (pin 8) |
| TR15 | BU508A | Horizontal output, hardest-working part |
| TR17 | BDX53A | On the flyback heatsink |
| TR18 | BC639 | White retrace lines |
| TR20 | TIPL762 (or BU508) | Voltage regulator, under the 330 Ω resistor |
| R81 | 4.7 Ω 9 W | Check alongside the flyback |
| R90 | 270 kΩ | Varying brightness if open |
| R94 | 3.9 Ω | Destroyed with IC1 — keep it off the board |
| R105 | 330 Ω 30 W | In parallel with the regulator — boiling = protection active |
| R110 | 33 kΩ | Replace with ½ W minimum |
| R126 | 47 Ω | All-white screen |
| R62 | — | Glowing red = linearity coil open |
| RV7 | 220 kΩ pot | Value collapses with age |
| C9 | 100 µF 35 V | Intermittent horizontal sync |
| C18 | 10 µF 25 V | No vertical sync |
| C34 | 22 µF 160 V | 60–70 V instead of 130 V, whistling, ripple |
| C38 | 1 µF 63 V | Horizontal hold failing after 5–10 min |
| C42 | 4.7 µF 50 V non-polarised | Picture width |
| C53 | 470 µF | Low 130 V; 170–180 V expected across it |
| C57 | 1000 µF 35 V | Brightness at the edges |
| C36, C37, C40, C41 | — | Check if the X-ray protection trips |
| C205 | — | 190 V DC expected; white screen otherwise |
| D4 | 1N4148 | Horizontal sync |
| D5 | 1N4004 | 26 V supply to IC1 (TP13) |
| D10 | — | X-ray protection — desolder only to test |
| D15 | BYD 33G | All-white screen |
| D19–D22 | 400 V 1.5 A (BYV96C, 1N4007) | Fuse blowing immediately |
| ZD1 | 12 V zener | Shorted, it kills the 12 V feed to the TDA 2595 |
| SW4 | Slide switch | Vertical sync |
| TP10 | Test point | 130 V measurement |
| TP13 | Test point | 26 V supply to IC1 |
Procedure — working through a chassis ✅¶
Discharge the anode before anything else
The tube holds its charge with the cabinet unplugged, and so does the main filter capacitor. Discharge it, keep one hand in your pocket, and do not work on it alone. → CRT safety
Hot chassis: the ground is not earth
Some arcade chassis are referenced to the mains. On those, chassis ground is not earth, and an earthed oscilloscope clipped to it makes a dead short through your probe. Work through an isolation transformer. → CRT safety
1. Cold, before switching on. Cracked solder joints are the fault on these chassis — around the connectors, the flyback and anything heavy enough to work its own joints loose. Also swollen capacitors, cooked resistors, the brown halo of something that has been running hot. Reflow what looks suspect before diagnosing: a good share of intermittent chassis faults end there.
2. Fuse and primary side. A fuse that goes again is a short downstream, not a fuse problem — find it before fitting another.
3. Is there EHT at all? The tick of the flyback at switch-on, the filament glowing in the neck. No EHT points at the supply or the line stage. EHT but no picture points at video or the G2 — two very different jobs, and this is the measurement that separates them.
4. Recap — before any adjustment. This page does not carry a single list: take the one for your exact chassis. On a chassis of this age recap is not optional: the electrolytics are thirty years old and have been running hot since day one. → Recap
5. Adjustments, and only now. ⚠️ Never before the recap. Setting the geometry of a chassis whose capacitors are dying records the drift and makes you do the whole job twice. Write down where every pot was before you touch it. → CRT safety
6. Scan rate. This page covers several chassis with different capabilities — take the line for yours from its table. A board whose rate the chassis does not accept shows nothing, and nothing is faulty.
7. Verification. Let it run warm for a good while and check the geometry stops moving. A chassis that is right cold and wrong after twenty minutes is still a thermal fault — usually a joint, sometimes a capacitor you left in.
See also¶
Sources & attribution¶
- Thierry 04 — Le dépannage des moniteurs Hantarex MTC9000, 12/2006 — a freely circulated personal document, built from information found on the web plus his own experience. The author said he could be reached on the flippers-jukeboxes.net forums. Archived PDF: hantarex-mtc9000-depannage-thierry04-2006.pdf
- Hantarex — MTC 9000 service manual / schematic — still to reference (the author kept a copy on
the.nerv.free.fr, now offline)
Review & corrections
How this space is used
Spotted a wrong value, an outdated procedure, a chip reference that does not match your board? Say so here, with what you observed (model, board revision, serial number, measurement). Every report is cross-checked against a source before anything changes — an unverifiable correction is published as “reported by …, not cross-checked” rather than silently applied.
Reading is open to everyone; posting requires signing in with Discord. Reports from the wiki's declared reviewers are handled first; anyone else's are read too, but go through a human before anything is changed.